Preservation of immune response during chemotherapy regimens

Abstract

To provide a method for treating a host with a cancer or tumor that increases the preservation of the host's innate immune system during and / or after chemotherapy.SOLUTION: The addition of a selective, fast-acting, short half-life CDK 4 / 6 inhibitor in a very specific dosage regimen to the combination of chemotherapy with a checkpoint inhibitor provides superior results in the treatment of a tumor or cancer. The short pulsatile specifically-timed administration of a selective, fast-acting, short half-life CDK 4 / 6 inhibitor during administration of the chemotherapy portion of the triple combination therapy has a profound effect on the immune cells in the cancer microenvironment.SELECTED DRAWING: Figure 1

Description

Background of the Invention

[0001] STATEMENT OF RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 62 / 430,302, filed December 5, 2016, and U.S. Provisional Application No. 62 / 479,605, filed March 31, 2017, the entire contents of which are incorporated herein by reference for all purposes.

[0002] Technical Field The present invention is in the field of improving anti-cancer and anti-tumor treatment regimens that alter the tumor microenvironment to promote a pro-inflammatory microenvironment.

[0003] background Cancer immunotherapy uses the host's innate immune system to fight cancer or tumors by stimulating the immune system to work more actively and intelligently. A key part of the immune system is its ability to distinguish normal cells from foreign cells. To do this, the immune system uses "checkpoints," molecules on specific cells that must be activated (or inactivated) to mount a response. Cancers and tumors can find ways to use these checkpoints to evade attack by the immune system. Examples of "off switches" are the proteins PD-1, PDL-1, and CTLA-4. Recent advances in cancer treatment include administering antibodies against these checkpoint "off switches" to inactivate them and allow the host's immune system to increase its capabilities against diseased cells.

[0004] Several immune checkpoint inhibitors have been approved by the U.S. Food and Drug Administration (FDA). The first such drug approved for the treatment of advanced melanoma, ipilimumab (Yervoy™, Bristol-Myers Squibb), blocks the activity of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), a checkpoint protein expressed on the surface of activated immune cells called cytotoxic T lymphocytes. CTLA-4 acts as a "switch" that inactivates these T cells, thereby reducing the intensity of the immune response, but ipilimumab binds to CTLA-4 and prevents it from sending its inhibitory signal.

[0005] Two other FDA-approved checkpoint inhibitors, nivolumab (Opdivo™, Bristol-Myers Squibb) and pembrolizumab (Keytrud™, Merck), work similarly but target a different checkpoint protein, programmed cell death protein 1 (PD-1), on activated T cells. Nivolumab is approved for treating some patients with advanced melanoma or advanced lung cancer, and pembrolizumab is approved for treating some patients with advanced melanoma. Additional PD-1-targeted inhibitors currently in development include pidulizumab (Medivation), MGA012 (MacroGenics), and BGB-A317 (BeiGene). PD-1 inhibitors are also described by Novartis AG in U.S. Patent Nos. 9,683,048 and 9,683,048. Also under development are checkpoint inhibitors that disrupt the interaction between PD-1 and its ligands on the surface of cancer cells known as PD-L1 and PD-L2, which downregulate PD-1 activity: durvalumab (Imfinzi™, Astrazeneca), avelumab (Bavencio™, Pfizer), and atezolizumab (Tecentriq™, Genentech / Roche). Additional PD-L1-targeted inhibitors currently in development include Ca-170 (Curis) and LY3300054 (Eli Lilly). PD-L1 inhibitors have also been described by Novartis AG in US2017 / 0296659 and WO2016 / 040892.

[0006] Although several immune checkpoint inhibitors have been shown to be effective and produce durable responses in patients with various cancers, only a minority of patients respond. Furthermore, some checkpoint immune inhibitors, such as the anti-PD-L1 compound BMS-936559, have not been further developed due to low response rates. An approach to increasing the response rate of immune checkpoint inhibitors is to combine them with chemotherapy to promote the killing of immunogenic cells and "prime" the immune system. However, chemotherapy itself can cause damage to various cell types of the immune system, including hematopoietic stem and progenitor cells (HSPCs) and immune effector cells such as T lymphocytes, potentially reducing the efficacy of the chemotherapy / checkpoint inhibitor combination.

[0007] It is an object of the present invention to provide a therapeutic approach for treating a host with cancer or tumor that enhances the protection of the host's innate immune system during and / or after chemotherapy so as to enhance the body's ability to use its inherent immune mechanisms to destroy diseased cells in the short and / or long term. Summary of the Invention

[0008] Surprisingly and unexpectedly, it has been discovered that the addition of a selective, rapid-acting, short-half-life CDK4 / 6 inhibitor to a combination of chemotherapy and checkpoint inhibitors in a highly specific dosing regimen results in superior tumor or cancer treatment. The unexpected finding is that timed administration of a CDK4 / 6 inhibitor before each chemotherapy dose in this triple combination therapy has a profound effect on immune cells in the cancer microenvironment. This result is remarkable in that administration of a CDK4 / 6 inhibitor as described herein provides one or more of the following: (i) protection against damage to immune tumor cell infiltrates; (ii) increased duration of immune responses with higher frequencies of tumor-specific memory T cells; (iii) greater reduction in intratumoral Treg cells, which are immunosuppressive; and / or (iv) altered gene expression of proinflammatory factors. Expression of genes functionally enriched for lymphocyte activation and upregulation of the proinflammatory cytokine interferon-γ is significantly enhanced. In parallel, several genes involved in immunosuppressive reactive oxygen species metabolic processes are downregulated. These findings suggest that timing the administration of CDK4 / 6 inhibitors results in modulation of gene expression, creating a favorable pro-inflammatory tumor microenvironment that enhances the efficacy of checkpoint inhibitor activity while reducing the deleterious effects of chemotherapy, an improvement that represents a significant advance in the state of the art in cancer treatment.

[0009] The net result of this effect on the tumor microenvironment is to improve the ability of the host's innate immune response to effectively fight the cancer or tumor and enhance the ability to achieve a short-term response (up to approximately 1, 2, 3, 4, 5, or 6 months), a long-term response (up to 7, 8, 9, 10, 11, or 12 months or longer), or a complete response.

[0010] In contrast, the significant benefits of this particular dosing regimen for triple combination chemotherapy, checkpoint inhibitor, and CDK4 / 6 inhibitor therapy have been found not to be achieved when the CDK4 / 6 inhibitor is administered in a continuous or substantially continuous manner, resulting in continuous CDK4 / 6 inhibition of immune effector cells, in which case the immune effector cells of the tumor microenvironment remain suppressed for a sufficient period of time such that their ability to destroy diseased cells is significantly reduced.

[0011] Specific benefits of this therapy may include one or more of the following: Short-term intratumoral immune cell types (CD4+ T, CD8+ T, Treg, NK, and MDSC subsets) are highly proliferative and sensitive to CDK4 / 6 inhibition, allowing for temporary cell cycle arrest by CDK4 / 6 inhibitors to protect immune infiltrates from chemotherapy-induced damage, as do hematopoietic progenitor cells in the bone marrow. With timed administration according to the present invention, for example, proliferation of one or more of these cell types can be maximally inhibited by about 50, 60, 70, 75, or 80% or more in approximately 6 to 24 hours, with recovery within approximately 30, 40, 45, 48, 50, or 60 hours.

[0012] Protection of intratumor immune cells by timed administration of a CDK4 / 6 inhibitor when added to a chemotherapy / checkpoint inhibitor combination results in increased duration of therapeutic response. Higher frequencies of tumor-specific memory T cells can be found. In some instances, the median frequency at 50 days post-treatment can be at least approximately 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, or 2.6-fold higher with a timed CDK4 / 6 inhibitor / chemotherapy / checkpoint inhibitor regimen than with a chemotherapy / checkpoint inhibitor regimen alone. The longer duration of memory T cells provides the host with long-term protection from diseased cells.

[0013] The addition of timed administration of a CDK4 / 6 inhibitor to a chemotherapy / checkpoint inhibitor combination regimen results in a greater reduction in the intratumoral Treg population. In certain embodiments, the proportion of intratumoral Tregs in the CD4+ T cell population using this improved regimen can be reduced by up to about 10, 20, 25, 30, 35, 40, or 50% compared to chemotherapy / checkpoint inhibitor therapy alone at least 7, 8, 9, 10, or 15 days after treatment or later. In certain embodiments, the kinetics of inhibition of Treg proliferation is delayed relative to CD8+ T cells, indicating better protection of CD8+ T cells.

[0014] In one non-limiting embodiment, the timed administration of the CDK4 / 6 inhibitor includes the selective, fast-acting, short-half-life CDK4 / 6 inhibitor Compound I (see below), a chemotherapeutic agent cytotoxic to immune effector cells, such as oxaliplatin, and an antibody against PD1, PD-L1, or CTLA4. In another embodiment, the timed administration of the CDK4 / 6 inhibitor includes Compound I, carboplatin, and an antibody against PD1, PD-L1, or CTLA4. In one aspect of the invention, the cancer is small cell lung cancer (SCLC). In yet another embodiment, the timed administration of the CDK4 / 6 inhibitor includes Compound I, etoposide, and an antibody against PD1, PD-L1, or CTLA4. In one aspect of these embodiments, the cancer is small cell lung cancer. In another aspect, carboplatin and etoposide are used in combination.

[0015] A summary of embodiments of the present invention is described in further detail below.

[0016] In various aspects, the present invention provides methods for treating cancer or tumors in a subject by enhancing a pro-inflammatory microenvironment through the use of a planned treatment protocol comprising the timed administration of a CDK4 / 6 inhibitor, e.g., a selective, fast-acting, short-half-life CDK4 / 6 inhibitor, in combination with a chemotherapeutic agent, e.g., a chemotherapeutic agent that is cytotoxic to immune effector cells, and an immune checkpoint inhibitor. It has been found that the use of a CDK4 / 6 inhibitor in a combination chemotherapeutic agent / immune checkpoint inhibitor treatment regimen protects immune effector cells, such as T lymphocytes, from chemotherapeutic agent toxicity and releases them from transient cell cycle arrest in the presence of chemotherapy-induced immunogenic cell death in a manner that provides significantly improved priming and activation of anti-cancer immune responses and anti-cancer effects compared to the absence of a CDK4 / 6 inhibitor. It has also been found that the use of CDK4 / 6 inhibitors during chemotherapy / immune checkpoint inhibitor treatment regimens enhances anti-tumor activity, including selective reduction of intratumoral Treg populations, protection of pro-inflammatory immune effector cells such as tumor-infiltrating lymphocytes, and prolonged duration of therapeutic response, through cell cycle-independent and -dependent mechanisms. Controlled inhibition of CDK4 / 6 by a CDK4 / 6 inhibitor, e.g., a selective, short-half-life CDK4 / 6 inhibitor, in combination with a chemotherapy and immune checkpoint inhibitor as described herein provides significantly enhanced anti-tumor efficacy compared to administration of a chemotherapy and immune checkpoint inhibitor alone, or continuous inhibition of CDK4 / 6 by a CDK4 / 6 inhibitor, including a longer-acting CDK4 / 6 inhibitor administered daily in combination with an immune checkpoint inhibitor.

[0017] Many chemotherapeutic agents, including but not limited to protein synthesis inhibitors or DNA-damaging chemotherapeutic agents, tend to be nonspecific and toxic to normal rapidly dividing cells, including immune effector cells, and hematologic toxicity, such as bone marrow suppression, is a common side effect of chemotherapy. Immune effector cells generally require CDK4 / 6 activity for proliferation; that is, immune effector cells are CDK4 / 6 replication-dependent (see Roberts et al. Multiple Roles of Cyclin-Dependent Kinase 4 / 6 Inhibitors in Cancer Therapy. JNCI 2012;104(6):476-487). All major intratumoral immune cell types, such as CD4+ T cells, CD8+ T cells, natural killer (NK) cells, and myeloid-derived suppressor cells (MDSCs), are sensitive to CDK4 / 6 inhibition. By using selective, fast-acting, short-half-life CDK4 / 6 inhibitors during chemotherapy treatment, immune effector cells that are proliferating and sensitive to the damaging effects of chemotherapy drugs are temporarily arrested in the G0 / G1 phase of the cell cycle. By protecting these cells from the damaging effects of chemotherapy drugs, the use of timed administration of CDK4 / 6 inhibitors preserves immune function, enhances T cell activation, and increases the efficacy of immune checkpoint inhibitors, significantly improving anti-cancer immune responses.

[0018] In non-limiting exemplary embodiments, Examples 5 and 9 and Figures 10, 11, 19, and 20 confirm that timed administration of a CDK4 / 6 inhibitor in combination with a chemotherapeutic agent and an immune checkpoint inhibitor selectively protects pro-inflammatory intratumoral immune cell infiltrates while selectively reducing intratumoral populations of anti-inflammatory infiltrates, such as CD4+ / CD25+ Treg cells. This demonstrates that controlled inhibition of the CDK4 / 6 pathway reduces the suppressive function of Treg cells and alters their ability to inhibit T cell proliferation. Again, as an exemplary embodiment, Example 5 and Figure 11 show that animals receiving a timed CDK4 / 6 inhibitor / chemotherapeutic agent / immune checkpoint inhibitor combination had a 40% lower percentage of intratumoral Treg cells compared to animals receiving a chemotherapeutic agent and immune checkpoint inhibitor without the timed administration of a CDK4 / 6 inhibitor. Thus, incorporating timed administration of selective, fast-acting, short half-life CDK4 / 6 inhibitors as described herein provides a targeted approach to remove unwanted Treg cells and increase pro-inflammatory immune effector cell infiltrates.

[0019] Although timed administration of CDK4 / 6 inhibitors results in a significant initial reduction in immune cell proliferation (see Example 10, a reduction of more than 75%), in animal models, beneficial T cell proliferation generally fully recovers by at least 1.5, 2, 2.5, or 3 days. Furthermore, the overall expression of genes associated with lymphocyte activation and upregulation of the proinflammatory cytokine interferon-γ is significantly increased (see non-limiting illustrative Examples 12 and 13, Figures 25-31). In comparison, genes associated with immunosuppressive oxygen species metabolic processes are downregulated, indicating that transient cell cycle arrest in the tumor immune infiltrate can result in modulation of gene expression, creating a proinflammatory tumor microenvironment favorable to enhanced immune checkpoint inhibitor activity (see non-limiting illustrative Example 14, Figures 32-37).

[0020] Importantly, timed administration of a selective, fast-acting, short-half-life CDK4 / 6 inhibitor in combination with a chemotherapy agent and an immune checkpoint inhibitor results in an extended duration of therapeutic response. A non-limiting example is shown in Example 11 and Figures 23 and 24, which confirm that in this example a higher frequency of tumor-specific memory T cells is observed in a tumor model when a CDK4 / 6 inhibitor is added to the chemotherapy agent / immune checkpoint inhibitor combination therapy, doubling the population of tumor-specific memory T cells compared to the chemotherapy agent / immune checkpoint inhibitor combination treatment without the CDK4 / 6 inhibitor. Additionally, delay of tumor progression is also significantly improved with timed administration of a selective, fast-acting, short half-life CDK4 / 6 inhibitor in combination with a chemotherapy drug and immune checkpoint inhibitor compared to chemotherapy drug and immune checkpoint inhibitor treatment without a CDK4 / 6 inhibitor or sequential CDK4 / 6 inhibition with a CDK4 / 6 inhibitor administered daily in combination with an immune checkpoint inhibitor (see Examples 7 and 16, Figures 14, 15, and 38).

[0021] Thus, in one aspect, the present invention provides an improved method of treating a host, e.g., a human, having a cancer or tumor, comprising providing to the subject a timed administration of a selective CDK4 / 6 inhibitor in combination with a chemotherapy agent and an immune checkpoint inhibitor treatment regimen. In one embodiment, the administration of the selective CDK4 / 6 inhibitor is timed prior to or concurrent with the administration of the chemotherapy agent. In one embodiment, the CDK4 / 6 inhibitor is administered only prior to or concurrently with the administration of the chemotherapy agent. In one embodiment, the treatment comprises a multi-day treatment cycle comprising an induction phase and a maintenance phase, wherein the induction phase comprises timed administration of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and a checkpoint inhibitor, where the selective CDK4 / 6 inhibitor is administered concurrently or only about 8 hours, 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, 1 hour, or 30 minutes before administration of the chemotherapeutic agent; and the maintenance phase comprises administration of the checkpoint inhibitor alone, where the maintenance phase occurs after one or more induction phases. In one embodiment, the maintenance phase comprises administration of one or more immune checkpoint inhibitors. In one embodiment, the CDK4 / 6 inhibitor is a selective, fast-acting, short-half-life inhibitor that provides temporary protection of immune effector cells, allowing them to rapidly re-enter the cell cycle and activate and proliferate after the effects of chemotherapy have worn off during the induction phase. In one embodiment, the chemotherapeutic agent is an agent that is cytotoxic or cytostatic to immune effector cells, including, but not limited to, protein synthesis inhibitors, DNA damaging chemotherapeutic agents, alkylating agents, topoisomerase inhibitors, RNA synthesis inhibitors, DNA complex binders, thiolate alkylating agents, guanine alkylating agents, tubulin binders, DNA polymerase inhibitors, anticancer enzymes, RAC1 inhibitors, thymidylate synthase inhibitors, oxazophosphorine compounds, cilengitide, integrin inhibitors such as camptothecin or homocamptothecin, antifolates or antifolates, or combinations thereof.

[0022] In another aspect, the present invention provides a method for increasing the proinflammatory immune effector cell population in an intratumoral immune cell infiltrate population in a subject with cancer or a tumor, comprising timed administration of an effective amount of a selective CDK4 / 6 inhibitor to a subject, e.g., a human, during a course of treatment with a chemotherapeutic agent and an immune checkpoint inhibitor as described herein. In one embodiment, the proinflammatory immune effector cell population is increased by up to 10%, 20%, 30%, 40%, 50%, or more compared to the proinflammatory immune effector cell population in the intratumoral immune cell infiltrate population without the timed administration of the selective CDK4 / 6 inhibitor. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0023] In another aspect, the present invention provides a method of enhancing activation of T cells in an intratumoral immune cell infiltrate population in a subject with cancer or tumor, comprising administering to the subject effective amounts of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor as described herein. In one embodiment, the activated T cells are CD4+ T cells. In one embodiment, the activated T cells are CD8+ T cells. In one embodiment, the activated T cells produce interferon-γ. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 5%, 10%, 15%, 20%, or more. In one embodiment, interferon-γ production is increased due to upregulation of the INFG gene. In one embodiment, interferon-γ production is increased due to upregulation of the IL2 gene. In one embodiment, interferon-γ production is increased due to upregulation of the IL18 gene. In one embodiment, interferon-γ production is increased due to upregulation of the LTA gene. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

[0024] In one aspect of the present invention, provided herein is a method for reducing the regulatory T cell (Treg) population in an intratumoral immune cell infiltrate population in a subject suffering from cancer, comprising administering to the subject effective amounts of a CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor as described herein. In one embodiment, the Treg is a CD4+CD25+ Treg. In one embodiment, the regulatory T cell population in the intratumoral immune cell infiltrate population is reduced by about 10%, 20%, 30%, 40% or more compared to the intratumoral cellular infiltrate population from a subject not receiving a CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor in a treatment regimen as described herein. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0025] In one aspect, the present invention provides a method for inhibiting the immunosuppressive function of regulatory T cells in an intratumoral immune cell infiltrate population in a subject with cancer or tumor, comprising administering to the subject effective amounts of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor as described herein. In one embodiment, the Tregs are CD4+CD25+ Tregs. In one embodiment, the reduction in the immunosuppressive function of regulatory T cells is measured by a decrease in Phospho-Rb. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by at least approximately 5%, 10%, 15%, 20% or more compared to untreated regulatory T cells. In one embodiment, the reduction in the immunosuppressive function of regulatory T cells results in, for example, at least a 10%, 20%, 30%, 40%, 50% or more increase in CD8+ T cell proliferation compared to the intratumoral cellular infiltrate population from a subject not receiving the selective CDK4 / 6 inhibitor, chemotherapeutic agent, and immune checkpoint inhibitor for a particular time period in a treatment regimen as described herein. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0026] In one aspect, the present invention provides a method for increasing the generation of tumor-specific memory T cells in a subject with cancer or a tumor, comprising administering to the subject effective amounts of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor as described herein for a specified period of time. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by at least about 0.25%, 0.5%, 0.75%, 1%, or more relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by at least about 0.5%, 1%, 1.5%, or more relative to the total T cell population. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0027] In one aspect of the present invention, the present invention provides a method for protecting intratumoral immune cells from chemotherapy in a subject with cancer or tumor, comprising administering to the subject effective amounts of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor as described herein for a specific time period. Protecting intratumoral immune cells from chemotherapy toxicity results in an enhanced antitumor immune response. In one embodiment, the protected intratumoral immune cells are selected from CD8+ T cells, CD4+ T cells, natural killer (NK) cells, monocytic myeloid-derived suppressor cells (mMDSCs), and granulocytic myeloid-derived suppressor cells (gMDSCs). In one embodiment, the percentage expansion of intratumoral immune cells is at least approximately 5%, 10%, 15%, 20%, 25%, or 30% higher than the expansion of immune cells found in the spleen. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0028] The CDK4 / 6 inhibitor used in this treatment regimen can be any selective CDK4 / 6 inhibitor that achieves the desired objective, such as, but not limited to, trilaciclib (G1 Therapeutics, Inc.), ribociclib (Novartis), palbociclib (Pfizer), or abemaciclib (Eli Lily). In one embodiment, the CDK4 / 6 inhibitor is selected from a selective, fast-acting, short-half-life, sustained CDK4 / 6 inhibitor, such as Compound I (trilaciclib), II, III, or IV, as described herein, or a pharmaceutically acceptable composition, salt, isotopic analog, or prodrug thereof. [ka]

[0029] In one embodiment, the selective, fast-acting, short half-life CDK4 / 6 inhibitor is Compound I (trilaciclib), or a pharmaceutically acceptable composition, salt, isotopic analog, or prodrug thereof.

[0030] As provided herein, a selective CDK4 / 6 inhibitor is administered in a timed treatment regimen using a chemotherapeutic agent and an immune checkpoint inhibitor. The chemotherapeutic agent can be any chemotherapeutic agent effective or useful for treating cancer, tumors, or abnormal cell proliferation. In one embodiment, the selective CDK4 / 6 inhibitor is administered before or concurrently with the administration of the chemotherapeutic agent so that immune effector cells are arrested within the therapeutic range of the chemotherapeutic agent, thereby reducing or eliminating the toxic effects of the chemotherapeutic agent on immune effector cells. In one embodiment, the selective CDK4 / 6 inhibitor is administered to a subject about 24 hours, about 20 hours, about 16 hours, about 12 hours, about 8 hours, about 4 hours, about 2.5 hours, about 2 hours, less than about 1 hour, or about 1 / 2 hour before treatment with the chemotherapeutic agent. In a specific embodiment, the selective CDK4 / 6 inhibitor is administered about 1 / 2 hour before administration of the chemotherapeutic agent. Generally, the selective CDK4 / 6 inhibitor is administered to a subject prior to chemotherapy treatment so that the CDK4 / 6 inhibitor reaches a peak serum concentration before or during chemotherapy treatment, allowing it to inhibit the proliferation of immune effector cells and thus protect them from the adverse effects of chemotherapy. In one embodiment, the CDK4 / 6 inhibitor is administered concurrently with or close to chemotherapy exposure. Alternatively, the CDK4 / 6 inhibitor described herein can be administered after chemotherapy exposure if it is desired to alleviate immune effector cell damage associated with chemotherapy exposure. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0031] As contemplated herein, timed administration of a selective, fast-acting, short-half-life CDK4 / 6 inhibitor as described herein can be administered in any chemotherapy / immune checkpoint inhibitor combination therapy protocol. For example, a selective, fast-acting, short-half-life CDK4 / 6 inhibitor can be administered such that CDK4 / 6 replication-dependent HSPCs and immune effector cells are arrested in G1 phase during chemotherapy exposure, whereby the rapid disappearance of the G1 arresting effect of the selective, fast-acting, short-half-life CDK4 / 6 inhibitor described herein allows a significant number of immune effector cells to reenter the cell cycle and become capable of replicating and activating some time after chemotherapy exposure, when chemotherapy-induced cancer cell death and tumor antigen exposure are at their peak. In certain embodiments, the selective, fast-acting, short half-life CDK4 / 6 inhibitor is administered prior to or concurrently with the administration of a chemotherapeutic agent, where the chemotherapeutic agent is administered, for example, on days 1-3 every 21 days; days 1-3 every 28 days; day 1 every 3 weeks; days 1, 8, and 15 every 28 days, days 1 and 8 every 28 days; days 1 and 8 every 21 days; days 1-5 every 21 days; day 1, 1, 22, and 43 every week for 6-8 weeks; days 1 and 2 every week; days 1-4 and 22-25; days 1-4, 22-25, and 43-46; and similar types of chemotherapeutic regimens. In one embodiment, the selective, fast-acting, short half-life CDK4 / 6 inhibitor is administered prior to or concurrently with at least one dose of a chemotherapeutic agent in a chemotherapeutic regimen. In one embodiment, the selective, fast-acting, short half-life CDK4 / 6 inhibitor is administered prior to or concurrently with one or more doses of the chemotherapeutic agent in a chemotherapy regimen. In one embodiment, the selective, fast-acting, short half-life CDK4 / 6 inhibitor is administered prior to or concurrently with each dose of the chemotherapeutic agent in a chemotherapy regimen.

[0032] The present invention encompasses the administration of immune checkpoint inhibitors. Immune checkpoint inhibitors are known in the art and include, but are not limited to, PD-1 inhibitors, PD-L1 inhibitors, and CTLA-4 inhibitors, as well as others as described herein, where the inhibitor can be a small molecule, antibody, other protein, or biologic. In one embodiment, the immune checkpoint inhibitor is administered concurrently with the administration of a CDK4 / 6 inhibitor and a chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered concurrently with the administration of a CDK4 / 6 inhibitor and a chemotherapeutic agent, and then at regular intervals thereafter, for example, once weekly, twice weekly, three times weekly, or more, to maintain the effect of the immune checkpoint inhibitor. In other embodiments, the immune checkpoint inhibitor can be administered according to a predetermined treatment cycle, for example, on day 1 of a 21-day cycle, or on days 1, 8, and 15 of a 21-day cycle.

[0033] One aspect of the present invention provides a method of treating cancer in a subject, comprising administering to the subject a dosing regimen comprising administering a chemotherapeutic agent in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. The CDK4 / 6 inhibitor is administered in a timed manner prior to or concurrently with the administration of the chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered prior to or concurrently with each administration of the chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered prior to or concurrently with at least one administration of the chemotherapeutic agent and the CDK4 / 6 inhibitor. In one embodiment, the immune checkpoint inhibitor is administered prior to or concurrently with each administration of the chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered to the subject one or more times in combination with the chemotherapeutic agent and the CDK4 / 6 inhibitor during an initial induction phase. In one embodiment, the immune checkpoint inhibitor is administered to the subject one or more times in combination with the chemotherapeutic agent and the CDK4 / 6 inhibitor during the induction phase, and one or more times alone during the maintenance phase, e.g., without concurrent administration of the chemotherapeutic agent and the CDK4 / 6 inhibitor. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

[0034] In one embodiment, the CDK4 / 6 inhibitor is administered between or concurrently with each administration of a chemotherapy agent in a standard chemotherapy protocol, such as, for example, a 21-day cycle, with the checkpoint inhibitor administered on day 1. After cessation of the standard chemotherapy protocol, the immune checkpoint inhibitor is further administered alone at a maintenance dose. In one embodiment, the immune checkpoint inhibitor is further administered once, twice, three or more times per week for at least 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 weeks, or longer. In one embodiment, the checkpoint inhibitor is administered once every 21 days. In one embodiment, both the induction phase and the maintenance phase are repeated at least twice, at least three times, at least four or more times. In one embodiment, the induction phase is repeated at least four times, and the maintenance phase is repeated four or more times, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12 or more times. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

[0035] As contemplated herein, a time-specific CDK4 / 6 inhibitor as described herein, e.g., a fast-acting, short-half-life CDK4 / 6 inhibitor, is administered in combination with a chemotherapy agent and an immune checkpoint inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is administered concurrently with the administration of the chemotherapy agent. In one embodiment, the immune checkpoint inhibitor is administered subsequent to the administration of the CDK4 / 6 inhibitor and the chemotherapy agent. In one embodiment, the immune checkpoint inhibitor is administered once, twice, three times, or more times in a chemotherapy cycle. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0036] Also contemplated herein is timed administration of a CDK4 / 6 inhibitor in combination with an immune checkpoint inhibitor, such as a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor, wherein the CDK4 / 6 inhibitor / immune checkpoint inhibitor combination is administered to maintain immune effector cell responses after completion of a CDK4 / 6 inhibitor / chemotherapeutic agent / immune checkpoint inhibitor treatment regimen. For example, after completion of a CDK4 / 6 inhibitor / chemotherapeutic agent / immune checkpoint inhibitor treatment regimen (i.e., induction phase), the CDK4 / 6 inhibitor in combination with the immune checkpoint inhibitor can be administered to a subject at periodic intervals to maintain immune effector cell responses (i.e., maintenance phase). In one embodiment, a maintenance regimen of the CDK4 / 6 inhibitor / immune checkpoint inhibitor combination is administered at least once or more after cessation of the original treatment regimen. In one embodiment, the maintenance regimen is administered weekly, twice a month, monthly, once every six weeks, or as needed. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

[0037] In certain aspects, following completion of the CDK4 / 6 inhibitor / chemotherapeutic agent / immune checkpoint inhibitor treatment regimen (i.e., induction phase), the immune checkpoint inhibitor alone can be administered to the subject at periodic intervals for maintenance of the immune effector cell response (i.e., maintenance phase).

[0038] As contemplated herein, the subject may have any type of cancer, tumor, or abnormal cell proliferation. In one embodiment, the subject has a CDK4 / 6 replication-independent cancer. The CDK4 / 6 replication-independent cancer may be one of, but not limited to, small cell lung cancer, triple-negative breast cancer, HPV-positive head and neck cancer, retinoblastoma, Rb-negative bladder cancer, Rb-negative prostate cancer, osteosarcoma, or cervical cancer. In one embodiment, the subject has small cell lung cancer.

[0039] In one embodiment, the subject has a CDK4 / 6 replication-dependent cancer. The CDK4 / 6 replication-dependent cancer may be one of, but not limited to, non-small cell lung cancer, Rb-positive breast cancer, colon cancer, ovarian cancer, non-small cell lung cancer, prostate cancer, and glioblastoma. In one embodiment, the CDK4 / 6 replication-dependent cancer is Rb-positive breast cancer. In one embodiment, the CDK4 / 6 replication-dependent cancer is non-small cell lung cancer.

[0040] In one embodiment, the subject has a cancer that expresses PD-L1. In one embodiment, the PD-L1-expressing cancer is selected from small cell lung cancer, non-small cell lung cancer, bladder cancer, renal cell carcinoma, gastric cancer, head and neck cancer, mesothelioma, Merkel cell carcinoma, ovarian cancer, melanoma, or other solid tumors.

[0041] In one embodiment, the subject has bladder cancer, gastroesophageal cancer, soft tissue sarcoma, bile duct / gallbladder cancer, ovarian cancer, or cervical cancer.

[0042] In one embodiment, the subject has small cell lung cancer and is administered a chemotherapeutic agent selected from the group consisting of carboplatin, cisplatin, etoposide, and topotecan, or a combination thereof, in combination with a timed administration of a CDK4 / 6 inhibitor and also an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I, and the immune checkpoint inhibitor is selected from a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is etoposide. In one embodiment, the chemotherapeutic agent is carboplatin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising carboplatin and etoposide. In one embodiment, the chemotherapeutic agent is cisplatin. In one embodiment, the chemotherapeutic agent is topotecan.

[0043] In one embodiment, the subject has melanoma and a chemotherapeutic agent selected from the group consisting of dacarbazine, temozolomide, nab-paclitaxel, paclitaxel, cisplatin, oxaliplatin, carboplatin, vinblastine, or a combination thereof is administered in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is dacarbazine. In one embodiment, the chemotherapeutic agent is temozolomide. In one embodiment, the chemotherapeutic agent is nab-paclitaxel. In one embodiment, the chemotherapeutic agent is paclitaxel. In one embodiment, the chemotherapeutic agent is cisplatin. In one embodiment, the chemotherapy agent is carboplatin. In one embodiment, the chemotherapy agent is vinblastine. In one embodiment, the chemotherapy agent is a platinum drug.

[0044] In one embodiment, the subject has renal cell carcinoma and a chemotherapeutic agent selected from the group consisting of vinblastine, floxuridine, 5-fluorouracil (5-FU), capecitabine, and gemcitabine, or a combination thereof, is administered in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is selected from a PD-L1 inhibitor, a PD-1 inhibitor, and a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is vinblastine. In one embodiment, the chemotherapeutic agent is floxuridine. In one embodiment, the chemotherapeutic agent is 5-fluorouracil. In one embodiment, the chemotherapeutic agent is capecitabine. In one embodiment, the chemotherapeutic agent is gemcitabine.

[0045] In one embodiment, the subject has bladder cancer and a chemotherapeutic agent selected from the group consisting of carboplatin, oxaliplatin, cisplatin, fluorouracil, mitomycin, methotrexate, vinblastine, doxorubicin, gemcitabine, paclitaxel, or a combination thereof, is administered in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is selected from PD-L1, a PD-1 inhibitor, and a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is cisplatin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and 5-fluorouracil. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising mitomycin and 5-fluorouracil. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin and gemcitabine. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin, methotrexate, vinblastine, and doxorubicin. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin, methotrexate, and vinblastine. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising carboplatin and paclitaxel. In one embodiment, the chemotherapy agent is oxaliplatin.

[0046] In one embodiment, the subject has urothelial carcinoma and a chemotherapeutic agent selected from the group consisting of carboplatin, cisplatin, oxaliplatin, fluorouracil, mitomycin, methotrexate, vinblastine, doxorubicin, gemcitabine, paclitaxel, or a combination thereof, is administered in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is selected from a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is cisplatin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and 5-fluorouracil. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising mitomycin and 5-fluorouracil. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin and gemcitabine. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin, methotrexate, vinblastine, and doxorubicin. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin, methotrexate, and vinblastine. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising carboplatin and paclitaxel. In one embodiment, the chemotherapy agent is oxaliplatin.

[0047] In one embodiment, the subject has breast cancer and a chemotherapeutic agent selected from the group consisting of carboplatin, oxaliplatin, cisplatin, doxorubicin, 5-fluorouracil, paclitaxel, cyclophosphamide, and gemcitabine, or a combination thereof, is administered in combination with a CDK4 / 6 inhibitor and a checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is carboplatin. In one embodiment, the chemotherapeutic agent is cisplatin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and 5-fluorouracil. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and gemcitabine. In one embodiment, the chemotherapy agent is doxorubicin. In one embodiment, the chemotherapy agent is cyclophosphamide. In one embodiment, the chemotherapy agent is paclitaxel. In one embodiment, the chemotherapy agent is oxaliplatin.

[0048] In one embodiment, the subject has colorectal cancer and a chemotherapeutic agent selected from the group consisting of 5-fluorouracil, capecitabine, irinotecan, oxaliplatin, trifluridine, and tipiracil, or a combination thereof, is administered in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is 5-fluorouracil. In one embodiment, the chemotherapeutic agent is capecitabine. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising trifluridine and tipiracil. In one embodiment, the chemotherapeutic agent is irinotecan. In one embodiment, the chemotherapeutic agent is oxaliplatin.

[0049] In one embodiment, the subject has castration-resistant prostate cancer, and a chemotherapeutic agent selected from the group consisting of docetaxel, cabazitaxel, mitoxantrone, and estramustine, or a combination thereof, is administered in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, a PD-1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is docetaxel. In one embodiment, the chemotherapeutic agent is cabazitaxel. In one embodiment, the chemotherapeutic agent is mitoxantrone. In one embodiment, the chemotherapeutic agent is estramustine.

[0050] In one embodiment, the subject has a PD-L1-expressing tumor and a chemotherapeutic agent selected from the group consisting of carboplatin, cisplatin, gemcitabine, etoposide, 5-fluorouracil, paclitaxel, oxaliplatin, and topotecan, or a combination thereof, is administered in combination with Compound I and atezolizumab. In one embodiment, the chemotherapeutic agent is etoposide. In one embodiment, the chemotherapeutic agent is carboplatin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising carboplatin and etoposide. In one embodiment, the chemotherapeutic agent is cisplatin. In one embodiment, the chemotherapeutic agent is topotecan. In one embodiment, the chemotherapeutic agent is oxaliplatin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and 5-fluorouracil. In one embodiment, the chemotherapeutic agent is doxorubicin.

[0051]

[0010] In one aspect of the present invention, a method of treating a subject with cancer is provided, comprising administering to the subject a treatment regimen comprising an induction phase and a maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of a selective CDK4 / 6 inhibitor, administering to the subject an effective amount of a chemotherapeutic agent, and administering to the subject an effective amount of an immune checkpoint inhibitor; the CDK4 / 6 inhibitor is administered prior to or concurrently with administration of the chemotherapeutic agent; and the chemotherapeutic agent is cytotoxic to immune effector cells; and the maintenance phase comprises administering to the subject at least one dose of an effective amount of the immune checkpoint inhibitor, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0052] In one embodiment, a method of treating a subject with small cell lung cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of carboplatin on day 1 of a 21-day cycle; administering to the subject an effective amount of etoposide on days 1, 2, and 3 of the 21-day cycle; administering to the subject an effective amount of a selective CDK4 / 6 inhibitor on days 1, 2, and 3 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0053] In one embodiment, a method of treating a subject with small cell lung cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of carboplatin on day 2 of a 21-day cycle; administering to the subject an effective amount of etoposide on days 2, 3, and 4 of the 21-day cycle; administering to the subject an effective amount of a selective CDK4 / 6 inhibitor on days 1-4 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and wherein the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, the maintenance phase being administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0054] In one embodiment, a method of treating a subject with small cell lung cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of topotecan on days 1-5 of a 21-day cycle; administering to the subject an effective amount of a selective CDK4 / 6 inhibitor on days 1-5 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0055] In one embodiment, a method of treating a subject with small cell lung cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of topotecan on days 2-6 of a 21-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1-6 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and wherein the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, the maintenance phase being administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0056] In one embodiment, a method of treating a subject with stage IV triple-negative breast cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of carboplatin on days 1 and 8 of a 21-day cycle; administering to the subject an effective amount of gemcitabine on days 1 and 8 of the 21-day cycle; and administering to the subject an effective amount of a selective CDK4 / 6 inhibitor on days 1 and 8 of the 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0057] In one embodiment, a method of treating a subject with stage IV triple-negative breast cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of carboplatin on days 2 and 9 of a 21-day cycle; administering to the subject an effective amount of gemcitabine on days 2 and 9 of the 21-day cycle; and administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1, 2, 8, and 9 of the 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0058] In one embodiment, a method of treating a subject with small cell lung cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase may be repeated up to four times, the induction phase comprising administering to the subject an effective amount of carboplatin on day 1 of each 21-day cycle; administering to the subject an effective amount of etoposide on days 1, 2, and 3 of each 21-day cycle; administering atezolizumab on day 1 of each 21-day cycle; and administering a CDK4 / 6 inhibitor on days 1, 2, and 3 of each 21-day cycle; and the maintenance phase comprises administering atezolizumab on day 1 of each 21-day cycle, the maintenance phase being administered after the final induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0059] In one embodiment, a method of treating a subject with small cell lung cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase may be repeated up to four times, the induction phase comprising administering to the subject an effective amount of carboplatin on day 2 of each 21-day cycle; administering to the subject an effective amount of etoposide on days 2, 3, and 4 of each 21-day cycle; administering atezolizumab on day 1 of each 21-day cycle; and administering a CDK4 / 6 inhibitor on days 1-4 of each 21-day cycle; and the maintenance phase comprising administering atezolizumab on day 1 of each 21-day cycle, wherein the maintenance phase is administered after the final induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0060] In one embodiment, a method of treating a subject with advanced or metastatic non-squamous small cell lung cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase may be repeated up to four times, the induction phase comprising: administering to the subject an effective amount of carboplatin on day 1 of each 21-day cycle; administering to the subject an effective amount of pemetrexed on day 1 of each 21-day cycle; administering to the subject an effective amount of pembrolizumab on day 1 of each 21-day cycle; and administering to the subject an effective amount of a CDK4 / 6 inhibitor on day 1 of each 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of pembrolizumab on day 1 of each 21-day cycle, the maintenance phase being administered after the final induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0061] In one embodiment, a method of treating a subject with Stage IIIB or Stage IV non-squamous small cell lung cancer without a targetable EGFR or ALK genetic abnormality is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase may be repeated up to four times, the induction phase comprising: administering to the subject an effective amount of carboplatin on day 2 of each 21-day cycle; administering to the subject an effective amount of pemetrexed on day 2 of each 21-day cycle; administering to the subject an effective amount of pembrolizumab on day 1 of each 21-day cycle; and administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1 and 2 of each 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of pembrolizumab on day 1 of each 21-day cycle, wherein the maintenance phase is administered after the cessation of the final induction phase. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

[0062] In one embodiment, a method of treating a subject with metastatic recurrent or refractory colorectal cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of irinotecan on day 1 of a 21-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on day 1 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0063] In one embodiment, a method of treating a subject with metastatic recurrent or refractory colorectal cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of irinotecan on day 2 of a 21-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1 and 2 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0064] In one embodiment, a method of treating a subject with metastatic recurrent or refractory colorectal cancer is provided, comprising administering to the subject a treatment regimen comprising a 6-week induction phase and a 6-week maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of irinotecan on days 1, 8, 15, and 22 of a 6-week cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1, 8, 15, and 22 of the 6-week cycle; and administering an immune checkpoint inhibitor on days 1 and 22 of the 6-week cycle, and wherein the maintenance phase comprises administering an effective amount of the checkpoint inhibitor on days 1 and 22 of the 6-week cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0065] In one embodiment, a method of treating a subject with metastatic recurrent or refractory colorectal cancer is provided, comprising administering to the subject a treatment regimen comprising a 6-week induction phase and a 6-week maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of irinotecan on days 2, 9, 16, and 23 of a 6-week cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1, 2, 8, 9, 15, 16, 22, and 23 of the 6-week cycle; and administering an immune checkpoint inhibitor on days 1 and 22 of the 6-week cycle, and the maintenance phase comprises administering an effective amount of the checkpoint inhibitor on days 1 and 22 of the 6-week cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0066] In one embodiment, a method of treating a subject with recurrent platinum-sensitive ovarian cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase may be repeated up to six times, the induction phase comprising: administering to the subject an effective amount of carboplatin on day 1 of each 21-day cycle; administering to the subject an effective amount of docetaxel on day 1 of each 21-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on day 1 of each 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of each 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of the immune checkpoint inhibitor on day 1 of the 21-day cycle, the maintenance phase being administered after the final induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0067] In one embodiment, a method of treating a subject with recurrent platinum-sensitive ovarian cancer is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase may be repeated up to six times, the induction phase comprising: administering to the subject an effective amount of carboplatin on day 2 of each 21-day cycle; administering to the subject an effective amount of docetaxel on day 2 of each 21-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1 and 2 of each 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of each 21-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, the maintenance phase being administered after the final induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0068] In one embodiment, a method of treating a subject with metastatic pancreatic cancer is provided, comprising administering to the subject a treatment regimen comprising a 14-day induction phase and a 14-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of a combination of 5-FU and leucovorin on days 1 and 2 of a 14-day cycle; administering to the subject an effective amount of oxaliplatin on day 1 of the 14-day cycle; administering to the subject an effective amount of irinotecan on day 1 of the 14-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1 and 2 of the 14-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 14-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 14-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0069] In one embodiment, a method of treating a subject with metastatic pancreatic cancer is provided, comprising administering to the subject a treatment regimen comprising a 14-day induction phase and a 14-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of a combination of 5-FU and leucovorin on days 2 and 3 of a 14-day cycle; administering to the subject an effective amount of oxaliplatin on day 2 of the 14-day cycle; administering to the subject an effective amount of irinotecan on day 2 of the 14-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1-3 of the 14-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 14-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 14-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0070] In one embodiment, a method of treating a subject with metastatic pancreatic cancer is provided, comprising administering to the subject a treatment regimen comprising a 28-day induction phase and a 28-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of gemcitabine on days 1, 8, and 15 of a 28-day cycle; administering to the subject an effective amount of Abraxane on days 1, 8, and 15 of the 28-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1, 8, and 15 of the 28-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 28-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 28-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0071] In one embodiment, a method of treating a subject with metastatic pancreatic cancer is provided, comprising administering to the subject a treatment regimen comprising a 28-day induction phase and a 28-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of gemcitabine on days 2, 9, and 16 of a 28-day cycle; administering to the subject an effective amount of Abraxane on days 2, 9, and 16 of the 28-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1, 2, 8, 9, 15, and 16 of the 28-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 28-day cycle; and the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 28-day cycle, wherein the maintenance phase is administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0072] In one embodiment, a method of treating a subject with soft tissue sarcoma is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of doxorubicin on day 1 of a 21-day cycle; administering to the subject an effective amount of ifosfamide on days 1-4 of the 21-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1-4 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and wherein the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, the maintenance phase being administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor.

[0073] In one embodiment, a method of treating a subject with soft tissue sarcoma is provided, comprising administering to the subject a treatment regimen comprising a 21-day induction phase and a 21-day maintenance phase, wherein the induction phase comprises administering to the subject an effective amount of doxorubicin on day 2 of a 21-day cycle; administering to the subject an effective amount of ifosfamide on days 2-5 of the 21-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1-5 of the 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle; and wherein the maintenance phase comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of the 21-day cycle, the maintenance phase being administered after the induction phase has ceased. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0074] In one embodiment, a selective, fast-acting, short half-life CDK4 / 6 inhibitor administered as described herein is combined with an immune checkpoint inhibitor in a single dosage form. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab.

[0075] In one embodiment, a selective, fast-acting, short half-life CDK4 / 6 inhibitor is combined with a CTLA-4 inhibitor in a single dosage form. In one embodiment, the CTLA-4 inhibitor is ipilimumab (Yervoy™).

[0076] In one embodiment, a selective, fast-acting, short-half-life CDK4 / 6 inhibitor is combined with a PD-1 inhibitor in a single dosage form. In one embodiment, the PD-1 inhibitor is nivolumab (Opdivo™). In one embodiment, the PD-1 inhibitor is pembrolizumab (Keytruda™).

[0077] In one embodiment, the subject or host is a mammal, including a human. [Brief explanation of the drawings]

[0078] [Figure 1] Figure 1 depicts tumor growth rates over 100 days following treatment with (1) vehicle, (2) Compound I (100 mg / kg), (3) oxaliplatin, (4) anti-mouse PD-L1, (5) Compound I + oxaliplatin, (6) oxaliplatin (administered on days 1, 8, and 15) and anti-mouse PD-L1 (administered on days 1, 4, 8, and 11), and (7) Compound I + oxaliplatin (administered on days 1, 8, and 15) + anti-mouse PD-L1 (administered on days 1, 4, 8, and 11) in a syngeneic MC38 mouse tumor model. The x-axis represents study length in days, and the y-axis represents tumor volume in mm3. [Figure 2]Figure 2 depicts overall survival over 100 days following treatment with (1) vehicle, (2) Compound I (100 mg / kg), (3) oxaliplatin, (4) anti-mouse PD-L1, (5) Compound I plus oxaliplatin, (6) oxaliplatin (administered on days 1, 8, and 15) and anti-mouse PD-L1 (administered on days 1, 4, 8, and 11), and (7) Compound I plus oxaliplatin (administered on days 1, 8, and 15) plus anti-mouse PD-L1 (administered on days 1, 4, 8, and 11) in a syngeneic MC38 mouse tumor model. The x-axis represents the length of the study in days, and the y-axis represents percent survival. [Figure 3] Figure 3 depicts the dosing schedule for the xenograft study as described in Examples 2 and 3. Mice were administered one of the chemotherapy / checkpoint inhibitor dosing schedules with or without Compound I. Specifically, the checkpoint inhibitor was administered only during chemotherapy treatment (I), only after chemotherapy treatment (M), or during and after chemotherapy treatment (IM) until complete response or animal death. In the test cohort, Compound I was administered 30 minutes before chemotherapy treatment. [Figure 4] Figure 4 shows tumor growth rates over 100 days following treatment with (1) vehicle, (2) oxaliplatin plus murine anti-PD-LI in the (IM) dosing schedule, (3) Compound I plus oxaliplatin plus murine anti-PD-LI in the (IM) dosing schedule, (4) oxaliplatin plus murine anti-PD-LI in the (M) dosing schedule, (5) Compound I plus oxaliplatin plus murine anti-PD-LI in the (M) dosing schedule, (6) oxaliplatin plus murine anti-PD-LI in the (I) dosing schedule, and (7) Compound I plus oxaliplatin plus murine anti-PD-LI in the (I) dosing schedule in a syngeneic MC38 mouse tumor model, as described in Example 2. The x-axis represents the length of the study, measured in days, and the y-axis represents tumor volume, measured in mm3. [Figure 5]Figure 5 shows overall survival over 100 days following treatment with (1) vehicle, (2) oxaliplatin plus murine anti-PD-LI in the (IM) dosing schedule, (3) Compound I plus oxaliplatin plus murine anti-PD-LI in the (IM) dosing schedule, (4) oxaliplatin plus murine anti-PD-LI in the (M) dosing schedule, (5) Compound I plus oxaliplatin plus murine anti-PD-LI in the (M) dosing schedule, (6) oxaliplatin plus murine anti-PD-LI in the (I) dosing schedule, and (7) Compound I plus oxaliplatin plus murine anti-PD-LI in the (I) dosing schedule in a syngeneic MC38 mouse tumor model, as described in Example 2. The x-axis represents the length of the study in days, and the y-axis represents percent survival. * corresponds to p≦0.05. [Figure 6] Figure 6 depicts tumor growth rates over 60 days following treatment with (1) vehicle, (2) oxaliplatin in the (IM) dosing schedule plus murine anti-PD-I, and (3) Compound I plus oxaliplatin in the (IM) dosing schedule plus murine anti-PD-I in the syngeneic MC38 mouse tumor model, as described in Example 3. The x-axis represents study length in days, and the y-axis represents tumor volume in mm. [Figure 7] 7 depicts overall survival 60 days following treatment with (1) vehicle, (2) oxaliplatin plus murine anti-PD-I in the (IM) dosing schedule, and (3) Compound I plus oxaliplatin plus murine anti-PD-Ib in the (IM) dosing schedule in the syngeneic MC38 mouse tumor model, as described in Example 3. The x-axis represents the length of the study in days, and the y-axis represents percent survival. [Figure 8]Figure 8 shows tumor growth rate over 30 days following treatment in a syngeneic MC38 mouse tumor model with (1) vehicle, (2) 5-FU + murine anti-PD-LI on the (IM) dosing schedule, (3) Compound I + 5-FU + murine anti-PD-LI on the (IM) dosing schedule, (4) 5-FU + murine anti-PD-LI on the (M) dosing schedule, (5) Compound I + 5-FU + murine anti-PD-LI on the (M) dosing schedule, (6) 5-FU + murine anti-PD-LI on the (I) dosing schedule, and (7) Compound I + 5-FU + murine anti-PD-LI on the (I) dosing schedule, as described in Example 4. The x-axis represents the length of the study, measured in days, and the y-axis represents tumor volume, measured in mm3. [Figure 9] Figure 9 shows overall survival 30 days after treatment with (1) vehicle, (2) 5-FU + murine anti-PD-LI on the (IM) dosing schedule, (3) Compound I + 5-FU + murine anti-PD-LI on the (IM) dosing schedule, (4) 5-FU + murine anti-PD-LI on the (M) dosing schedule, (5) Compound I + 5-FU + murine anti-PD-LI on the (M) dosing schedule, (6) 5-FU + murine anti-PD-LI on the (I) dosing schedule, and (7) Compound I + 5-FU + murine anti-PD-LI on the (I) dosing schedule in the syngeneic MC38 mouse tumor model, as described in Example 4. The x-axis represents the length of the study in days, and the y-axis represents percent survival. [Figure 10] Figure 10 shows the percentage of CD4+ T cells analyzed by flow cytometry in MC38 tumor-bearing mice treated with vehicle, oxaliplatin + anti-PPD-L1, or oxaliplatin + murine anti-PD-L1 + Compound I. Tumors were harvested for analysis of immune cell infiltrates 5 days after the final treatment, as described in Example 5. Error bars represent SEM (standard error of the mean); statistics were evaluated using one-way ANOVA (**p<0.01 and ****p<0.0001). The x-axis represents treatment condition, and the y-axis represents CD4+ T cells evaluated as a percentage. [Figure 11]Figure 11 shows the percentage of CD4+ T cells analyzed by flow cytometry in MC38 tumor-bearing mice treated with vehicle, oxaliplatin plus murine anti-PPD-L1, or oxaliplatin plus murine anti-PD-L1 plus Compound I. Tumors were harvested for analysis of immune cell infiltrates 9 days after the final treatment, as described in Example 5. Error bars represent SEM (standard error of the mean); statistics were evaluated using one-way ANOVA (**p<0.01, ***p<0.001, ****p<0.0001). The x-axis represents treatment condition, and the y-axis represents CD4+ T cells evaluated as a percentage. [Figure 12] Figure 12 shows IL-2 concentrations after ex-vivo splenocyte stimulation in C57BL / 6 mice, as described in Example 6. Mice were administered three daily IP doses of vehicle, 5-FU, or 5-FU + Compound I, and 2 and 7 days after the final treatment, mice were euthanized and spleens were harvested. Error bars represent SEM (standard error of the mean); statistics were evaluated using two-way ANOVA (*p<0.05). The x-axis represents treatment condition, and the y-axis represents IL-2 concentration, assessed in pg / mL. [Figure 13] Figure 13 shows the concentration of IFNγ after ex-vivo splenocyte stimulation in C57BL / 6 mice, as described in Example 6. Mice were administered three daily IP doses of vehicle, 5-FU, or 5-FU plus Compound I, and 2 and 7 days after the final treatment, the mice were euthanized and the spleens were harvested. Error bars represent SEM (standard error of the mean); statistics were evaluated using two-way ANOVA (*p<0.05 and **p<0.01). The x-axis represents treatment condition, and the y-axis represents IFNγ concentration, scaled in pg / mL. [Figure 14] Figure 14 depicts the growth of CT26 tumors in mice, as described in Example 7. Mice were treated with Compound I (IP, 100 mg / kg, 3 times per week), anti-PD-L1 (IP, 5 mg / animal, 2 times per week until termination), and / or oxaliplatin (IP, 10 mg / kg, 3 times per week), and tumors were assessed. The x-axis represents the length of the study in days, and the y-axis represents tumor volume in mm3. [Figure 15]Figure 15 depicts the growth of CT26 tumors in mice, as described in Example 7. Mice were treated with Compound I (IP, 100 mg / kg, 3 times per week), anti-PD-L1 (IP, 5 mg / animal, 2 times per week until termination), and / or oxaliplatin (IP, 10 mg / kg, 3 times per week), and tumors were assessed. The x-axis represents the length of the study in days, and the y-axis represents tumor volume in mm3. [Figure 16] Figure 16 shows CD4+ T cell activation in MC38 tumor-bearing C5BL / 6 mice, as described in Example 8. Mice were treated with oxaliplatin (10 mg / kg, IP) and murine anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) for 4 days, either with (TOP) or without (OP) Compound I (100 mg / kg, IP). 24 hours after the final dose, mice were euthanized and their spleens were harvested. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents activated CD4+ T cells, assessed as a percentage. [Figure 17] Figure 17 shows the activation of CD8+ T cells in MC38 tumor-bearing C5BL / 6 mice, as described in Example 8. Mice were treated with oxaliplatin (10 mg / kg, IP) and murine anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) for 4 days, either with (TOP) or without (OP) Compound I (100 mg / kg, IP). 24 hours after the final dose, mice were euthanized and their spleens were harvested. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents activated CD8+ T cells, assessed as a percentage. [Figure 18]Figure 18 shows the percent proliferation of CD8+ T cells in the presence or absence of Tregs, as described in Example 8. Mice were treated with oxaliplatin (10 mg / kg, IP) and mouse anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) for 4 days, either with (TOP) or without (OP) Compound I (100 mg / kg, IP). 24 hours after the final dose, mice were euthanized and their spleens were harvested. Splenocytes were stimulated ex vivo with anti-CD3 / CD28 antibodies for 72 hours and then stained with IL-2 antibody for flow cytometry analysis. Error bars represent SEM (standard error of the mean). The x-axis represents treatment conditions, and the y-axis represents IL-2-expressing cells, assessed as a percentage. [Figure 19] Figure 19 shows ex vivo phosphorylation of Rb in Tregs isolated from C57BL / 6 mice, as described in Example 9. CD4+CD25+ Tregs were purified from the spleen using a two-step magnetic bead separation method to remove all non-CD4+ cells, followed by positive selection of CD25+ cells. Purified Tregs were cultured ex vivo with anti-CD3 / CD8 antibodies and IL-2 with 0, 250, or 1000 nM of Compound I for 48 hours. Cultured Tregs were then stained with CD4, Foxp3, and phosphor-Rb antibodies for flow cytometry analysis. Error bars represent SEM (standard error of the mean). The x-axis represents the nanomolar concentration of Compound I, and the y-axis represents phospho-Rb+ cells assessed as a percentage. [Figure 20]Figure 20 shows the ex vivo proliferation of CD8+ T cells in the presence of Tregs treated with Compound I, as described in Example 9. Mice were treated with oxaliplatin (10 mg / kg, IP) and mouse anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) for 4 days, either with Compound I (100 mg / kg, IP) (TOP) or without Compound I (OP). 24 hours after the final dose, mice were euthanized and their spleens were harvested. Cells were stained with anti-CD4 and CD8 antibodies, and T cell proliferation was assessed by flow cytometry analysis, as measured by the dilution of the mean fluorescence intensity of CFSE in CD4-CD8+ T cells. Error bars represent SEM (standard error of the mean). The x-axis represents the nanomolar concentration of Compound I, and the y-axis represents the proliferation of CD8+ T cells, assessed as a percentage. [Figure 21] Figure 21 shows the transient inhibition of intratumoral immune cell proliferation in MC38 tumor-bearing C57Bl / 6 mice, as described in Example 10. Mice were treated with a single dose of Compound I (100 mg / kg, IP) followed by incorporation of EdU (200 μg / mouse, IP) 6 to 48 hours after Compound I treatment. Mice were euthanized, and tumors were harvested for analysis. Immune cell labeling was performed for the following immune cell populations: (1) CD8+ T cells; (2) CD4+ T cells; (3) Tregs; (4) NK cells; (5) monocytic myeloid-derived suppressor cells (mMDSCs); (6) granulocytic myeloid-derived suppressor cells (gMDSCs); and (7) macrophages. EdU incorporation was detected by click chemistry followed by flow cytometry analysis. Error bars represent SEM (standard error of the mean). The x-axis represents treatment time in hours, and the y-axis represents EdU+ cells assessed as a percentage. [Figure 22]Figure 22 shows the transient inhibition of intratumoral immune cell proliferation in MC38 tumor-bearing C57Bl / 6 mice, as described in Example 10. Mice were treated with a single dose of Compound I (100 mg / kg, IP) followed by incorporation of EdU (200 μg / mouse, IP) 6 to 48 hours after Compound I treatment. Mice were euthanized, and tumors were harvested for analysis. Immune cells were labeled with antibodies for the following immune cell populations: (1) CD8+ T cells; (2) CD4+ T cells; (3) Tregs; (4) NK cells; (5) monocytic myeloid-derived suppressor cells (mMDSCs); (6) granulocytic myeloid-derived suppressor cells (gMDSCs); and (7) macrophages. EdU incorporation was detected by click chemistry followed by flow cytometry analysis. Error bars represent SEM (standard error of the mean). The x-axis represents treatment time in hours, and the y-axis represents EdU+ cells assessed as a percentage. [Figure 23] Figure 23 shows the enhanced generation of tumor-specific T cells in MC38 tumor-bearing C57BL / 6 mice, as described in Example 11. Mice were treated with oxaliplatin (10 mg / kg, IP) and murine anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with or without (TOP) Compound I (100 mg / kg, IP) for 58 days according to the IM schedule shown in Figure 3. Mice were euthanized and their spleens (Figure 23) and peripheral blood (Figure 24) were collected for analysis. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents tumor-specific T cells assessed as a percentage. [Figure 24]Figure 24 shows the enhanced generation of tumor-specific T cells in MC38 tumor-bearing C57BL / 6 mice, as described in Example 11. Mice were treated with oxaliplatin (10 mg / kg, IP) and murine anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with or without (TOP) Compound I (100 mg / kg, IP) for 58 days according to the IM schedule shown in Figure 3. Mice were euthanized and their spleens (Figure 23) and peripheral blood (Figure 24) were collected for analysis. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents tumor-specific T cells assessed as a percentage. [Figure 25] Figure 25 shows the upregulation of genes that positively regulate interferon-γ expression in MC38 tumor-bearing C57BL / 6 mice, as described in Example 12. Mice were treated with two weekly doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Il2 (Figure 25), Il18 (Figure 26), and Lta (Figure 27) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 26] Figure 26 shows the upregulation of genes that positively regulate interferon-γ expression in MC38 tumor-bearing C57BL / 6 mice, as described in Example 12. Mice were treated with two weekly doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Il2 (Figure 25), Il18 (Figure 26), and Lta (Figure 27) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 27]Figure 27 shows the upregulation of genes that positively regulate interferon-γ expression in MC38 tumor-bearing C57BL / 6 mice, as described in Example 12. Mice were treated with two weekly doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Il2 (Figure 25), Il18 (Figure 26), and Lta (Figure 27) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 28] Figure 28 shows the upregulation of interferon-γ gene expression in MC38 tumor-bearing C57BL / 6 mice, as described in Example 13. Mice were treated for 8 days with compound I (100 mg / kg, IP) (Figure 28); oxaliplatin (100 mg / kg, IP) with (TO) or without (O) compound I (100 mg / kg, IP) (Figure 29); anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TP) or without (P) compound I (100 mg / kg, IP) (Figure 30); and both oxaliplatin (100 mg / kg, IP) and anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TOP) or without (OP) compound I (100 mg / kg, IP) (Figure 31). Twenty-four hours after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents Ifng-normalized and Log2-transformed expression values. [Figure 29]Figure 29 shows the upregulation of interferon-γ gene expression in MC38 tumor-bearing C57BL / 6 mice, as described in Example 13. Mice were treated for 8 days with compound I (100 mg / kg, IP) (Figure 28); oxaliplatin (100 mg / kg, IP) with (TO) or without (O) compound I (100 mg / kg, IP) (Figure 29); anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TP) or without (P) compound I (100 mg / kg, IP) (Figure 30); and both oxaliplatin (100 mg / kg, IP) and anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TOP) or without (OP) compound I (100 mg / kg, IP) (Figure 31). Twenty-four hours after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents Ifng-normalized and Log2-transformed expression values. [Figure 30]Figure 30 shows the upregulation of interferon-γ gene expression in MC38 tumor-bearing C57BL / 6 mice, as described in Example 13. Mice were treated for 8 days with compound I (100 mg / kg, IP) (Figure 28); oxaliplatin (100 mg / kg, IP) with (TO) or without (O) compound I (100 mg / kg, IP) (Figure 29); anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TP) or without (P) compound I (100 mg / kg, IP) (Figure 30); and both oxaliplatin (100 mg / kg, IP) and anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TOP) or without (OP) compound I (100 mg / kg, IP) (Figure 31). Twenty-four hours after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents Ifng-normalized and Log2-transformed expression values. [Figure 31]Figure 31 shows the upregulation of interferon-γ gene expression in MC38 tumor-bearing C57BL / 6 mice, as described in Example 13. Mice were treated for 8 days with compound I (100 mg / kg, IP) (Figure 28); oxaliplatin (100 mg / kg, IP) with (TO) or without (O) compound I (100 mg / kg, IP) (Figure 29); anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TP) or without (P) compound I (100 mg / kg, IP) (Figure 30); and both oxaliplatin (100 mg / kg, IP) and anti-PD-L1 (clone 10F.9G2, 100 μg / mouse, IP) with (TOP) or without (OP) compound I (100 mg / kg, IP) (Figure 31). Twenty-four hours after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents Ifng-normalized and Log2-transformed expression values. [Figure 32] Figure 32 shows downregulation of genes related to reactive oxygen species metabolism in MC38 tumor-bearing C57BL / 6 mice, as described in Example 14. Mice were treated weekly with two doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Cdku1a (Figure 32), Cxcl1 (Figure 33), Il6 (Figure 34), Il10 (Figure 35), Il19 (Figure 36), and Ptgs2 (Figure 37) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 33]Figure 33 shows downregulation of genes related to reactive oxygen species metabolism in MC38 tumor-bearing C57BL / 6 mice, as described in Example 14. Mice were treated with two weekly doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Cdku1a (Figure 32), Cxcl1 (Figure 33), Il6 (Figure 34), Il10 (Figure 35), Il19 (Figure 36), and Ptgs2 (Figure 37) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 34] Figure 34 shows downregulation of genes related to reactive oxygen species metabolism in MC38 tumor-bearing C57BL / 6 mice, as described in Example 14. Mice were treated with two weekly doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Cdku1a (Figure 32), Cxcl1 (Figure 33), Il6 (Figure 34), Il10 (Figure 35), Il19 (Figure 36), and Ptgs2 (Figure 37) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 35]Figure 35 shows downregulation of genes related to reactive oxygen species metabolism in MC38 tumor-bearing C57BL / 6 mice, as described in Example 14. Mice were treated weekly with two doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Cdku1a (Figure 32), Cxcl1 (Figure 33), Il6 (Figure 34), Il10 (Figure 35), Il19 (Figure 36), and Ptgs2 (Figure 37) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 36] Figure 36 shows downregulation of genes related to reactive oxygen species metabolism in MC38 tumor-bearing C57BL / 6 mice, as described in Example 14. Mice were treated weekly with two doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Cdku1a (Figure 32), Cxcl1 (Figure 33), Il6 (Figure 34), Il10 (Figure 35), Il19 (Figure 36), and Ptgs2 (Figure 37) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 37]Figure 37 shows downregulation of genes related to reactive oxygen species metabolism in MC38 tumor-bearing C57BL / 6 mice, as described in Example 14. Mice were treated with two weekly doses of Compound I (100 mg / kg, IP). One day after the final dose, mice were euthanized and tumors were harvested for analysis. Gene expression analysis for Cdku1a (Figure 32), Cxcl1 (Figure 33), Il6 (Figure 34), Il10 (Figure 35), Il19 (Figure 36), and Ptgs2 (Figure 37) was performed on whole tumors using the PanCancer Immune Profiling Panel. Error bars represent SEM (standard error of the mean). The x-axis represents treatment condition, and the y-axis represents normalized and Log2-transformed expression values ​​for selected genes. [Figure 38] Figure 38 shows MC38 tumor growth in mice treated continuously with Compound I (28 daily doses) with or without anti-PD-L1 (2 doses twice weekly). The x-axis represents the length of the study in days, and the y-axis represents tumor volume in mm. [Figure 39] Figure 39 shows intratumoral immune cell proliferation in MC38 tumor-bearing C57BL / 6 mice treated with Compound I, as described in Example 15. Error bars represent SEM (standard error of the mean). The x-axis represents intratumoral immune cell types, and the y-axis represents proliferation assessed as a percentage. [Figure 40] Figure 40 shows intratumoral immune cell proliferation in MC38 tumor-bearing C57BL / 6 mice treated with Compound I, as described in Example 15. Error bars represent SEM (standard error of the mean). The x-axis represents intratumoral immune cell types, and the y-axis represents proliferation assessed as a percentage. [Figure 41] Figure 41 depicts a flow chart outlining the organizational structure of the clinical trial outlined in Example 17. The clinical trial is organized into two phases: induction and maintenance, which can be repeated up to four times. Compound I or placebo is administered in combination with etoposide / carboplatin / atezolizumab (E / P / A) therapy during the induction phase. Atezolizumab alone is administered during the maintenance phase.

[0079] Detailed Description Surprisingly and unexpectedly, it has been discovered that adding a CDK4 / 6 inhibitor to a combination of chemotherapy and checkpoint inhibitors in a highly specific dosing regimen can produce superior results in tumor or cancer treatment. The unexpected finding is that timed administration of a selective CDK4 / 6 inhibitor during the chemotherapy portion of this triple combination therapy has a profound effect on immune cells in the tumor microenvironment. These results are remarkable in that the highly timed administration of a selective, fast-acting, short-half-life CDK4 / 6 inhibitor provides one or more of the following: protection from immune tumor cell infiltrate damage; increased duration of the immune response with a higher frequency of tumor-specific memory T cells; a greater reduction in the immunosuppressive intratumoral Treg cells; and / or altered gene expression of proinflammatory factors. Expression of genes functionally enriched for lymphocyte activation and upregulation of the proinflammatory cytokine interferon-γ is significantly enhanced. In parallel, several genes involved in immunosuppressive reactive oxygen species metabolic processes are downregulated. These findings indicate that timed administration of CDK4 / 6 inhibitors, such as fast-acting, short-half-life CDK4 / 6 inhibitors, results in modulation of gene expression, creating a pro-inflammatory tumor microenvironment favorable for enhancing checkpoint inhibitor activity, an improvement that represents a significant advance in the state of the art in cancer treatment.

[0080] Non-limiting examples of CDK4 / 6 inhibitors contemplated for use herein include, but are not limited to, Compounds I, II, III, and IV, which are highly potent, selective, reversible cyclin-dependent kinase (CDK) 4 / 6 inhibitors that transiently arrest the G0 / G1 cell cycle of HSPCs and immune effector cells. These cells depend on CDK4 / 6 for proliferation and are arrested in the G0 / G1 phase of the cell cycle when exposed to, for example, Compound I. The transient arrest of HSPCs and other immune effector cells in G0 / G1 renders them more resistant to the DNA-damaging effects of chemotherapy, thus reducing subsequent immune cytotoxicity. Furthermore, it has been found that the combination of CDK4 / 6 inhibitors with chemotherapy drugs and immune checkpoint inhibitors for cancer treatment enhances anti-cancer immune responses. The specific timing of administration of CDK4 / 6 inhibitors protects immune effector cells from chemotherapy drug damage and allows them to return to cell replication some time after the DNA-damaging effects of chemotherapy drugs have dissipated, resulting in improved immune responsiveness compared to strategies using CDK4 / 6 inhibitors administered in a daily manner, which results in complete and permanent inhibition of CDK4 / 6.

[0081] Initial attempts at immunotherapy focused on the combination of chemotherapy and cytokines, so-called "chemoimmunotherapy." However, this approach was hampered by high rates of toxicity without significant improvement in survival outcomes (Atzpodien, J.; Kirchner, H.; Rebmann, U.; Soder, M.; Gertenbach, U.; Siebels, M.; Roigas, J.; Raschke, R.; Salm, S.; Schwindi, B.; et al. Interleukin-2 / interferon-alpha2a / 13-retinoic acid-based chemoimmunotherapy in advanced renal cell carcinoma: Results of a prospectively randomized trial of the German Cooperative Renal Carcinoma Chemoimmunotherapy Group (DGCIN). Br. J. Cancer 2006, 95, 463-469). Interestingly, cytokine therapy provided robust benefit only in a subset of patients, mostly those with clinical or serologic evidence of autoimmunity (Gogas, H.; Ioannovich, J.; Dafni, U.; Stavropoulou-Giokas, C.; Frangia, K.; Tsoutsos, D.; Panagiotou, P.; Polyzos, A.; Papadopoulos, O.; Stratigios, A.; et al. Prognostic significance of autoimmunity during treatment of melanoma with interferon. N. Engl. J. Med. 2006, 354, 709–718). Other immunomodulatory agents have also been administered, with mixed results.For example, the anthelmintic drug levamisole was found to have immune-enhancing properties and was approved for use in colon cancer as an adjunct to 5-fluorouracil (5-FU), but subsequent studies did not appear to demonstrate benefit (Wolmark, N.; Rockette, H.; Mamounas, E.; Jones, J.; Wieand, S.; Wickerham, DL; Bear, HD; Atkins, JN; Dimitrov, NV; Glass, AG; et al. Clinical trial to assess the relative efficacy of fluorouracil and leucovorin, fluorouracil and levamisole, and fluorouracil, leucovorin, and levamisole in patients with Dukes' B and C carcinoma of the colon: Results from National Surgical Adjuvant Breast and Bowel Project C-04. J. Clin. Oncol. 1999, 17, 3553-3559).Bacillus Calmette-Guérin (BCG), originally developed as a vaccine against tuberculosis, provides robust anticancer responses when given intravesically in bladder cancer and has remained the standard of care for superficial invasive bladder cancer since it was first approved for this indication in 1990 (Mungan, NA; Witjes, JA. Bacille Calmette-Guérin in superficial transitional cell carcinoma. Br. J. Urol. 1998, 82, 213-223; Sylvester, RJ; van der Meijden, AP; Witjes, JA; Kurth, K. Bacillus calmette-guerin versus chemotherapy for the intravesical treatment of patients with carcinoma in situ of the bladder: A meta-analysis of the published results of randomized clinical trials. J. Urol. 2005, 174, 86-91).

[0082] More recent approaches have focused on blocking the ability of certain proteins, called immune checkpoint proteins, to limit the strength and duration of immune responses. These proteins normally suppress immune responses by preventing overly strong responses that could harm normal and abnormal cells, but cancers that express these proteins can suppress immune responses (see Menon, S.; Shin, S.; Dy, G.; Advances in Cancer Immunotherapy in Solid Tumors, Cancers 2016, 8(12), 106). Blocking the activity of immune checkpoint proteins enhances the ability of immune effector cells to destroy cancer cells.

[0083] technical terms Compounds are described using standard nomenclature conventions. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0084] The terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referred item. The term "or" means "and / or." Unless otherwise stated herein, the recitation of ranges of values ​​is merely intended as a shorthand method of referring individually to each individual value falling within the range, and each individual value is incorporated herein as if it were individually listed herein. The endpoints of all ranges are included within the range and are independently combinable. All methods described herein can be performed in any suitable order unless otherwise stated herein or otherwise clearly contradicted by context. Examples or illustrative language (e.g., "etc.") are intended merely to better describe the present invention and do not pose limitations on the scope of the present invention unless otherwise stated. Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0085] In a non-limiting embodiment, a CDK4 / 6 inhibitor, such as, but not limited to, Compound I, Compound II, Compound III, or Compound IV, a chemotherapy, or a checkpoint inhibitor, can be used in a form having at least one desired isotopic substitution of an atom, in an amount that exceeds the natural abundance of the isotope, i.e., is enriched. Isotopes are atoms having the same atomic number but different mass numbers, i.e., the same number of protons but different numbers of neutrons.

[0086] Examples of isotopes that may be incorporated into CDK4 / 6 inhibitors, chemotherapeutics, or checkpoint inhibitors for use in the present invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, fluorine, chlorine, and iodine, e.g., 2 H,3 H, 11 C. 13 C. 14 C. 15 N, 18 F 31 P, 32 P, 35 S, 36 CI, and 125 In one non-limiting embodiment, the isotope-labeled compounds are used in metabolic studies such as positron emission tomography (PET) or single photon emission computed tomography (SPECT), including drug or substrate tissue distribution assays. 14 C), reaction kinetics studies (e.g., 2 H or 3 H), detection or imaging techniques, or radiation treatment of patients. 18 F-labeled compounds may be particularly desirable for PET or SPECT studies. Isotopically labeled compounds of the present invention and their prodrugs can generally be prepared by following the procedures disclosed in the schemes or examples and by substituting readily available isotopically labeled reagents for non-isotopically labeled reagents.

[0087] By way of general example and without limitation, isotopes of hydrogen, such as deuterium ( 2 H) and tritium ( 3 H) may be used anywhere within the depicted structures that achieves the desired result. Alternatively, or in addition, isotopes of carbon, such as 13 C and 14 C can also be used.

[0088] Isotopic substitution, e.g., deuterium substitution, can be partial or complete. Partial deuterium substitution means that at least one hydrogen is replaced with deuterium. In certain embodiments, the isotope is enriched at any location of interest by 90, 95, or 99% or more. In one non-limiting embodiment, deuterium is enriched at 90, 95, or 99% at any desired location.

[0089] The CDK4 / 6 inhibitors for use in the present invention may form solvates with solvents (including water). Thus, in one non-limiting embodiment, the present invention includes solvate forms of the compounds. The term "solvate" refers to a molecular complex of a compound of the present invention (including its salts) with one or more solvent molecules. Non-limiting examples of solvents include water, ethanol, dimethyl sulfoxide, acetone, and other common organic solvents. The term "hydrate" refers to a molecular complex comprising a compound of the present invention and water. Pharmaceutically acceptable solvates according to the present invention include solvates in which the solvent may be isotopically substituted, for example, DO, d6-acetone, d6-DMSO. The solvate may be in liquid or solid form.

[0090] As generally contemplated herein, the term hematopoietic stem and progenitor cells (HSPCs) includes, but is not limited to, long-term hematopoietic stem cells (LT-HSCs), short-term hematopoietic stem cells (ST-HSCs), hematopoietic progenitor cells (HPCs), multipotent progenitor cells (MPPs), oligodendrocyte progenitor cells (OPPs), monocytic progenitor cells, granulocytic progenitor cells, common myeloid progenitor cells (CMPs), common lymphoid progenitor cells (CLPs), granulocyte-monocytic progenitor cells (GMPs), granulocytic progenitor cells (GPCs), and granulocytic progenitor cells (GPCs). These include monocytic and erythroid progenitors (MEPs), megakaryocytic progenitors, erythroid progenitors, HSCs / MPPs (CD45dim / CD34+ / CD38-), OPPs (CD45dim / CD34+ / CD38+), monocytic progenitors (CD45+ / CD14+ / CD11b+), granulocytic progenitors (CD45+ / CD14- / CD11b+), erythroid progenitors (CD45- / CD71+), and megakaryocytic progenitors (CD45+ / CD61+).

[0091] The term "immune effector cells" generally refers to immune cells that perform one or more specific functions. Immune effector cells are known in the art and include, for example, but are not limited to, T cells, including naive T cells, memory T cells, activated T cells (T helper (CD4+) and cytotoxic T cells (CD8+)), TH1-activated T cells, TH2-activated T cells, and TH17-activated T cells, naive B cells, memory B cells, plasmablasts, dendritic cells, monocytes, myeloid-derived suppressor cells (MDSCs), and natural killer (NK) cells.

[0092] The term "selective CDK4 / 6 inhibitor," as used in reference to compounds described herein, refers to a compound having an IC50 or IC6 concentration required to inhibit CDK2 activity to the same extent in a standard phosphorylation assay. 50 IC at most about 50, 100, 200, 300, 400, 500, 1000, 1500, 1800, 2000, 5000, or 10,000 times lower than the molar concentration 50 Included are compounds that, at molar concentrations, inhibit CDK4 activity, CDK6 activity, or both CDK4 and CDK6 activity.

[0093] The term "rapid-acting CDK4 / 6 inhibitor" refers to a compound that exhibits a rapid onset of biological activity upon administration and a short period of C max For example, a fast-acting CDK4 / 6 inhibitor may achieve a T of about 2 hours, about 1 hour, less than about 30 minutes, or about 15 minutes or less after administration. max may have:

[0094] The term "short half-life CDK4 / 6 inhibitor" refers to a compound having a half-life of, for example, less than about 16 hours, 15 hours, 14 hours, 13 hours, 12 hours, 11 hours, 10 hours, 9 hours, or about 8 hours. In medical terms, the half-life of a drug is the time it takes for the plasma concentration of the drug to reach half of its original concentration.

[0095] The subject to be treated is generally a human subject, although it should be understood that the methods described herein are also effective for other animals, such as mammalian and vertebrate species. More particularly, the term subject includes animals used in assays, such as those used in preclinical trials, including, but not limited to, mice, rats, monkeys, dogs, pigs, and rabbits, as well as domestic swine (pigs and hogs), ruminants, horses, poultry, cats, cattle, mice, and dogs.

[0096] In some embodiments, the term "CDK4 / 6 replication-independent cancer" refers to a cancer that does not significantly require CDK4 / 6 activity for replication. These types of cancer are often, but not always, characterized by (e.g., have cells that exhibit) elevated levels of CDK2 activity or decreased expression of retinoblastoma tumor suppressor proteins or retinoblastoma family member proteins, such as, but not limited to, p107 and p130. The elevated levels of CDK2 activity or decreased or absent expression of retinoblastoma tumor suppressor proteins or retinoblastoma family member proteins may be elevated or decreased, for example, compared to normal cells. In some embodiments, the elevated levels of CDK2 activity may be associated with (e.g., resulting from or seen in conjunction with) amplification or overexpression of the MYC proto-oncogene. In some embodiments, the elevated levels of CDK2 activity may be associated with overexpression of cyclin E1, cyclin E2, or cyclin A.

[0097] In some embodiments, the term "CDK4 / 6 replication-dependent cancer" refers to cancers that require CDK4 / 6 activity for replication or proliferation, or whose growth can be inhibited by the activity of a selective CDK4 / 6 inhibitor. Such types of cancers and disorders can be characterized by the presence of functional retinoblastoma protein (e.g., have cells that exhibit the presence). Such cancers and disorders are classified as Rb-positive. Rb-positive abnormal cell proliferation disorders, and variations of this term, as used herein, refer to disorders or diseases caused by uncontrolled or abnormal cell division characterized by functional retinoblastoma protein, which can include cancer.

[0098] CDK4 / 6 inhibitors The present invention is directed to the use of timed administration of a CDK4 / 6-specific inhibitor in combination with a chemotherapeutic agent and an immune checkpoint inhibitor, e.g., a PD-1 inhibitor, a PD-L1 inhibitor, or a CTLA-4 inhibitor, to treat a subject with cancer.

[0099] Cell cycle regulation is governed and controlled by specific proteins that are activated and deactivated in a strictly timed manner, primarily through phosphorylation / dephosphorylation processes. Key proteins that regulate the initiation, progression, and completion of the cell cycle program are cyclin-dependent kinases (CDKs). Cyclin-dependent kinases belong to the serine-threonine protein kinase family. CDKs are heterodimeric complexes composed of a catalytic kinase subunit and a regulatory cyclin subunit. CDK activity is controlled by association with their corresponding regulatory subunits (cyclins) and CDK inhibitor proteins (Cip & Kip proteins, INK4), their phosphorylation status, and ubiquitin-mediated proteolysis (see DG Johnson, CL Walker, Annu. Rev. Pharmacol. Toxicol 39 (1999) 295-312; DO Morgan, Annu. Rev. Cell Dev. Biol. 13 (1997) 261-291; CJ Sherr, Science 274 (1996) 1672-1677; T. Shimamura et al., Bioorg. Med. Chem. Lett. 16 (2006) 3751-3754).

[0100] There are four CDKs significantly involved in cell proliferation: CDK1, which primarily regulates the G2 to M phase transition, and CDK2, CDK4, and CDK6, which regulate the G1 to S phase transition (Malumbres M, Barbacid M. Cell cycle, CDKs and cancer: a changing paradigm. Nat. Rev. Cancer 2009;9(3):153-166). At the beginning of mid-G1, if the cell is responsive to mitogenic stimuli, activation of CDK4-cyclin D and CDK6-cyclin D induces phosphorylation of the retinoblastoma protein (pRb). Phosphorylation of pRb liberates the transcription factor E2F, which enters the nucleus and activates the transcription of other cyclins that promote further progression through the cell cycle (see J.A. Diehl, Cancer Biol. Ther. 1 (2002) 226-231; C.J. Sherr, Cell 73 (1993) 1059-1065). CDK4 and CDK6 are closely related proteins with essentially indistinguishable biochemical properties (see M. Malumbres, M. Barbacid, Trends Biochem. Sci. 30 (2005) 630-641).

[0101] A variety of pyrimidine-based drugs have been developed for the treatment of hyperproliferative diseases.Tavares and Strum have filed for U.S. Patent No. 8,822,683; U.S. Patent No. 8,598,197; U.S. Patent No. 8,598,186, U.S. Patent No. 8,691,830, U.S. Patent No. 8,829,102, U.S. Patent No. 9,102,683 and U.S. Patent No. 9,260,442, and corresponding WO2012 / 061156, which are assigned to G1 Therapeutics, describe the cyclin-dependent kinase inhibitor of N-(heteroaryl)-pyrrolo[3,2-d]pyrimidin-2-amine type, including formula (wherein variables are as defined herein). [ka]

[0102] WO 2013 / 148748 (USSN 61 / 617,657) entitled "Lactam Kinase Inhibitors," WO 2013 / 163239 (USSN 61 / 638,491) entitled "Synthesis of Lactams," and WO 2015 / 061407 filed by Tavares and also assigned to G1 Therapeutics, describe the synthesis of N-(heteroaryl)-pyrrolo[3,2-d]pyrimidin-2-amines and their use as lactam kinase inhibitors.

[0103] Other publications include: WO2014 / 144326, filed by Strum et al. and assigned to G1 Therapeutics, describes compounds and methods for protecting normal cells during chemotherapy using pyrimidine-based CDK4 / 6 inhibitors; WO2014 / 144596, filed by Strum et al. and assigned to G1 Therapeutics, describes compounds and methods for protecting hematopoietic stem and progenitor cells from electromagnetic radiation using pyrimidine-based CDK4 / 6 inhibitors; WO2014 / 144847, filed by Strum et al. and assigned to G1 Therapeutics, describes HSPC tolerance treatment of abnormal cell proliferation using pyrimidine-based CDK4 / 6 inhibitors; WO2014 / 144740, filed by Strum et al. and assigned to G1 Therapeutics, describes highly active antineoplastic and antiproliferative pyrimidine-based CDK4 / 6 inhibitors; WO2014 / 144847, filed by Strum et al. and assigned to G1 Therapeutics, describes HSPC tolerance treatment of abnormal cell proliferation using pyrimidine-based CDK4 / 6 inhibitors; WO 2015 / 161285, filed by Strum et al. and assigned to G1 Therapeutics, describes tricyclic pyrimidine CDK inhibitors for use in radioprotection; WO 2015 / 161287, filed by Strum et al. and assigned to G1 Therapeutics, describes similar tricyclic pyrimidine CDK inhibitors for the protection of cells during chemotherapy; WO 2015 / 161283, filed by Strum et al. and assigned to G1 Therapeutics, describes similar tricyclic pyrimidine CDK inhibitors for use in SPC tolerance treatment of RB-positive abnormal cell growth; WO 2015 / 161288, filed by Strum et al. and assigned to G1 Therapeutics, describes similar tricyclic pyrimidine CDK inhibitors for use as anti-neoplastic and anti-proliferative agents; WO 2015 / 161289, filed by Strum et al. and assigned to G1 Therapeutics, describes similar tricyclic pyrimidine CDK inhibitors for use as anti-neoplastic and anti-proliferative agents. WO2016 / 040858, assigned to G1 Therapeutics, describes the use of pyrimidine CDK4 / 6 inhibitors in combination with other anti-neoplastic agents; WO2016 / 040848, filed by Strum et al. and assigned to G1 Therapeutics, describes compounds and methods for treating Rb-negative cancers with CDK4 / 6 inhibitors and topoisomerase inhibitors;WO2016 / 126889, filed by Strum et al. and assigned to G1 Therapeutics, describes specific formulations for the treatment of cancer with CDK4 / 6 inhibitors.

[0104] WO2003 / 062236 identifies a series of 2-(pyridin-2-ylamino-pyrido[2,3]pyrimidin-7-ones that exhibit selectivity for CDK4 / 6 for the treatment of Rb-positive cancers, including 6-acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino(ylamino))-8H-pyrido-[2,3-d]-pyrimidin-7-one (PD0332991), which has received accelerated approval by the FDA and is currently marketed by Pfizer as Ibrance™ (palbociclib) for the treatment of metastatic breast cancer. [ka]

[0105] VanderWel et al. have described iodine-containing pyrido[2,3-d]pyrimidin-7-ones (CKIAs) as potent and selective CDK4 inhibitors (see VanderWel et al., J. Med. Chem. 48 (2005) 2371-2387).

[0106] WO2010 / 020675, filed by Novartis AG, describes pyrrolopyrimidine compounds as CDK inhibitors, and WO2011 / 101409, also filed by Novartis, describes pyrrolopyrimidines with CDK4 / 6 inhibitory activity. U.S. Patent Nos. 8,324,225; 8,415,355; 8,685,980; 9,962,630; 9,193,732; and 9,416,136, filed by Novartis AG and Astex Therapeutics Limited, describe pyrrolopyrimidine compounds as CDK inhibitors, including 7-cyclopentyl-N,N-dimethyl-2-((5-(piperidin-4-yl)pyridin-2-yl)amino)-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide, which has been approved by the FDA for the treatment of metastatic breast cancer and is currently sold as Kisqali™ (ribociclib). [ka]

[0107] U.S. Patent No. 7,855,211 describes benzimidazole compounds useful as CDK4 / 6 inhibitors, including N-(5-((4-ethylpiperazin-1-yl)methyl)pyridin-2-yl)-5-fluoro-4-(4-fluoro-1-isopropyl-2-methyl-1H-benzo[d]imidazol-6-yl)pyrimidin-2-amine, which has been approved by the FDA for the treatment of certain types of breast cancer and is currently sold by Eli Lilly and Company as Verzenio™ (abemaciclib). [ka]

[0108] Johnson et al. reported that pharmacological inhibition of CDK4 / 6 using the CDK4 / 6 inhibitors 6-acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino(ylammino))-8H-pyrido-[2,3-d]-pyrimidin-7-one (PD0332991) and 2-bromo-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4]carbazole-5,6-dione (2BrIC) exhibited IR-protective properties in CDK4 / 6-dependent cell lines (Johnson et al. Mitigation of hematological radiation toxicity in mice through pharmacological quiescence induced by CDK4 / 6 inhibition. J Clin. Invest. 2010;120(7):2528-2536).

[0109] Compounds I, II, III, and IV can be prepared as previously described in WO2014 / 144326, the entire contents of which are incorporated herein by reference.

[0110] In certain examples, as contemplated herein, the CDK4 / 6 inhibitor is selected from any known CDK4 / 6 inhibitor, such as trilaciclib, palbociclib, abemaciclib, and ribociclib. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the fast-acting, short-half-life CDK4 / 6 inhibitor is selected from Compound I (trilaciclib), Compound II, Compound III, or Compound IV, or a pharmaceutically acceptable composition, salt, isotopic analog, or prodrug thereof. In certain embodiments, the CDK4 / 6 inhibitor is Compound I. In certain embodiments, the CDK4 / 6 inhibitor is Compound II. In certain embodiments, the CDK4 / 6 inhibitor is Compound III. In certain embodiments, the CDK4 / 6 inhibitor is Compound IV.

[0111] Immune checkpoint inhibitors Immune checkpoint inhibitors for use in the methods described herein include, but are not limited to, PD-1 inhibitors, PD-L1 inhibitors, PD-L2 inhibitors, CTLA-4 inhibitors, LAG-3 inhibitors, TIM-3 inhibitors, and V-domain Ig suppressor of T-cell activation (VISTA) inhibitors, or combinations thereof.

[0112] In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor that blocks the interaction between PD-1 and PD-L1 by binding the PD-1 receptor, thereby inhibiting immunosuppression. In one embodiment, the immune checkpoint inhibitor is a PD-1 immune checkpoint inhibitor selected from nivolumab (Opdivo™), pembrolizumab (Keytruda™), pidilizumab, AMP-224 (AstraZeneca and MedImmune), PF-06801591 (Pfizer), MEDI0680 (AstraZeneca), PDR001 (Novartis), REGN2810 (Regeneron), MGA012 (MacroGenics), BGB-A317 (BeiGene) SHR-12-1 (Jiangsu Hengrui Medicine Company and Incyte Corporation), TSR-042 (Tesaro), and the PD-L1 / VISTA inhibitor CA-170 (Curis Inc.). In one embodiment, the PD-1 inhibitor is used in combination with a CDK4 / 6 inhibitor selected from Compound I or Compound II. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0113] In one embodiment, the immune checkpoint inhibitor is the PD-1 immune checkpoint inhibitor nivolumab (Opdivo™) administered in an effective amount for the treatment of Hodgkin's lymphoma, melanoma, non-small cell lung cancer, hepatocellular carcinoma, or ovarian cancer. Nivolumab has received FDA approval for use in metastatic melanoma, non-small cell lung cancer, and renal cell carcinoma. In another aspect of this embodiment, the immune checkpoint inhibitor is the PD-1 immune checkpoint inhibitor pembrolizumab (Keytruda™) administered in an effective amount for the treatment of melanoma, non-small cell lung cancer, small cell lung cancer, head and neck cancer, or urothelial carcinoma. In a further aspect of this embodiment, the immune checkpoint inhibitor is the PD-1 immune checkpoint inhibitor pidilizumab (Medivation) administered in an effective amount for refractory diffuse large B-cell lymphoma (DLBCL) or metastatic melanoma.

[0114] In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor that blocks the interaction between PD-1 and PD-L1 by binding to the PD-L1 receptor, thereby inhibiting immunosuppression. PD-L1 inhibitors include, but are not limited to, atezolizumab, durvalumab, KN035CA-170 (Curis Inc.), and LY3300054 (Eli Lilly). In one embodiment, the PD-L1 inhibitor is used in combination with a CDK4 / 6 inhibitor selected from Compound I or Compound II. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the PD-L1 inhibitor blocks the interaction between PD-L1 and CD80, thereby inhibiting immunosuppression.

[0115] In one embodiment, the immune checkpoint inhibitor is the PD-L1 immune checkpoint inhibitor atezolizumab (Tecentriq™) administered in an amount effective for treating metastatic bladder cancer, metastatic melanoma, metastatic non-small cell lung cancer, or metastatic renal cell carcinoma. In another aspect of this embodiment, the immune checkpoint inhibitor is durvalumab (AstraZeneca and MedImmune) administered in an amount effective for treating non-small cell lung cancer or bladder cancer. In yet another aspect of this embodiment, the immune checkpoint inhibitor is KN035 (Alphamab) administered in an amount effective for treating PD-L1-positive solid tumors. A further example of a PD-L1 immune checkpoint inhibitor is BMS-936559 (Bristol-Myers Squibb), although clinical trials with this inhibitor are on hold for 2015.

[0116] In one aspect of this embodiment, the immune checkpoint inhibitor is a CTLA-4 immune checkpoint inhibitor that binds to CTLA-4 and inhibits immunosuppression. CTLA-4 inhibitors include, but are not limited to, ipilimumab, tremelimumab (AstraZeneca and MedImmune), AGEN1884, and AGEN2041 (Agenus). In one embodiment, the CTLA-4 inhibitor is combined with a CDK4 / 6 inhibitor selected from Compound I or Compound II. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0117] In one embodiment, the CTLA-4 immune checkpoint inhibitor is ipilimumab (Yervoy™) administered in an amount effective for the treatment of metastatic melanoma, adjuvant melanoma, or non-small cell lung cancer. In one embodiment, the CTLA-4 inhibitor is combined with a CDK4 / 6 inhibitor selected from Compound I or Compound II. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0118] In another embodiment, the immune checkpoint inhibitor is a LAG-3 immune checkpoint inhibitor. Examples of LAG-3 immune checkpoint inhibitors include, but are not limited to, BMS-986016 (Bristol-Myers Squibb), GSK2831781 (GlaxoSmithKline), IMP321 (Prima BioMed), LAG525 (Novartis), and the PD-1 and LAG-3 dual inhibitor MGD013 (MacroGenics). In yet another aspect of this embodiment, the immune checkpoint inhibitor is a TIM-3 immune checkpoint inhibitor. Specific TIM-3 inhibitors include, but are not limited to, TSR-022 (Tesaro).

[0119] Other immune checkpoint inhibitors for use in the invention described herein include, but are not limited to, B7-H3 / CD276 immune checkpoint inhibitors such as MGA217, indoleamine 2,3-dioxygenase (IDO) immune checkpoint inhibitors such as indoximod and INCB024360, killer immunoglobulin-like receptor (KIR) immune checkpoint inhibitors such as lirilumab (BMS-986015), carcinoembryonic antigen cell adhesion molecule (CEACAM) inhibitors (e.g., CEACAM-1, -3 and / or -5). Exemplary anti-CEACAM-1 antibodies are described in WO2010 / 125571, WO2013 / 082366, and WO2014 / 022332, such as monoclonal antibodies 34B1, 26H7, and 5F4; or recombinant versions thereof, such as those described in US2004 / 0047858, U.S. Patent No. 7,132,255, and WO99 / 052552. In other embodiments, the anti-CEACAM antibody binds to CEACAM-5, e.g., as described in Zheng et al. PLoS One. 2010 September 2; 5(9). pii: e12529 (DOI:10:1371 / journal.pone.0021146), or cross-reacts with CEACAM-1 and CEACAM-5, e.g., as described in WO2013 / 054331 and US2014 / 0271618.Yet other checkpoint inhibitors can be molecules against the B and T lymphocyte attenuator (BTLA), as described, for example, in Zhang et al., Monoclonal antibodies to B and T lymphocyte attenuator (BTLA) have no effect on in vitro B cell proliferation and act to inhibit in vitro T cell proliferation when presented in a cis, but not trans, format relative to the activating stimulus, Clin Exp Immunol. 2011 Jan; 163(1): 77-8.

[0120] chemotherapy drugs As contemplated herein, timed administration of selective, fast-acting, short half-life CDK4 / 6 inhibitors can be combined with any standard chemotherapy treatment, and can also be combined with immune checkpoint inhibitors.

[0121] In one embodiment, the chemotherapeutic agent is toxic to immune effector cells. In one embodiment, the chemotherapeutic agent inhibits cell growth. In one embodiment, the administered cytotoxic chemotherapeutic agent is a DNA-damaging chemotherapeutic agent. In one embodiment, the chemotherapeutic agent is a protein synthesis inhibitor, a DNA-damaging chemotherapeutic agent, an alkylating agent, a topoisomerase inhibitor, an RNA synthesis inhibitor, a DNA complex binder, a thiolate alkylating agent, a guanine alkylating agent, a tubulin binder, a DNA polymerase inhibitor, an anticancer enzyme, a RAC1 inhibitor, a thymidylate synthase inhibitor, an oxyazophosphorine compound, an integrin inhibitor (e.g., cilengitide, camptothecin, or homocamptothecin), an antifolate, or an antifolate.

[0122] Cytotoxic chemotherapy drugs Cytotoxic DNA-damaging chemotherapeutic agents tend to be nonspecific and, especially at high doses, are toxic to normal, rapidly dividing cells such as HSPCs and immune effector cells. As used herein, the term "DNA-damaging" chemotherapy or chemotherapeutic agent refers to treatment with a cytostatic or cytotoxic agent (i.e., a compound) to reduce or suppress the growth or proliferation of unwanted cells, such as cancer cells, where the cytotoxic effect of the agent can be the result of one or more of nucleic acid intercalation or binding, DNA or RNA alkylation, inhibition of RNA or DNA synthesis, inhibition of another nucleic acid-related activity (e.g., protein synthesis), or any other cytotoxic effect. Such compounds include, but are not limited to, DNA-damaging compounds that can kill cells. "DNA-damaging" chemotherapeutic agents include, but are not limited to, alkylating agents, DNA intercalators, protein synthesis inhibitors, DNA or RNA synthesis inhibitors, DNA base analogs, topoisomerase inhibitors, telomerase inhibitors, and telomeric DNA-binding compounds. For example, alkylating agents include alkyl sulfonates such as busulfan, improsulfan, and piposulfan; aziridines such as benzodizepa, carboquone, meturedepa, and uredepa; ethyleneimines and methylmelamines such as altretamine, triethylenemelamine, triethylenephosphoramide, triethylenethiophosphoramide, and trimethylolmelamine; nitrogen mustards such as chlorambucil, chlornaphazine, cyclophosphamide, estramustine, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, nobembine, phenesterine, prednimustine, trofosfamide, and uracil mustard; and nitrosoureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, and ranimustine. Other DNA-damaging chemotherapy drugs include daunorubicin, doxorubicin, idarubicin, epirubicin, mitomycin, and streptozocin.Chemotherapeutic antimetabolites include gemcitabine, mercaptopurine, thioguanine, cladribine, fludarabine phosphate, fluorouracil (5-FU), floxuridine, cytarabine, pentostatin, methotrexate, azathioprine, acyclovir, adenine β-1-D-arabinoside, amethopterin, aminopterin, 2-aminopurine, aphidicolin, 8-azaguanine, azaserine, 6-azauracil, 2'-azido-2'-deoxynucleosides, 5-bromodeoxycytidine, cytosine β-1-D-arabinoside, diazooxynorleucine, dideoxynucleosides, 5-fluorodeoxycytidine, 5-fluorodeoxyuridine, and hydroxyurea.

[0123] Chemotherapeutic protein synthesis inhibitors include abrin, aurintricarboxylic acid, chloramphenicol, colicin E3, cycloheximide, diphtheria toxin, edeine A, emetine, erythromycin, ethionine, fluoride, 5-fluorotryptophan, fusidic acid, guanylylmethylenediphosphonic acid and guanylylimidodiphosphate, kanamycin, kasugamycin, kirromycin, and O-methylthreonine. Additional protein synthesis inhibitors include modeccin, neomycin, norvaline, pactamycin, paromomycin, puromycin, ricin, Shiga toxin, showdomycin, sparsomycin, spectinomycin, streptomycin, tetracycline, thiostrepton, and trimethoprim.

[0124] Inhibitors of DNA synthesis include alkylating agents such as dimethyl sulfate, nitrogen and sulfur mustards; intercalating agents such as acridine dyes, actinomycin, anthracene, benzopyrene, ethidium bromide, and propidium diiodide-intertwining; and other agents such as distamycin and netropsin. Topoisomerase inhibitors such as irinotecan, teniposide, coumermycin, nalidixic acid, novobiocin, and oxolinic acid; cell division inhibitors including colcemid, mitoxantrone, colchicine, vinblastine, and vincristine; and RNA synthesis inhibitors including actinomycin D, α-amanitin and other fungal amatoxins, cordycepin (3'-deoxyadenosine), dichlororibofuranosylbenzimidazole, rifampicin, streptovaricin, and streptolydigin are also useful DNA-damaging compounds.

[0125] In one embodiment, the chemotherapeutic agent is a DNA complex binding agent such as camptothecin or etoposide; a thiolate alkylating agent such as nitrosourea, BCNU, CCNU, ACNU, or fotemustine; a guanine alkylating agent such as temozolomide; vinblastine, vincristine, vinorelbine, vinflunine, cryptophycin 52, halichondrins (e.g., halichondrin B), dolastatin (e.g., dolastatin 10 and dolastatin 15), hemiasterlins (e.g., hemiasterlin A and hemiasterlin B), colchicine, combrestatin, 2-methoxameridine, benzodiazepine, benzophenone, benzodiazepine, benzophenone, benzodiazepine, benzophenone, benzodiazepine, benzophenone, benzophenone, benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-4, benzophenone-5, benzophenone-6, benzophenone-7, benzophenone-8, benzophenone-9, benzophenone-11, benzophenone-12, benzophenone-13, benzophenone-14, benzophenone-15, benzophenone-15-one, benzophenone-15-one, benzophenone-16, benzophenone-17, benzophenone-18, benzophenone-19, benzophenone-20, benzophenone-21, benzophenone-22, benzophenone-23, benzophenone-24, benzophenone-25, benzophenone-26, benzophenone-27, benzophenone-28, benzophenone-29, benzophenone-30, benzophenone-31, benzophenone-32, benzophenone-33 tubulin binding agents such as schiestradiol, E7010, paclitaxel, docetaxel, epothilone, discodermolide; DNA polymerase inhibitors such as cytarabine; anticancer enzymes such as asparaginase; Rac1 inhibitors such as 6-thioguanine; thymidylate synthase inhibitors such as capecitabine or 5-FU; oxyazophosphorine compounds such as cytoxan; integrin inhibitors such as cilengitide; antifolates such as pralatrexate; antifolates such as pemetrexed; or camptothecins or homocamptothecins, e.g., diflomotecan.

[0126] In one embodiment, the topoisomerase inhibitor is a type I inhibitor. In another embodiment, the topoisomerase inhibitor is a type II inhibitor.

[0127] Other DNA-damaging chemotherapeutic agents whose toxic effects may be mitigated by the presently disclosed selective CDK4 / 6 inhibitors include, but are not limited to, cisplatin, hydrogen peroxide, carboplatin, procarbazine, ifosfamide, bleomycin, plicamycin, taxol, transplatin, thiotepa, and oxaliplatin, as well as similarly acting agents. In one embodiment, the DNA-damaging chemotherapeutic agent is selected from the group consisting of cisplatin, carboplatin, camptothecin, and etoposide.

[0128] Other suitable chemotherapeutic agents include, but are not limited to, radioactive molecules, toxins (also called cytotoxins or cytotoxic agents, which include any agent detrimental to cell viability, multiple agents, and liposomes or other vesicles containing chemotherapeutic compounds). Common anti-cancer pharmaceutical agents include vincristine (Oncovin™), liposomal vincristine (Marqibo™), doxorubicin (Adriamycin™), cytarabine (cytosine arabinoside, ara-C, or Cytosar™), L-asparaginase (Elspar™) or PEG-L-asparaginase (pegaspargase or Oncaspar™), etoposide (VP-16), teniposide (Vumon™), 6-mercaptopurine (6-MP or Purinethol™), prednisone, and dexamethasone (Decadron).Examples of additional suitable chemotherapeutic agents include, but are not limited to, 5-fluorouracil, dacarbazine, alkylating agents, anthramycin (AMC), mitotic inhibitors, cis-dichlorodiamineplatinum(II) (DDP) cisplatin, diaminodichloroplatinum, anthracyclines, antibiotics, antimetabolites, asparaginase, live BCG (intravesical), bleomycin sulfate, calicheamicin, cytochalasin B, dactinomycin (formerly actinomycin), daunorubicin HCl, daunorubicin citrate, denileukin diftitox, dihydroxyanthracene dione, docetaxel, doxorubicin, cyclosporin ... These include rubicin HCl, Escherichia coli L-asparaginase, Erwinia L-asparaginase, etoposide citrovorum factor, toposide erin, gemcitabine HCl, idarubicin HCl, interferon alpha-2b, irinotecan HCl, maytansinoids, mechlorethamine HCl, melphalan HCl, mithramycin, mitomycin C, mitotane, paclitaxel, polifeprosan 20 with carmustine implant, procarbazine HCl, streptozotocin, teniposide, thiotepa, topotecan HCl, valrubicin, vinblastine sulfate, vincristine sulfate, and vinorelbine tartrate.

[0129] Additional cytotoxic chemotherapeutic agents for use with the present invention include epirubicin, abraxane, taxotere, epothilones, tafluposide, vismodegib, azacitidine, doxifluridine, vindesine, and vinorelbine.

[0130] In one embodiment, the chemotherapeutic agent is not an aromatase inhibitor. In one embodiment, the chemotherapeutic agent is not a steroid. In one embodiment, the chemotherapeutic agent is not a BCR-ABL inhibitor.

[0131] In one embodiment, the chemotherapeutic agent is a DNA complex binding agent. In one embodiment, the chemotherapeutic agent is a tubulin binding agent. In one embodiment, the chemotherapeutic agent is an alkylating agent. In one embodiment, the chemotherapeutic agent is a thiolate alkylating agent.

[0132] Additional chemotherapy drugs Additional chemotherapeutic agents that can be used as described herein can include 2-methoxyestradiol or 2ME2, finasunate, etaracizumab (MEdi-522), HLL1, huN901-DM1, atiprimod, saquinavir mesylate, ritonavir, nelfinavir mesylate, indinavir sulfate, plitidepsin, P276-00, tipifarnib, lenalidomide, thalidomide, pomalidomide, simvastatin, and celecoxib. Chemotherapeutic agents useful in the present invention include, but are not limited to, trastuzumab (Herceptin™), pertuzumab (Perjeta™), lapatinib (Tykerb™), gefitinib (Iressa™), erlotinib (Tarceva™), cetuximab (Erbitux™), panitumumab (Vectibix™), vandetanib (Caprelsa™), vemurafenib (Zelboraf™), vorinostat (Zolinza™), romidepsin (Istodax™), bexarotene (Tarceva™), tetanib (Tykerb ... These include: Targretin™), alitretinoin (Panretin™), tretinoin (Vesanoid™), carfilzomib (Kyprolis™), pralatrexate (Folotyn™), bevacizumab (Avastin™), Ziv-aflibercept (Zaltrap™), sorafenib (Nexavar™), sunitinib (Sutent™), pazopanib (Votrient™), regorafenib (Stivarga™), and cabozantinib (Cometriq™).

[0133] Additional chemotherapeutic agents contemplated include, but are not limited to, calcineurin inhibitors, e.g., cyclosporine or ascomycin, e.g., cyclosporine A (Neoral™), FK506 (tacrolimus), pimecrolimus, mTOR inhibitors, e.g., rapamycin or derivatives thereof, e.g., sirolimus (Rapamune™), everolimus (Certican™), temsirolimus, zotarolimus, biolimus-7, biolimus-9, rapalogs, e.g., ridaforolimus, campath1H, S1P receptor modulators, dual mTORC1·mTORC1 inhibitors, RC2 inhibitors, e.g., Vistusertib (AZD2014), e.g., Fingolimod or an analogue thereof, anti-IL-8 antibodies, mycophenolic acid or a salt thereof, e.g., the sodium salt, or a prodrug thereof, e.g., Mycophenolate Mofetil (CellCept™), OKT3 (Orthoclone OKT3™), Prednisone, ATGAM™, Thymoglobulin™, Brequinar Sodium, OKT4, T10B9.A-3A, 33B3.1, 15-Deoxyspergualin, Tresperimus, Leflunomide Arava™, anti-CD25, anti-IL2R, Basiliximab (Simulect™), Daclizumab (Zenapax™), Mizoribine, Dexamethasone, ISAtx-247, SDZ ASM981 (pimecrolimus, Elidel™), abatacept, belatacept, LFA3lg, etanercept (sold as Enbrel™ by ImmuneXcite), adalimumab (Humira™), infliximab (Remicade™), anti-LFA-1 antibody, natalizumab (Antegren™), enlimomab, gavilimomab, golimumab, anti-thymocyte immunoglobulin linalitraline, siplizumab, alefacept, efalizumab, Pentasa, mesalazine, asacol, codeine phosphate, benorylate, fenbufen, naprosyn, diclofenac, etodolac, indomethacin, dasatinib (Sprycel™), nilotinib (Tasigna™), bosutinib (Bosulif™), imatinib mesylate (Gleevec™), and ponatinib (Iclusig )(trademark)) Amifostine, Dolasetron Mesylate, Dronabinol, Epoetin-α, Etidronate, Filgrastim, Fluconazole, Goserelin Acetate, Gramicidin D, Granisetron, Leucovorin Calcium, Lidocaine, Mesna, Ondansetron HCl, Pilocarpine HCl, Porfimer Sodium, Vatalanib, 1-Dehydrotestosterone, Allopurinol Sodium, Betamethasone, Sodium Phosphate and Betamethasone Acetate, Calcium Leucovorin, Conjugated Estrogens, Dextromethorphan These include razoxane, dibromomannitol, esterified estrogens, estradiol, estramustine sodium phosphate, ethinyl estradiol, flutamide, folinic acid, glucocorticoids, leuprolide acetate, levamisole HCl, medroxyprogesterone acetate, megestrol acetate, methyltestosterone, nilutamide, octreotide acetate, pamidronate disodium, procaine, propranolol, testolactone, tetracaine, toremifene citrate, and sargramostim.

[0134] In one embodiment, the chemotherapeutic agent is an estrogen receptor ligand such as tamoxifen, raloxifene, fulvestrant, anordrin, bazedoxifene, broparestriol, chlorotrianisene, clomiphene citrate, cyclophenyl, lasofoxifene, ormeloxifene, or toremifene; bicalutamide, enzalutamide, apalutamide, cyproterone acetate, chlormadinone acetate, spironolactone, canrenone, drospirenone, ketoconazole, topirutamide, avila acetate, or rivaroxaban. androgen receptor ligands such as telonol or cimetidine; aromatase inhibitors such as letrozole, anastrozole, or exemestane; anti-inflammatory drugs such as prednisone; oxidase inhibitors such as allopurinol; anti-cancer antibodies; anti-cancer monoclonal antibodies; antibodies against CD40 such as lucatumumab or dacetuzumab; antibodies against CD20 such as rituximab; CD52-binding antibodies such as alemtuzumab; integrin-binding antibodies such as volociximab or natalizumab; antibodies against the interleukin-6 receptor such as tocilizumab antibodies targeting IGF1, such as figitumumab; antibodies targeting DR4, such as mapatumumab; antibodies targeting TRAIL-R2, such as lexatumumab or dulanermin; fusion proteins, such as atacicept; B-cell inhibitors, such as atacicept; proteasome inhibitors, such as carfilzomib, bortezomib, or marizomib; HSP90 inhibitors, such as tanespimycin; HDAC inhibitors, such as vorinostat, belinstat, or panobistat; MAPK ligands, such as talmapimod. ; PKC inhibitors such as enzastaurin; HER2 receptor ligands such as trastuzumab, lapatinib, or pertuzumab; EGFR inhibitors such as gefitinib, erlotinib, cetuximab, panitumumab, or vandetanib; natural products such as romidepsin; retinoids such as bexarotene, tretinoin, or alitretinoin; receptor tyrosine kinase (RTK) inhibitors such as sunitinib, regorafenib, or pazopanib; or VEGF inhibitors such as ziv-aflibercept, bevacizumab, or dovitinib.

[0135] In one embodiment, the combination of the CDK4 / 6 inhibitor, chemotherapeutic agent, and immune checkpoint inhibitor is administered with other agents, including, but not limited to, granulocyte colony-stimulating factor (G-CSF, e.g., sold as Neupogen™ (filgrastim), Neulasta™ (pegfilgrastim), or lenograstim), granulocyte-macrophage colony-stimulating factor (GM-CSF, e.g., sold as molgramostim and sargramostim (Leukine™)), M-CSF (macrophage colony-stimulating factor), thrombopoietin (megakaryocyte growth development factor), or erythrombopoietin (megakaryocyte growth development factor). MGDF, such as those sold as Romiplostim™ and Eltrombopag™, interleukin (IL)-12, interleukin-3, interleukin-11 (adipogenesis inhibitory factor or oprelvekin), SCF (stem cell factor, steel factor, kit-ligand, or KL), and erythropoietin (EPO), and their derivatives (e.g., darbepoetin, Epocept, Nanokine, Epofit, Epogen, Epoprotease inhibitors, etc.), epoetin-α, such as Eprex, and Procrit; epoetin-β (sold, for example, as NeoRecormon, Recormon, and Micera), epoetin-δ (sold, for example, as Dynepo), epoetin-ω (sold, for example, as Epomax), epoetin ζ (sold, for example, as Silapo and Retacrit) and other steroids such as Epocept, Epotrust, Eryprosafe Safe, Repoitin, Vintor, Epofit, Erykine, Wepox, Espogen, Relipoietin, Shampoo The present invention is further combined with the use of hematopoietic growth factors, including Shanpoietin, Zyrop, and EPIAO. In one embodiment, Compound I, Compound II, Compound III, or Compound IV is administered prior to the administration of the hematopoietic growth factor. In one embodiment, the administration of the hematopoietic growth factor is timed such that the effect of the CDK4 / 6 inhibitor on HSPCs has disappeared. In one embodiment, the growth factor is administered at least 20 hours after the administration of the CDK4 / 6 inhibitor.

[0136] In this specification, additional chemotherapeutic agents contemplated for the treatment of abnormal tissues of the female reproductive system, such as breast cancer, ovarian cancer, endometrial cancer or uterine cancer, include but are not limited to estrogen inhibitors, including SERM (selective estrogen receptor modulator), SERD (selective estrogen receptor degrader), complete estrogen receptor degrader or other forms of partial or complete estrogen antagonist.Partial anti-estrogen agents such as raloxifene and tamoxifen retain some estrogen-like effects, including estrogen-like stimulation of uterine growth, and in some cases, the estrogen-like effects during the progression of breast cancer, which actually stimulate tumor growth.In contrast, fulvestrant, a complete anti-estrogen agent, does not have estrogen-like effects on the uterus, and is effective against tamoxifen-resistant tumors. Non-limiting examples of anti-estrogen compounds are set forth in WO2014 / 19176 assigned to Astra Zeneca, WO2013 / 090921, WO2014 / 203129, WO2014 / 203132, and US2013 / 0178445 assigned to Olema Pharmaceuticals, and U.S. Patent Nos. 9,078,871, 8,853,423, and 8,703,810, and U.S. Patent Nos. 2015 / 0005286, WO2014 / 205136, and WO2014 / 205138. Further non-limiting examples of anti-estrogen compounds include SERMS such as anordrin, bazedoxifene, broparestriol, clomiphene citrate, cyclophenyl, lasofoxifene, ormeloxifene, raloxifene, tamoxifen, toremifene, and fulvestrant; aromatase inhibitors such as aminoglutethimide, testolactone, anastrozole, exemestane, fadrozole, formestane, and letrozole; and antigonadotropins such as leuprorelin, cetrorelix, allylestrenol, chlormadinone acetate, delmadinone acetate, dydrogesterone, medroxyprogesterone acetate, megestrol acetate, nomegestrol acetate, norethisterone acetate, progesterone, and spironolactone.

[0137] In this specification, additional chemotherapeutic agents contemplated for the treatment of abnormal tissues of the male reproductive system, such as prostate cancer or testicular cancer, include, but are not limited to, androgen (e.g., testosterone) inhibitors, including, but not limited to, selective androgen receptor modulators, selective androgen receptor degraders, complete androgen receptor degraders, or other forms of partial or complete androgen antagonists.In one embodiment, prostate cancer or testicular cancer is androgen-resistant.Non-limiting examples of antiandrogen compounds are listed in WO2011 / 156518 and U.S. Patent Nos. 8,455,534 and 8,299,112.Further non-limiting examples of antiandrogen compounds include chlormadinone acetate, spironolactone, canrenone, drospirenone, ketoconazole, topirutamide, abiraterone acetate, and cimetidine.

[0138] Chemotherapeutic agents may include kinase inhibitors, including, but not limited to, phosphoinositide 3-kinase (PI3K) inhibitors, Bruton's tyrosine kinase (BTK) inhibitors, or spleen tyrosine kinase (Syk) inhibitors, or combinations thereof.

[0139] PI3k inhibitors are well known. Examples of PI3 kinase inhibitors include, but are not limited to, wortmannin, demethoxyviridine, perifosine, idelalisib, pictilisib, palomid 529, ZSTK474, PWT33597, CUDC-907, and AEZS-136, duvelisib, GS-9820, GDC-0032 (2-[4-[2-(2-isopropyl-5-methyl-1,2,4-triazol-3-yl)-5,6-dihydroimidazo[1,2-d][1,4]benzoxazepin-9-yl]pyrazol-1-yl]-2-methylpropanol, and the like. or methyl(oxo){[(2R)-l-phenoxy-2-butanyl]oxy}phosphonium)), MLN-1117 ((2R)-l-phenoxy-2-butanyl hydrogen (S)-methylphosphonate; or methyl(oxo){[(2R)-l-phenoxy-2-butanyl]oxy}phosphonium)), BYL-719 ((2S)-N1-[4-methyl-5-[2-(2,2,2-trifluoro-1,1-dimethylethyl)-4-pyridinyl]-2-thiazolyl]-1,2-pyrrolidinedicarboxamide), GSK2126458 (2,4-difluoro-N-{2-(methyloxy)-5-[4-(4-pyridazinyl) {R)-6-quinolinyl]-3-pyridinyl}benzenesulfonamide), TGX-221 ((±)-7-methyl-2-(morpholin-4-yl)-9-(l-phenylaminoethyl)-pyrido[l,2-a]-pyrimidin-4-one), GSK2636771 (2-methyl-1-(2-methyl-3-(trifluoromethyl)benzyl)-6-morpholino-lH-benzo[d]imidazole-4-carboxylic acid dihydrochloride), KIN-193 ((R)-2-((l-(7-methyl-2-morpholino-4-oxo-4H-pyrido[1,2-a ]pyrimidin-9-yl)ethyl)amino)benzoic acid), TGR-1202 / RP5264, GS-9820 ((S)-l-(4-((2-(2-aminopyrimidin-5-yl)-7-methyl-4-mohydroxypropan-1-one), GS-1101 (5-fluoro-3-phenyl-2-([S)]-1-[9H-purin-6-ylamino]-propyl)-3H-quinazolin-4-one), AMG-319, GSK-2269557, SAR245409 (N-(4-(N-(3-((3,5-Dimethoxyphenyl)amino)quinoxalin-2-yl)sulfamoyl)phenyl)-3-methoxy-4-methylbenzamide), BAY80-6946 (2-amino-N-(7-methoxy-8-(3-morpholinopropoxy)-2,3-dihydroimidazo[l,2-c]quinazol), AS 252424 (5-[l-[5-(4-fluoro-2-hydroxy-phenyl)-furan-2-yl]-meth-(Z)-ylidene]-thiazolidine-2,4-dione), CZ 24832 (5-(2-amino-8-fluoro-[l,2,4]triazolo[l,5-a]pyridin-6-yl)-N-tert-butylpyridine-3-sulfonamide), buparlisib (5-[2,6-di(4-morpholinyl)-4-pyrimidinyl]-4-(trifluoromethyl)-2-pyridinamine), GDC-0941 (2-(lH-indazol-4-yl)-6-[[4-(methylsulfonyl)-l -piperazinyl]methyl]-4-(4-morpholinyl)thieno[3,2-d]pyrimidine), GDC-0980 ((S)-1-(4-((2-(2-aminopyrimidin-5-yl)-7-methyl-4-morpholinothieno[3,2-d]pyrimidin-6yl)methyl)piperazin-l-yl)-2-hydroxypropan-l-one (also known as RG7422)), SF1126 ((8S,14S,17S)- 14-(carboxymethyl)-8-(3-guanidinopropyl)-17-(hydroxymethyl)-3,6,9,12,15-pentaoxo-1-(4-(4-oxo-8-phenyl-4H-chromen-2-yl)morpholin-4-ium)-2-oxa-7,10,13,16-tetraazaoctadecane-18-oate), PF-05212384 (N-[4-[[4-(dimethylamino)-1-piperidinyl ]carbonyl]phenyl]-N'-[4-(4,6-di-4-morpholinyl-l,3,5-triazin-2-yl)phenyl]urea), LY3023414, BEZ235 (2-methyl-2-{4-[3-methyl-2-oxo-8-(quinolin-3-yl)-2,3-dihydro-lH-imidazo[4,5-c]quinolin-l-yl]phenyl}propanenitrile), XL-765 (N-(3-(N-(3-(3,5-dimethoxyphenylamino)quinoxalin-2-yl)sulfamoyl)phenyl)-3-methoxy-4-methylbenzamide), and GSK1059615 (5-[[4-(4-pyridinyl)-6-quinolinyl]methylene]-2,4-thiazolidenedione), PX886 ([(3aR,6E,9S,9aR,10R,11aS)-6-[[bis(prop-2-enyl)amino]methylidene]-5-hydroxy-9-(methoxymethyl)-9a,11a-dimethyl-1,4,7-trioxo-2,3,3a,9,10,11-hexahydroindeno[4,5h]isochromen-10-yl]acetate (also known as sonolicib)), and the structure described in WO2014 / 071109 having the formula:

[0140] BTK inhibitors are well known. Examples of BTK inhibitors include ibrutinib (also known as PCI-32765) (Imbruvica™) (1-[(3R)-3-[4-amino-3-(4-phenoxy-phenyl)pyrazolo[3,4-d]pyrimidin-1-yl]piperidin-1-yl]prop-2-en-1-one), dianilinopyrimidine inhibitors {e.g., AVL-101 and AVL-291 / 292 (N-(3-((5-fluoro-2-((4-(2-methoxyethoxy)phenyl)amino)pyrimidin-4-yl)amino)phenyl)acrylamide) (Avila Therapeutics (see U.S. Patent Application Publication No. 2011 / 0117073, the entire contents of which are incorporated herein by reference)}, dasatinib ([N-(2-chloro-6-methylphenyl)-2-(6-(4-(2-hydroxyethyl)piperazin-1-yl)-2-methylpyrimidin-4-ylamino)thiazole-5-carboxamide], LFM-A13 (α-cyano-β-hydroxy-β-methyl-N -(2,5-ibromophenyl)propanamide), GDC-0834 ([RN-(3-(6-(4-(1,4-dimethyl-3-oxopiperazin-2-yl)phenylamino)-4-methyl-5-oxo-4,5-dihydropyrazin-2-yl)-2-methylphenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxamide], CGI-560 4-(tert-butyl)-N-(3-(8-(phenylamino)imidazo[1,2-a]pyrazin-6-yl)phenyl)benzamide, CGI-1746 (4-(tert-butyl)-N-(2-methyl-3-(4-methyl-6-((4-(morpholine-4-carbonyl)phenyl)amino)-5-oxo-4,5-dihydropyrazin-2-yl)phenyl)benzamide), CNX-774 (4-(4-((4-((3-acrylamidophenyl)amino)-5-fluoropyrimidin-2-yl)amino)phenoxy)-N-methylpicolinamide), CTA056 (7-benzyl-1-(3-(piperidin-1-yl)propyl)-2-(4-(pyridin-4-yl)phenyl)-1H-imidazo[4,5-g]quinoxalin-6(5H)-one), GDC-0834 ((R)-N-(3-(6-((4-(1,4-dimethyl-3-oxopiperazin-2-yl)phenyl)amino)-4-methyl-5-oxo-4,5-dihydropyrazin-2-yl)-2-methylphenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxamide), GDC- 0837 ((R)-N-(3-(6-((4-(1,4-dimethyl-3-oxopiperazin-2-yl)phenyl)amino)-4-methyl-5-oxo-4,5-dihydropyrazin-2-yl)-2-methylphenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxamide), HM-71224, ACP-196, ONO-4059 (Ono Pharmaceuticals), PRT062607 (4-((3-(2H-1,2,3-triazol-2-yl)phenyl)amino)-2-(((1R,2S)-2-aminocyclohexyl)amino)pyrimidine-5-carboxamide hydrochloride), QL-47 (1-(1-acryloylindolin-6-yl)-9-(1-methyl-1H-pyrazol-4-yl)benzo[h][1,6]naphthyridin-2(1H)-one) and RN486 (6-cyclopropyl-8-fluoro-2-(2-hydroxymethyl-3-{1-methyl-5-[5-(4-methyl-piperazin-1-yl)-pyridin-2-ylamino]-6-oxo-1,6-dihydro-pyridin-3-yl}-phenyl)-2H-isoquinolin-1-one), and other molecules that can inhibit BTK activity, such as the BTK inhibitors disclosed in Akinleye et al., Journal of Hematology & Oncology, 2013, 6:59, the entire contents of which are incorporated herein by reference.

[0141] Syk inhibitors are well known and include, for example, celdulatinib (4-(cyclopropylamino)-2-((4-(4-(ethylsulfonyl)piperazin-1-yl)phenyl)amino)pyrimidine-5-carboxamide), entospletinib (6-(1H-indazol-6-yl)-N-(4-morpholinophenyl)imidazo[1,2-a]pyrazin-8-amine), fostamatinib ([6-({5-fluoro-2-[(3,4,5-trimethoxyphenyl)amino]-4 -pyrimidinyl}amino)-2,2-dimethyl-3-oxo-2,3-dihydro-4H-pyrido[3,2-b][1,4]oxazin-4-yl]methyl dihydrogen phosphate), fostamatinib disodium salt (sodium (6-((5-fluoro-2-((3,4,5-trimethoxyphenyl)amino)pyrimidin-4-yl)amino)-2,2-dimethyl-3-oxo-2H-pyrido[3,2-b][1,4]oxazin-4(3H)-yl)methyl phosphate), BAY 61-3606 (2-(7-(3,4-dimethoxyphenyl)-imidazo[1,2-c]pyrimidin-5-ylamino)-nicotinamide HCl), RO9021 (6-[(1R,2S)-2-amino-cyclohexylamino]-4-(5,6-dimethyl-pyridin-2-ylamino)-pyridazine-3-carboxylic acid amide), imatinib (Gleevec; 4-[(4-methylpiperazin-1-yl)methyl]-N-(4-methyl-3-{[4-(pyridin-3-yl)pyrimidin-2-yl]amino}phenyl)benzamide), staurosporine, GSK143 (2-(((3R,4R)-3-aminotetrahydrofuran) Hydro-2H-pyran-4-yl)amino)-4-(p-tolylamino)pyrimidine-5-carboxamide), PP2 (1-(tert-butyl)-3-(4-chlorophenyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine), PRT-060318 (2-(((1R,2S)-2-aminocyclohexyl)amino)-4-(m-tolylamino)pyrimidine-5-carboxamide), PRT-062607 (4-((3-(2H-1,2,3-triazol-2-yl)phenyl)amino)-2-(((1R,2S)-2-aminocyclohexyl)amino)pyrimidine-5-carboxamide hydrochloride), R112 (3,3'-((5-fluoropyrimidine-2,4-diyl)bis(azanediyl))diphenol), R348 (3-ethyl-4-methylpyridine), R406 (6-((5-fluoro-2-((3,4,5-trimethoxyphenyl)amino)pyrimidin-4-yl)amino)-2,2-dimethyl-2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one), YM193306 (see Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643), 7-azaindole, piceatannol, ER-27319 (Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, the entire contents of which are incorporated herein by reference). J. Med. Chem. 2012, 55, 3614-3643), Compound D (Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire contents of which are incorporated herein by reference), PRT060318 (Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire contents of which are incorporated herein by reference), luteolin (Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire contents of which are incorporated herein by reference), 3614-3643), apigenin (Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, vol. 1, pp. 1311-1314, 2003, the entire contents of which are incorporated herein by reference).J. Med. Chem. 2012, 55, 3614-3643), quercetin (Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire contents of which are incorporated herein by reference), fisetin (Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire contents of which are incorporated herein by reference), myricetin (Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire contents of which are incorporated herein by reference), 3614-3643), and morin (Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire contents of which are incorporated herein by reference).

[0142] The chemotherapeutic agent may also be a B-cell lymphoma 2 (Bcl-2) protein inhibitor. BCL-2 inhibitors are known in the art, and include, for example, ABT-199 (4-[4-[[2-(4-chlorophenyl)-4,4-dimethylcyclohex-1-en-1-yl]methyl]piperazin-1-yl]-N-[[3-nitro-4-[[(tetrahydro-2H-pyran-4-yl)methyl]amino]phenyl]sulfonyl]-2-[(1H-pyrrolo[2,3-b]pyridin-5-yl)oxy]benzamide), ABT-737 (4-[4-[[2-(4-chlorophenyl)furan-1-yl]methyl]piperazin-1-yl]-N-[[3-nitro-4-[[(tetrahydro-2H-pyran-4-yl)methyl]amino]phenyl]sulfonyl]-2-[(1H-pyrrolo[2,3-b]pyridin-5-yl)oxy]benzamide), phenyl]methyl]piperazin-1-yl]-N-[4-[[(2R)-4-(dimethylamino)-1-phenylsulfanylbutan-2-yl]amino]-3-nitrophenyl]sulfonylbenzamide), ABT-263 ((R)-4-(4-((4'-chloro-4,4-dimethyl-3,4,5,6-tetrahydro-[l,l'-biphenyl]-2-yl)methyl)piperazin-1-yl)-N-((4-((4-morpholino-1-(phenylthio)butan-2-yl)amino)- 3((trifluoromethyl)sulfonyl)phenyl)sulfonyl)benzamide), GX15-070 (Ovatoclax mesylate, (2Z)-2-[(5Z)-5-[(3,5-dimethyl-1H-pyrrol-2-yl)methylidene]-4-methoxypyrrol-2-ylidene]indole; methanesulfonic acid)), 2-methoxy-antimycin A3, YC137 (4-(4,9-dioxo-4,9-dihydronaphtho[2,3-d]thiazol-2-ylamino)-phenyl ester ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate, nilotinib-d3, TW-37 (N-[4-[[2-(1,1-dimethylethyl)phenyl]sulfonyl]phenyl]-2,3,4-trihydroxy-5-[[2-(1-methylethyl)phenyl]methyl]benzamide), apogossypolone (ApoG2), or G3139 (Oblimersen).

[0143] Additional chemotherapeutic agents for use in the methods contemplated herein include, but are not limited to, midazolam, MEK inhibitors, RAS inhibitors, ERK inhibitors, ALK inhibitors, HSP inhibitors (e.g., HSP70 and HSP90 inhibitors, or combinations thereof), RAF inhibitors, apoptotic compounds, topoisomerase inhibitors, AKT inhibitors (including, but not limited to, MK-2206, GSK690693, perifosine, (KRX-0401), GDC-0068, triciribine, AZD53 63, Honokiol, PF-04691502, and Miltefosine), or FLT-3 inhibitors (including but not limited to P406, Dovitinib, Quizartinib (AC220), Amuvatinib (MP-470), Tandutinib (MLN518), ENMD-2076, and KW-2449), or combinations thereof. Examples of MEK inhibitors include, but are not limited to, trametinib / GSKl120212 (N-(3-{3-cyclopropyl-5-[(2-fluoro-4-iodophenyl)amino]-6,8-dimethyl-2,4,7-trioxo-3,4,6,7-tetrahydropyrido[4,3-d]pyrimidin-l(2H-yl}phenyl)acetamide), selumetinib (6-(4-bromo-2-chloroanilino)-7-fluoro-N-(2-hydroxyethoxy)-3-methylbenzimidazole-5-carboxamide), pimasertib / AS703026 / MSC1935369 ((S)-N-(2,3-dihydroxypropyl)-3-((2-fluoro-4-iodophenyl)amino)isonicotinamide), XL-518 / GDC-0973 (l-({3,4-difluoro-2-[(2-fluoro-4-iodophenyl)amino]phenyl}carbonyl)-3-[(2S)-piperidin-2-yl]azetidin-3-ol), rafametinib / BAY869766 / RDEAl19 (N-(3,4-difluoro-2-(2-fluoro-4-iodophenylamino)-6-methoxyphenyl)-1-(2,3-dihydroxypropyl)cyclopropane-1-sulfonamide), PD-0325901 (N-[(2R)-2,3-dihydroxypropoxy]-3,4-difluoro-2-[(2-fluoro-4-iodophenyl)amino]-benzamide), TAK733 ((R)-3-(2,3-dihydroxypropyl)-6-fluoro-5-(2-fluoro-4-iodophenylamino)-8-methylpyrido[2,3d]pyrimidine-4,7(3H,8H)-dione), MEK162 / ARRY438162 (5-[(4-bromo-2-fluorophenyl)amino]-4-fluoro-N-(2-hydroxyethoxy)-1-methyl-1H-benzimidazole-6-carboxamide amide), R05126766 (3-[[3-fluoro-2-(methylsulfamoylamino)-4-pyridyl]methyl]-4-methyl-7-pyrimidin-2-yloxychromen-2-one), WX-554, R04987655 / CH4987655 (3,4-difluoro-2-((2-fluoro-4-iodophenyl)amino)-N-(2-hydroxyethoxy)-5-((3-oxo-1,2-oxazinan-2yl)methyl)benzamide), or AZD8330 (2-((2-fluoro-4-iodophenyl)amino)-N-(2-hydroxyethoxy)-1,5-dimethyl-6-oxo-1,6-dihydropyridine-3-carboxamide). Examples of RAS inhibitors include, but are not limited to, leolysin and siG12D LODER. Examples of ALK inhibitors include, but are not limited to, crizotinib, AP26113, and LDK378. HSP inhibitors include, but are not limited to, geldanamycin or 17-N-allylamino-17-demethoxygeldanamycin (17AAG), and radicicol.

[0144] Known ERK inhibitors include SCH772984 (Merck / Schering-Plough), VTX-11e (Vertex), DEL-22379, ulixertinib (BVD-523, VRT752271), GDC-0994, FR180204, XMD8-92, and ERK5-IN-1.

[0145] Raf inhibitors are well known and include, for example, vemurafenib (N-[3-[[5-(4-chlorophenyl)-1H-pyrrolo[2,3-b]pyridin-3-yl]carbonyl]-2,4-difluorophenyl]-1-propanesulfonamide), sorafenib tosylate (4-[4-[[4-chloro-3-(trifluoromethyl)phenyl]carbamoylamino]phenoxy]-N- Methylpyridine-2-carboxamide; 4-methylbenzenesulfonate), AZ628 (3-(2-cyanopropan-2-yl)-N-(4-methyl-3-(3-methyl-4-oxo-3,4-dihydroquinazolin-6-ylamino)phenyl)benzamide), NVP-BHG712 (4-methyl-3-(1-methyl-6-(pyridin-3-yl)-1H-pyrazolo[3,4-d]pyrimidine-4 -ylamino)-N-(3-(trifluoromethyl)phenyl)benzamide), RAF-265 (1-methyl-5-[2-[5-(trifluoromethyl)-1H-imidazol-2-yl]pyridin-4-yl]oxy-N-[4-(trifluoromethyl)phenyl]benzimidazol-2-amine), 2-bromoardisine (2-bromo-6,7-dihydro-1H,5H-pyrrolo[2,3-c] azepine-4,8-dione), Raf kinase inhibitor IV (2-chloro-5-(2-phenyl-5-(pyridin-4-yl)-1H-imidazol-4-yl)phenol), and sorafenib N-oxide (4-[4-[[[[4-chloro-3(trifluoromethyl)phenyl]amino]carbonyl]amino]phenoxy]-N-methyl-2 pyridinecarboxamide 1-oxide).

[0146] Known topoisomerase I inhibitors useful in the present invention include (S)-10-[(dimethylamino)methyl]-4-ethyl-4,9-dihydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14(4H,12H)-dione monohydrochloride (topotecan), (S)-4-ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14-(4H,12H)-dione (camptothecin), (1S,9S)-1-amino-9-ethyl-5-fluoro-1,2,3,9,12, 15-Hexahydro-9-hydroxy-4-methyl-10H,13H-benzo(de)pyrano(3',4':6,7)indolizino(1,2-b)quinoline-10,13-dione (exatecan), (7-(4-methylpiperazinomethylene)-10,11-ethylenedioxy-20(S)-camptothecin (lurtotecan), or (S)-4,11-diethyl-3,4,12,14-tetrahydro-4-hydroxy-3,14-dioxo1H-pyrano[3',4':6,7]-indolizino[1,2-b]quinolin-9-yl-[1,4'bipiperidine] -1'-carboxylate (irinotecan), (R)-5-ethyl-9,10-difluoro-5-hydroxy-4,5-dihydrooxepino[3',4':6,7]indolizino[1,2-b]quinoline-3,15(1H,13H)-dione (diflomotecan), (4S)-11-((E)-((1,1-dimethylethoxy)imino)methyl)-4-ethyl-4-hydroxy-1,12-dihydro-14H-pyrano(3',4':6,7)indolizino(1,2-b)quinoline-3,14(4H)-dione (gimatecan), (S)-8-ethyl-8-hydroxepino[3',4':6,7]indolizino[1,2-b]quinoline-3,15(1H,13H)-dione oxi-15-((4-methylpiperazin-1-yl)methyl)-11,14-dihydro-2H-[1,4]dioxino[2,3-g]pyrano[3',4':6,7]indolizino[1,2-b]quinoline-9,12(3H,8H)-dione (lurtotecan), (4S)-4-ethyl-4-hydroxy-11-[2-[(1-methylethyl)amino]ethyl]-1H-pyrano[3?,4?:6,7]indolizino[1,2-b]quinoline-3,14(4H,12H)-dione (belotecan), 6-((1,3-dihydroxypropan-2-yl)amino)-2,10-Dihydroxy-12-((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (edotecarin), 8,9-dimethoxy-5-(2-N,N-dimethylaminoethyl)-2,3-methylenedioxy-5H-dibenzo(c,h)(1,6)naphtho Lysin-6-one (Topovale), benzo[6,7]indolizino[1,2-b]quinolin-11(13H)-one (rosettacin), (S)-4-ethyl-4-hydroxy-11-(2-(trimethylsilyl)ethyl)-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14(4H,12H)-dione (cositecan), tetrakis{(4S)-9-[([1,4'-bipiperidinyl]-1'- carbonyl)oxy]-4,11-diethyl-3,14-dioxo-3,4,12,14-tetrahydro-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinolin-4-yl}N,N',N'',N'''-{methanetetrayltetrakis[methylenepoly(oxyethylene)oxy(1-oxoethylene)]}tetraglycinic acid tetrahydrochloride (ethirinotecan pegol), 10-hydroxy-camptothecin (HOCPT), 9-nitrocan Camptothecin (rubitecan), SN38 (7-ethyl-10-hydroxycamptothecin), and 10-hydroxy-9-nitrocamptothecin (CPT109), (R)-9-chloro-5-ethyl-5-hydroxy-10-methyl-12-((4-methylpiperidin-1-yl)methyl)-4,5-dihydrooxepino[3',4':6,7]indolizino[1,2-b]quinoline-3,15(1H,13H)-dione (elmotecan).

[0147] In one embodiment, the chemotherapeutic agent is not an aromatase inhibitor, hi one embodiment, the chemotherapeutic agent is not an estrogen or androgen receptor agonist or antagonist.

[0148] growth factors In one embodiment, the combination of the CDK4 / 6 inhibitor, chemotherapeutic agent, and checkpoint inhibitor is administered with, but not limited to, granulocyte colony-stimulating factor (G-CSF, e.g., sold as Neupogen (filgrastim), Neulasta (pegfilgrastim), or lenograstim), granulocyte-macrophage colony-stimulating factor (GM-CSF, e.g., sold as molgramostim and sargramostim (Leukine)), M-CSF (macrophage colony-stimulating factor), thrombopoietin (megakaryocyte growth and development factor (MGDF), e.g., sold as romiplostim and eltrombopag), interleukin (IL)-12, interleukin-3, interleukin-11 (adipogenesis inhibitory factor or oprelvekin), SCF (stem cell factor, steel factor, kit-ligand), or combinations thereof. , or KL) and erythropoietin (EPO), and their derivatives (e.g., sold as epoetin-α, such as darbepoetin, Epocept, Nanokine, Epofit, Epogen, Eprex, and Procrit); epoetin-β (e.g., NeoRecormon, Further combinations include the use of hematopoietic growth factors including, for example, Epocept, Epotrust, Erypro Safe, Repoitin, Vintor, Epofit, Erykine, Wepox, Espogen, Relipoietin, Shanpoietin, Zyrop, and EPIAO.In one embodiment, Compound I, Compound II, Compound III, or Compound IV is administered before the administration of the hematopoietic growth factor. In one embodiment, the administration of the hematopoietic growth factor is timed such that the effect of the CDK4 / 6 inhibitor on HSPCs has disappeared. In one embodiment, the growth factor is administered at least 20 hours after the administration of the CDK4 / 6 inhibitor.

[0149] Cancer or tumor type As contemplated herein, the timed use of CDK4 / 6 inhibitors in combination with chemotherapeutic agents and immune checkpoint inhibitors can be used in the treatment of subjects with cancer or tumors. In one embodiment, the cancer or tumor is a CDK4 / 6 replication-dependent cancer or tumor. In one embodiment, the cancer or tumor is a CDK4 / 6 replication-independent cancer or tumor. In one embodiment, the cancer is a solid cancer or tumor. In one embodiment, the cancer or tumor is a non-solid cancer or tumor. In one embodiment, the solid tumor expresses PD-L1. In one embodiment, the cancer is a hematological cancer. In certain aspects, the cancer is leukemia, lymphoma, or multiple myeloma.

[0150] In particular, the methods described herein can be used to treat subjects with Rb-positive cancer or other Rb-positive abnormal cell proliferation disorders. In some embodiments, the cancer or cell proliferation disorder is a CDK4 / 6 replication-dependent cancer or cell proliferation disorder, which refers to a cancer or cell proliferation disorder that requires CDK4 / 6 activity for replication or proliferation or whose growth can be inhibited through the activity of a CDK4 / 6 inhibitor. Cancers and disorders of this type can be characterized by the presence of functional Retinoblastoma protein (e.g., have cells that exhibit the presence of such protein). Such cancers and disorders are classified as Rb-positive. Rb-positive abnormal cell proliferation disorders, and variations of this term, as used herein, refer to disorders or disorders caused by uncontrolled or abnormal cell division characterized by the presence of functional Retinoblastoma protein and may include cancer. In one aspect of the present invention, the use of CDK4 / 6 inhibitors in combination with additional therapeutic agents and methods described herein can be used to treat non-cancerous Rb-positive abnormal cell proliferation disorders. Examples of such diseases may include non-malignant lymphoproliferation, non-malignant breast neoplasms, psoriasis, arthritis, dermatitis, pre-cancerous colon lesions or soft masses, angiogenic disorders, immune-mediated and non-immune-mediated inflammatory diseases, arthritis, age-related macular degeneration, diabetes, and other non-cancerous or benign cell proliferative diseases.

[0151] Suitable target cancers for administration of the compounds described herein include Rb-positive: estrogen receptor-positive cancer, HER2-negative advanced breast cancer, late-stage metastatic breast cancer, liposarcoma, non-small cell lung cancer, liver cancer, ovarian cancer, glioblastoma, refractory solid tumors, retinoblastoma-positive breast cancer and retinoblastoma-positive endometrial, vaginal, ovarian cancer and lung and bronchial cancer, colon adenocarcinoma, rectal adenocarcinoma, central nervous system germ cell tumors, teratoma, estrogen receptor-negative breast cancer, estrogen receptor-positive breast cancer, familial testicular germ cell tumors, HER2-negative breast cancer, HER2-positive breast cancer, male breast cancer, ovarian immature teratoma, ovarian mature teratoma, monodermal and highly restricted teratoma, progesterone-containing teratoma, and ovarian cancer. The tumor types may include progesterone receptor-negative breast cancer, progesterone receptor-positive breast cancer, recurrent breast cancer, recurrent colon cancer, recurrent extragonadal germ cell tumor, recurrent extragonadal nonseminomatous germ cell tumor, recurrent extragonadal seminoma, recurrent malignant testicular germ cell tumor, recurrent melanoma, recurrent ovarian germ cell tumor, recurrent rectal cancer, Stage III extragonadal nonseminomatous germ cell tumor, Stage III extragonadal seminoma, Stage III malignant testicular germ cell tumor, Stage III ovarian germ cell tumor, Stage IV breast cancer, Stage IV colon cancer, Stage IV extragonadal nonseminomatous germ cell tumor, Stage IV extragonadal seminoma, Stage IV melanoma, Stage IV ovarian germ cell tumor, Stage IV rectal cancer, testicular immature teratoma, and testicular mature teratoma. In particular examples, target cancers include estrogen receptor-positive, HER2-negative advanced breast cancer, late-stage metastatic breast cancer, liposarcoma, non-small cell lung cancer, liver cancer, ovarian cancer, glioblastoma, refractory solid tumors, retinoblastoma-positive breast cancer and retinoblastoma-positive endometrial, vaginal, ovarian and lung / bronchial cancer, metastatic colorectal cancer, metastatic melanoma with CDK4 mutation or amplification, or cisplatin-refractory unresectable germ cell tumors.

[0152] In one embodiment, the subject has bladder cancer, gastroesophageal cancer, soft tissue sarcoma, bile duct / gallbladder cancer, ovarian cancer, or cervical cancer.

[0153] In one embodiment, the Rb-positive cancer is selected from Rb-positive carcinomas and sarcomas, including, but not limited to, lung cancer, bone cancer, pancreatic cancer, skin cancer, cancer of the head or neck, cutaneous or intraocular melanoma, uterine cancer, ovarian cancer, rectal cancer, cancer of the anal region, stomach cancer, colon cancer, breast cancer, uterine cancer, carcinoma of the fallopian tubes, carcinoma of the endometrium, carcinoma of the cervix, carcinoma of the vagina, carcinoma of the vulva, cancer of the esophagus, cancer of the small intestine, cancer of the endocrine system, cancer of the thyroid gland, cancer of the parathyroid gland, cancer of the adrenal gland, sarcoma of soft tissue, cancer of the urethra, cancer of the penis, prostate cancer, cancer of the bladder, cancer of the kidney or ureter, renal cell carcinoma, carcinoma of the renal pelvis, neoplasms of the central nervous system (CNS), primary CNS lymphoma, spinal axis tumor, brain stem glioma, pituitary adenoma, or a combination of one or more of the foregoing cancers.

[0154] In one embodiment, the Rb positive cancer is Rb positive: fibrosarcoma, myxosarcoma, chondrosarcoma, osteosarcoma, chordoma, malignant fibrous histiocytoma, hemangiosarcoma, angiosarcoma, lymphangiosarcoma, mesothelioma, leiomyosarcoma, rhabdomyosarcoma, squamous cell carcinoma; epidermoid, malignant skin adnexal tumor, adenocarcinoma, hepatocellular carcinoma, renal cell carcinoma, adrenal gland tumor, cholangiocarcinoma, transitional cell carcinoma, cholangiocar ... Selected from the group consisting of hair carcinoma, seminoma, germ cell carcinoma, anaplastic glioma; glioblastoma multiforme, neuroblastoma, medulloblastoma, malignant meningioma, malignant schwannoma, neurofibrosarcoma, parathyroid carcinoma, medullary thyroid carcinoma, bronchial carcinoid, pheochromocytoma, pancreatic islet cell carcinoma, malignant carcinoid, malignant paraganglioma, melanoma, Merkel cell neoplasm, phyllodes cyst sarcoma, salivary gland carcinoma, thymic carcinoma, bladder carcinoma, and Wilms' tumor.

[0155] In further embodiments, Rb-positive cancers or disorders include, but are not limited to, hematological disorders or malignancies, including, among others, myeloid disorders, lymphoid disorders, leukemia, lymphoma, myelodysplastic syndromes (MDS), myeloproliferative disorders (MPD), mast cell disorders, and myelomas (e.g., multiple myeloma). Abnormal proliferation of T cells, B cells, and / or NK cells can result in a wide range of diseases, such as cancer, proliferative disorders, and inflammatory / immune diseases. A host, e.g., a human, afflicted with any of these disorders can be treated with an effective amount of a combination as described herein to achieve symptomatic relief (palliative drugs) or relief of the underlying disease (disease-modifying drugs).

[0156] Examples include T-cell or NK-cell lymphomas, including, but not limited to, peripheral T-cell lymphoma; anaplastic large cell lymphomas, e.g., anaplastic lymphoma kinase (ALK)-positive, ALK-negative anaplastic large cell lymphoma, or primary cutaneous anaplastic large cell lymphoma; angioimmunoblastic lymphoma; cutaneous T-cell lymphomas, e.g., mycosis fungoides, Sézary syndrome, primary cutaneous anaplastic large cell lymphoma, primary cutaneous CD30+ T-cell lymphoproliferative disorder; primary cutaneous aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma; primary cutaneous gamma-delta T-cell lymphoma; primary cutaneous small / medium cell CD4+ T-cell lymphoma, and lymphomatoid papulosis; These include human T-cell leukemia / lymphoma (ATLL); blastic NK-cell lymphoma; enteropathy-type T-cell lymphoma; hepatosplenic gamma-delta T-cell lymphoma; lymphoblastic lymphoma; nasal NK / T-cell lymphoma; therapy-related T-cell lymphoma; for example, lymphomas seen after solid organ or bone marrow transplant; T-cell prolymphocytic leukemia; T-cell large granular lymphocytic leukemia; chronic lymphoproliferative disease of NK cells; rapidly progressive NK-cell leukemia; pediatric systemic EBV+ T-cell lymphoproliferative disease (associated with chronic active EBV infection); vaccinia-like bullous lymphoma; adult T-cell leukemia / lymphoma; enteropathy-associated T-cell lymphoma; hepatosplenic T-cell lymphoma; or subcutaneous panniculitis-like T-cell lymphoma.

[0157] In one embodiment, the methods described herein can be used to treat a host, e.g., a human, having a lymphoma or a lymphocytic or myeloid proliferative disease or disorder. For example, the methods described herein can be administered to a host having Hodgkin's lymphoma or non-Hodgkin's lymphoma. For example, the host may have a non-Hodgkin's lymphoma, such as, but not limited to, AIDS-related lymphoma; anaplastic large cell lymphoma; angioimmunoblastic lymphoma; blastic NK-cell lymphoma; Burkitt's lymphoma; Burkitt-like lymphoma (small non-cleaved cell lymphoma); chronic lymphocytic leukemia / small cell lymphocytic lymphoma; cutaneous T-cell lymphoma; diffuse large B-cell lymphoma; enteropathic T-cell lymphoma; follicular lymphoma; hepatosplenic gamma-delta T-cell lymphoma; lymphoblastic lymphoma; mantle cell lymphoma; marginal zone lymphoma; nasal T-cell lymphoma; childhood lymphoma; peripheral T-cell lymphoma; primary central nervous system lymphoma; T-cell leukemia; malignant transitional lymphoma; therapy-related T-cell lymphoma; or Waldenstrom's macroglobulinemia.

[0158] Alternatively, the methods described herein can be used to treat a subject, e.g., a human, having Hodgkin lymphoma, such as, but not limited to, nodular sclerosing classical Hodgkin lymphoma (CHL); mixed cellularity CHL; lymphopenic CHL; lymphocyte-rich CHL; lymphocyte-predominant Hodgkin lymphoma; or nodular lymphocyte-predominant HL.

[0159] Alternatively, the methods described herein may be used to treat, but are not limited to, multiple myeloma; diffuse large B-cell lymphoma; follicular lymphoma; mucosa-associated lymphoid tissue lymphoma (MALT); small cell lymphocytic lymphoma; mediastinal large B-cell lymphoma; nodal marginal zone B-cell lymphoma (NMZL); splenic marginal zone lymphoma (SMZL); intravascular large B-cell lymphoma; primary effusion lymphoma; or lymphoid granulomatosis; B-cell prolymphocytic leukemia; hairy cell leukemia; splenic lymphoma / leukemia unclassifiable; splenic diffuse red pulp small B-cell lymphoma; hairy cell leukemia; lymphoplasmacytic lymphoma; heavy chain disease, e.g., alpha heavy chain disease, gamma heavy chain disease, mu heavy chain disease; plasma cell myeloma; isolated plasmacytoma of bone; extraskeletal plasma cell It can be used to treat certain B-cell lymphomas or proliferative disorders, such as: primary cutaneous follicle center lymphoma; T-cell / tissue-enriched large B-cell lymphoma; chronic inflammation-associated DLBCL; Epstein-Barr virus (EBV)+ DLBCL of the elderly; primary mediastinal (thymic) large B-cell lymphoma; primary cutaneous lower extremity DLBCL; ALK+ large B-cell lymphoma; plasmablastic lymphoma; HHV8-associated multicentric large B-cell lymphoma; Castleman's disease; unclassifiable B-cell lymphoma with features intermediate to diffuse large B-cell lymphoma; or unclassifiable B-cell lymphoma with features intermediate to diffuse large B-cell lymphoma, and classical Hodgkin's lymphoma.

[0160] In one embodiment, the methods described herein can be used to treat leukemia. For example, a subject may be suffering from acute or chronic leukemia of lymphoid or myeloid origin, such as, but not limited to, acute lymphoblastic leukemia (ALL); acute myeloid leukemia (AML); chronic lymphocytic leukemia (CLL); chronic myeloid leukemia (CML); juvenile myelomonocytic leukemia (JMML); hairy cell leukemia (HCL); acute promyelocytic leukemia (a variant of AML); large granular lymphocytic leukemia; or adult T-cell chronic leukemia. In one embodiment, the patient has acute myeloid leukemia, e.g., undifferentiated AML (M0); myeloblastic leukemia (M1; with or without final cell maturation); myeloblastic leukemia (M2; with cell maturation); promyelocytic leukemia (M3 or M3 mutated [M3V]); myelomonocytic leukemia (M4 or M4 mutated [M4E] with eosinophilia); monocytic leukemia (M5); erythroleukemia (M6); or megakaryoblastic leukemia (M7).

[0161] In some embodiments, the cancer to be treated is selected from estrogen receptor-positive, HER2-negative advanced breast cancer, late-stage metastatic breast cancer, liposarcoma, non-small cell lung cancer, liver cancer, ovarian cancer, glioblastoma, refractory solid tumors, retinoblastoma-positive breast cancer, and retinoblastoma-positive endometrial, vaginal, and ovarian cancer and lung and bronchial cancer.

[0162] For example, CDK4 / 6 replication-independent cell proliferation disorders, such as those found in certain cancers, may be characterized by one or a combination of increased activity of cyclin-dependent kinase 1 (CDK1), increased activity of cyclin-dependent kinase 2 (CDK2), decreased, absent, or absent retinoblastoma tumor suppressor protein (Rb) (Rb-null), high levels of MYC expression, increased cyclin E1, E2, and increased cyclin A. The cancer may be characterized by decreased expression of the retinoblastoma tumor suppressor protein or one or more retinoblastoma family member proteins (e.g., but not limited to, p107 and p130). In one embodiment, the subject has an Rb-null or Rb-deficient cancer, including, but not limited to, small cell lung cancer, triple-negative breast cancer, HPV-positive head and neck cancer, retinoblastoma, Rb-negative bladder cancer, Rb-negative prostate cancer, osteosarcoma, or cervical cancer.

[0163] CDK4 / 6 replication-dependent cancers can be derived based on tumor type and molecular genetics using standard techniques and may be characterized by one or more of the following: increased activity of CDK1 or CDK2; reduced, deficient, or absent retinoblastoma tumor suppressor protein (Rb); high levels of MYC expression; increased cyclin E (e.g., E1 or E2) and increased cyclin A; or expression of an Rb-inactivating protein (e.g., HPV-encoded E7). Such cancers may include, but are not limited to, HPV-positive malignancies such as small cell lung cancer, retinoblastoma, cervical cancer and certain head and neck cancers, MYC-amplified tumors such as Burkitt's lymphoma and triple-negative breast cancer; certain sarcomas, certain non-small cell lung cancers, certain melanomas, certain pancreatic cancers, certain leukemias, certain lymphomas, certain brain cancers, certain colon cancers, certain prostate cancers, certain ovarian cancers, certain uterine cancers, certain thyroid cancers and other endocrine tissue cancers, certain salivary gland cancers, certain thymus cancers, certain kidney cancers, certain bladder cancers, and certain testicular cancers.

[0164] In some embodiments, the cancer is selected from small cell lung cancer, retinoblastoma, and triple-negative (ER / PR / Her2-negative) or "basal-like" breast cancer, which almost always have an inactivated retinoblastoma tumor suppressor protein (Rb) and therefore do not require CDK4 / 6 activity for proliferation. Triple-negative (basal-like) breast cancer is also almost always generally or functionally Rb-null. In addition, certain virally induced cancers (e.g., cervical cancer and some head and neck cancers) express a viral protein (E7) that inactivates Rb, rendering these tumors functionally Rb-null. Some lung cancers are also thought to be caused by HPV. In one particular embodiment, the cancer is small cell lung cancer, and the patient is treated with a DNA-damaging agent selected from the group consisting of etoposide, carboplatin, and cisplatin, or a combination thereof.

[0165] The presence or absence of the retinoblastoma (Rb) tumor suppressor protein (Rb positive) can be determined by any of the standard assays known to those skilled in the art, including, but not limited to, Western blot, ELISA (enzyme-linked immunosorbent assay), IHC (immunohistochemistry), and FACS (fluorescence-activated cell sorting). The choice of assay will depend, for example, on the tissue, cell line, or surrogate tissue sample used. For example, Western blot and ELISA can be used with any and all types of tissue, cell line, or surrogate tissue, while IHC methods may be more appropriate when the tissue used in the methods of the present invention is a tumor biopsy. FACS analysis will be most applicable to cell lines and samples that are single-cell suspensions, such as isolated peripheral blood mononuclear cells. See, for example, US20070212736, "Functional Immunohistochemical Cell Cycle Analysis as a Prognostic Indicator for Cancer." Alternatively, molecular genetic testing may be used to determine retinoblastoma gene status. Molecular genetic testing for retinoblastoma includes those described in Lohmann and Gallie "Retinoblastoma. Gene Reviews" (2010): "A comprehensive, sensitive, and economical approach for the detection of mutations in the RB1 gene in retinoblastoma" Journal of Genetics, 88(4), 517-527 (2009).

[0166] In one embodiment, the subject has a cancer that expresses PD-L1. PD-L1 expression can be determined by methods known in the art. For example, PD-L1 expression can be detected using PD-L1 IHC 22C3 pharmDx, an FDA-approved in vitro diagnostic immunohistochemistry (IHC) test developed by Dako and Bristol-Meyers Squibb as an adjunct to treatment with pembrolizumab. This is a qualitative assay that uses the monoclonal mouse anti-PD-L1, clone 22C3 PD-L1, and the EnVision FLEX visualization system on the Autostainer Lin 48 to detect PD-L1 in formalin-fixed, paraffin-embedded (FFPE) human non-small cell lung cancer tissue. Expression levels can be measured using the tumor proportion score (TPS), which measures the percentage of viable tumor cells that show partial or complete membrane staining. Staining can indicate PD-L1 expression between 1% and 100%.

[0167] PD-L1 expression can also be detected using PD-L1 IHC 28-8 pharmDx, an FDA-approved in vitro diagnostic immunohistochemistry (IHC) test developed by Dako and Merck as an adjunct to treatment with nivolumab. This qualitative assay uses monoclonal rabbit anti-PD-L1, clone 28-8, on an Autostainer Lin 48 and the EnVision FLEX visualization system to detect PD-L1 in formalin-fixed, paraffin-embedded (FFPE) human non-small cell lung cancer tissue.

[0168] Other commercially available tests for PD-L1 detection include the Ventana SP263 assay (developed by Ventana in collaboration with AstraZeneca), which uses clone SP263, a monoclonal rabbit anti-PD-L1, and the Ventana SP142 assay (developed by Ventana in collaboration with Genentech / Roche), which uses clone SP142, a rabbit monoclonal anti-PD-L1.

[0169] In one embodiment, the PD-L1-expressing cancer is selected from small cell lung cancer, non-small cell lung cancer, bladder cancer, renal cell carcinoma, gastric cancer, head and neck cancer, mesothelioma, Merkel cell carcinoma, ovarian cancer, melanoma, pancreatic cancer, or other solid tumors.

[0170] Treatment planning As contemplated herein, the administration of chemotherapeutic agents, e.g., DNA-damaging chemotherapeutic agents, and CDK4 / 6 inhibitors in combination with immune checkpoint inhibitors, is timed at doses described herein so that the G0 / G1 arrest induced by the CDK4 / 6 inhibitor is short-lived and substantially transient. Cells arrested in the G1 phase of the cell cycle are more resistant to the damaging effects of chemotherapeutic agents than proliferating cells.

[0171] As described herein, the CDK4 / 6 inhibitor can be administered to the subject before chemotherapy treatment, during chemotherapy treatment, after chemotherapy exposure, or a combination thereof. As contemplated herein, the CDK4 / 6 inhibitor is generally administered in a manner that allows the drug to easily access the bloodstream, such as by intravenous (IV) injection. In one embodiment, the CDK4 / 6 inhibitor is administered to the subject within about 24 hours, 20 hours, 16 hours, 12 hours, 8 hours, or 4 hours, 2.5 hours, 2 hours, less than 1 hour, or 1 / 2 hour before chemotherapy treatment. In another embodiment, the compound is administered to the subject within about 48 hours, 40 hours, less than 36 hours, or 32 hours before chemotherapy treatment. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0172] Generally, the CDK4 / 6 inhibitor is administered to the subject before chemotherapy treatment so that the compound reaches its maximum serum concentration before or during chemotherapy treatment. In one embodiment, the CDK4 / 6 inhibitor is administered to the subject about 30 minutes before chemotherapy administration. In one embodiment, the CDK4 / 6 inhibitor is administered to the subject over about 30 minutes, and then the chemotherapy is administered to the subject. In one embodiment, the CDK4 / 6 inhibitor is administered concurrently or closely with chemotherapy. If desired, the compound can be administered multiple times during chemotherapy treatment to maximize inhibition, especially when the chemotherapy is administered over a long period of time or has a long half-life. In another embodiment, the CDK4 / 6 inhibitor can be administered after chemotherapy exposure, if desired, to mitigate damage to healthy cells associated with chemotherapy exposure. In certain embodiments, the CDK4 / 6 inhibitor is administered by about 1 / 2 hour, by about 1 hour, by about 2 hours, by about 4 hours, by about 8 hours, by about 10 hours, by about 12 hours, by about 14 hours, by about 16 hours, or by about 20 hours or more after chemotherapy exposure. In certain embodiments, the CDK4 / 6 inhibitor is administered between about 12 and 20 hours after chemotherapy exposure. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0173] In one aspect, a CDK4 / 6 inhibitor can be administered in combination with an immune checkpoint inhibitor for a multi-day cycle, using an induction dosing schedule that includes a standard chemotherapy dosing schedule or regimen. In one embodiment, the multi-day cycle is 21 days. In a further embodiment, the 21-day cycle is repeated 1, 2, 3, 4, or 5 or more times. For example, a CDK4 / 6 inhibitor can be administered to arrest CDK4 / 6 replication-dependent HSPCs and immune effector cells in G1 phase during chemotherapy exposure, during which time a significant number of healthy cells can return to the cell cycle and be activated and / or replicate shortly after chemotherapy exposure, for example, within about 24, 30, 40, or about 48 hours, due to the rapid disappearance of the compound's G1 arrest effect. In one embodiment, a CDK4 / 6 inhibitor is administered in combination with a chemotherapy agent and an immune checkpoint inhibitor, including, but not limited to, chemotherapy agents administered on days 1-3 every 21 days; days 1-3 every 28 days; day 1 every 3 weeks; days 1, 8, and 51 every 28 days, days 1 and 8 every 28 days; days 1 and 8 every 21 days; days 1-5 every 21 days; day 1 every week for 6-8 weeks; days 1, 22, and 43; days 1 and 2 every week; days 1-4 and 22-25; days 1-4, 22-25, and 43-46; and similar types of dosing regimens in which CDK4 / 6 replication-dependent cells are arrested in G1 phase during chemotherapy exposure. In further embodiments, the immune checkpoint inhibitor is administered daily, every other day, every third day, once a week, or twice a week. In one embodiment, the CDK4 / 6 inhibitor is Compound I and the immune checkpoint inhibitor is a PD-1, PD-L1, or CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is carboplatin and etoposide. In one embodiment, the chemotherapeutic agent is topotecan.

[0174] In one aspect, the CDK4 / 6 inhibitor can be administered in a maintenance administration schedule using a standard chemotherapy administration schedule or regimen and an immune checkpoint inhibitor, where the CDK4 / 6 inhibitor and chemotherapy are administered alone for a multi-day cycle, and the immune checkpoint inhibitor is administered upon completion of the multi-day cycle. In one embodiment, the CDK4 / 6 inhibitor and chemotherapy are administered for a 21-day cycle, and beginning on day 22, the immune checkpoint inhibitor is administered for at least 21 days, at least 42 days, at least 63 days, at least 84 days, or at least 105 days. In one embodiment, the 21-day cycle of CDK4 / 6 inhibitor and chemotherapy is repeated 1, 2, 3, 4, or 5 times before the immune checkpoint inhibitor is administered. In one embodiment, the immune checkpoint inhibitor is administered once daily. In one embodiment, the immune checkpoint inhibitor is administered every other day. In one embodiment, the immune checkpoint inhibitor is administered every three days. In one embodiment, the immune checkpoint inhibitor is administered once weekly. In one embodiment, the CDK4 / 6 inhibitor is Compound I, and the immune checkpoint inhibitor is a PD-1 inhibitor, a PD-L1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab, and the chemotherapy agent is carboplatin and etoposide. In one embodiment, the CDK4 / 6 inhibitor is Compound I, the immune checkpoint inhibitor is atezolizumab, and the chemotherapy agent is topotecan.

[0175] In one aspect, the CDK4 / 6 inhibitor can be administered in an induction and maintenance dosing schedule using a standard chemotherapy dosing schedule or regimen and an immune checkpoint inhibitor, wherein the CDK4 / 6 inhibitor, chemotherapy, and immune checkpoint inhibitor are administered for a multi-day cycle in an induction phase, and upon completion of the multi-day cycle, the immune checkpoint inhibitor is further administered in a maintenance phase. In one embodiment, the induction phase is a 21-day cycle. In a further embodiment, the 21-day induction phase is repeated 1, 2, 3, 4, or 5 times. In one embodiment, the maintenance phase is at least 21 days, at least 42 days, at least 63 days, at least 84 days, or at least 105 days. In one embodiment, the immune checkpoint inhibitor is administered once daily. In one embodiment, the immune checkpoint inhibitor is administered every other day. In one embodiment, the immune checkpoint inhibitor is administered every three days. In one embodiment, the immune checkpoint inhibitor is administered once weekly. In one embodiment, the CDK4 / 6 inhibitor is Compound I, and the immune checkpoint inhibitor is selected from a PD-1 inhibitor, a PD-L1 inhibitor, or a CTLA-4 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab, and the chemotherapy agent is carboplatin and etoposide. In one embodiment, the CDK4 / 6 inhibitor is Compound I, the immune checkpoint inhibitor is atezolizumab, and the chemotherapy agent is topotecan.

[0176] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to increase the proinflammatory immune effector cell population in an intratumoral immune infiltrate population in a subject with cancer or a tumor. In one embodiment, the proinflammatory immune effector cell population is increased by up to 10%, 20%, 30%, 40%, 50%, or more compared to the proinflammatory immune effector cell population in an intratumoral immune cell infiltrate population without a specific timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in an intratumoral immune cell infiltrate population is increased by about 10% compared to the proinflammatory immune effector cell population in an intratumoral immune cell infiltrate population without a specific timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 20% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without the timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 30% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without the timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 40% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without the timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 50% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without timed administration of a CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041.In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0177] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to enhance T cell activation in the intratumoral immune cell infiltrate population of a subject with cancer or tumor. In one embodiment, the activated T cells are CD4+ T cells. In one embodiment, the activated T cells are CD8+ T cells. In one embodiment, the activated T cells produce interferon-γ. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 5%, 10%, 15%, 20%, or more. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 5%. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 10%. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 15%. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 20%. In one embodiment, interferon-gamma production is increased due to upregulation of the IL2 gene, the IL18 gene, or the LTA gene. In one embodiment, interferon-gamma production is increased due to upregulation of the IL2 gene. In one embodiment, interferon-gamma production is increased due to upregulation of the IL18 gene. In one embodiment, interferon-gamma production is increased due to upregulation of the LTA gene. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0178] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to reduce the population of regulatory T cells (Tregs) in an intratumoral immune cell infiltrate population in a subject suffering from cancer or a tumor. In one embodiment, the Tregs are CD4+CD25+ Tregs. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 10%, 20%, 30%, 40% or more compared to an intratumoral cellular infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 10% compared to an intratumoral cellular infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 20% compared to an intratumoral cellular infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 30% compared to an intratumoral cellular infiltrate population from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 40% compared to an intratumoral cellular infiltrate population from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0179] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapy agent to inhibit the immunosuppressive function of regulatory T cells in intratumoral cellular infiltrate populations in subjects with cancer or tumors. In one embodiment, the Tregs are CD4+CD25+ Tregs. In one embodiment, the proportion of intratumoral Tregs in the CD4+ T cell population is 10, 20, 25, 30, 35, 40, or 50% lower at least 7, 8, 9, 10, or 15 days after treatment or later, compared to chemotherapy / checkpoint inhibitor alone. In one embodiment, the immunosuppressive function of regulatory T cells is measured by a decrease in Phospho-Rb. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by at least 10%, 20%, 30%, 40%, 50%, or more, compared to intratumoral immune cell infiltrate populations derived from subjects not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 10% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 20% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 30% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 40% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 50% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab.In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0180] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to enhance the generation of tumor-specific memory T cells in cancer- or tumor-bearing individuals. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by at least approximately 0.25%, 0.5%, 0.75%, 1%, or more relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 0.25% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 0.5% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 0.75% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 1% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by at least approximately 0.5%, 1%, 1.5%, or more relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by about 0.5% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by about 1% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by about 1.5% relative to the total T cell population. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0181] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapy drug to protect intratumoral immune cells from chemotherapy in a subject with cancer or tumor. In one embodiment, protecting intratumoral immune cells from chemotherapy toxicity results in an enhanced anti-tumor immune response. In one embodiment, the protected intratumoral immune cells are selected from CD8+ T cells, CD4+ T cells, natural killer cells, monocytic myeloid-derived suppressor cells (mMDSCs), and granulocytic myeloid-derived suppressor cells (gMDSCs). In one embodiment, the protected intratumoral immune cells are CD8+ T cells. In one embodiment, the protected intratumoral immune cells are CD4+ T cells. In one embodiment, the protected intratumoral immune cells are natural killer cells. In one embodiment, the protected intratumoral immune cells are mMDSCs. In one embodiment, the protected intratumoral immune cells are gMDSCs. In one embodiment, the percentage of proliferation of intratumoral immune cells is at least approximately 5%, 10%, 15%, 20%, 25%, or 30% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 5% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 10% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 15% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 20% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 25% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 30% higher than the proliferation of immune cells found in the spleen. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab.In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, intratumor immune cell proliferation can be inhibited by up to approximately 50%, 60%, 70%, 75%, 80%, or more in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 50% in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 60% in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 70% in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 75% in about 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 80% in about 6 to 24 hours. In one embodiment, intratumor immune cells can recover within about 30, 40, 45, 48, 50, or 60 hours. In one embodiment, intratumor immune cells recover in about 30 hours. In one embodiment, intratumor immune cells recover in about 40 hours. In one embodiment, intratumor immune cells recover in about 45 hours. In one embodiment, intratumor immune cells recover in about 48 hours. In one embodiment, intratumor immune cells recover in about 50 hours. In one embodiment, intratumor immune cells recover in about 60 hours. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0182] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to increase the proinflammatory immune effector cell population in an intratumoral immune infiltrate population in a subject with cancer or a tumor. In one embodiment, the proinflammatory immune effector cell population is increased by up to 10%, 20%, 30%, 40%, 50%, or more compared to the proinflammatory immune effector cell population in an intratumoral immune infiltrate population without a specific timed administration of a selective, fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in an intratumoral immune infiltrate population is increased by about 10% compared to the proinflammatory immune effector cell population in an intratumoral immune infiltrate population without a specific timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 20% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without the timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 30% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without the timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 40% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without the timed administration of a CDK4 / 6 inhibitor. In one embodiment, the proinflammatory immune effector cell population in the intratumoral immune infiltrate population is increased by about 50% compared to the proinflammatory immune effector cell population in the intratumoral immune infiltrate population without timed administration of a CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab.In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the selective CDK4 / 6 inhibitor is a fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0183] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to enhance T cell activation in the intratumoral immune cell infiltrate population of a subject with cancer or tumor. In one embodiment, the activated T cells are CD4+ T cells. In one embodiment, the activated T cells are CD8+ T cells. In one embodiment, the activated T cells produce interferon-γ. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 5%, 10%, 15%, 20%, or more. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 5%. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 10%. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 15%. In one embodiment, the percentage of activated T cells in the intratumoral immune cell infiltrate population is about 20%. In one embodiment, interferon-gamma production is increased due to upregulation of the IL2 gene, the IL18 gene, or the LTA gene. In one embodiment, interferon-gamma production is increased due to upregulation of the IL2 gene. In one embodiment, interferon-gamma production is increased due to upregulation of the IL18 gene. In one embodiment, interferon-gamma production is increased due to upregulation of the LTA gene. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0184] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to reduce the population of regulatory T cells (Tregs) in the intratumoral immune cell infiltrate population in a subject suffering from cancer or tumor. In one embodiment, the Tregs are CD4+CD25+ Tregs. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 10%, 20%, 30%, 40% or more compared to the intratumoral cellular infiltrate population derived from a subject not receiving the selective, fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 10% compared to the intratumoral cellular infiltrate population derived from a subject not receiving the selective, fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 20% compared to an intratumoral cellular infiltrate population derived from a subject not receiving a selective, fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 30% compared to an intratumoral cellular infiltrate population derived from a subject not receiving a selective, fast-acting, short-half-life CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cellular infiltrate population is reduced by about 40% compared to an intratumoral cellular infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0185] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapy agent to inhibit the immunosuppressive function of regulatory T cells in intratumoral cellular infiltrate populations in subjects with cancer or tumors. In one embodiment, the Tregs are CD4+CD25+ Tregs. In one embodiment, the proportion of intratumoral Tregs in the CD4+ T cell population is reduced by up to 10, 20, 25, 30, 35, 40, or 50% at least 7, 8, 9, 10, or 15 days after treatment, or later, compared to chemotherapy / checkpoint inhibitor alone. In one embodiment, the immunosuppressive function of regulatory T cells is measured by a decrease in Phospho-Rb. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by at least 10%, 20%, 30%, 40%, 50%, or more, compared to intratumoral immune cell infiltrate populations derived from subjects not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 10% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 20% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 30% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 40% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the level of Phospho-Rb in regulatory T cells is reduced by about 50% compared to an intratumoral immune cell infiltrate population derived from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab.In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0186] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to enhance the generation of tumor-specific memory T cells in a subject with cancer or tumor. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by at least approximately 0.25%, 0.5%, 0.75%, 1%, or more relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 0.25% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 0.5% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 0.75% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 1% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by at least approximately 0.5%, 1%, 1.5%, or more relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by about 0.5% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by about 1% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the subject's blood is increased by about 1.5% relative to the total T cell population. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0187] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapy drug to protect intratumoral immune cells from chemotherapy in a subject with cancer or tumor. In one embodiment, protecting intratumoral immune cells from chemotherapy toxicity results in an enhanced anti-tumor immune response. In one embodiment, the protected intratumoral immune cells are selected from CD8+ T cells, CD4+ T cells, natural killer cells, monocytic myeloid-derived suppressor cells (mMDSCs), and granulocytic myeloid-derived suppressor cells (gMDSCs). In one embodiment, the protected intratumoral immune cells are CD8+ T cells. In one embodiment, the protected intratumoral immune cells are CD4+ T cells. In one embodiment, the protected intratumoral immune cells are natural killer cells. In one embodiment, the protected intratumoral immune cells are mMDSCs. In one embodiment, the protected intratumoral immune cells are gMDSCs. In one embodiment, the percentage of proliferation of intratumoral immune cells is at least approximately 5%, 10%, 15%, 20%, 25%, or 30% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 5% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 10% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 15% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 20% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 25% higher than the proliferation of immune cells found in the spleen. In one embodiment, the percentage of proliferation of intratumoral immune cells is about 30% higher than the proliferation of immune cells found in the spleen. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab.In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, intratumor immune cell proliferation can be inhibited by up to approximately 50%, 60%, 70%, 75%, 80%, or more in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 50% in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 60% in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 70% in approximately 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 75% in about 6 to 24 hours. In one embodiment, intratumor immune cell proliferation can be inhibited by about 80% in about 6 to 24 hours. In one embodiment, intratumor immune cells can recover within about 30, 40, 45, 48, 50, or 60 hours. In one embodiment, intratumor immune cells recover in about 30 hours. In one embodiment, intratumor immune cells recover in about 40 hours. In one embodiment, intratumor immune cells recover in about 45 hours. In one embodiment, intratumor immune cells recover in about 48 hours. In one embodiment, intratumor immune cells recover in about 50 hours. In one embodiment, intratumor immune cells recover in about 60 hours.

[0188] In one embodiment, the subject has small cell lung cancer, and the CDK4 / 6 inhibitor compound I is administered intravenously over about 30 minutes before administering either etoposide or carboplatin on day 1 and etoposide on days 2 and 3 in a 21-day treatment cycle, wherein the subject receives both etoposide and carboplatin on day 1 and etoposide on days 2 and 3 in a 21-day cycle first-line treatment protocol, and the subject is further administered an immune checkpoint inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-1, CTLA-4 inhibitor, or PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, such as atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0189] In one embodiment, the subject has small cell lung cancer, and the CDK4 / 6 inhibitor compound I is administered intravenously over about 30 minutes, about 30 minutes before administration of topotecan, in a 21-day treatment cycle, wherein the subject is administered topotecan on days 1, 2, 3, 4, and 5 of the 21-day cycle of a second- or third-line treatment protocol, and the subject is further administered an immune checkpoint inhibitor. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, such as atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0190] In one embodiment, the subject has small cell lung cancer, and the CDK4 / 6 inhibitor compound I is administered intravenously over about 30 minutes, about 30 minutes before administration of topotecan, in a 21-day treatment cycle, wherein the subject is administered topotecan on days 1, 2, and 3 of the 21-day cycle of a second- or third-line treatment protocol, and the subject is further administered an immune checkpoint inhibitor. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor, such as atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0191] In one embodiment, the subject has small cell lung cancer, and the CDK4 / 6 inhibitor Compound I is administered in an induction and maintenance dosing schedule, wherein Compound I is administered intravenously over about 30 minutes, about 30 minutes before the administration of carboplatin, etoposide, and the immune checkpoint inhibitor, and carboplatin is administered on day 1 of a 21-day induction phase chemotherapy cycle. Etoposide is administered on days 1, 2, and 3, and the 21-day cycle is repeated 1, 2, 3, 4, or 5 times. The subject is further administered the immune checkpoint inhibitor alone in a maintenance phase beginning upon completion of the induction phase. In one embodiment, the immune checkpoint inhibitor is further administered for at least 21 days, at least 42 days, at least 63 days, at least 84 days, or at least 105 days in the maintenance phase. In one embodiment, the immune checkpoint inhibitor is administered once daily. In one embodiment, the immune checkpoint inhibitor is administered every other day. In one embodiment, the immune checkpoint inhibitor is administered every three days. In one embodiment, the immune checkpoint inhibitor is administered once a week. In one embodiment, the immune checkpoint inhibitor is atezolizumab.

[0192] In one embodiment, the subject has small cell lung cancer, and the CDK4 / 6 inhibitor Compound I is administered in an induction and maintenance dosing schedule, wherein Compound I is administered intravenously over about 30 minutes on each of days 1, 2, 3, 4, and 5 of a 21-day induction phase chemotherapy cycle, about 30 minutes before the administration of topotecan and the immune checkpoint inhibitor, the 21-day cycle being repeated four times, and the subject is further administered the immune checkpoint inhibitor alone in a maintenance phase beginning upon completion of the induction phase. In one embodiment, the immune checkpoint inhibitor is further administered for at least 21 days, at least 42 days, at least 63 days, at least 84 days, or at least 105 days in the maintenance phase. In one embodiment, the immune checkpoint inhibitor is administered once daily. In one embodiment, the immune checkpoint inhibitor is administered every other day. In one embodiment, the immune checkpoint inhibitor is administered every three days. In one embodiment, the immune checkpoint inhibitor is administered once weekly. In one embodiment, the immune checkpoint inhibitor is atezolizumab.

[0193] As contemplated herein, CDK4 / 6 inhibitors, in combination with immune checkpoint inhibitors, may be used in several standard of care chemotherapy treatment regimens, including, but not limited to, small cell lung cancer therapy protocols, such as, but not limited to, cisplatin 60 mg / m on day 1 every 21 days for 4 cycles. 2 IV and etoposide 120 mg / m on days 1–3 2 IV; cisplatin 80 mg / m on day 1 every 28 days for 4 cycles 2 IV and etoposide 100 mg / m on days 1–3 2 IV: cisplatin 60–80 mg / m on day 1 every 21–28 days 2 IV and etoposide 80–120 mg / m on days 1–3. 2 IV (maximum 4 cycles); carboplatin AUC 5-6 min on day 1 every 28 days * mg / mL IV and etoposide 80–100 mg / m on days 1–3 2IV (up to 4 cycles); cisplatin 60–80 mg / m on day 1 every 21–28 days 2 IV and etoposide 80–120 mg / m on days 1–3. 2 Carboplatin AUC 5-6 min on day 1 every 28 days * mg / mL IV and etoposide 80–100 mg / m on days 1–3 2 IV (maximum 6 cycles); cisplatin 60 mg / m on day 1 every 28 days 2 IV and irinotecan 60 mg / m on days 1, 8, and 15 2 IV (up to 6 cycles); cisplatin 30 mg / m on days 1 and 8 every 21 days 2 IV or 80 mg / m on day 1 2 IV plus irinotecan 65 mg / m on days 1 and 8 2 IV (maximum 6 cycles); carboplatin AUC 5 min on day 1 every 28 days * mg / mL IV on days 1, 8, and 15 with irinotecan 50 mg / m 2 IV (maximum 6 cycles); carboplatin AUC 4-5 min on day 1 every 21 days * mg / mL IV on day 1 and irinotecan 150–200 mg / m 2 IV (maximum 6 cycles); cyclophosphamide 800–1000 mg / m on day 1 every 21–28 days 2 IV and doxorubicin 40–50 mg / m on day 1 2 IV and vincristine 1 to 1.4 mg / m on day 1 2 IV (maximum 6 cycles); etoposide 50 mg / m daily for 3 weeks every 4 weeks 2 Topotecan 2.3 mg / m PO on days 1–5 every 21 days 2 Topotecan 1.5 mg / m PO on days 1–5 every 21 days 2 IV; carboplatin AUC 5 min on day 1 every 28 days * mg / mL IV on days 1, 8, and 15 with irinotecan 50 mg / m 2 IV: carboplatin AUC 4-5 IV on day 1 and irinotecan 150-200 mg / m on day 1 every 21 days 2 IV; cisplatin 30 mg / m on days 1, 8, and 15 every 28 days 2IV and irinotecan 60 mg / m on days 1, 8, and 15 2 IV; cisplatin 60 mg / m on day 1 every 28 days 2 IV and irinotecan 60 mg / m on days 1, 8, and 15 2 IV; cisplatin 30 mg / m on days 1 and 8 every 21 days 2 IV or 80 mg / m on day 1 2 IV plus irinotecan 65 mg / m on days 1 and 8 2 IV; Paclitaxel 80 mg / m every 6 weeks every 8 weeks 2 IV; Paclitaxel 175 mg / m on day 1 every 3 weeks 2 IV; etoposide 50 mg / m daily for 3 weeks every 4 weeks 2 Topotecan 2.3 mg / m PO on days 1–5 every 21 days 2 Topotecan 1.5 mg / m PO on days 1–5 every 21 days 2 IV; carboplatin AUC 5 min on day 1 every 28 days * mg / mL IV on days 1, 8, and 15 with irinotecan 50 mg / m 2 IV: Carboplatin AUC 4-5 on day 1 every 21 days * mg / mL IV on day 1 and irinotecan 150–200 mg / m 2 IV; cisplatin 30 mg / m on days 1, 8, and 15 every 28 days 2 IV and irinotecan 60 mg / m on days 1, 8, and 15 2 IV; cisplatin 60 mg / m on day 1 every 28 days 2 IV and irinotecan 60 mg / m on days 1, 8, and 15 2 IV; cisplatin 30 mg / m on days 1 and 8 every 21 days 2 IV or 80 mg / m on day 1 2 IV plus irinotecan 65 mg / m on days 1 and 8 2 IV; Paclitaxel 80 mg / m every 6 weeks every 8 weeks 2 IV; and paclitaxel 175 mg / m on day 1 every 3 weeks 2In another embodiment, Compound I may be administered in combination with, but not limited to, topotecan 2.0 mg / m IV on days 1-5 every 21 days. 2 Topotecan 1.5 to 2.3 mg / m PO on days 1 to 5 every 21 days 2 Etoposide 100 mg / m PO on days 1–3 2 intravenous (IV) plus cisplatin 50 mg / m on days 1 and 2 2 IV (administered every 3 weeks for up to 6 cycles); etoposide 100 mg / m on days 1–3 2 intravenous (IV) and carboplatin 300 mg / m on day 1 2 IV (administered every 3 weeks for up to 6 treatment cycles); carboplatin (300 mg / m on day 1) 2 IV) and 80 mg / m on days 1–3 2 Etoposide in escalating doses starting IV; carboplatin 125 mg / m given for 3 days 2 / day and etoposide 200 mg / m 2 / day combination; etoposide 80-200 mg / m on days 1-3 2 intravenous (IV) and carboplatin 125–450 mg / m on day 1 2 IV (treatment cycle is every 21-28 days); carboplatin AUC 5-6 min on day 1 of every 28 days * mg / mL IV and etoposide 80–200 mg / m on days 1–3 2 It is administered to provide chemoprotection in small cell lung cancer therapy protocols, such as IV (up to 4 cycles). In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0194] In one embodiment, a CDK4 / 6 inhibitor is used in combination with an immune checkpoint inhibitor in several standard of care chemotherapy treatment regimens, including, but not limited to, CDK4 / 6 replication-independent head and neck cancer treatment protocols, such as, but not limited to, cisplatin 100 mg / m on days 1, 22, and 43 weekly for 6-7 weeks. 2 IV or 40–50 mg / m 2 IV; Loading dose cetuximab 400 mg / m 1 week before the start of radiation therapy 2 IV, then weekly at 250 mg / m 2 (premedicated with dexamethasone, diphenhydramine, and ranitidine); cisplatin 20 mg / m on the second day of each week for up to 7 weeks 2 IV and paclitaxel 30 mg / m on day 1 of each week for up to 7 weeks 2 IV: cisplatin 20 mg / m on days 1–4 and 22–25 2 / day IV and 5-FU 1000mg / m by continuous IV infusion on days 1-4 and 22-25 2 / day on days 1–5; 5-FU 800 mg / m by continuous IV infusion administered on the day of radiation 2 and hydroxyurea 1g PO q12h (11 doses per cycle); chemotherapy and radiation administered every other week for a total of 13 weeks; carboplatin 70mg / m on days 1-4, 22-25, and 43-46 2 / day IV and 5-FU 600mg / m by continuous IV infusion on days 1-4, 22-25, and 43-46 2 / day; carboplatin AUC 1.5 IV on day 1 of each week and paclitaxel 45 mg / m on day 1 of each week 2 IV: cisplatin 100 mg / m on days 1, 22, and 43 for 6–7 weeks 2 IV or weekly 40–50 mg / m 2 IV; docetaxel 75 mg / m on day 1 every 3 weeks for 3 cycles 2 IV and cisplatin 100 mg / m on day 1 2 IV and 5-FU 100 mg / m by continuous IV infusion on days 1–42 / day, then 3–8 weeks later, carboplatin AUC 1.5 IV weekly for up to 7 weeks during radiation therapy; docetaxel 75 mg / m on day 1 every 3 weeks for 4 cycles 2 IV and cisplatin 75 mg / m on day 1 2 IV and 5-FU 750 mg / m by continuous IV infusion on days 1–4 2 / day; cisplatin 100 mg / m on day 1 every 3 weeks for 6 cycles 2 IV and 5-FU 1000 mg / m by continuous IV infusion on days 1–4 every 3 weeks for 6 cycles 2 / day on day 1 and cetuximab 400 mg / m 2 IV loading dose, then 250 mg / m weekly until disease progression 2 IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); carboplatin AUC 5 min on day 1 every 3 weeks for 6 cycles * mg / mL IV and 5-FU 1000mg / m by continuous IV infusion on days 1–4 every 3 weeks for 6 cycles 2 / day on day 1 and cetuximab 400 mg / m 2 IV loading dose, then 250 mg / m weekly until disease progression 2 IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and docetaxel 75 mg / m on day 1 2 IV; cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and paclitaxel 175 mg / m on day 1 2 IV; carboplatin AUC 6 IV on day 1 and docetaxel 65 mg / m on day 1 every 3 weeks 2 IV; carboplatin AUC 6 IV on day 1 and paclitaxel 200 mg / m on day 1 every 3 weeks 2 IV: cisplatin 75–100 mg / m on day 1 every 3–4 weeks 2 IV and cetuximab 400 mg / m on day 1 2 IV loading dose, then 250 mg / m weekly 2IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); cisplatin 100 mg / m on day 1 every 3 weeks 2 IV and 5-FU 1000mg / m by continuous IV infusion on days 1–4 2 / day; methotrexate 40 mg / m every week 2 IV (3-week cycle); paclitaxel 200 mg / m every 3 weeks 2 IV docetaxel 75 mg / m every 3 weeks 2 IV; cetuximab 400 mg / m on day 1 2 IV loading dose, then 250 mg / m weekly until disease progression 2 IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); cisplatin 100 mg / m on day 1 every 3 weeks for 6 cycles 2 IV and 5-FU 1000 mg / m by continuous IV infusion on days 1–4 every 3 weeks for 6 cycles 2 / day on day 1 and cetuximab 400 mg / m 2 IV loading dose, then 250 mg / m weekly 2 IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); carboplatin AUC 5 min on day 1 every 3 weeks for 6 cycles * mg / mL IV and 5-FU 1000mg / m by continuous IV infusion on days 1–4 every 3 weeks for 6 cycles 2 / day on day 1 and cetuximab 400 mg / m 2 IV loading dose, then 250 mg / m weekly 2 IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and docetaxel 75 mg / m on day 1 2 IV; cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and paclitaxel 175 mg / m on day 1 2 IV; carboplatin AUC 6 IV on day 1 and docetaxel 65 mg / m on day 1 every 3 weeks 2 IV; carboplatin AUC 6 IV on day 1 and paclitaxel 200 mg / m on day 1 every 3 weeks 2IV: cisplatin 75–100 mg / m on day 1 every 3–4 weeks 2 IV and cetuximab 400 mg / m on day 1 2 IV loading dose, then 250 mg / m weekly 2 IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); cisplatin 100 mg / m on day 1 every 3 weeks 2 IV and 5-FU 1000mg / m by continuous IV infusion on days 1–4 2 / day; methotrexate 40 mg / m every week 2 IV (3-week cycle); paclitaxel 200 mg / m every 3 weeks 2 IV docetaxel 75 mg / m every 3 weeks 2 IV; cetuximab 400 mg / m on day 1 2 IV loading dose, then 250 mg / m weekly until disease progression 2 IV (premedicated with dexamethasone, diphenhydramine, and ranitidine); cisplatin 100 mg / m with radiation on days 1, 22, and 43 every 4 weeks for 3 cycles 2 IV, followed by cisplatin 80 mg / m on day 1 2 IV and 5-FU 1000mg / m by continuous IV infusion on days 1–4 2 / day; cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and docetaxel 75 mg / m on day 1 2 IV; cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and paclitaxel 175 mg / m on day 1 2 IV; carboplatin AUC 6 IV on day 1 and docetaxel 65 mg / m on day 1 every 3 weeks 2 IV; carboplatin AUC 6 IV on day 1 and paclitaxel 200 mg / m on day 1 every 3 weeks 2 IV; cisplatin 100 mg / m on day 1 every 3 weeks 2 IV and 5-FU 1000mg / m by continuous IV infusion on days 1–4 2 / day; cisplatin 50–70 mg / m on day 1 every 4 weeks 2 IV and gemcitabine 1000 mg / m on days 1, 8, and 152 IV gemcitabine 1000 mg / m on days 1, 8, and 15 every 4 weeks 2 Gemcitabine 1250 mg / m IV or on days 1 and 8 every 3 weeks 2 IV weekly methotrexate 40 mg / m 2 IV (3-week cycle); paclitaxel 200 mg / m every 3 weeks 2 IV docetaxel 75 mg / m every 3 weeks 2 IV; cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and docetaxel 75 mg / m on day 1 2 IV; cisplatin 75 mg / m on day 1 every 3 weeks 2 IV and paclitaxel 175 mg / m on day 1 2 IV; carboplatin AUC 6 IV on day 1 and docetaxel 65 mg / m on day 1 every 3 weeks 2 IV; carboplatin AUC 6 IV on day 1 and paclitaxel 200 mg / m on day 1 every 3 weeks 2 IV; cisplatin 100 mg / m on day 1 every 3 weeks 2 IV and 5-FU 1000mg / m by continuous IV infusion on days 1–4 2 / day; cisplatin 50–70 mg / m on day 1 every 4 weeks 2 IV and gemcitabine 1000 mg / m on days 1, 8, and 15 2 IV gemcitabine 1000 mg / m on days 1, 8, and 15 every 4 weeks 2 Gemcitabine 1250 mg / m IV or on days 1 and 8 every 3 weeks 2 IV weekly methotrexate 40 mg / m 2 IV (3-week cycle); paclitaxel 200 mg / m every 3 weeks 2 IV; and docetaxel 75 mg / m every 3 weeks 2IV. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0195] In one embodiment, CDK4 / 6 inhibitors can be used in combination with immune checkpoint inhibitors in combination with several standard of care chemotherapy treatment regimens, including, but not limited to, CDK4 / 6 replication-independent triple-negative breast cancer treatment protocols, such as, but not limited to, dose-dense doxorubicin (Adriamycin) and cyclophosphamide (Cytoxan) every two weeks for four cycles, followed by dose-dense paclitaxel (Taxol™) every two weeks for four cycles; Adriamycin / paclitaxel / cyclophosphamide every three weeks for a total of four cycles; Adriamycin / paclitaxel / cyclophosphamide every two weeks for a total of four cycles; Adriamycin / cyclophosphamide every three weeks for four cycles, followed by paclitaxel (Taxol™); and Adriamycin / cyclophosphamide every two weeks for four cycles, followed by paclitaxel (Taxol™). In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0196] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard-of-care chemotherapy regimens, including, but not limited to, CDK4 / 6 replication-independent bladder cancer treatment protocols, such as, but not limited to, adjuvant intravesical chemotherapy for non-muscle-invasive bladder cancer, first-line chemotherapy for muscle-invasive bladder cancer, and second-line chemotherapy for muscle-invasive bladder cancer. Non-limiting examples of postoperative chemotherapy for bladder cancer include a single dose of mitomycin (40 mg), epirubicin (80 mg), thiotepa (30 mg), or doxorubicin (50 mg). Non-limiting examples of first-line chemotherapy for bladder cancer include gemcitabine 1000 mg / m on days 1, 8, and 15 and cisplatin 70 mg / m on days 1 or 2 every 28 days for a total of four cycles. 2 methotrexate 30 mg / m on days 1, 15, and 22 every 28 days for a total of 3 cycles 2 IV and vinblastine 3 mg / m on days 2, 15, and 22 2 IV and doxorubicin 30 mg / m on day 2 2 IV and cisplatin 70 mg / m on day 2 2 and the above-described dose-dense regimens administered with growth factor stimulators. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0197] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in combination with several standard of care chemotherapy treatment regimens, including, but not limited to, CDK4 / 6 replication-independent retinoblastoma treatment protocols, including, but not limited to, administration of carboplatin, vincristine, or etoposide along with surgery, radiation therapy, cryotherapy, hyperthermia, or other local therapeutic techniques. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0198] In one embodiment, a CDK4 / 6 inhibitor is used in combination with an immune checkpoint inhibitor in several standard of care chemotherapy treatment regimens, including but not limited to, CDK4 / 6 replication-independent cervical cancer treatment protocols, including but not limited to, cisplatin 40 mg / m weekly. 2 IV: cisplatin 50–75 mg / m on day 1 2 IV and 5-fluorouracil (5-FU) 1000 mg / m on days 2–5 and 30–33 2 cisplatin 50–75 mg / m on day 1 every 3 weeks for 3–4 cycles 2 IV and 5-FU 1000 mg / m over 24 hours on days 1–4 2bevacizumab 15 mg / kg IV over 30-90 minutes with cisplatin on day 1 or 2 and paclitaxel on day 1 every three weeks; bevacizumab and paclitaxel with topotecan on day 1 on days 1-3 every three weeks; paclitaxel on day 1 followed by cisplatin on day 1 every three weeks; topotecan on days 1-3 followed by cisplatin on day 1 every three weeks; and paclitaxel on day 1 every three weeks. In another embodiment, the cervical cancer therapy protocol is administered in addition to radiation, surgery, or another procedure, as described above. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0199] In one embodiment, CDK4 / 6 inhibitors can be combined with immune checkpoint inhibitors and several standard-of-care chemotherapy regimens for triple-negative breast cancer (TNBC). TNBC is defined as the absence of estrogen receptor, progesterone receptor, and HER2 / neu staining. TNBC is refractory to some of the most effective therapies available for breast cancer treatment, including HER2-directed therapy such as trastuzumab and endocrine therapy such as tamoxifen or aromatase inhibitors. Combination cytotoxic chemotherapy, typically administered in dose-dense or metronomic schedules, remains the standard of care for early-stage TNBC. Platinum agents have recently emerged as promising agents for the treatment of TNBC with paclitaxel and carboplatin in addition to adriamycin and cyclophosphamide chemotherapy in the neoadjuvant setting. Poly(ADP-ribose) polymerase (PARP) inhibitors, including niraparib (Tesaro), are in development as potential therapeutics for TNBC. PARP is a family of enzymes involved in multiple cellular processes, including DNA repair. In one embodiment, the TNBC therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the TNBC therapy is the PARP inhibitor niraparib. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0200] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in combination with several standard of care chemotherapy treatment regimens for AML, including cytarabine (cytosine arabinoside or ara-C) and anthracycline drugs (e.g., daunorubicin / daunomycin, idarubicin, and mitoxantrone). Other chemotherapy agents that can be used to treat AML include cladribine (Leustatin™, 2-CdA), fludarabine (Fludara™), topotecan, etoposide (VP-16), 6-thioguanine (6-TG), hydroxyurea (Hydrea™), corticosteroids such as prednisone or dexamethasone (Decadron™), methotrexate (MTX), 6-mercaptopurine (6-MP), azacitidine (Vidaza™), decitabine (Dacogen™). In one embodiment, the AML therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0201] In one embodiment, CDK4 / 6 inhibitors can be combined with immune checkpoint inhibitors and some standard-of-care chemotherapy treatment regimens for CLL and other lymphomas. CLL treatments include purine analogs such as fludarabine (Fludara™), pentostatin (Nipent™), and cladribine (2-CdA, Leustatin™), as well as alkylating agents including chlorambucil (Leukeran™) and cyclophosphamide (Cytoxan™) and bendamustine (Treanda™). Other drugs sometimes used for CLL include doxorubicin (Adriamycin™), methotrexate, oxaliplatin, vincristine (Oncovin™), etoposide (VP-16), and cytarabine (ara-C). Other drugs include rituximab (Rituxan™), obinutuzumab (Gazyva™), ofatumumab (Arzerra™), alemtuzumab (Campath™), and ibrutinib (Imbruvica™). In one embodiment, the CLL therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0202] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in conjunction with several standard of care chemotherapy regimens for CML. CML treatments include interferon, imatinib (Gleevec™), the chemotherapy drugs hydroxyurea (Hydrea™), cytarabine (Ara-C), busulfan, cyclophosphamide (Cytoxan™), and vincristine (Oncovin™). Omacetaxine (Synribo™) is a chemotherapy drug approved for treating CML resistant to some currently used TKIs. In one embodiment, CML therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0203] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used with several standard of care chemotherapy treatment regimens for CMML. CMML treatments include deferasirox (Exjade™), cytarabine and idarubicin, cytarabine and topotecan, and cytarabine and fludarabine, hydroxyurea (hydroxycarbamate, Hydrea™), azacitidine (Vidaza™), and decitabine (Dacogen™). In one embodiment, CMML therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0204] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard of care chemotherapy regimens for multiple myeloma. Multiple myeloma treatments include pomalidomide (Pomalyst™), carfilzomib (Kyprolis™), everolimus (Afinitor™), dexamethasone (Decadron™), prednisone and methylprednisolone (Solu-medrol™), and hydrocortisone. In one embodiment, the multiple myeloma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0205] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard of care chemotherapy treatment regimens for Hodgkin's disease. Hodgkin's disease treatments include brentuximab vedotin (Adcetris™): anti-CD30, rituximab, Adriamycin™ (doxorubicin), bleomycin, vinblastine, and dacarbazine (DTIC). In one embodiment, the Hodgkin's disease therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0206] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used with several standard of care chemotherapy treatment regimens for non-Hodgkin's disease. Non-Hodgkin's disease treatments include rituximab (Rituxan™), ibritumomab (Zevalin™), tositumomab (Bexxar™), alemtuzumab (Campath™) (CD52 antigen), ofatumumab (Alzera™), brentuximab vedotin (Adcetris™), and lenalidomide (Revlimid™). In one embodiment, the non-Hodgkin's disease therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0207] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard chemotherapy treatment regimens for diffuse large B-cell lymphoma (DLBCL). DLBCL treatments include CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) and the monoclonal antibody rituximab (Rituxan™). This regimen, known as R-CHOP, is usually administered for approximately six months. In one embodiment, DLBCL therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0208] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in combination with several standard of care chemotherapy treatment regimens for primary mediastinal B-cell lymphoma. Primary mediastinal B-cell lymphoma treatments include R-CHOP. In one embodiment, primary mediastinal B-cell lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0209] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and some standard chemotherapy regimens for follicular lymphoma. Follicular lymphoma treatments include rituximab (Rituxan™) in combination with chemotherapy, using single-agent chemotherapy drugs (e.g., bendamustine or fludarabine) or drug combinations such as CHOP or CVP (cyclophosphamide, vincristine, prednisone) regimens. The radioactive monoclonal antibodies ibritumomab (Zevalin™) and tositumomab (Bexar™) are also potential treatment options. For patients who cannot tolerate the more intensive chemotherapy regimen of rituximab alone, milder chemotherapy drugs (e.g., chlorambucil or cyclophosphamide) are used. In one embodiment, follicular lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0210] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in conjunction with several standard of care chemotherapy regimens for chronic lymphocytic leukemia / small cell lymphocytic lymphoma. The chronic lymphocytic leukemia / small cell lymphocytic lymphoma treatment includes R-CHOP. In one embodiment, the chronic lymphocytic leukemia / small cell lymphocytic lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0211] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used with several standard chemotherapy treatment regimens for mantle cell lymphoma. Mantle cell lymphoma treatments include fludarabine, cladribine, or pentostatin; bortezomib (Velcade™), lenalidomide (Revlimid™), and ibrutinib (Imbruvica™). In one embodiment, mantle cell lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0212] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard chemotherapy treatment regimens for mucosa-associated lymphoid tissue (MALT) extranodal marginal zone B-cell lymphoma. Mucosa-associated lymphoid tissue (MALT) treatments include combinations such as rituximab; chlorambucil or fludarabine, or CVP, often with rituximab. In one embodiment, mucosa-associated lymphoid tissue (MALT) therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0213] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard chemotherapy regimens for nodal marginal zone B-cell lymphoma. Nodal marginal zone B-cell lymphoma treatments include rituximab (Rituxan™) in combination with chemotherapy, using single-agent chemotherapy drugs (e.g., bendamustine or fludarabine) or drug combinations such as CHOP or CVP (cyclophosphamide, vincristine, prednisone) regimens. The radioactive monoclonal antibodies ibritumomab (Zevalin™) and tositumomab (Bexar™) are also potential treatment options. For patients who cannot tolerate the more intensive chemotherapy regimen of rituximab alone, milder chemotherapy drugs (e.g., chlorambucil or cyclophosphamide) are used. In one embodiment, nodal marginal zone B-cell lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0214] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in combination with several standard of care chemotherapy treatment regimens for splenic marginal zone B-cell lymphoma. The splenic marginal zone B-cell lymphoma treatment includes rituximab. In one embodiment, the splenic marginal zone B-cell lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0215] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard chemotherapy regimens for Burkitt lymphoma. Burkitt lymphoma treatments include methotrexate; hyper-CVAD - cyclophosphamide, vincristine, doxorubicin (also known as Adriamycin™), and dexamethasone. Course B consists of methotrexate and cytarabine; CODOX-M - cyclophosphamide, doxorubicin, high-dose methotrexate / ifosfamide, etoposide, and high-dose cytarabine; and etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone (EPOCH). In one embodiment, Burkitt lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0216] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in conjunction with several standard of care chemotherapy treatment regimens for lymphoplasmacytic lymphoma. The lymphoplasmacytic lymphoma treatment includes rituximab. In one embodiment, the lymphoplasmacytic lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0217] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard of care chemotherapy treatment regimens for hairy cell leukemia. Hairy cell leukemia treatments include cladribine (2-CdA) or pentostatin; rituximab; and interferon-α. In one embodiment, hairy cell leukemia therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0218] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used with several standard-of-care chemotherapy regimens for precursor T-lymphoblastic lymphoma / leukemia. Precursor T-lymphoblastic lymphoma / leukemia treatments include cyclophosphamide, doxorubicin (Adriamycin™), vincristine, L-asparaginase, methotrexate, prednisone, and, in some cases, cytarabine (ara-C). Due to the risk of spread to the brain and spinal cord, chemotherapy drugs such as methotrexate are also administered into the cerebrospinal fluid. In one embodiment, precursor T-lymphoblastic lymphoma / leukemia therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0219] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard of care chemotherapy treatment regimens for cutaneous lymphoma. Cutaneous lymphoma treatments include gemcitabine, liposomal doxorubicin (Doxil™); methotrexate; chlorambucil; cyclophosphamide; pentostatin; etoposide; temozolomide; pralatrexate; and R-CHOP. In one embodiment, the cutaneous lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN 1884, and AGEN 2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0220] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in conjunction with several standard of care chemotherapy treatment regimens for angioimmunoblastic T-cell lymphoma. The angioimmunoblastic T-cell lymphoma treatment includes prednisone or dexamethasone. In one embodiment, the angioimmunoblastic T-cell lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0221] In one embodiment, a CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor in conjunction with several standard of care chemotherapy regimens for extranodal natural killer / T-cell lymphoma, nasal type. Treatments for extranodal natural killer / T-cell lymphoma, nasal type include CHOP. In one embodiment, the extranodal natural killer / T-cell lymphoma, nasal type therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0222] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard chemotherapy treatment regimens for anaplastic large cell lymphoma. Anaplastic large cell lymphoma treatments include CHOP; pralatrexate (Folotyn™), targeted drugs such as bortezomib (Velcade™) or romidepsin (Istodax), or immunotherapeutics such as alemtuzumab (Campus™) and denileukin diftitox (Ontak™). In one embodiment, anaplastic large cell lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0223] In one embodiment, a CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in conjunction with several standard-of-care chemotherapy treatment regimens for primary central nervous system (CNS) lymphoma. Primary central nervous system (CNS) lymphoma treatments include methotrexate; rituximab. In one embodiment, primary central nervous system (CNS) lymphoma therapy is combined with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0224] In one embodiment, the subject has small cell lung cancer and is administered a chemotherapy agent selected from the group consisting of carboplatin, cisplatin, oxaliplatin, etoposide, and topotecan, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab.

[0225] In one embodiment, the chemotherapeutic agent is etoposide, the CDK4 / 6 inhibitor is compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is carboplatin, the CDK4 / 6 inhibitor is compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising carboplatin and etoposide, the CDK4 / 6 inhibitor is compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is cisplatin, the CDK4 / 6 inhibitor is compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is topotecan, the CDK4 / 6 inhibitor is compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is oxaliplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0226] In one embodiment, the subject has melanoma and is administered a chemotherapy agent selected from the group consisting of dacarbazine, temozolomide, nab-paclitaxel, paclitaxel, cisplatin, oxaliplatin, carboplatin, vinblastine, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is dacarbazine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is temozolomide, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is nab-paclitaxel, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is paclitaxel, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is cisplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is carboplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.In one embodiment, the chemotherapeutic agent is vinblastine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is oxaliplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0227] In one embodiment, the subject has renal cell carcinoma and is administered a chemotherapy agent selected from the group consisting of vinblastine, floxuridine, 5-fluorouracil, capecitabine, and gemcitabine, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is vinblastine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is floxuridine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is 5-fluorouracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is capecitabine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is gemcitabine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0228] In one embodiment, the subject has bladder cancer and is administered a chemotherapy agent selected from the group consisting of carboplatin, oxaliplatin, cisplatin, fluorouracil, mitomycin, methotrexate, vinblastine, doxorubicin, gemcitabine, paclitaxel, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is cisplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and 5-fluorouracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising mitomycin and 5-fluorouracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin and gemcitabine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.In one embodiment, the chemotherapy agents are a combination treatment regimen comprising cisplatin, methotrexate, vinblastine, and doxorubicin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agents are a combination treatment regimen comprising cisplatin, methotrexate, and vinblastine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agents are a combination treatment regimen comprising carboplatin and paclitaxel, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is oxaliplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0229] In one embodiment, the subject has urothelial carcinoma and is administered a chemotherapy agent selected from the group consisting of carboplatin, cisplatin, oxaliplatin, fluorouracil, mitomycin, methotrexate, vinblastine, doxorubicin, gemcitabine, paclitaxel, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is cisplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and 5-fluorouracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising mitomycin and 5-fluorouracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin and gemcitabine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.In one embodiment, the chemotherapy agents are a combination treatment regimen comprising cisplatin, methotrexate, vinblastine, and doxorubicin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agents are a combination treatment regimen comprising cisplatin, methotrexate, and vinblastine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agents are a combination treatment regimen comprising carboplatin and paclitaxel, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is oxaliplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0230] In one embodiment, the subject has breast cancer and is administered a chemotherapy agent selected from the group consisting of carboplatin, oxaliplatin, cisplatin, doxorubicin, 5-fluorouracil, paclitaxel, cyclophosphamide, gemcitabine, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is carboplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is cisplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin and 5-fluorouracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is a combination treatment regimen comprising cisplatin and gemcitabine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is doxorubicin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is cyclophosphamide, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.In one embodiment, the chemotherapeutic agent is paclitaxel, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is oxaliplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0231] In one embodiment, the subject has colorectal cancer and is administered a chemotherapy agent selected from the group consisting of 5-fluorouracil, capecitabine, irinotecan, oxaliplatin, trifluridine, oxaliplatin, and tipiracil, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapy agent is 5-fluorouracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is capecitabine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising trifluridine and tipiracil, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is irinotecan, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is oxaliplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0232] In one embodiment, the subject has castration-resistant prostate cancer and is administered a chemotherapeutic agent selected from the group consisting of docetaxel, cabazitaxel, mitoxantrone, and estramustine, or a combination thereof, in combination with Compound I and atezolizumab. In one embodiment, the chemotherapeutic agent is docetaxel. In one embodiment, the chemotherapeutic agent is cabazitaxel. In one embodiment, the chemotherapeutic agent is mitoxantrone. In one embodiment, the chemotherapeutic agent is estramustine. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is docetaxel, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is cabazitaxel, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is mitoxantrone, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is estramustine, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab.

[0233] In one embodiment, the subject has a PD-L1-expressing tumor and is administered a chemotherapeutic agent selected from the group consisting of carboplatin, cisplatin, gemcitabine, etoposide, 5-fluorouracil, paclitaxel, oxaliplatin, and topotecan, or a combination thereof, in combination with a CDK4 / 6 inhibitor and an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I or Compound II. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor, a PD-1 inhibitor, or a PD-L1 inhibitor. In one embodiment, the immune checkpoint inhibitor is a PD-L1 inhibitor selected from durvalumab, avelumab, and atezolizumab. In one embodiment, the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is etoposide, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the immune checkpoint inhibitor is a CTLA-4 inhibitor selected from the group consisting of ipilimumab (Yervoy™), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo™), pembrolizumab (Keytruda™), and pidilizumab. In one embodiment, the chemotherapeutic agent is carboplatin, the CDK4 / 6 inhibitor is Compound I, and the PD-L1 inhibitor is atezolizumab. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising carboplatin ...

Claims

1. 1. A method of treating a subject having cancer, comprising administering to said subject a treatment regimen comprising: a) an induction phase; and b) a maintenance phase; The induction period is i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. comprising wherein the CDK4 / 6 inhibitor is administered only prior to or concurrently with the administration of a chemotherapeutic agent; and the chemotherapeutic agent is cytotoxic to immune effector cells; The maintenance phase comprises: i) administering at least one dose of an effective amount of an immune checkpoint inhibitor; comprising The maintenance phase is administered after the cessation of the induction phase. method.

2. 2. The method of claim 1, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

3. 3. The method of claim 2, wherein the selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemical 1】

4. 4. The method of any one of claims 1 to 3, wherein the immune checkpoint inhibitor is selected from the group consisting of a programmed cell death-1 (PD-1) inhibitor, a programmed cell death-ligand 1 (PD-L1) inhibitor, and a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitor.

5. The method of claim 4, wherein the immune checkpoint inhibitor is a PD-L1 inhibitor.

6. 6. The method of claim 5, wherein the PD-L1 inhibitor is selected from the group consisting of atezolizumab, avelumab, and durvalumab.

7. The method of claim 4, wherein the immune checkpoint inhibitor is a PD-1 inhibitor.

8. 8. The method of claim 7, wherein the PD-1 inhibitor is selected from the group consisting of nivolumab, pidilizumab, and pembrolizumab.

9. 5. The method of claim 4, wherein the immune checkpoint inhibitor is a CTLA-4 inhibitor.

10. 10. The method of claim 9, wherein the CTLA-4 inhibitor is selected from the group consisting of ipilimumab and tremelimumab.

11. 11. The method of any one of claims 1 to 10, wherein the chemotherapeutic agent is selected from the group consisting of protein synthesis inhibitors, DNA damaging chemotherapeutics, alkylating agents, topoisomerase inhibitors, RNA synthesis inhibitors, DNA complex binders, thiolate alkylating agents, guanine alkylating agents, tubulin binding agents, DNA polymerase inhibitors, anti-cancer enzymes, RAC1 inhibitors, thymidylate synthase inhibitors, oxyazophosphorine compounds, cilengitide, integrin inhibitors such as camptothecin or homocamptothecin, antifolates and antifolates.

12. 11. The method of any one of claims 1 to 10, wherein the chemotherapeutic agent is selected from carboplatin, cisplatin, oxaliplatin, 5-fluorouracil, floxuridine, capecitabine, gemcitabine, mitomycin, cyclophosphamide, dacarbazine, abraxane, ifosfamide, topotecan, irinotecan, docetaxel, temozolomide, paclitaxel, and etoposide, pemetrexed, or a combination thereof.

13. The method of any one of claims 1 to 12, wherein the CDK4 / 6 inhibitor is a compound of the following formula or a pharmaceutically acceptable salt thereof: 【Chemistry 2】

14. The method of any one of claims 1 to 13, wherein the CDK4 / 6 inhibitor is administered to the subject about 30 minutes prior to administration of the chemotherapeutic agent during the induction phase.

15. 15. The method of any one of claims 1 to 14, wherein the immune checkpoint inhibitor is administered to the subject every three weeks during the induction and maintenance phases.

16. The method of any one of claims 1 to 15, wherein the immune checkpoint inhibitor is administered to the subject only once in both the induction phase and the maintenance phase.

17. The method of any one of claims 1 to 16, wherein the cancer is a CDK4 / 6 replication-dependent cancer.

18. The method of any one of claims 1 to 16, wherein the cancer is a CDK4 / 6 replication-independent cancer.

19. 17. The method of any one of claims 1 to 16, wherein the cancer is selected from the group consisting of small cell lung cancer, non-small cell lung cancer, triple-negative breast cancer, colorectal cancer, ovarian cancer, pancreatic cancer, bladder cancer, gastroesophageal cancer, bile duct cancer, cervical cancer, and soft tissue sarcoma.

20. 1. A method of treating a subject with small cell lung cancer, comprising administering a treatment regimen comprising: a) an induction phase; and b) a maintenance phase; The induction period is i) administering to said subject an effective amount of a selective CDK4 / 6 inhibitor; ii) administering to said subject an effective amount of one or more chemotherapeutic agents; and iii) administering to said subject an effective amount of an immune checkpoint inhibitor. comprising wherein the CDK4 / 6 inhibitor is administered only prior to or concurrently with the administration of one or more chemotherapeutic agents; and the chemotherapeutic agent is cytotoxic to immune effector cells; The maintenance phase comprises: i) administering at least one dose of an effective amount of an immune checkpoint inhibitor; wherein the maintenance phase is administered after the induction phase has ceased. method.

21. 21. The method of claim 20, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

22. 22. The method of claim 21 , wherein the CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 3】

23. 23. The method of any one of claims 20 to 22, wherein the immune checkpoint inhibitor is selected from the group consisting of a programmed cell death-1 (PD-1) inhibitor, a programmed cell death-ligand 1 (PD-L1) inhibitor, and a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitor.

24. 24. The method of claim 23, wherein the immune checkpoint inhibitor is a PD-L1 inhibitor.

25. 25. The method of claim 24, wherein the PD-L1 inhibitor is selected from the group consisting of atezolizumab, avelumab, and durvalumab.

26. 24. The method of claim 23, wherein the immune checkpoint inhibitor is a PD-1 inhibitor.

27. 27. The method of claim 26, wherein the PD-1 inhibitor is selected from the group consisting of nivolumab, pidilizumab, and pembrolizumab.

28. 24. The method of claim 23, wherein the immune checkpoint inhibitor is a CTLA-4 inhibitor.

29. 29. The method of claim 28, wherein the CTLA-4 inhibitor is selected from the group consisting of ipilimumab and tremelimumab.

30. 30. The method of any one of claims 20 to 29, wherein the chemotherapeutic agent is selected from the group consisting of carboplatin, etoposide, cisplatin, and topotecan.

31. 30. The method of any one of claims 20 to 29, wherein the chemotherapeutic agent is carboplatin.

32. 30. The method of any one of claims 20 to 29, wherein the chemotherapeutic agent is etoposide.

33. 30. The method of any one of claims 20 to 29, wherein the chemotherapeutic agent is topotecan.

34. 30. The method of any one of claims 20-29, wherein carboplatin is administered on day 1 of a 21-day treatment cycle during the induction phase, etoposide is administered on days 1, 2, and 3 of a 21-day treatment cycle during the induction phase, and a CDK4 / 6 inhibitor is administered on days 1, 2, and 3 of a 21-day treatment cycle during the induction phase.

35. 30. The method of any one of claims 20-29, wherein carboplatin is administered on day 2 of a 21-day treatment cycle during the induction phase, etoposide is administered on days 2, 3, and 4 of a 21-day treatment cycle during the induction phase, and the CDK4 / 6 inhibitor is administered on days 1, 2, 3, and 4 of a 21-day treatment cycle.

36. 30. The method of claims 20-29, wherein topotecan is administered on days 1-5 of a 21-day treatment cycle during the induction phase, and the CDK4 / 6 inhibitor is administered on days 1-5 of a 21-day treatment cycle during the induction phase.

37. 30. The method of any one of claims 20 to 29, wherein topotecan is administered on days 2 to 6 of a 21-day treatment cycle during the induction phase, and the CDK4 / 6 inhibitor is administered on days 1 to 6 of a 21-day treatment cycle during the induction phase.

38. 30. The method of any one of claims 20 to 29, wherein etoposide is administered on days 1, 2, and 3 of a 21-day treatment cycle during the induction phase.

39. 39. The method of any one of claims 34 to 38, wherein the immune checkpoint inhibitor is administered on day 1 of a 21-day treatment cycle during the induction phase.

40. 40. The method of claim 39, wherein the immune checkpoint inhibitor is administered on day 1 of a 21-day treatment cycle during the maintenance phase.

41. The method of any one of claims 20 to 40, wherein the CDK4 / 6 inhibitor is a compound of the following formula or a pharmaceutically acceptable salt thereof: 【Chemistry 4】

42. 42. The method of any one of claims 20 to 41, wherein the CDK4 / 6 inhibitor is administered to the subject during the induction phase about 30 minutes prior to administration of the chemotherapeutic agent.

43. The method of any one of claims 34 to 42, wherein the immune checkpoint inhibitor is the PD-L1 inhibitor atezolizumab.

44. 44. The method of any one of claims 1 to 43, wherein the induction period is repeated two or more times.

45. 44. The method of any one of claims 1 to 43, wherein the induction period is repeated three or more times.

46. 44. The method of any one of claims 1 to 43, wherein the induction period is repeated four or more times.

47. 47. The method of any one of claims 1 to 46, wherein the maintenance phase is repeated two or more times.

48. 47. The method of any one of claims 1 to 46, wherein the maintenance phase is repeated three or more times.

49. 47. The method of any one of claims 1 to 46, wherein the maintenance phase is repeated four or more times.

50. 1. A method of treating a subject having small cell lung cancer, comprising administering a therapeutic regimen comprising: a) an induction phase comprising a 21-day cycle; and b) a maintenance phase comprising a 21-day cycle; The induction period is i) administering to the subject on days 1, 2, and 3 of a 21 day cycle an effective amount of the following formula: 【Chemistry 5】 administering a selective CDK4 / 6 inhibitor of ii) administering an effective amount of carboplatin on day 1 of a 21-day cycle; iii) administering an effective amount of etoposide on days 1, 2, and 3 of a 21-day cycle; and administering an effective amount of atezolizumab on day 1 of a 21-day cycle; comprising the CDK4 / 6 inhibitor is administered only prior to or concurrently with the administration of carboplatin and etoposide; The maintenance phase i) administering an effective amount of atezolizumab on day 1 of a 21-day cycle comprising The maintenance phase is administered after the cessation of the induction phase. method.

51. 51. The method of claim 50, wherein the CDK4 / 6 inhibitor is administered within about 4 hours prior to administration of carboplatin and / or etoposide.

52. 56. The method of claim 55, wherein the CDK4 / 6 inhibitor is administered about 30 minutes before the administration of carboplatin and / or etoposide.

53. The CDK4 / 6 inhibitor is about 220 to 260 mg / m ２ 53. The method of any one of claims 50 to 52, wherein the compound is administered intravenously at a dose of

54. The CDK4 / 6 inhibitor is about 240 mg / m ２ 53. The method of any one of claims 50 to 52, wherein the compound is administered intravenously at a dose of

55. 53. The method of any one of claims 50 to 52, wherein the carboplatin is administered intravenously at a dose that exhibits an AUC of about 5.

56. The etoposide is about 100 mg / m ２ 56. The method of any one of claims 50 to 55, wherein the compound is administered intravenously at a dose of

57. 57. The method of any one of claims 50-56, wherein the atezolizumab is administered at a dose of about 1200 mg.

58. 58. The method of any one of claims 50 to 57, wherein the induction period is repeated at least twice.

59. 58. The method of any one of claims 50 to 57, wherein the induction period is repeated at least three times.

60. 58. The method of any one of claims 50 to 57, wherein the induction period is repeated at least four times.

61. 61. The method of any one of claims 50 to 60, wherein the maintenance phase is repeated at least twice.

62. 61. The method of any one of claims 50 to 60, wherein the maintenance phase is repeated at least three times.

63. 61. The method of any one of claims 50 to 60, wherein the maintenance phase is repeated at least four times.

64. 1. A method of treating a subject having cancer, comprising administering to the subject: i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. and administering the compound according to a treatment regimen comprising: wherein said CDK4 / 6 inhibitor is administered only prior to or concurrently with administration of said chemotherapeutic agent; and the chemotherapeutic agent is cytotoxic to immune effector cells; method.

65. 65. The method of claim 64, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

66. 66. The method of claim 65, wherein said selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 6】

67. 67. The method of any one of claims 64 to 66, wherein the immune checkpoint inhibitor is selected from the group consisting of a programmed cell death-1 (PD-1) inhibitor, a programmed cell death-ligand 1 (PD-L1) inhibitor, and a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitor.

68. 68. The method of claim 67, wherein the immune checkpoint inhibitor is a PD-L1 inhibitor.

69. 69. The method of claim 68, wherein the PD-L1 inhibitor is selected from the group consisting of atezolizumab, avelumab, and durvalumab.

70. 68. The method of claim 67, wherein the immune checkpoint inhibitor is a PD-1 inhibitor.

71. 70. The method of claim 69, wherein the PD-1 inhibitor is selected from the group consisting of nivolumab, pidilizumab, and pembrolizumab.

72. 68. The method of claim 67, wherein the immune checkpoint inhibitor is a CTLA-4 inhibitor.

73. 71. The method of claim 70, wherein the CTLA-4 inhibitor is selected from the group consisting of ipilimumab and tremelimumab.

74. 74. The method of any one of claims 64 to 73, wherein the chemotherapeutic agent is selected from the group consisting of protein synthesis inhibitors, DNA damaging chemotherapeutics, alkylating agents, topoisomerase inhibitors, RNA synthesis inhibitors, DNA complex binders, thiolate alkylating agents, guanine alkylating agents, tubulin binding agents, DNA polymerase inhibitors, anti-cancer enzymes, RAC1 inhibitors, thymidylate synthase inhibitors, oxyazophosphorine compounds, cilengitide, integrin inhibitors such as camptothecin or homocamptothecin, antifolates and antifolates.

75. 74. The method of any one of claims 64 to 73, wherein the chemotherapeutic agent is selected from carboplatin, cisplatin, oxaliplatin, 5-fluorouracil, floxuridine, capecitabine, gemcitabine, mitomycin, cyclophosphamide, dacarbazine, abraxane, ifosfamide, topotecan, irinotecan, docetaxel, temozolomide, paclitaxel, and etoposide, pemetrexed, or a combination thereof.

76. 76. The method of any one of claims 64 to 75, wherein the CDK4 / 6 inhibitor is a compound of the following formula or a pharmaceutically acceptable salt thereof: 【Chemistry 7】

77. 77. The method of any one of claims 64 to 76, wherein the CDK4 / 6 inhibitor is administered to the subject during an induction phase about 30 minutes prior to administration of the chemotherapeutic agent.

78. 78. The method of any one of claims 64 to 77, wherein the cancer is selected from the group consisting of small cell lung cancer, non-small cell lung cancer, triple-negative breast cancer, colorectal cancer, ovarian cancer, pancreatic cancer, bladder cancer, gastroesophageal cancer, bile duct cancer, cervical cancer, and soft tissue sarcoma.

79. 1. A method of increasing a pro-inflammatory immune effector cell population in an intratumoral immune cell infiltrate population in a subject having cancer or a tumor, comprising administering to the subject: i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. and administering the compound according to a treatment regimen comprising: wherein the proinflammatory immune effector cell population is increased by more than about 10%, 20%, 30%, 40%, or 50% compared to the proinflammatory immune effector cell population in an intratumoral immune cell infiltrate population in a subject not receiving the therapeutic regimen. method.

80. 80. The method of claim 79, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

81. 81. The method of claim 80, wherein said selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 8】

82. 80. The method of claim 79, further comprising administering an additional effective amount of an immune checkpoint inhibitor during a break in the treatment regimen.

83. 1. A method of increasing the activation level of T cells in an intratumoral immune cell infiltrate population in a subject having cancer or a tumor, comprising administering to the subject: i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. and administering the compound according to a treatment regimen comprising: the activated T cells are CD4+ T cells or CD8+ T cells, and The percentage of activated T cells in the intratumoral immune cell infiltrate population is increased by about 5%, 10%, 15%, or 20%; method.

84. 84. The method of claim 83, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

85. 85. The method of claim 84, wherein said selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 9】

86. 84. The method of claim 83, further comprising administering an additional effective amount of an immune checkpoint inhibitor during a break in the treatment regimen.

87. 1. A method for reducing a regulatory T cell population in an intratumoral immune cell infiltrate population in a subject having cancer or a tumor, comprising administering to the subject: i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. and administering the compound according to a treatment regimen comprising: wherein the regulatory T cell population in the intratumoral immune cell infiltrate population is reduced by about 10%, 20%, 30%, or 40% compared to the intratumoral immune cell infiltrate population in a subject not receiving said therapeutic regimen; method.

88. 88. The method of claim 87, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

89. 89. The method of claim 88, wherein said selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 10】

90. 88. The method of claim 87, further comprising administering an additional effective amount of an immune checkpoint inhibitor during a break in the treatment regimen.

91. 1. A method for inhibiting the immunosuppressive function of regulatory T cells in an intratumoral immune cell infiltrate population in a subject having cancer or a tumor, comprising administering to the subject: i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. and administering the compound according to a treatment regimen comprising: the level of phosphorylated retinoblastoma (Phospho-Rb) in regulatory T cells is reduced by about 5%, 10%, 15%, or 20%; and the reduction in the immunosuppressive function of the regulatory T cells results in about a 10%, 20%, 30%, 40%, or 50% increase in proliferation of CD8+ T cells; method.

92. 92. The method of claim 91, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

93. 93. The method of claim 92, wherein said selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 11】

94. 92. The method of claim 91, further comprising administering an additional effective amount of an immune checkpoint inhibitor during a break in the treatment regimen.

95. 1. A method for long-term enhancement of tumor-specific memory T cell generation in a subject having cancer or a tumor, comprising administering to the subject: i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. and administering the compound according to a treatment regimen comprising: the percentage of tumor-specific memory T cells found in the subject's spleen is increased by about 0.25%, 0.5%, 0.75%, or 1%; and the percentage of tumor-specific memory T cells found in the subject's blood is increased by about 0.5%, 1%, or 1.5%; method.

96. 96. The method of claim 95, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

97. 97. The method of claim 96, wherein said selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 12】

98. 96. The method of claim 95, further comprising administering an additional effective amount of an immune checkpoint inhibitor during a break in the treatment regimen.

99. 1. A method for protecting intratumoral immune cells from chemotherapy in a subject having cancer or a tumor, comprising administering to the subject: i) administering an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor; ii) administering an effective amount of a chemotherapeutic agent; and iii) administering an effective amount of an immune checkpoint inhibitor. and administering the compound according to a treatment regimen comprising: wherein the intratumoral immune cells are CD8+ T cells, CD4+ T cells, natural killer (NK) cells, monocytic myeloid-derived suppressor cells (mMDSCs), or granulocytic myeloid-derived suppressor cells (gMDSCs), and the percent proliferation of the intratumoral immune cells is about 5%, 10%, 15%, 20%, 25%, or 30% greater than the proliferation of immune cells found in the spleen; method.

100. 100. The method of claim 99, wherein the selective CDK4 / 6 inhibitor is a fast-acting, short half-life CDK4 / 6 inhibitor.

101. 101. The method of claim 100, wherein said selective, fast-acting, short half-life CDK4 / 6 inhibitor is selected from the group consisting of: 【Chemistry 13】

102. 100. The method of claim 99, further comprising administering an additional effective amount of an immune checkpoint inhibitor during a break in the treatment regimen.

103. The method of any one of claims 1 to 102, wherein the subject is a human.

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