Protection of the immune response during chemotherapy regimens

Abstract

To provide a method for treating a subject having cancer.SOLUTION: Addition of a selective, fast-acting, short half-life CDK 4 / 6 inhibitor in a very specific dosage regimen to a combination of chemotherapy with a checkpoint inhibitor provides superior results in treatment of a tumor or cancer. The unexpected discovery is that short pulsatile specifically-timed administration of a selective, fast-acting, short half-life CDK 4 / 6 inhibitor during administration of a chemotherapy portion of the triple combination therapy has a profound effect on immune cells in a 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 Dec. 5, 2016, and U.S. Provisional Application No. 62 / 479,605, filed Mar. 31, 2017, the entire contents of which are hereby incorporated by reference in their entirety for all purposes.

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

[0003] Background Cancer immunotherapy uses the host's natural immune system to fight cancer or tumors by stimulating the immune system to work more actively and sensitively. An important part of the immune system is the ability to distinguish normal cells from foreign cells. To do this, the immune system uses “checkpoints,” which are molecules on certain cells that must be activated (or inactivated) to initiate a response. Cancers and tumors can find ways to use these checkpoints to avoid 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 the administration of antibodies against these checkpoint “off switches” to inactivate this off switch and enable the host's immune system to increase its ability against diseased cells.

[0004] Several immune checkpoint inhibitors have been approved by the US Food and Drug Administration (FDA). The first such drug to receive approval for the treatment of advanced melanoma, ipilimumab (Yervoy (trademark), 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 weakening 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® (trademark), Bristol-Myers Squibb) and pembrolizumab (Keytruda® (trademark), Merck), also work similarly but target a different checkpoint protein on activated T cells, programmed cell death protein 1 (PD-1). Nivolumab is approved to treat some patients with advanced melanoma or advanced lung cancer, and pembrolizumab is approved to treat 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 in U.S. Patent No. 9,683,048 and U.S. Patent No. 9,683,048 by Novartis AG. Also, 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 that downregulate the activity of PD-1, namely, durvalumab (Imfinzi® (trademark), Astrazeneca), avelumab (Bavencio® (trademark), Pfizer), and atezolizumab (Tecentriq® (trademark), Genentech / Roche), have also been developed. Additional PD-L1 targeted inhibitors currently in development include Ca-170 (Curis) and LY3300054 (Eli Lilly). PD-L1 inhibitors are also described in US2017 / 0296659 and WO2016 / 040892 by Novartis AG.

[0006] Although several immune checkpoint inhibitors have been shown to be effective in patients with various cancers and result in durable responses, 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 their low response rates. An approach to increasing the response rate of immune checkpoint inhibitors is to combine them with chemotherapy to promote the death of immunogenic cells and "prime" the immune system. However, chemotherapy itself can damage various cell types of the immune system, including hematopoietic stem and progenitor cells (HSPC) and immune effector cells such as T lymphocytes, potentially reducing the effectiveness of the chemotherapy / checkpoint inhibitor combination.

[0007] The object of the present invention is to provide a therapeutic approach for treating a host having a 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 intrinsic immune mechanisms to destroy diseased cells, either short-term and / or long-term.

Summary of the Invention

[0008] Surprisingly and unexpectedly, it has been found that adding a selective, immediate-acting, short half-life CDK4 / 6 inhibitor in a very specific dosing schedule to the combination of chemotherapy and checkpoint inhibitors results in superior outcomes in the treatment of tumors or cancer. It is an unexpected finding that the specific timed administration of the CDK4 / 6 inhibitor prior to each administration of the chemotherapy portion of this triple combination therapy has a significant effect on immune cells in the cancer microenvironment. These results are remarkable in that administration of a CDK4 / 6 inhibitor as described herein provides one or more of: (i) protection of immune tumor cell infiltrates from damage, (ii) an increased duration of the immune response by more frequent tumor-specific memory T cells, (iii) a greater reduction in intratumoral Treg cells, which are immunosuppressive factors; and / or (iv) a change in the gene expression of inflammatory-inducing factors. The expression of genes functionally enriched for lymphocyte activation and upregulation of the inflammatory cytokine interferon-γ is significantly enhanced. In parallel, several genes involved in immunosuppressive reactive oxygen species metabolic processes are downregulated. These findings indicate that the timing of administration of the CDK4 / 6 inhibitor results in modulation of gene expression, creating a pro-inflammatory tumor microenvironment that is advantageous for enhancing the effectiveness of checkpoint inhibitor activity while reducing the harmful effects of chemotherapy. This improvement represents a significant advance over the current state of the art in cancer treatment.

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

[0010] In contrast, the significant benefits of this specific dosing schedule in the triple combination therapy of chemotherapeutic agents, checkpoint inhibitors, and CDK4 / 6 inhibitors are not achieved when the CDK4 / 6 inhibitor is administered in a continuous or substantially continuous manner that results in continuous CDK4 / 6 inhibition of immune effector cells. In this case, the immune effector cells in the tumor microenvironment remain suppressed for a sufficient time such that their ability to destroy diseased cells is significantly reduced.

[0011] Specific benefits of this therapy include one or more of the following: · Short-term intratumoral immune cell populations (CD4+T, CD8+T, Treg, NK, and MDSC subsets) are highly proliferative and sensitive to CDK4 / 6 inhibition, and like hematopoietic progenitor cells in the bone marrow, are enabled by CDK4 / 6 inhibitors to undergo transient cell cycle arrest that protects the immune infiltrate from chemotherapy-induced damage. With the specific timed administration according to the present invention, for example, the proliferation of one or more of these cell populations is maximally inhibited to about 50, 60, 70, 75, or 80% or more in approximately 6 - 24 hours and can recover within approximately 30, 40, 45, 48, 50, or 60 hours.

[0012] · Protection of intratumoral immune cells by timed administration of the CDK4 / 6 inhibitor when added to the combination of chemotherapy / checkpoint inhibitor results in an increase in the duration of therapeutic efficacy. Higher frequencies of tumor-specific memory T cells can be found. In some examples, the median frequency on day 50 after treatment can be at least approximately 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, or 2.6 times or higher than in the case of the chemotherapy / checkpoint inhibitor regimen alone in the timed CDK4 / 6 inhibitor / chemotherapy / checkpoint inhibitor regimen. The longer duration of memory T cells provides long-term protection to the host from diseased cells.

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

[0014] In one non-limiting embodiment, the limited-time administration of the CDK4 / 6 inhibitor includes a selective, immediate-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 limited-time administration of the CDK4 / 6 inhibitor includes compound I, carboplatin and an antibody against PD1, PD-L1 or CTLA4. In one aspect of the present invention, the cancer is small cell lung cancer (SCLC). In yet another embodiment, the limited-time 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] The overview of the embodiments of the present invention will be described in more detail below.

[0016] In multiple aspects, the present invention provides a method for treating cancer or tumors in a subject by enhancing an inflammatory microenvironment through the use of a planned treatment protocol comprising the administration of a CDK4 / 6 inhibitor, such as a selective, immediate-acting, short half-life CDK4 / 6 inhibitor, in combination with a chemotherapeutic agent, such as a chemotherapeutic agent cytotoxic to immune effector cells and an immune checkpoint inhibitor. By using a CDK4 / 6 inhibitor during a chemotherapeutic agent / immune checkpoint inhibitor combination therapy regimen, immune effector cells such as T lymphocytes are protected from chemotherapeutic agent toxicity and are found to be released from temporary cell cycle arrest in the presence of chemotherapy-induced immunogenic cell death, in a manner that provides significantly improved priming and activation of the anti-cancer immune response and anti-cancer effect compared to the case where no CDK4 / 6 inhibitor is used. Also, by using a CDK4 / 6 inhibitor during a chemotherapeutic agent / immune checkpoint inhibitor therapy regimen, anti-tumor activity is enhanced, including selective reduction of the intratumoral Treg population, protection of inflammatory immune effector cells such as tumor-infiltrating lymphocytes, and extension of the duration of therapeutic efficacy, by cell cycle-independent and -dependent mechanisms. The controlled inhibition of CDK4 / 6 by a CDK4 / 6 inhibitor, such as a selective, short half-life CDK4 / 6 inhibitor, in combination with a chemotherapeutic agent and an immune checkpoint inhibitor as described herein provides a significant enhancement of the anti-tumor effect compared to continuous inhibition of CDK4 / 6 by an inhibitor, including administration of only a chemotherapeutic agent and an immune checkpoint inhibitor, or a more long-acting CDK4 / 6 administered daily in combination with an immune checkpoint inhibitor.

[0017] Many chemotherapeutic agents, such as, but not limited to, protein synthesis inhibitors or DNA-damaging chemotherapeutic agents, tend to be non-specific and toxic to normal rapidly dividing cells, including immune effector cells, and hematotoxicities such as myelosuppression are common side effects of chemotherapeutic agent treatment. Immune effector cells generally require the activity of CDK4 / 6 for proliferation, i.e., 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 (MDSC), are sensitive to CDK4 / 6 inhibition. By using a selective, immediate-acting, short half-life CDK4 / 6 inhibitor during chemotherapy treatment, immune effector cells that are sensitive to the damaging effects of chemotherapeutic agents during proliferation are temporarily arrested in the G0 / G1 phase of the cell cycle. By protecting these cells from the damaging effects of chemotherapeutic agents, the use of a time-limited administration of a CDK4 / 6 inhibitor protects immune function, enhances T cell activation, increases the efficacy of immune checkpoint inhibitors, and significantly improves the anti-cancer immune response.

[0018] In non-limiting exemplary embodiments, as in Examples 5 and 9, FIGS. 10, 11, 19, and 20, it has been confirmed that the timed administration of a CDK4 / 6 inhibitor in combination with a chemotherapeutic agent and an immune checkpoint inhibitor selectively protects the pro-inflammatory intratumoral immune cell infiltrate while selectively reducing the intratumoral population of anti-inflammatory infiltrates such as CD4+ / CD25+ Treg cells. This indicates that the controlled inhibition of the CDK4 / 6 pathway results in a decrease in the suppressive function of Treg cells and changes their ability to inhibit T cell proliferation. Also here, as an exemplary embodiment, FIG. 11 in Example 5 shows that in animals receiving a combination of a timed CDK4 / 6 inhibitor / chemotherapeutic agent / immune checkpoint inhibitor, the proportion of intratumoral Treg cells was 40% lower compared to animals receiving a chemotherapeutic agent and an immune checkpoint inhibitor without the timed administration of the CDK4 / 6 inhibitor. Thus, incorporating the timed administration of a selective, immediate-acting, short half-life CDK4 / 6 inhibitor as described herein provides a targeted approach to removing unwanted Treg cells and increasing the pro-inflammatory immune effector cell infiltrate.

[0019] The timed administration of the CDK4 / 6 inhibitor results in a significant initial reduction in immune cell proliferation (see Example 10, the reduction exceeds 75%), but in animal models, the beneficial T cell proliferation generally fully recovers by at least 1.5, 2, 2.5, or 3 days later. Furthermore, the total expression of genes associated with lymphocyte activation and the upregulation of the pro-inflammatory cytokine interferon-γ is significantly increased (see non-limiting exemplary Examples 12 and 13, FIGS. 25 - 31). In comparison, genes associated with the immunosuppressive reactive oxygen species metabolic process are downregulated, indicating that the transient cell cycle arrest in the tumor immune infiltrate results in modulation of gene expression and can give rise to a pro-inflammatory tumor microenvironment that is favorable for enhancing immune checkpoint inhibitor activity (see non-limiting exemplary Example 14, FIGS. 32 - 37).

[0020] Importantly, the administration of a selective, immediate-acting, short half-life CDK4 / 6 inhibitor for a defined period of time in combination with chemotherapeutic agents and immune checkpoint inhibitors results in an extended duration of treatment response. Non-limiting examples are shown in Example 11, Figures 23 and 24, which confirm that in this example, when a CDK4 / 6 inhibitor is added to a chemotherapeutic agent / immune checkpoint inhibitor combination therapy, more frequent tumor-specific memory T cells are seen in the tumor model, and the population of tumor-specific memory T cells is twice that in the case of a chemotherapeutic agent / immune checkpoint inhibitor combination treatment without a CDK4 / 6 inhibitor. Additionally, the delay in tumor progression is also significantly improved when using the administration of a selective, immediate-acting, short half-life CDK4 / 6 inhibitor for a defined period of time in combination with chemotherapeutic agents and immune checkpoint inhibitors compared to treatment with chemotherapeutic agents and immune checkpoint inhibitors without a CDK4 / 6 inhibitor, or continuous inhibition of CDK4 / 6 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 of the present invention, the present invention provides an improved method of treating a host, e.g., a human, having cancer or a tumor, comprising providing a limited-time administration of a selective CDK4 / 6 inhibitor in combination with a treatment regimen of a chemotherapeutic agent and an immune checkpoint inhibitor. In one embodiment, the administration of the selective CDK4 / 6 inhibitor is made for a limited time before or at the time of administration of the chemotherapeutic agent. In one embodiment, the CDK4 / 6 inhibitor is administered only before or at the time of administration of the chemotherapeutic 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 a limited-time administration of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and a checkpoint inhibitor, and the selective CDK4 / 6 inhibitor is administered concurrently or only, for example, less than about 8 hours, less than about 7 hours, less than about 6 hours, less than about 5 hours, less than about 4 hours, less than about 3 hours, less than about 2 hours, less than about 1 hour, or less than about 30 minutes before the administration of the chemotherapeutic agent; the maintenance phase comprises an administration of the checkpoint inhibitor alone, wherein the maintenance phase occurs after one or more induction phases. In one embodiment, the maintenance phase comprises one or more administrations of an immune checkpoint inhibitor. In one embodiment, the CDK4 / 6 inhibitor is a selective, immediate-acting, short half-life inhibitor that provides transient protection of immune effector cells, enables the immune effector cells to rapidly return to the cell cycle, and enables activation and proliferation after the disappearance of the chemotherapeutic effect during the induction phase. In one embodiment, the chemotherapeutic agent is an agent that is cytotoxic or cytostatic to immune effector cells, e.g., but not limited to, a protein synthesis inhibitor, a DNA-damaging chemotherapeutic agent, an alkylating agent, a topoisomerase inhibitor, an RNA synthesis inhibitor, a DNA complex-binding agent, a thiolate alkylating agent, a guanine alkylating agent, a tubulin-binding agent, a DNA polymerase inhibitor, an anti-cancer enzyme, a RAC1 inhibitor, a thymidylate synthase inhibitor, an oxazophosphorine compound, a sirengetide, an integrin inhibitor such as camptothecin or homocamptothecin, a folic acid antagonist or folic acid antimetabolite, or a combination thereof.

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

[0023] In another aspect of the invention, the invention provides a method of enhancing the activation of T cells in the intratumoral immune cell infiltrate in a subject having cancer or a tumor, the method comprising administering to the subject a therapeutically effective amount 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 is about 5%, 10%, 15%, 20% or more. In one embodiment, the production of interferon γ is increased due to upregulation of the INFG gene. In one embodiment, the production of interferon γ is increased due to upregulation of the IL2 gene. In one embodiment, the production of interferon γ is increased due to upregulation of the IL18 gene. In one embodiment, the production of interferon γ is increased due to upregulation of the LTA gene. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0024] In one aspect of the present invention, there is provided a method for reducing the regulatory T cell (Treg) population in the intratumoral immune cell infiltrate population in a subject suffering from cancer, the method comprising administering to the subject an effective amount 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 cell infiltrate population is reduced by about 10%, 20%, 30%, 40% or more compared to the intratumoral cell 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 an immediate-acting, short half-life CDK4 / 6 inhibitor.

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

[0026] In one aspect of the present invention, the present invention provides a method for increasing the generation of tumor-specific memory T cells in a subject having cancer or a tumor, the method comprising administering to the subject an effective amount of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor as described herein for a specific time period. In one embodiment, the percentage of tumor-specific memory T cells found in the spleen of the subject increases 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 blood of the subject increases by at least approximately 0.5%, 1%, 1.5% or more relative to the total T cell population. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-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 having cancer or a tumor, the method comprising administering to the subject an effective amount of a selective CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor as described herein for a specific time period. Protection of intratumoral immune cells from the toxicity of chemotherapy results in enhanced anti-tumor immune responses. In one embodiment, the intratumoral immune cells to be protected are selected from CD8+ T cells, CD4+ T cells, natural killer (NK) cells, monocytic myeloid-derived suppressor cells (mMDSC), and granulocytic myeloid-derived suppressor cells (gMDSC). In one embodiment, the percentage increase in the 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 selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0028] The CDK4 / 6 inhibitor used in this treatment plan can be any optional CDK4 / 6 inhibitor that achieves the desired purpose, such as, but not limited to, trilaciclib (G1 Therapeutics, Inc.), ribociclib (Novartis), palbociclib (Pfizer), or abemaciclib (Eli Lilly). In one embodiment, the CDK4 / 6 inhibitor is a selective, immediate-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 analogue, or prodrug thereof.

Chemical formula

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

[0030] As provided herein, the selective CDK4 / 6 inhibitor is administered in a defined time-limited treatment regimen using a chemotherapeutic agent and an immune checkpoint inhibitor. The chemotherapeutic agent can be any chemotherapeutic agent that is effective or useful for treating cancer, tumors, or abnormal cell proliferation. In one embodiment, the selective CDK4 / 6 inhibitor is administered prior to or concurrently with the administration of the chemotherapeutic agent such that immune effector cells arrest in the treatment field of the chemotherapeutic agent and the toxic effects of the chemotherapeutic agent on the immune effector cells are reduced or eliminated. In one embodiment, the selective CDK4 / 6 inhibitor is administered to the 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 within about 1 / 2 hour prior to treatment with the chemotherapeutic agent. In certain embodiments, the selective CDK4 / 6 inhibitor is administered about 1 / 2 hour prior to the administration of the chemotherapeutic agent. Generally, the selective CDK4 / 6 inhibitor is administered to the subject such that the CDK4 / 6 inhibitor reaches its maximum serum concentration prior to or during treatment with the chemotherapeutic agent, enabling inhibition of the proliferation of immune effector cells and thus protecting them from the deleterious effects of chemotherapy. In one embodiment, the CDK4 / 6 inhibitor is administered concurrently with or in close proximity to chemotherapeutic agent exposure. Alternatively, the CDK4 / 6 inhibitors described herein can be administered after chemotherapeutic agent exposure if it is desired to mitigate damage to immune effector cells associated with chemotherapeutic agent exposure. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0031] As contemplated herein, the timed administration of a selective, immediate-acting, short half-life CDK4 / 6 inhibitor as described herein can be administered to any chemotherapy / immune checkpoint inhibitor combination therapy protocol. For example, a selective, immediate-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 drug exposure, where, due to the rapid disappearance of the G1 arrest effect of the selective, immediate-acting, short half-life CDK4 / 6 inhibitor described herein, a significant number of immune effector cells return to the cell cycle and can replicate and activate when cancer cell death and tumor antigen exposure induced by the chemotherapy drug are maximized some time after chemotherapy drug exposure. In certain embodiments, the selective, immediate-acting, short half-life CDK4 / 6 inhibitor is administered before or concurrently with the administration of the chemotherapy drug, where the chemotherapy drug 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; 1 day per 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; days 22-25, and 43-46; and in similar types of chemotherapy drug regimens. In one embodiment, the selective, immediate-acting, short half-life CDK4 / 6 inhibitor is administered before or concurrently with at least one administration of the chemotherapy drug in a chemotherapy drug treatment regimen. In one embodiment, the selective, immediate-acting, short half-life CDK4 / 6 is administered before or concurrently with one or more administrations of the chemotherapy drug in a chemotherapy drug treatment regimen. In one embodiment, the selective, immediate-acting, short half-life CDK4 / 6 inhibitor is administered before or concurrently with each administration of the chemotherapy drug in a chemotherapy drug treatment regimen.

[0032] The present invention includes administration of an immune checkpoint inhibitor. Immune checkpoint inhibitors are known in the art and include, for example, but 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, an antibody, other protein, or a biological agent. In one embodiment, the immune checkpoint inhibitor is administered in parallel with the administration of a CDK4 / 6 inhibitor and a chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered in parallel with the administration of a CDK4 / 6 inhibitor and a chemotherapeutic agent, and then, subsequently, is administered at regular intervals, such as once a week, twice a week, three times a week or more, in order 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, such as on the first day of a 21-day cycle, the first day, the eighth day, and the fifteenth day of a 21-day cycle, etc.

[0033] In one aspect of the present invention, there is provided a method of treating cancer in a subject, the method comprising administering to the subject a dosing regimen comprising the administration of a CDK4 / 6 inhibitor and a chemotherapeutic agent in combination with an immune checkpoint inhibitor. The CDK4 / 6 inhibitor is administered in a specific time-limited manner before or concurrently with the administration of the chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered before or concurrently with each administration of the chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered before 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 before 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 period. 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 induction period and alone during a maintenance period, for example, without concurrent administration of the chemotherapeutic agent and the CDK4 / 6 inhibitor, one or more times. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0034] In one embodiment, the CDK4 / 6 inhibitor is administered during or concurrently with each administration of the chemotherapeutic agent in a standard chemotherapeutic agent protocol, such as a 21-day cycle, and the checkpoint inhibitor is administered on day 1. After a break in the standard chemotherapeutic agent 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 times or more 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 times or more. 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 times or more. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0035] As contemplated herein, a timed CDK4 / 6 inhibitor as described herein, such as an immediate-acting, short half-life CDK4 / 6 inhibitor, is administered in combination with a chemotherapeutic 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 chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered subsequent to the administration of the CDK4 / 6 inhibitor and the chemotherapeutic agent. In one embodiment, the immune checkpoint inhibitor is administered once, twice, three times, or more in a chemotherapeutic agent cycle. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0036] Also contemplated herein is the administration for a defined period of time 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, where the combination of CDK4 / 6 inhibitor / immune checkpoint inhibitor is administered to maintain an immune effector cell response after completion of a CDK4 / 6 inhibitor / chemotherapy agent / immune checkpoint inhibitor treatment regimen. For example, after completion of a CDK4 / 6 inhibitor / chemotherapy agent / immune checkpoint inhibitor treatment regimen (i.e., induction phase), a CDK4 / 6 inhibitor in combination with an immune checkpoint inhibitor can be administered to a subject at periodic intervals (i.e., maintenance phase) to maintain an immune effector cell response. In one embodiment, the maintenance regimen of the CDK4 / 6 inhibitor / immune checkpoint inhibitor combination is administered at least once or more after a break in the original treatment regimen. In one embodiment, the maintenance regimen is administered once a week, twice a month, once a month, once every six weeks, or as needed on an as-needed basis. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

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

[0038] As contemplated herein, a subject can have any type of cancer, tumor, or abnormal cell proliferation. In one embodiment, the subject has a CDK4 / 6 replication-independent cancer. CDK4 / 6 replication-independent cancers can be, but are not limited to, one of 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 can be, but is not limited to, one of 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 a chemotherapeutic agent selected from the group consisting of carboplatin, cisplatin, etoposide, and topotecan, or a combination thereof, is administered in combination with a specified-time 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 chemotherapeutic agent is carboplatin. In one embodiment, the chemotherapeutic agent is vinblastine. In one embodiment, the chemotherapeutic 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 chemotherapeutic agent is a combination treatment regimen comprising cisplatin and gemcitabine. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin, methotrexate, vinblastine and doxorubicin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin, methotrexate, and vinblastine. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising carboplatin and paclitaxel. In one embodiment, the chemotherapeutic 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 chemotherapeutic agent is a combination treatment regimen comprising cisplatin and gemcitabine. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin, methotrexate, vinblastine and doxorubicin. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising cisplatin, methotrexate, and vinblastine. In one embodiment, the chemotherapeutic agent is a combination treatment regimen comprising carboplatin and paclitaxel. In one embodiment, the chemotherapeutic 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, 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 chemotherapeutic agent is doxorubicin. In one embodiment, the chemotherapeutic agent is cyclophosphamide. In one embodiment, the chemotherapeutic agent is paclitaxel. In one embodiment, the chemotherapeutic 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] In one aspect of the invention, a method of treating a subject having cancer, 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 before or concurrently with the 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 an immune checkpoint inhibitor, and the maintenance phase is administered after a rest period of the induction phase. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0052] In one embodiment, a method of treating a subject having small cell lung cancer, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period comprises: administering an effective amount of carboplatin to the subject on day 1 of a 21-day cycle; administering an effective amount of etoposide to the subject on days 1, 2, and 3 of a 21-day cycle; administering an effective amount of a selective CDK4 / 6 inhibitor to the subject on days 1, 2, and 3 of a 21-day cycle; and administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle; and the maintenance period comprises administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle, and the maintenance period is administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0053] In one embodiment, a method of treating a subject having small cell lung cancer, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period comprises: administering an effective amount of carboplatin to the subject on day 2 of a 21-day cycle; administering an effective amount of etoposide to the subject on days 2, 3, and 4 of a 21-day cycle; administering an effective amount of a selective CDK4 / 6 inhibitor to the subject on days 1 to 4 of a 21-day cycle; and administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle; and the maintenance period comprises administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle, and the maintenance period is administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0054] In one embodiment, a method of treating a subject having small cell lung cancer, comprising administering to the subject according to a treatment plan including a 21-day induction period and a 21-day maintenance period, wherein the induction period comprises: administering an effective amount of topotecan to the subject on days 1 to 5 of a 21-day cycle; administering an effective amount of a selective CDK4 / 6 inhibitor to the subject on days 1 to 5 of a 21-day cycle; and administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle; and the maintenance period comprises administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle, and the maintenance period is administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0055] In one embodiment, a method of treating a subject having small cell lung cancer, comprising administering to the subject according to a treatment plan including a 21-day induction period and a 21-day maintenance period, wherein the induction period comprises: administering an effective amount of topotecan to the subject on days 2 to 6 of a 21-day cycle; administering an effective amount of a CDK4 / 6 inhibitor to the subject on days 1 to 6 of a 21-day cycle; and administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle; and the maintenance period comprises administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle, and the maintenance period is administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-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 having stage IV triple-negative breast cancer, comprising administering to the subject a treatment regimen comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period 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 a 21-day cycle; and administering to the subject an effective amount of a selective CDK4 / 6 inhibitor on days 1 and 8 of a 21-day cycle; and wherein the maintenance period comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 21-day cycle, and the maintenance period is administered after a rest period of the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

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

[0058] In one embodiment, a method of treating a subject having small cell lung cancer, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period may be repeated up to 4 times, and the induction period comprises administering an effective amount of carboplatin to the subject on day 1 of each 21-day cycle; administering an effective amount of etoposide to the subject 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 period comprises administering atezolizumab on day 1 of a 21-day cycle, and the maintenance period is administered after a rest following the final induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0059] In one embodiment, a method of treating a subject having small cell lung cancer, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period may be repeated up to 4 times, and the induction period comprises administering an effective amount of carboplatin to the subject on day 2 of each 21-day cycle; administering an effective amount of etoposide to the subject 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 to 4 of each 21-day cycle; and the maintenance period comprises administering atezolizumab on day 1 of a 21-day cycle, and the maintenance period is administered after a rest following the final induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0060] In one embodiment, a method of treating a subject having advanced or metastatic non-squamous small cell lung cancer, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period may be repeated up to 4 times, and the induction period comprises 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 period comprises administering to the subject an effective amount of pembrolizumab on day 1 of each 21-day cycle, and the maintenance period is administered after a rest following the final induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0061] In one embodiment, a method of treating a subject having stage IIIB or stage IV non-squamous small cell lung cancer without targetable EGFR or ALK gene abnormalities, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period may be repeated up to 4 times, and the induction period comprises 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 period comprises administering to the subject an effective amount of pembrolizumab on day 1 of each 21-day cycle, and the maintenance period is administered after a rest following the final induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

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

[0063] In one embodiment, a method of treating a subject having metastatic recurrent or refractory colorectal cancer, comprising administering to the subject a treatment regimen comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period 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 a 21-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 21-day cycle; and wherein the maintenance period comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 21-day cycle, and the maintenance period is administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0064] In one embodiment, a method of treating a subject having metastatic recurrent or refractory colorectal cancer, comprising administering to the subject according to a treatment plan comprising a 6-week induction period and a 6-week maintenance period, the induction period comprising administering an effective amount of irinotecan to the subject on days 1, 8, 15, and 22 of a 6-week cycle; administering an effective amount of a CDK4 / 6 inhibitor to the subject on days 1, 8, 15, and 22 of a 6-week cycle; and administering an immune checkpoint inhibitor to the subject on days 1 and 22 of a 6-week cycle, and the maintenance period comprising administering an effective amount of a checkpoint on days 1 and 22 of a 6-week cycle, the maintenance period being administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0065] In one embodiment, a method of treating a subject having metastatic recurrent or refractory colorectal cancer, comprising administering to the subject according to a treatment plan comprising a 6-week induction period and a 6-week maintenance period, the induction period comprising administering an effective amount of irinotecan to the subject on days 2, 9, 16, and 23 of a 6-week cycle; administering an effective amount of a CDK4 / 6 inhibitor to the subject on days 1, 2, 8, 9, 15, 16, 22, and 23 of a 6-week cycle; and administering an immune checkpoint inhibitor to the subject on days 1 and 22 of a 6-week cycle, and the maintenance period comprising administering an effective amount of a checkpoint on days 1 and 22 of a 6-week cycle, the maintenance period being administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0066] In one embodiment, a method of treating a subject having recurrent platinum-sensitive ovarian cancer, comprising administering to the subject according to a treatment plan including a 21-day induction period and a 21-day maintenance period, wherein the induction period may be repeated up to 6 times, and the induction period comprises 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 period comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 21-day cycle, and the maintenance period is administered after a rest following the final induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0067] In one embodiment, a method of treating a subject having recurrent platinum-sensitive ovarian cancer, comprising administering to the subject according to a treatment plan including a 21-day induction period and a 21-day maintenance period, wherein the induction period may be repeated up to 6 times, and the induction period comprises 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 period comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 21-day cycle, and the maintenance period is administered after a rest following the final induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0068] In one embodiment, a method of treating a subject having metastatic pancreatic cancer, comprising administering to the subject according to a treatment plan comprising a 14-day induction period and a 14-day maintenance period, wherein the induction period 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 a 14-day cycle; administering to the subject an effective amount of irinotecan on day 1 of a 14-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1 and 2 of a 14-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 14-day cycle; and wherein the maintenance period comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 14-day cycle, and the maintenance period is administered after a rest period of the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0069] In one embodiment, a method of treating a subject having metastatic pancreatic cancer, comprising administering to the subject according to a treatment plan comprising a 14-day induction period and a 14-day maintenance period, wherein the induction period 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 a 14-day cycle; administering to the subject an effective amount of irinotecan on day 2 of a 14-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1 to 3 of a 14-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 14-day cycle; and wherein the maintenance period comprises administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 14-day cycle, and the maintenance period is administered after a rest period of the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0070] In one embodiment, a method of treating a subject having metastatic pancreatic cancer, comprising administering to the subject according to a treatment plan comprising a 28-day induction period and a 28-day maintenance period, the induction period comprising 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 a 28-day cycle; administering to the subject an effective amount of a CDK4 / 6 inhibitor on days 1, 8, and 15 of a 28-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 28-day cycle; and the maintenance period comprising administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 28-day cycle, the maintenance period being administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0071] In one embodiment, a method of treating a subject having metastatic pancreatic cancer, comprising administering to the subject according to a treatment plan comprising a 28-day induction period and a 28-day maintenance period, the induction period comprising 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 a 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 a 28-day cycle; and administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 28-day cycle; and the maintenance period comprising administering to the subject an effective amount of an immune checkpoint inhibitor on day 1 of a 28-day cycle, the maintenance period being administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0072] In one embodiment, a method of treating a subject having soft tissue sarcoma, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period comprises administering an effective amount of doxorubicin to the subject on day 1 of a 21-day cycle; administering an effective amount of ifosfamide to the subject on days 1 to 4 of a 21-day cycle; administering an effective amount of a CDK4 / 6 inhibitor to the subject on days 1 to 4 of a 21-day cycle; and administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle; and wherein the maintenance period comprises administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle, and the maintenance period is administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor.

[0073] In one embodiment, a method of treating a subject having soft tissue sarcoma, comprising administering to the subject according to a treatment plan comprising a 21-day induction period and a 21-day maintenance period, wherein the induction period comprises administering an effective amount of doxorubicin to the subject on day 2 of a 21-day cycle; administering an effective amount of ifosfamide to the subject on days 2 to 5 of a 21-day cycle; administering an effective amount of a CDK4 / 6 inhibitor to the subject on days 1 to 5 of a 21-day cycle; and administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle; and wherein the maintenance period comprises administering an effective amount of an immune checkpoint inhibitor to the subject on day 1 of a 21-day cycle, and the maintenance period is administered after a break in the induction period. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0074] In one embodiment, the selective, immediate-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, the selective, immediate-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 (trademark)).

[0076] In one embodiment, the selective, immediate-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 (trademark)). In one embodiment, the PD-1 inhibitor is pembrolizumab (Keytruda (trademark)).

[0077] In one embodiment, the subject or host is a mammal including a human. BRIEF DESCRIPTION OF THE DRAWINGS

[0078]

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Figure 41

[0079] Detailed Description Surprisingly and unexpectedly, it has been found that adding a CDK4 / 6 inhibitor in a very specific dosing schedule to the combination of chemotherapy and checkpoint inhibitors results in significantly better outcomes in the treatment of tumors or cancer. It is an unexpected finding that the specific-time dosing of a selective CDK4 / 6 inhibitor during the administration of the chemotherapy portion of this triple combination therapy has a significant effect on immune cells in the cancer microenvironment. These results are remarkable in that the very specific time-limited dosing of a selective, immediate-acting, short half-life CDK4 / 6 inhibitor provides one or more of protection against damage to the immune tumor cell infiltrate, an increased duration of the immune response by more frequent tumor-specific memory T cells, a greater reduction in intratumoral Treg cells, which are immunosuppressive factors; and / or a change in the gene expression of inflammatory-inducing factors. The expression of genes functionally enriched for lymphocyte activation and upregulation of the inflammatory cytokine interferon-γ is significantly enhanced. In parallel, several genes involved in the immunosuppressive reactive oxygen species metabolic process are downregulated. These findings indicate that the specific-time dosing of a CDK4 / 6 inhibitor, such as an immediate-acting, short half-life CDK4 / 6 inhibitor, results in modulation of gene expression and creates an inflammatory tumor microenvironment that is advantageous for enhancing checkpoint inhibitor activity. This improvement represents a significant advance over the current state of the art in cancer treatment.

[0080] Non-limiting examples of CDK4 / 6 inhibitors contemplated for use herein are, for example, but not limited to, Compounds I, II, III, and IV, which are extremely potent, selective, reversible, cyclin-dependent kinase (CDK)4 / 6 inhibitors that transiently cause G0 / G1 cell cycle arrest in HSPCs and immune effector cells. These cells are dependent on CDK4 / 6 for proliferation and, for example, arrest in the G0 / G1 phase of the cell cycle when exposed to Compound I. HSPCs and other immune effector cells transiently arrest in G0 / G1, where they become more resistant to the DNA-damaging effects of chemotherapy and thus reduce subsequent immunocytotoxicity. Additionally, the combination of CDK4 / 6 inhibitors for cancer treatment with chemotherapeutic agents and immune checkpoint inhibitors has also been found to enhance the anti-cancer immune response. Depending on the specific timing of administration of the CDK4 / 6 inhibitor, immune effector cells are protected from the damage of chemotherapeutic agents and are able to return to cell replication some time after the DNA-damaging effects of the chemotherapeutic agent have waned, resulting in an improvement in immunoreactivity compared to strategies using CDK4 / 6 inhibitors administered in a daily manner that result in complete and permanent inhibition of CDK4 / 6.

[0081] The first attempts at immunotherapy focused on the combination of chemotherapy and cytokines, so-called "chemoimmunotherapy." However, this approach was hampered by a high rate of toxicity without a 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 randomised trial of the German Cooperative Renal Carcinoma Chemoimmunotherapy Group (DGCIN). Br. J. Cancer 2006, 95, 463-469). Interestingly, cytokine therapy provided robust benefits only to some patients, mostly those who showed clinical or serological 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 drugs were also administered, but the results were mixed.For example, the anthelmintic drug levamisole has been found to have immunostimulatory properties and was approved for use in colorectal cancer as an adjunct to 5-fluorouracil (5-FU), but subsequent studies did not appear to show benefit (Wolmark, N.; Rockette, H.; Mamounas, E.; Jones, J.; Wieand, S.; Wickerham, D.L.; Bear, H.D.; Atkins, J.N.; Dimitrov, N.V.; Glass, A.G.; 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-Guerin (BCG) was developed as a vaccine against tuberculosis but provides a robust anti-cancer response when given into the bladder cavity in bladder cancer and has remained the standard treatment for superficial invasive bladder since its first approval for this indication in 1990 (Mungan, N.A.; Witjes, J.A. Bacille Calmette-Guerin in superficial transitional cell carcinoma. Br. J. Urol. 1998, 82, 213-223; Sylvester, R.J.; van der Meijden, A.P.; Witjes, J.A.; 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 the immune response. These proteins normally suppress the immune response by avoiding an overly strong response that could damage normal as well as abnormal cells, but cancers that express these proteins can suppress the immune response (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 rules. 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 the presence of at least one of the items. The term "or" means "and / or". The recitation of a range of values herein is merely intended to serve as a shorthand method of referring individually to each value falling within the range, unless otherwise indicated herein, and each individual value is incorporated herein as if it were individually recited herein. All endpoints of ranges are included within the range and can be combined independently. All methods described herein can be performed in a suitable order, unless otherwise indicated herein or unless the context clearly dictates otherwise. Examples or illustrative language (e.g., "such as") are merely intended to better describe the invention and do not impose a limitation on the scope of the invention unless otherwise claimed. 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.

[0085] In non-limiting embodiments, a CDK4 / 6 inhibitor, such as, but not limited to, Compound I, Compound II, Compound III, or Compound IV, chemotherapy, or a checkpoint inhibitor can be used in a form having at least one desired isotope substitution of an atom in an amount that exceeds the natural abundance of the isotope, i.e., in an enriched amount. Isotopes are atoms that have 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 can be incorporated into a CDK4 / 6 inhibitor, chemotherapy, or checkpoint inhibitor for use in the present invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, fluorine, chlorine, and iodine, such as, respectively 2 H,3 H, 11 C, 13 C, 14 C, 15 N, 18 F 31 P, 32 P, 35 S, 36 Cl, and 125 I are included. In one non-limiting embodiment, the isotope-labeled compound can be used in metabolic tests such as positron emission tomography (PET) or single photon emission computed tomography (SPECT), including drug or substrate tissue distribution assays ( 14 using C), kinetic tests (e.g., 2 using H or 3 H), detection or imaging techniques, or radiotherapy of patients. In particular, 18 F-labeled compounds can be particularly desirable for PET or SPECT tests. The isotope-labeled compounds of the present invention and their prodrugs can generally be prepared by implementing the following production methods by replacing the procedures and non-isotope-labeled reagents disclosed in the schemes or examples with readily available isotope-labeled reagents.

[0087] Without limitation, by way of general example, isotopes of hydrogen, such as deuterium ( 2 H) and tritium ( 3 H), can be used at any position within the described structures to achieve the desired results. Alternatively, or in addition, isotopes of carbon, such as 13 C and 14 C can also be used.

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

[0089] The CDK4 / 6 inhibitors for use in the present invention can 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 (including its salts) of the present invention with one or more solvent molecules. Non-limiting examples of solvents are 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, D2O, d6-acetone, d6-DMSO. Solvates can be in liquid or solid form.

[0090] As generally contemplated herein, the term hematopoietic stem and progenitor cells (HSPC) includes, but is not limited to, long-term hematopoietic stem cells (LT-HSC), short-term hematopoietic stem cells (ST-HSC), hematopoietic progenitor cells (HPC), multipotent progenitor cells (MPP), oligodendrocyte progenitor cells (OPP, monocyte progenitor cells, granulocyte progenitor cells, myeloid common progenitor cells (CMP), lymphoid common progenitor cells (CLP), granulocyte-monocyte progenitor cells (GMP), granulocyte progenitor cells, monocyte progenitor cells, and megakaryocyte-erythroid progenitor cells (MEP), megakaryocyte progenitor cells, erythroid progenitor cells, HSC / MPP (CD45dim / CD34+ / CD38-), OPP (CD45dim / CD34+ / CD38+), monocyte progenitor cells (CD45+ / CD14+ / CD11b+), granulocyte progenitor cells (CD45+ / CD14- / CD11b+), erythroid progenitor cells (CD45- / CD71+), and megakaryocyte progenitor cells (CD45+ / CD61+).

[0091] The term "immune effector cell" 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, 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, 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] As used herein with respect to the compounds described herein, the term "selective CDK4 / 6 inhibitor" refers to an IC 50 required to inhibit CDK2 activity to the same extent in a standard phosphorylation assay at a molar concentration of at most about 50, 100, 200, 300, 400, 500, 1000, 1500, 1800, 2000, 5000, or 10,000th of the IC 50 molar concentration that inhibits CDK4 activity, CDK6 activity, or both CDK4 and CDK6 activities.

[0093] The term "immediate-acting CDK4 / 6 inhibitor" refers to a rapid onset of biological activity upon administration of the compound and reaching C max in a short time. For example, an immediate-acting CDK4 / 6 inhibitor can have a T max of about 2 hours, about 1 hour, less than about 30 minutes, or less than about 15 minutes after the start of administration.

[0094] The term "short half-life CDK4 / 6 inhibitor" refers to a compound having a half-life of, for example, about 16 hours, 15 hours, 14 hours, 13 hours, 12 hours, 11 hours, 10 hours, 9 hours, or less than 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, but the methods described herein should be understood to be effective for other animals such as mammalian and vertebrate species. More specifically, the term "subject" includes, but is not limited to, animals used in assays such as those used in preclinical trials including mice, rats, monkeys, dogs, pigs and rabbits, as well as farm pigs (pigs and castrated pigs), ruminants, horses, poultry, cats, cows, mice, and dogs, etc.

[0096] In some embodiments, the term "CDK4 / 6 replication-independent cancer" refers to a cancer that does not significantly require the activity of CDK4 / 6 for replication. Such types of cancers often, but not always, are characterized by (e.g., have cells that exhibit) an increase in the level of CDK2 activity or a decrease in the expression of retinoblastoma tumor suppressor protein or retinoblastoma family member proteins, such as, but not limited to, p107 and p130. The increase in the level of CDK2 activity or the decrease or absence of the expression of retinoblastoma tumor suppressor protein or retinoblastoma family member protein may be increased or decreased, for example, compared to normal cells. In some embodiments, the increase in the level of CDK2 activity may be associated with (e.g., may result from or be seen with) amplification or overexpression of the MYC oncogene. In some embodiments, the increase in the level of CDK2 activity can 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 a cancer that may be a growth that requires the activity of CDK4 / 6 for replication or proliferation, or that is inhibited by the activity of a selective CDK4 / 6 inhibitor. Cancers and disorders of such types may be characterized by the presence of a functional retinoblastoma protein (e.g., having cells that exhibit its 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 a functional retinoblastoma protein, which may include cancer.

[0098] CDK4 / 6 Inhibitor The present invention is directed to the use of a CDK4 / 6-specific inhibitor in a timed administration 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, for treating a subject having cancer.

[0099] The regulation of the cell cycle is governed and controlled by specific proteins that are activated and inactivated primarily through phosphorylation / dephosphorylation processes in a strictly timed manner. 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 their association with their corresponding regulatory subunits (cyclins) and CDK inhibitor proteins (Cip & Kip proteins, INK4), their phosphorylation state, and ubiquitin-mediated proteolysis (see D.G. Johnson, C.L. Walker, Annu. Rev. Pharmacol. Toxicol 39 (1999) 295-312; D.O. Morgan, Annu. Rev. Cell Dev. Biol. 13 (1997) 261-291; C.J. Sherr, Science 274 (1996) 1672-1677; T. Shimamura et al., Bioorg. Med. Chem. Lett. 16 (2006) 3751-3754).

[0100] There are four CDKs that significantly participate in cell proliferation: CDK1, which mainly regulates the transition from the G2 phase to the M phase, and CDK2, CDK4, and CDK6, which regulate the transition from the G1 phase to the S phase (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, the activation of CDK4-cyclin D and CDK6-cyclin D induces the phosphorylation of the retinoblastoma protein (pRb). The phosphorylation of pRb releases the transcription factor E2F, which enters the nucleus and activates the transcription of other cyclins that promote further progression of 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] Various pyrimidine-based agents have been developed for the treatment of proliferative diseases. U.S. Patent Nos. 8,822,683; 8,598,197; 8,598,186; 8,691,830; 8,829,102; 9,102,683; and 9,260,442, and corresponding WO2012 / 061156, filed by Tavares and Strum and assigned to G1 Therapeutics, describe cyclin-dependent kinase inhibitors of N-(heteroaryl)-pyrrolo[3,2-d]pyrimidin-2-amine species of the formula (where the variables are as defined herein).

Chemical formula

[0102] WO2013 / 148748 (U.S.S.N. 61 / 617,657) under the name "Lactam Kinase Inhibitor", WO2013 / 163239 (U.S.S.N. 61 / 638,491) under the name "Synthesis of Lactams", and WO2015 / 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 the following: WO2014 / 144326, filed by Strum et al. and assigned to G1 Therapeutics, describes compounds and methods for protecting normal cells using pyrimidine-based CDK4 / 6 inhibitors during chemotherapy; 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-tolerant 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 anti-neoplastic and anti-proliferative pyrimidine-based CDK4 / 6 inhibitors; WO2015 / 161285, filed by Strum et al. and assigned to G1 Therapeutics, describes tricyclic pyrimidine-based CDK inhibitors for use in radiation protection; WO2015 / 161287, filed by Strum et al. and assigned to G1 Therapeutics, describes similar tricyclic pyrimidine-based CDK inhibitors for protecting cells during chemotherapy; WO2015 / 161283, filed by Strum et al. and assigned to G1 Therapeutics, describes similar tricyclic pyrimidine-based CDK inhibitors for use in SPC-tolerant treatment of RB-positive abnormal cell proliferation; WO2015 / 161288, filed by Strum et al. and assigned to G1 Therapeutics, describes similar tricyclic pyrimidine-based CDK inhibitors for use as anti-neoplastic and anti-proliferative agents; WO2016 / 040858, filed by Strum et al. and assigned to G1 Therapeutics, describes the use of combinations of pyrimidine-based CDK4 / 6 inhibitors and other anti-neoplastic drugs; 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 a particular formulation 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 are selective for CDK4 / 6 and contain 6-acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido-[2,3-d]-pyrimidin-7-one (PD0332991), which has received fast track approval from the FDA and is currently marketed by Pfizer as Ibrance™ (palbociclib) for the treatment of metastatic breast cancer.

Chemical formula

[0105] VanderWel et al. describe an iodine-containing pyrido[2,3-d]pyrimidin-7-one (CKIA) as a potent and selective CDK4 inhibitor (see VanderWel et al., J. Med. Chem. 48 (2005) 2371-2387).

[0106] WO2010 / 020675, filed by Novartis AG, describes pyrrolopyrimidine compounds as CDK inhibitors. WO2011 / 101409, also filed by Novartis, describes pyrrolopyrimidines having 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 is approved by the FDA for the treatment of metastatic breast cancer and is currently sold as Kisqali (trademark) (ribociclib).

Chemical formula

[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)pyrimidine-2-amine, which is approved by the FDA for the treatment of certain breast cancers and is currently sold by Eli Lilly and Company as Verzenio (trademark) (abemaciclib).

Chemical formula

[0108] Johnson et al. reported that pharmacological inhibition of CDK4 / 6 with the CDK4 / 6 inhibitors 6-acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-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 protection features 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 according to WO2014 / 144326, the entire content of which is incorporated herein by reference in its entirety.

[0110] In certain embodiments, 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 Inhibitor 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 to the PD-1 receptor and then inhibits 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 nivolumab (Opdivo™), a PD-1 immune checkpoint inhibitor, which is administered in an effective amount for the treatment of Hodgkin 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 pembrolizumab (Keytruda™), a PD-1 immune checkpoint inhibitor, which is 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 cancer. In a further aspect of this embodiment, the immune checkpoint inhibitor is pidilizumab (Medivation), a PD-1 immune checkpoint inhibitor, which is administered in an effective amount for the treatment of 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, and then inhibits immunosuppression. PD-L1 inhibitors include, but are not limited to, atezolizumab, durvalumab, KN035 CA-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 to inhibit immunosuppression.

[0115] In one embodiment, the immune checkpoint inhibitor is atezolizumab (Tecentriq™), a PD-L1 immune checkpoint inhibitor administered in an amount effective for the treatment of 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 the treatment of 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 the treatment of 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 administered in combination 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 administered in combination 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 present 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), and 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 and include, for example, monoclonal antibodies 34B1, 26H7, and 5F4; or those described in, for example, US2004 / 0047858, US Patent No. 7,132,255, and WO99 / 052552 or their recombinant forms. In other embodiments, the anti-CEACAM antibody binds to CEACAM-5 as described, for example, 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 as described, for example, in WO2013 / 054331 and US2014 / 0271618.Still other checkpoint inhibitors can be molecules against 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 Drug As contemplated herein, the administration of a selective, immediate-acting, short half-life CDK4 / 6 inhibitor for a specified time period can be combined with any standard chemotherapy drug treatment regimen and further combined with an immune checkpoint inhibitor.

[0121] In one embodiment, the chemotherapy drug is toxic to immune effector cells. In one embodiment, the chemotherapy drug inhibits cell growth. In one embodiment, the cytotoxic chemotherapy drug administered is a DNA-damaging chemotherapy drug. In one embodiment, the chemotherapy drug is a protein synthesis inhibitor, a DNA-damaging chemotherapy drug, 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 oxazaphosphorine compound, an integrin inhibitor (e.g., sirendide, camptothecin or homocamptothecin), a folic acid antagonist or a folic acid metabolism antagonist.

[0122] Cytotoxic Chemotherapy Drug Cytotoxic DNA-damaging chemotherapeutic agents tend to be non-specific and, particularly 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 inhibit the growth or proliferation of unwanted cells, such as cancer cells, and the cytotoxic action of the agent can result from intercalation or binding of nucleic acids, alkylation of DNA or RNA, inhibition of RNA or DNA synthesis, inhibition of another nucleic acid-related activity (e.g., protein synthesis), or any other of the cytotoxic actions. Such compounds include, but are not limited to, DNA-damaging compounds capable of killing 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 benzodepa, carboquone, meturedepa, and uredepa; ethyleneimines and methylmelamines such as altretamine, triethylenemelamine, triethylenephosphoramide, triethylenethiophosphoramide, and trimethylolmelamine; nitrogen mustards such as chlorambucil, chloronaphazine, cyclophosphamide, estramustine, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, nobenbiptin, phenesterine, prednimustine, trofosfamide, and uracil mustard; and nitrosoureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, and ranimustine. Other DNA-damaging chemotherapeutic agents include daunorubicin, doxorubicin, idarubicin, epirubicin, mitomycin, and streptozocin.As metabolic antagonists for chemotherapy, 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'-deoxynucleoside, 5-bromodeoxycytidine, cytosine β-1-D-arabinoside, diazooxynorleucine, dideoxynucleoside, 5-fluorodeoxycytidine, 5-fluorodeoxyuridine, and hydroxyurea are included.

[0123] As protein synthesis inhibitors for chemotherapeutic drugs, abrin, aurintricarboxylic acid, chloramphenicol, colicin E3, cycloheximide, diphtheria toxin, edeine A, emetine, erythromycin, ethionine, fluorid, 5-fluorotryptophan, fusidic acid, guanylylmethylene diphosphonic acid and guanylylimidodiphosphate, kanamycin, kasugamycin, kirromycin, and O-methylthreonine are included. Further protein synthesis inhibitors include modecin, neomycin, norvaline, pactamycin, paromomycin, puromycin, lysine, 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, propidium diiodide-intertwining; and other agents such as distamycin and netropsin. Topoisomerase inhibitors such as irinotecan, teniposide, cumermycin, 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 streptothricin can also be used as DNA-damaging compounds.

[0125] In one embodiment, the chemotherapeutic agent is a DNA complex-binding agent such as camptothecin or etoposide; a thiolatoalkylating agent such as nitrosourea, BCNU, CCNU, ACNU, or fotemustine; a guanine alkylating agent such as temozolomide; a tubulin-binding agent such as vinblastine, vincristine, vinorelbine, vinflunine, cryptophycin 52, halichondrin (e.g., halichondrin B), dolastatin (e.g., dolastatin 10 and dolastatin 15), hemiasterlin (e.g., hemiasterlin A and hemiasterlin B), colchicine, combretastatin, 2-methoxyestradiol, E7010, paclitaxel, docetaxel, epothilone, discodermolide; a DNA polymerase inhibitor such as cytarabine; an anticancer enzyme such as asparaginase; a Rac1 inhibitor such as 6-thioguanine; a thymidylate synthase inhibitor such as capecitabine or 5-FU; an oxazaphosphorine compound such as cyclophosphamide; an integrin inhibitor such as cilengitide; a folic acid antagonist such as pralatrexate; a folic acid metabolism antagonist such as pemetrexed; or camptothecin or homocamptothecin, e.g., difluorocamptothecin.

[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 can be mitigated by the selectively disclosed CDK4 / 6 inhibitors include, but are not limited to, cisplatin, hydrogen peroxide, carboplatin, procarbazine, ifosfamide, bleomycin, plicamycin, taxol, transplatin, thiotepa, and oxaliplatin, and drugs of similar action types. 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 referred to as cytotoxins or cytotoxic agents, which include any agent, multiple agents, and liposomes or other vesicles containing chemotherapeutic compounds that are harmful to the viability of cells). Common anticancer pharmaceutical agents include vincristine (Oncovin (trademark)), liposomal vincristine (Marqibo (trademark)), doxorubicin (Adriamycin (trademark)), cytarabine (cytosine arabinoside, ara-C, or Cytosar (trademark)), L-asparaginase (Elspar (trademark)) or PEG-L-asparaginase (pegaspargase or Oncaspar (trademark)), etoposide (VP-16), teniposide (Vumon (trademark)), 6-mercaptopurine (6-MP or Purinethol (trademark)), prednisone, and dexamethasone (Decadron).Examples of further suitable chemotherapeutic agents include, but are not limited to, 5-fluorouracil, dacarbazine, alkylating agents, anthramycin (AMC), mitotic inhibitors, cis-dichlorodiammineplatinum(II) (DDP) (cisplatin), diaminodichloroplatinum, anthracyclines, antibiotics, antimetabolites, asparaginase, BCG live bacteria (intravesical), bleomycin sulfate, calicheamicin, cytochalasin B, dactinomycin (formerly actinomycin), daunorubicin HCl, daunorubicin citrate, denileukin diftitox, dihydroxyanthracenedione, docetaxel, doxorubicin HCl, Escherichia coli L-asparaginase, Erwinia L-asparaginase, etoposide (VP-16), topotecan phosphate, gemcitabine HCl, idarubicin HCl, interferon α-2b, irinotecan HCl, maytansinoids, mechlorethamine HCl, melphalan HCl, mitomycin, mitomycin C, mitotane, paclitaxel, polyphaseprozan 20 with carmustine implant, procarbazine HCl, streptozotocin, teniposide, thiotepa, topotecan HCl, valrubicin, vinblastine sulfate, vincristine sulfate, and vinorelbine tartrate.

[0129] Further cytotoxic chemotherapeutic agents for use with the present invention include epirubicin, abraxane, taxotere, epothilone, tafurposide, besimodegib, 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 thiolatoalkylating agent.

[0132] Additional Chemotherapy Drug Additional chemotherapeutic agents that can be used as described in this specification may include 2-methoxyestradiol or 2ME2, finasunate, etaracizumab (ME Di-522), HLL1, huN901-DM1, atiprimod, saquinavir mesylate, ritonavir, nelfinavir mesylate, indinavir sulfate, proteasome inhibitor 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 (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 such as cyclosporine or ascomycin such as cyclosporine A (Neoral (trademark)), FK506 (tacrolimus), pimecrolimus, mTOR inhibitors such as rapamycin or its derivatives such as sirolimus (Rapamune (trademark)), everolimus (Certican (trademark)), temsirolimus, zotarolimus, biolimus-7, biolimus-9, rapalogs such as ridafolimus, Campath 1H, S1P receptor modulators, dual mTORC1·mTORC2 inhibitors such as vistusertib (AZD2014), such as fingolimod or its analogs, anti-IL-8 antibodies, mycophenolic acid or its salts such as the sodium salt, or its prodrugs such as mycophenolate mofetil (CellCept (trademark)), OKT3 (Orthoclone OKT3 (trademark)), prednisone, ATGAM (trademark), thymoglobulin (trademark), brequinarium sodium, OKT4, T10B9.A-3A, 33B3.1, 15-deoxyspergualin, tresperimus, leflunomide Arava (trademark), anti-CD25, anti-IL2R, basiliximab (Simulect (trademark)), daclizumab (Zenapax (trademark)), mizoribine, dexamethasone, ISAtx-247, SDZ ASM981 (pimecrolimus, Elidel (trademark)), abatacept, belatacept, LFA3lg, etanercept (sold as Enbrel (trademark) by ImmuneXcite), adalimumab (Humira (trademark)), infliximab (Remicade (trademark)), anti-LFA-1 antibody, natalizumab (Antegren (trademark)), enlimomab, gavrilimomab, golimumab, antithymocyte immunoglobulin, cyprazumab, alefacept, efalizumab, Pentasa, mesalazine, Asacol, codeine phosphate, benorylate, fenbufen, naproxen, diclofenac, etodolac, indomethacin, dasatinib (Sprycel (trademark)), nilotinib (Tasigna (trademark)), bosutinib (Bosulif (trademark)), imatinib mesylate (Gleevec (trademark)) and ponatinib (Iclusig (trademark)), amifostine, droxidopa mesylate, dronabinol, epoetin-α, etidronate, filgrastim, fluconazole, goserelin acetate, gramicidin D, granisetron, leucovorin calcium, lidocaine, mesna, ondansetron HCl, pilocarpine HCl, porfimer sodium, batranib, 1-dehydrotestosterone, allopurinol sodium, betamethasone, sodium phosphate and betamethasone acetate, calcium leucovorin, conjugated estrogen, dexrazoxane, dibromomannitol, esterified estrogen, estradiol, estramustine phosphate sodium, ethinyl estradiol, flutamide, folic acid, glucocorticoid, leuprolide acetate, levamisole HCl, medroxyprogesterone acetate, megestrol acetate, methyltestosterone, nilutamide, octreotide acetate, pamidronate disodium, procaine, propranolol, testolactone, tetracaine, tamoxifen citrate, and sargramostim are included.

[0134] In one embodiment, the chemotherapeutic agent is an estrogen receptor ligand such as tamoxifen, raloxifene, fulvestrant, anordrin, bazedoxifene, broparestriol, chlortrianisene, clomiphene citrate, cyclophenyl, lasofoxifene, ormeloxifene, or toremifene; an androgen receptor ligand such as bicalutamide, enzalutamide, apalutamide, cyproterone acetate, chloromadinone acetate, spironolactone, canrenone, drospirenone, ketoconazole, topilutamide, abiraterone acetate, or cimetidine; an aromatase inhibitor such as letrozole, anastrozole, or exemestane; an anti-inflammatory agent such as prednisone; an oxidase inhibitor such as allopurinol; an anti-cancer antibody; an anti-cancer monoclonal antibody; an antibody against CD40 such as lucatumumab or dacetuzumab; an antibody against CD20 such as rituximab; a CD52-binding antibody such as alemtuzumab; an integrin-binding antibody such as borosikizumab or natalizumab; an antibody against interleukin-6 receptor such as tocilizumab; an interleukin-2 mimetic such as aldesleukin; an IGF1-targeting antibody such as figitumumab; an antibody against DR4 such as mapatumumab; an antibody against TRAIL-R2 such as lexatumumab or dulalumin; a fusion protein such as atacicept; a B cell inhibitor such as atacicept; a proteasome inhibitor such as carfilzomib, bortezomib, or marizomib; an HSP90 inhibitor such as tanespimycin; an HDAC inhibitor such as vorinostat, belinostat, or panobinostat; a MAPK ligand such as talmapimod; a PKC inhibitor such as enzastaurin; a HER2 receptor ligand such as trastuzumab, lapatinib, or pertuzumab; an EGFR inhibitor such as gefitinib, erlotinib, cetuximab, panitumumab, or vandetanib; a natural product such as romidepsin; a retinoid such as bexarotene, tretinoin, or alitretinoin; a receptor tyrosine kinase (RTK) inhibitor such as sunitinib, regorafenib, or pazopanib; or a VEGF inhibitor such as ziv-aflibercept, bevacizumab, or dovitinib.

[0135] In one embodiment, a combination of a CDK4 / 6 inhibitor, a chemotherapeutic agent, and an immune checkpoint inhibitor is used, including but not limited to granulocyte colony-stimulating factor (G-CSF, e.g., sold as Neupogen (trademark) (filgrastim), Neulasta (trademark) (pegfilgrastim), or lenograstim), granulocyte macrophage colony-stimulating factor (GM-CSF, e.g., sold as molgramostim and sargramostim (Leukine (trademark))), M-CSF (macrophage colony-stimulating factor), thrombopoietin (megakaryocyte growth development factor (MGDF), e.g., sold as Romiplostim (trademark) and Eltrombopag (trademark)), 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, epoetin-α sold as Epogen, Eprex, and Procrit; epoetin-β (e.g., sold as NeoRecormon, Recormon, and Micera), epoetin-δ (e.g., sold as Dynepo), epoetin-ω (e.g., sold as Epomax), epoetin ζ (e.g., sold as Silapo and Retacrit) and, for example, epocept, epotrust, erypro safe, repoitin, vintor, epofit, erykine, wepox, espogen, relipoietin, shan It is further combined with the use of hematopoietic growth factors including poietin (Shanpoietin), zyrop (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, in particular, 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 SERMs (selective estrogen receptor modulators), SERDs (selective estrogen receptor degrader), complete estrogen receptor degrader, or another form of partial or complete estrogen antagonist. Partial antiestrogenic agents such as raloxifene and tamoxifen retain some estrogen-like effects including estrogen-like stimulation of uterine growth and, in some cases, estrogen-like effects that actually stimulate tumor growth during breast cancer progression. In contrast, fulvestrant, a complete antiestrogenic agent, has no estrogen-like effects on the uterus and is effective against tamoxifen-resistant tumors. Non-limiting examples of antiestrogenic compounds are shown 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 US2015 / 0005286, WO2014 / 205136, and WO2014 / 205138. Further non-limiting examples of antiestrogenic compounds include SERMs such as arnoduline, 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 anti-gonadotropins such as leuprorelin, cetrorelix, allylestrenol, chloromadinone acetate, delmadinone acetate, dydrogesterone, medroxyprogesterone acetate, megestrol acetate, nomegestrol acetate, norethisterone acetate, progesterone, and spironolactone.

[0137] In this specification, in particular, as additional chemotherapeutic agents contemplated in the treatment of abnormal tissues of the male reproductive system such as prostate cancer or testicular cancer, but not limited to, androgen inhibitors including selective androgen receptor modulators, selective androgen receptor degraders, complete androgen receptor degraders, or another form of partial or complete androgen antagonist are included. In one embodiment, the prostate cancer or testicular cancer is androgen resistant. Non-limiting examples of anti-androgen compounds are shown in WO2011 / 156518 and U.S. Patent Nos. 8,455,534 and 8,299,112. Further non-limiting examples of anti-androgen compounds include chlormadinone acetate, spironolactone, canrenone, drospirenone, ketoconazole, topilutamide, abiraterone acetate, and cimetidine.

[0138] The chemotherapeutic agent may include, but is not limited to, a kinase inhibitor including a phosphoinositide 3-kinase (PI3K) inhibitor, a Bruton's tyrosine kinase (BTK) inhibitor, or a spleen tyrosine kinase (Syk) inhibitor, or a combination thereof.

[0139] PI3k inhibitors are well-known. Examples of PI3 kinase inhibitors include, but are not limited to, wortmannin, demethoxybilirubin, perifosine, idelalisib, pictilisib, paromide 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-methylpropanamide), MLN-1117 ((2R)-1-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)-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), BAY 80-6946 (2-Amino-N-(7-methoxy-8-(3-morpholinopropoxy)-2,3-dihydroimidazo[l,2-c]quinaz), 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)morpholino-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-1-yl]phenyl}propanenitrile), XL-765 (N-(3-(N-(3-(3,(5-((4-(4-pyridinyl)-6-quinolinyl)methylene)-2,4-thiazolidinedione), 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-hexahydroinden[4,5h]isochromen-10-yl]acetate (also known as sonolisib)), and the structures described in WO2014 / 071109 having the formula are included.,

[0140] BTK inhibitors are well-known. Examples of BTK inhibitors include ibrutinib (also known as PCI-32765) (Imbruvica (trademark)) (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-based 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 content of which is 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-i bromophenyl)propanamide), GDC-0834 ([R-N-(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 capable of inhibiting BTK activity, such as the BTK inhibitors disclosed in Akinleye et al., Journal of Hematology & Oncology, 2013, 6:59, which is incorporated herein by reference in its entirety.,

[0141] Syk inhibitors are well-known. For example, cerdulatinib (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]pyrazine-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)pyrimidine-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-aminocyclohexylamino]-4-(5,6-dimethyl-pyridin-2-ylamino)-pyridazine-3-carboxamide), 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-aminotetrahydro-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 (see Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire content of which is incorporated herein by reference), Compound D (see Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire content of which is incorporated herein by reference), PRT060318 (see Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire content of which is incorporated herein by reference), Luteolin (see Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614-3643, the entire content of which is incorporated herein by reference), Apigenin (see Singh et al. Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors,See Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614 - 3643 (the entire content of which is incorporated herein by reference), quercetin (see Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614 - 3643, the entire content of which is incorporated herein by reference), fisetin (see Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614 - 3643, the entire content of which is incorporated herein by reference), myricetin (see Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614 - 3643, the entire content of which is incorporated herein by reference), morin (see Singh et al., Discovery and Development of Spleen Tyrosine Kinase (SYK) Inhibitors, J. Med. Chem. 2012, 55, 3614 - 3643, the entire content of which is incorporated herein by reference).

[0142] The chemotherapeutic agent can 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)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-[1,1'-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 (obatoclax 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), pogostin, 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, apoptosis compounds, topoisomerase inhibitors, AKT inhibitors (including, but not limited to, MK-2206, GSK690693, perifosine, (KRX-0401), GDC-0068, triciribine, AZD5363, 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-1(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 (1-({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), R05126766 (3-[[3-fluoro-2-(methylsulfamoyl amino)-4-pyridyl]methyl]-4-methyl-7-pyrimidin-2-yloxycoumen-2-one), WX-554, R04987655 / CH4987655 (3,4-difluoro-2-((2-fluoro-4-iodophenyl)amino)-N-(2-hydroxyethoxy)-5-((3-oxo-1,2-oxazinane-2-yl)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, reolysin 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. 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]pyrimidin-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]benzimidazole-2-amine), 2-bromoaldisine (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-2pyridinecarboxamide 1-oxide) can be mentioned.

[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-hydroxy-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 (berotecan), 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)naphthyridin-6-one (topotecar), 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[methylene poly(oxyethylene)oxy(1-oxoethylene)]} tetra-glycinate tetrahydrochloride (ethylinotecan pegol), 10-hydroxy-camptothecin (HOCPT), 9-nitrocamptothecin (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 (erlotecan) may be mentioned.,

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

[0148] Growth Factor In one embodiment, a combination of a CDK4 / 6 inhibitor, a chemotherapeutic agent, and a checkpoint inhibitor is further combined with the use of a hematopoietic growth factor 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 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 KL) and erythropoietin (EPO), and derivatives thereof (e.g., darbepoetin (sold as darbepoetin, epocept, nanokine, epofit, epoetin-α such as Epogen, Eprex, and Procrit); epoetin-β (e.g., sold as NeoRecormon, Recormon, and Micera), epoetin-δ (e.g., sold as Dynepo), epoetin-ω (e.g., sold as Epomax), epoetin zeta (e.g., sold as Silapo and Retacrit) and, for example, epocept, epotrust, erypro safe, repoitin, vintor, epofit, erykine, wepox, espogen, relipoietin, shanpoietin, zyrop, and EPIAO). One embodiment In this case, 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 worn off. 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 a CDK4 / 6 inhibitor in combination with a chemotherapeutic agent and an immune checkpoint inhibitor is useful in the treatment of a subject having cancer or a tumor. 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 blood 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 having Rb-positive cancers or other Rb-positive abnormal cell proliferative diseases. In some embodiments, the cancer or cell proliferative disease is a CDK4 / 6 replication-dependent cancer or cell proliferative disease, which refers to a cancer or cell proliferative disease that requires the activity of CDK4 / 6 for replication or proliferation or whose growth can be inhibited via the activity of a CDK4 / 6 inhibitor. This type of cancer and disease can be characterized by the presence of a functional Retinoblastoma protein (e.g., having cells that exhibit its presence). Such cancers and diseases are classified as Rb-positive. Rb-positive abnormal cell proliferative diseases, and variations of this term, as used herein, refer to disorders or diseases caused by uncontrolled or abnormal cell division that are characterized by the presence of a functional Retinoblastoma protein and can include cancer. In one aspect of the invention, the use of a CDK4 / 6 inhibitor in combination with the additional therapeutic agents and methods described herein can be used to treat non-cancerous Rb-positive abnormal cell proliferative diseases. Examples of such diseases can include non-malignant lymphoproliferation, non-malignant breast neoplasms, psoriasis, arthritis, dermatitis, precancerous colonic lesions or polyps, angiogenesis 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] Target cancers suitable for administration of the compounds described herein include Rb positive: estrogen receptor positive cancers, HER2 negative advanced breast cancer, late metastatic breast cancer, liposarcoma, non-small cell lung cancer, liver cancer, ovarian cancer, glioblastoma, refractory solid tumors, Retinoblastoma positive breast cancer as well as Retinoblastoma positive endometrial / vaginal / ovarian cancer and lung / bronchial cancer, colorectal adenocarcinoma, rectal adenocarcinoma, central nervous system germ cell tumor, teratoma, estrogen receptor negative breast cancer, estrogen receptor positive breast cancer, familial testicular germ cell tumor, HER2 negative breast cancer, HER2 positive breast cancer, male breast cancer, ovarian immature teratoma, ovarian mature teratoma, unidermal and highly restricted teratoma, progesterone receptor negative breast cancer, progesterone receptor positive breast cancer, recurrent breast cancer, recurrent colon cancer, recurrent extragonadal germ cell tumor, recurrent extragonadal non-seminoma 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 non-seminoma 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 non-seminoma germ cell tumor, stage IV extragonadal seminoma, stage IV melanoma, stage IV ovarian germ cell tumor, stage IV rectal cancer, testicular immature teratoma, testicular mature teratoma. In certain embodiments, target cancers include estrogen receptor positive, HER2 negative advanced breast cancer, late metastatic breast cancer, liposarcoma, non-small cell lung cancer, liver cancer, ovarian cancer, glioblastoma, refractory solid tumors, retinoblastoma positive breast cancer as well as retinoblastoma positive endometrial / vaginal / ovarian cancer and lung / bronchial cancer, metastatic colorectal cancer, metastatic melanoma having a CDK4 mutation or amplification, or cisplatin refractory unresectable germ cell tumor.

[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, 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, gastric cancer, colon cancer, breast cancer, uterine cancer, fallopian tube carcinoma, endometrial carcinoma, cervical carcinoma, vaginal carcinoma, vulvar carcinoma, esophageal cancer, small intestine cancer, endocrine system cancer, thyroid cancer, parathyroid cancer, adrenal cancer, soft tissue sarcoma, urethral cancer, penile cancer, prostate cancer, bladder cancer, kidney or ureteral cancer, renal cell carcinoma, renal pelvic carcinoma, central nervous system (CNS) neoplasm, primary CNS lymphoma, spinal cord axis tumor, brainstem glioma, pituitary adenoma, or an Rb-positive carcinoma, sarcoma including one or more combinations of the above cancers.

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

[0155] In further embodiments, Rb-positive cancers or disorders include, but are not limited to, hematological disorders or hematological malignancies such as myeloid disorders, lymphoid disorders, leukemia, lymphoma, myelodysplastic syndrome (MDS), myeloproliferative disease (MPD), mast cell disorders, and myeloma (e.g., multiple myeloma). Abnormal proliferation of T cells, B cells, and / or NK cells can give rise to a wide range of diseases such as cancer, proliferative disorders, and inflammatory / immune diseases. A host, such as a human, afflicted with any of these disorders can be treated with an effective amount of the combinations as described herein to achieve symptom reduction (prophylactic agents) or reduction of the underlying disease (disease-modifying agents).

[0156] Examples include T cell or NK cell lymphomas such as, but not limited to, peripheral T cell lymphoma; anaplastic large cell lymphoma, such as anaplastic lymphoma kinase (ALK)-positive, ALK-negative anaplastic large cell lymphoma, or primary cutaneous anaplastic large cell lymphoma; angioimmunoblastic lymphoma; cutaneous T cell lymphoma such as mycosis fungoides, Sézary syndrome, primary cutaneous anaplastic large cell lymphoma, primary cutaneous CD30+ T cell proliferative disorder; primary cutaneous rapidly progressive epidermotropic CD8+ cytotoxic T cell lymphoma; primary cutaneous γ-δ T cell lymphoma; primary cutaneous small / medium cell type CD4+ T cell lymphoma, and lymphomatoid papulosis; adult T cell leukemia / lymphoma (ATLL); blastic NK cell lymphoma; enteropathy-type T cell lymphoma; hepatosplenic γ-δ T cell lymphoma; lymphoblastic lymphoma; nasal NK / T cell lymphoma; therapy-related T cell lymphoma; e.g., lymphoma seen after solid organ or bone marrow transplantation; T cell prolymphocytic leukemia; T cell large granular lymphocytic leukemia; chronic lymphoproliferative disorder of NK cells; rapidly progressive NK cell leukemia; pediatric systemic EBV+ T cell proliferative disorder (associated with chronic active EBV infection); vaccinia-like lymphoproliferative disorder; 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, such as a human, having a lymphoma or a lymphocytic or myelocytic proliferative disorder or abnormality. For example, a method as described herein can be administered to a host having Hodgkin lymphoma or non-Hodgkin lymphoma. For example, the host can have, but is not limited to, an AIDS-related lymphoma; undifferentiated large cell lymphoma; angioimmunoblastic lymphoma; blastic NK cell lymphoma; Burkitt 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; enteropathy-type T cell lymphoma; follicular lymphoma; hepatosplenic γ-δ T cell lymphoma; lymphoblastic lymphoma; mantle cell lymphoma; marginal zone lymphoma; nasal T cell lymphoma; pediatric lymphoma; peripheral T cell lymphoma; primary central nervous system lymphoma; T cell leukemia; malignant transitional lymphoma; therapy-related T cell lymphoma; or a non-Hodgkin lymphoma such as Waldenström macroglobulinemia.

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

[0159] Alternatively, the methods described herein, although not limited thereto, can be used to treat multiple myeloma; diffuse large B-cell lymphoma; follicular lymphoma; mucosa-associated lymphoid tissue lymphoma (MALT); small 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 lymphomatoid granulomatosis; B-cell prolymphocytic leukemia; hairy cell leukemia; unclassifiable splenic lymphoma / leukemia; splenic diffuse red pulp small B-cell lymphoma; hairy cell leukemia variant; lymphoplasmacytic lymphoma; H-chain disease, e.g., alpha heavy chain disease, gamma heavy chain disease, mu heavy chain disease; plasmacytic myeloma; solitary plasmacytoma of bone; extramedullary plasmacytoma; primary cutaneous follicle center lymphoma; T-cell / histiocyte-rich large B-cell lymphoma; chronic inflammation-associated DLBCL; elderly Epstein-Barr virus (EBV)+ DLBCL; primary mediastinal (thymic) large B-cell lymphoma; primary cutaneous DLBCL of the lower extremities; ALK+ large B-cell lymphoma; plasmablastic lymphoma; HHV8-associated multicentric large B-cell lymphoma; Castleman disease; unclassifiable B-cell lymphoma with intermediate features of diffuse large B-cell lymphoma; or unclassifiable B-cell lymphoma with intermediate features of diffuse large B-cell lymphoma, and certain B-cell lymphomas or proliferative disorders such as classical Hodgkin lymphoma.

[0160] In one embodiment, the methods described herein can be used to treat leukemia. For example, the subject can have an acute or chronic leukemia of lymphoid or myeloid origin, including 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 subtype of AML); large granular lymphocytic leukemia; or adult T-cell chronic leukemia. In one embodiment, the patient has acute myeloid leukemia, such as undifferentiated AML (M0); myeloblastic leukemia (M1; with or without terminal cell maturation); myeloblastic leukemia (M2; with cell maturation); promyelocytic leukemia (M3 or M3 variant [M3V]); myelomonocytic leukemia (M4 or M4 variant with eosinophilia [M4E]); 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 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 cancers.

[0162] CDK4 / 6 replication-independent cell proliferation disorders, such as those found in certain cancers, can be characterized by one or a combination of enhanced cyclin-dependent kinase 1 (CDK1) activity, enhanced cyclin-dependent kinase 2 (CDK2) activity, reduced, defective, or absent retinoblastoma tumor suppressor protein (Rb) (Rb-null), high levels of MYC expression, increased cyclin E1, E2, and increased cyclin A. Cancers can be characterized by reduced expression of 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 can be characterized by one or more of a group including but not limited to enhanced CDK1 or CDK2 activity, reduced, defective, 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 can include but are not limited to small cell lung cancer, retinoblastoma, cervical cancer, and HPV-positive malignancies such as certain head and neck cancers, MYC-amplified tumors such as Burkitt 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 thymic 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 a retinoblastoma tumor suppressor protein (Rb) that is inactivated, and thus do not require CDK4 / 6 activity for proliferation. Triple negative (basal-like) breast cancer also almost always is generally or functionally Rb-null. Also, some virus-induced cancers (e.g., cervical cancer and some head and neck cancers) express a viral protein (E7) that inactivates Rb and makes 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 combinations 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 of skill 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 vary, for example, depending on the tissue, cell line, or surrogate tissue sample being used. For example, Western blot and ELISA can be used with any type of tissue, cell line, or surrogate tissue, while the IHC method may be more appropriate when the tissue used in the method of the invention is a tumor biopsy. FACS analysis will likely be most applicable to samples that are single cell suspensions such as cell lines and isolated peripheral blood mononuclear cells. See, e.g., US20070212736 “Functional Immunohistochemical Cell Cycle Analysis as a Prognostic Indicator for Cancer”. Alternatively, molecular genetic tests may be used to determine the status of the retinoblastoma gene. Molecular genetic tests for retinoblastoma include 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 cancer expressing PD-L1. The expression of PD-L1 can be determined by methods known in the art. For example, the expression of PD-L1 can be detected using the PD-L1 IHC 22C3 pharmDx, an FDA-approved in vitro diagnostic immunohistochemistry (IHC) test developed by Dako and Bristol-Meyers Squibb as an adjunctive test for treatment with pembrolizumab. This is a qualitative assay using the monoclonal mouse anti-PD-L1 clone 22C3 PD-L1 and the EnVision FLEX visualization system on an Autostainer Lin 48 for detecting PD-L1 in formalin-fixed paraffin-embedded (FFPE) human non-small cell lung cancer tissue. The expression level can be measured using the tumor proportion score (TPS), which measures the percentage of viable tumor cells showing partial or complete membrane staining. Staining can show PD-L1 expression from 1% to 100%.

[0167] The expression of PD-L1 can also be detected using the PD-L1 IHC 28-8 pharmDx, an FDA-approved in vitro diagnostic immunohistochemistry (IHC) test developed by Dako and Merck as an adjunctive test for treatment with nivolumab. In this qualitative assay, the monoclonal rabbit anti-PD-L1 clone 28-8 and the EnVision FLEX visualization system are used on an Autostainer Lin 48 for detecting 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 jointly by Ventana and AstraZeneca) using the monoclonal rabbit anti-PD-L1 clone SP263 and the Ventana SP142 assay (developed jointly by Ventana and Genentech / Roche) using the rabbit monoclonal anti-PD-L1 clone SP142.

[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 Plan As contemplated herein, the administration of a chemotherapeutic agent, such as a DNA-damaging chemotherapeutic agent, and a CDK4 / 6 inhibitor in combination with an immune checkpoint inhibitor is for a specific time limit at the doses described herein such 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, during, after, or in combination with treatment with a chemotherapeutic agent. As contemplated herein, the CDK4 / 6 inhibitor is generally administered in a manner that allows easy access of the drug to the bloodstream, such as, for example, by intravenous (IV) injection. In one embodiment, the CDK4 / 6 inhibitor is administered to the subject about 24 hours, 20 hours, 16 hours, 12 hours, 8 hours, or 4 hours, 2.5 hours, 2 hours, less than 1 hour, within 1 / 2 hour before treatment with a chemotherapeutic agent. In another embodiment, the compound is administered to the subject about 48 hours, 40 hours, less than 36 hours, or within 32 hours before treatment with a chemotherapeutic agent. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0172] Generally, a CDK4 / 6 inhibitor is administered to a subject prior to treatment with a chemotherapeutic agent such that the compound reaches its maximum serum concentration before or during treatment with the chemotherapeutic agent. In one embodiment, the CDK4 / 6 inhibitor is administered to the subject approximately 30 minutes prior to administration of the chemotherapeutic agent. In one embodiment, the CDK4 / 6 inhibitor is administered to the subject over a period of about 30 minutes and then the chemotherapeutic agent is administered to the subject. In one embodiment, the CDK4 / 6 inhibitor is administered concurrently with or in proximity to the chemotherapeutic agent. If desired, particularly if the chemotherapeutic agent is administered over a long period of time or has a long half-life, the compound can be administered multiple times during chemotherapeutic treatment to maximize inhibition. In another embodiment, the CDK4 / 6 inhibitor can be administered after chemotherapeutic agent exposure, if desired, to mitigate damage to healthy cells associated with chemotherapeutic agent exposure. In certain embodiments, the CDK4 / 6 inhibitor is administered up to about 1 / 2 hour, up to about 1 hour, up to about 2 hours, up to about 4 hours, up to about 8 hours, up to about 10 hours, up to about 12 hours, up to about 14 hours, up to about 16 hours, or up to or beyond about 20 hours after chemotherapeutic agent exposure. In certain embodiments, the CDK4 / 6 inhibitor is administered from about 12 hours to up to 20 hours after chemotherapeutic agent exposure. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0173] In one aspect, the CDK4 / 6 inhibitor can be administered in an induction dosing schedule that includes a standard chemotherapy drug dosing schedule or regimen, in combination with an immune checkpoint inhibitor, over a multi-day cycle. 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 times or more. For example, the CDK4 / 6 inhibitor can be administered such that CDK4 / 6 replication-dependent HSPCs and immune effector cells are arrested in the G1 phase during chemotherapy drug exposure, during which period, due to the rapid disappearance of the G1 arrest effect of the compound, a significant number of healthy cells return to the cell cycle and can be activated and / or replicated, for example, within about 24, 30, 40, or less than about 48 hours after chemotherapy drug exposure. In one embodiment, but not limited to, the chemotherapy drug is 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; 6-8 weeks, day 1 every week; 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 in a treatment regimen including a dosing schedule of the same type, such that CDK4 / 6 replication-dependent cells are arrested in the G1 phase during chemotherapy drug exposure, the CDK4 / 6 inhibitor is administered in combination with the chemotherapy drug and the immune checkpoint inhibitor. In a further embodiment, the immune checkpoint inhibitor is administered daily, every other day, every 3 days, 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 chemotherapy drug is carboplatin and etoposide. In one embodiment, the chemotherapy drug is topotecan.

[0174] In one aspect, the CDK4 / 6 inhibitor can be administered according to a standard chemotherapy drug administration schedule or regimen and a maintenance administration schedule using an immune checkpoint inhibitor, where the CDK4 / 6 inhibitor and the chemotherapy drug are each administered for several days in a cycle, and upon completion of the several-day cycle, the immune checkpoint inhibitor is administered. In one embodiment, the CDK4 / 6 inhibitor and the chemotherapy drug are administered for 21 days in a cycle, starting on the 22nd day, and 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 administration 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 3 days. In one embodiment, the immune checkpoint inhibitor is administered once a week. 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 drugs are carboplatin and etoposide. In one embodiment, the CDK4 / 6 inhibitor is Compound I, the immune checkpoint inhibitor is atezolizumab, and the chemotherapy drug is topotecan.

[0175] In one aspect, the CDK4 / 6 inhibitor can be administered in a standard chemotherapy drug administration schedule or regimen and an induction and maintenance administration schedule using an immune checkpoint inhibitor, where the CDK4 / 6 inhibitor, the chemotherapy drug, and the immune checkpoint inhibitor are administered during a multi-day cycle in the induction period, and upon completion of the multi-day cycle, the immune checkpoint inhibitor is further administered in the maintenance period. In one embodiment, the induction period is a 21-day cycle. In a further embodiment, the 21-day induction period is repeated up to 1, 2, 3, 4, or 5 times. In one embodiment, the maintenance period 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 3 days. In one embodiment, the immune checkpoint inhibitor is administered once a week. 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 drug is carboplatin and etoposide. In one embodiment, the CDK4 / 6 inhibitor is Compound I, the immune checkpoint inhibitor is atezolizumab, and the chemotherapy drug is topotecan.

[0176] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to increase the population of pro-inflammatory immune effector cells in the intratumoral immune infiltrate population in a subject having cancer or a tumor. In one embodiment, the population of pro-inflammatory immune effector cells is increased by up to 10%, 20%, 30%, 40%, 50% or more compared to the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population without administration of the CDK4 / 6 inhibitor for a specific time period. In one embodiment, the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population is increased by about 10% compared to the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population without administration of the CDK4 / 6 inhibitor for a specific time period. In one embodiment, the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population is increased by about 20% compared to the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population without administration of the CDK4 / 6 inhibitor for a specific time period. In one embodiment, the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population is increased by about 30% compared to the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population without administration of the CDK4 / 6 inhibitor for a specific time period. In one embodiment, the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population is increased by about 40% compared to the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population without administration of the CDK4 / 6 inhibitor for a specific time period. In one embodiment, the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population is increased by about 50% compared to the population of pro-inflammatory immune effector cells in the intratumoral immune cell infiltrate population without administration of the CDK4 / 6 inhibitor for a specific time period. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041.In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0177] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to enhance the activation of T cells in the population of tumor-infiltrating immune cells in a subject having cancer or a 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 population of tumor-infiltrating immune cells is about 5%, 10%, 15%, 20% or more. In one embodiment, the percentage of activated T cells in the population of tumor-infiltrating immune cells is about 5%. In one embodiment, the percentage of activated T cells in the population of tumor-infiltrating immune cells is about 10%. In one embodiment, the percentage of activated T cells in the population of tumor-infiltrating immune cells is about 15%. In one embodiment, the percentage of activated T cells in the population of tumor-infiltrating immune cells is about 20%. In one embodiment, the production of interferon γ increases for the upregulation of the IL2 gene, the IL18 gene, or the LTA gene. In one embodiment, the production of interferon γ increases for the upregulation of the IL2 gene. In one embodiment, the production of interferon γ increases for the upregulation of the IL18 gene. In one embodiment, the production of interferon γ increases for the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0178] In one embodiment, the 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 population of intratumoral immune cell infiltrates 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 cell infiltrate population is reduced by about 10%, 20%, 30%, 40% or more compared to the intratumoral cell infiltrate population from a subject not receiving the CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 10% compared to the intratumoral cell infiltrate population from a subject not receiving the CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 20% compared to the intratumoral cell infiltrate population from a subject not receiving the CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 30% compared to the intratumoral cell infiltrate population from a subject not receiving the CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 40% compared to the intratumoral cell infiltrate population from a subject not receiving the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0179] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to inhibit the immunosuppressive function of regulatory T cells in the intratumoral cell infiltrate population in a subject having cancer or a tumor. In one embodiment, the Treg is CD4+CD25+ Treg. 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 or more after treatment compared to the case of chemotherapeutic agent / immune 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 the 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 10% compared to the 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 the 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 the 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 the 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 the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0180] In one embodiment, the 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 pair having cancer or a tumor. In one embodiment, the percentage of tumor-specific memory T cells found in the spleen of the subject increases 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 spleen of the subject increases by approximately 0.25% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the spleen of the subject increases by approximately 0.5% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the spleen of the subject increases by approximately 0.75% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the spleen of the subject increases by approximately 1% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the blood of the subject increases 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 blood of the subject increases by approximately 0.5% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the blood of the subject increases by approximately 1% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the blood of the subject increases by approximately 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

[0181] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to protect intratumoral immune cells from chemotherapy in a subject having cancer or a tumor. In one embodiment, protection of intratumoral immune cells from the toxicity of chemotherapy results in enhancement of the antitumor immune response. In one embodiment, the intratumoral immune cells to be protected are selected from CD8+ T cells, CD4+ T cells, natural killer cells, monocytic myeloid-derived suppressor cells (mMDSC), and granulocytic myeloid-derived suppressor cells (gMDSC). In one embodiment, the intratumoral immune cells to be protected are CD8+ T cells. In one embodiment, the intratumoral immune cells to be protected are CD4+ T cells. In one embodiment, the intratumoral immune cells to be protected are natural killer cells. In one embodiment, the intratumoral immune cells to be protected are mMDSC. In one embodiment, the intratumoral immune cells to be protected are gMDSC. In one embodiment, the percentage of proliferation of intratumoral immune cells is at least about 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 50%, 60%, 70%, 75%, 80% or more, up to approximately 50% at most in about 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 50% in about 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 60% in about 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 70% in about 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 75% in about 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 80% in about 6 to 24 hours. In one embodiment, the intratumoral immune cells can recover within approximately 30, 40, 45, 48, 50, or 60 hours. In one embodiment, the intratumoral immune cells recover in about 30 hours. In one embodiment, the intratumoral immune cells recover in about 40 hours. In one embodiment, the intratumoral immune cells recover in about 45 hours. In one embodiment, the intratumoral immune cells recover in about 48 hours. In one embodiment, the intratumoral immune cells recover in about 50 hours. In one embodiment, the intratumoral immune cells recover in about 60 hours. In one embodiment, the selective CDK4 / 6 inhibitor is an immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the CDK4 / 6 inhibitor is Compound I.

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

[0183] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to enhance the activation of T cells in the population of immune cell infiltrates within the tumor of a subject having cancer or a 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 population of immune cell infiltrates within the tumor is about 5%, 10%, 15%, 20% or more. In one embodiment, the percentage of activated T cells in the population of immune cell infiltrates within the tumor is about 5%. In one embodiment, the percentage of activated T cells in the population of immune cell infiltrates within the tumor is about 10%. In one embodiment, the percentage of activated T cells in the population of immune cell infiltrates within the tumor is about 15%. In one embodiment, the percentage of activated T cells in the population of immune cell infiltrates within the tumor is about 20%. In one embodiment, the production of interferon γ increases for the upregulation of the IL2 gene, the IL18 gene, or the LTA gene. In one embodiment, the production of interferon γ increases for the upregulation of the IL2 gene. In one embodiment, the production of interferon γ increases for the upregulation of the IL18 gene. In one embodiment, the production of interferon γ increases for the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0184] In one embodiment, the 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 a tumor. In one embodiment, the Tregs are CD4+CD25+Tregs. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 10%, 20%, 30%, 40% or more compared to the intratumoral cell infiltrate population from a subject not receiving a selective, immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 10% compared to the intratumoral cell infiltrate population from a subject not receiving a selective, immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 20% compared to the intratumoral cell infiltrate population from a subject not receiving a selective, immediate-acting, short half-life CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 30% compared to the intratumoral cell infiltrate population from a subject not receiving a CDK4 / 6 inhibitor. In one embodiment, the population of regulatory T cells in the intratumoral cell infiltrate population is reduced by about 40% compared to the intratumoral cell 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0185] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to inhibit the immunosuppressive function of regulatory T cells in the population of intratumoral cell infiltrates in a subject having cancer or a tumor. In one embodiment, the Treg is CD4+CD25+Treg. In one embodiment, the proportion of intratumoral Tregs in the CD4+ T cell population is up to 10, 20, 25, 30, 35, 40 or 50% lower at least 7, 8, 9, 10 or 15 days or later after treatment compared to the case of chemotherapeutic agent / immune checkpoint inhibitor alone. In one embodiment, the immunosuppressive function of regulatory T cells is measured by the 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 the population of intratumoral immune cell infiltrates 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 10% compared to the population of intratumoral immune cell infiltrates 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 the population of intratumoral immune cell infiltrates 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 the population of intratumoral immune cell infiltrates 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 the population of intratumoral immune cell infiltrates 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 the population of intratumoral immune cell infiltrates 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0186] In one embodiment, the 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 having cancer or a tumor. In one embodiment, the percentage of tumor-specific memory T cells found in the spleen of the subject increases 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 spleen of the subject increases 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 spleen of the subject increases 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 spleen of the subject increases 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 spleen of the subject 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 blood of the subject increases by at least about 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 blood of the subject increases 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 blood of the subject increases by about 1% relative to the total T cell population. In one embodiment, the percentage of tumor-specific memory T cells found in the blood of the subject increases 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0187] In one embodiment, the CDK4 / 6 inhibitor can be used in combination with an immune checkpoint inhibitor and a chemotherapeutic agent to protect intratumoral immune cells from chemotherapy in a subject having cancer or a tumor. In one embodiment, protection of intratumoral immune cells from the toxicity of chemotherapy results in enhanced antitumor immune responses. In one embodiment, the intratumoral immune cells to be protected are selected from CD8+ T cells, CD4+ T cells, natural killer cells, monocytic myeloid-derived suppressor cells (mMDSC), and granulocytic myeloid-derived suppressor cells (gMDSC). In one embodiment, the intratumoral immune cells to be protected are CD8+ T cells. In one embodiment, the intratumoral immune cells to be protected are CD4+ T cells. In one embodiment, the intratumoral immune cells to be protected are natural killer cells. In one embodiment, the intratumoral immune cells to be protected are mMDSC. In one embodiment, the intratumoral immune cells to be protected are gMDSC. In one embodiment, the percentage of proliferation of intratumoral immune cells is at least about 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 50%, 60%, 70%, 75%, 80% or more, up to approximately 50%, 60%, 70%, 75%, 80% or more, at approximately 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 50% at approximately 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 60% at approximately 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 70% at approximately 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 75% at approximately 6 to 24 hours. In one embodiment, the proliferation of intratumoral immune cells can be inhibited by approximately 80% at approximately 6 to 24 hours. In one embodiment, the intratumoral immune cells can recover within approximately 30, 40, 45, 48, 50, or 60 hours. In one embodiment, the intratumoral immune cells recover at approximately 30 hours. In one embodiment, the intratumoral immune cells recover at approximately 40 hours. In one embodiment, the intratumoral immune cells recover at approximately 45 hours. In one embodiment, the intratumoral immune cells recover at approximately 48 hours. In one embodiment, the intratumoral immune cells recover at approximately 50 hours. In one embodiment, the intratumoral immune cells recover at approximately 60 hours.

[0188] In one embodiment, the subject has small cell lung cancer, and the CDK4 / 6 inhibitor compound I is intravenously administered over about 30 minutes on day 1 of a 21-day treatment cycle, either etoposide or carboplatin, and approximately 30 minutes prior to the administration of etoposide on days 2 and 3, where the subject is administered both etoposide and carboplatin on day 1 and etoposide on days 2 and 3 in a first-choice treatment protocol of a 21-day cycle, 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), 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 prior to the administration of topotecan, in a 21-day treatment cycle, where the subject is administered topotecan on days 1, 2, 3, 4, and 5 in a second or third alternative treatment protocol of the 21-day cycle, 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), 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 prior to the administration of topotecan, in a 21-day treatment cycle, where the subject is administered topotecan on days 1, 2, and 3 in a second or third alternative treatment protocol of the 21-day cycle, 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0191] In one embodiment, the subject has small cell lung cancer and the CDK4 / 6 inhibitor compound I is administered on an induction and maintenance dosing schedule, where compound I is administered intravenously over about 30 minutes approximately 30 minutes prior to the administration of carboplatin, etoposide, and the immune checkpoint inhibitor, and carboplatin is administered on day 1 of a 21-day induction chemotherapy drug cycle. Etoposide is administered on days 1, 2, and 3, and the 21-day cycle is repeated 1, 2, 3, 4, or 5 times, and the subject is further administered the immune checkpoint inhibitor alone during a maintenance period that begins when the induction period is completed. 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 during the maintenance period. 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 3 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, where compound I is administered intravenously over about 30 minutes approximately 30 minutes prior to the administration of topotecan and an immune checkpoint inhibitor on each of days 1, 2, 3, 4, and 5 of a 21-day induction chemotherapy drug cycle, the 21-day cycle is repeated 4 times, and the subject is further administered an immune checkpoint inhibitor alone in a maintenance period beginning when the induction period is completed. 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 during the maintenance period. 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 3 days. In one embodiment, the immune checkpoint inhibitor is administered once a week. In one embodiment, the immune checkpoint inhibitor is atezolizumab.

[0193] As contemplated herein, the CDK4 / 6 inhibitor, in combination with an immune checkpoint inhibitor, is used in several standard treatment chemotherapy treatment regimens, such as, but not limited to, small cell lung cancer treatment protocols, such as, but not limited to, 60 mg / m 2 IV of cisplatin on day 1 every 21 days for 4 cycles and 120 mg / m 2 IV of etoposide on days 1 - 3; 80 mg / m 2 IV of cisplatin on day 1 every 28 days for 4 cycles and 100 mg / m 2 IV of etoposide on days 1 - 3; 60 - 80 mg / m 2 IV of cisplatin on day 1 every 21 - 28 days and 80 - 120 mg / m 2 IV of etoposide on days 1 - 3 (maximum 4 cycles); 5 - 6 minutes of AUC of carboplatin on day 1 every 28 days * mg / mL IV and 80 - 100 mg / m 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 on days 1-3 and etoposide 80-100 mg / m 2 IV (up to 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 (up to 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 (up to 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 (up to 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 (up to 6 cycles); etoposide 50 mg / m daily for 3 weeks every 4 weeks 2 Topotecan 2.3 mg / m PO on days 1 to 5 every 21 days 2 Topotecan 1.5 mg / m PO on days 1 to 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 2Irinotecan 60 mg / m on day 1, 8, and 15 of cycle IV 2 Cisplatin 60 mg / m on day 1 every 28 days; IV 2 Irinotecan 60 mg / m on day 1, 8, and 15 of cycle IV 2 Cisplatin 30 mg / m on day 1 and 8 every 21 days; IV 2 IV or 80 mg / m on day 1 2 Irinotecan 65 mg / m on day 1 and 8 of cycle IV 2 Paclitaxel 80 mg / m weekly for 6 weeks every 8 weeks; IV 2 Paclitaxel 175 mg / m on day 1 every 3 weeks; IV 2 Etoposide 50 mg / m daily for 3 weeks every 4 weeks; IV 2 Topotecan 2.3 mg / m on days 1 - 5 every 21 days; PO 2 Topotecan 1.5 mg / m on days 1 - 5 every 21 days; PO 2 Carboplatin AUC 5 on day 1 every 28 days; IV * Irinotecan 50 mg / m on day 1, 8, and 15 of cycle IV; mg / mL IV 2 Carboplatin AUC 4 - 5 on day 1 every 21 days; IV * Irinotecan 150 - 200 mg / m on day 1; mg / mL IV 2 Cisplatin 30 mg / m on day 1, 8, and 15 of cycle IV every 28 days; IV 2 Irinotecan 60 mg / m on day 1, 8, and 15 of cycle IV 2 Cisplatin 60 mg / m on day 1 every 28 days; IV 2 Irinotecan 60 mg / m on day 1, 8, and 15 of cycle IV 2 Cisplatin 30 mg / m on day 1 and 8 every 21 days; IV 2 IV or 80 mg / m on day 1 2 Irinotecan 65 mg / m on day 1 and 8 of cycle IV 2 Paclitaxel 80 mg / m weekly for 6 weeks every 8 weeks; IV 2 Paclitaxel 175 mg / m on day 1 every 3 weeks; and IV 2It can be used in combination with IV. In another embodiment, Compound I is, but not limited to, topotecan 2.0 mg / m on days 1 to 5 every 21 days 2 PO; topotecan 1.5 - 2.3 mg / m on days 1 to 5 every 21 days 2 PO; etoposide 100 mg / m on days 1 to 3 2 Intravenous (IV) and cisplatin 50 mg / m on days 1 and 2 2 IV (treatment cycles are administered every 3 weeks up to a maximum of 6 cycles); etoposide 100 mg / m on days 1 to 3 2 Intravenous (IV) and carboplatin 300 mg / m on day 1 2 IV (treatment cycles are administered every 3 weeks up to a maximum of 6 cycles); carboplatin (300 mg / m on day 1 2 IV) and 80 mg / m on days 1 to 3 2 Increasing - dose etoposide starting with IV; carboplatin 125 mg / m administered for 3 days 2 / day and etoposide 200 mg / m 2 / day combination; etoposide 80 - 200 mg / m on days 1 to 3 2 Intravenous (IV) and carboplatin 125 - 450 mg / m on day 1 2 IV (treatment cycles are administered every 21 - 28 days); carboplatin AUC 5 - 6 min on day 1 every 28 days * mg / mL IV and etoposide 80 - 200 mg / m on days 1 to 3 2 IV (maximum 4 cycles) etc. are administered to provide chemoprotection in small - cell lung cancer therapy protocols. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD - 1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0194] In one embodiment, the CDK4 / 6 inhibitor is combined with an immune checkpoint inhibitor in several standard treatment chemotherapy regimens, such as, but not limited to, a CDK4 / 6 replication-independent head and neck cancer treatment protocol, such as, but not limited to, cisplatin 100 mg / m 2 IV or 40 - 50 mg / m 2 IV; a loading dose of cetuximab 400 mg / m 2 IV, then 250 mg / m 2 (with pretreatment of dexamethasone, diphenhydramine, and ranitidine); cisplatin 20 mg / m 2 IV on day 2 of each week up to 7 weeks and paclitaxel 30 mg / m 2 IV on day 1 of each week up to 7 weeks; cisplatin 20 mg / m 2 / day IV and 5 - FU 1000 mg / m 2 / day by continuous IV infusion on days 1 - 4 and 22 - 25; 5 - FU 800 mg / m 2 by continuous IV infusion on the day of radiotherapy and hydroxyurea 1 g PO q12h (11 doses per cycle); chemotherapy and radiotherapy administered every other week for a total of 13 weeks; carboplatin 70 mg / m 2 / day IV on days 1 - 4, 22 - 25, and 43 - 46 and 5 - FU 600 mg / m 2 / day by continuous IV infusion on days 1 - 4, 22 - 25, and 43 - 46; carboplatin AUC 1.5 IV on day 1 of each week and paclitaxel 45 mg / m 2 IV on days 1, 22, and 43 for 6 - 7 weeks; cisplatin 100 mg / m 2 IV or 40 - 50 mg / m 2 IV every week; docetaxel 75 mg / m 2 IV on day 1 and cisplatin 100 mg / m 2 IV and 5 - FU 100 mg / m2 / day, and then, 3 to 8 weeks later, during radiotherapy, carboplatin AUC 1.5 IV weekly up to 7 weeks; 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 to 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 to 4 every 3 weeks for 6 cycles 2 / day and cetuximab 400 mg / m on day 1 2 IV loading dose, then 250 mg / m weekly until disease progression 2 IV (pretreatment with dexamethasone, diphenhydramine, and ranitidine); carboplatin AUC 5 mg / mL IV on day 1 every 3 weeks for 6 cycles and 5-FU 1000 mg / m by continuous IV infusion on days 1 to 4 every 3 weeks for 6 cycles * and cetuximab 400 mg / m on day 1 2 IV loading dose, then 250 mg / m weekly until disease progression 2 IV (pretreatment 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 and docetaxel 65 mg / m on day 1 every 3 weeks 2 IV; carboplatin AUC 6 IV and paclitaxel 200 mg / m on day 1 every 3 weeks 2 IV; cisplatin 75 - 100 mg / m on day 1 every 3 to 4 weeks 2 IV and cetuximab 400 mg / m on day 1 2 IV loading dose, then 250 mg / m weekly 2 IV loading dose, then 250 mg / m weekly 2IV (pretreatment with dexamethasone, diphenhydramine, and ranitidine); cisplatin 100 mg / m on day 1 every 3 weeks 2 IV and 5-FU 1000 mg / m by continuous IV infusion on days 1 to 4 2 / day; methotrexate 40 mg / m IV every week 2 IV (3 weeks is equivalent to 1 cycle); paclitaxel 200 mg / m IV every 3 weeks 2 IV; docetaxel 75 mg / m IV every 3 weeks 2 IV; cetuximab 400 mg / m IV on day 1 2 IV loading dose, then 250 mg / m IV every week until disease progression 2 IV (pretreatment with dexamethasone, diphenhydramine, and ranitidine); cisplatin 100 mg / m IV on day 1 every 3 weeks for 6 cycles 2 IV and 5-FU 1000 mg / m by continuous IV infusion on days 1 to 4 every 3 weeks for 6 cycles 2 / day and cetuximab 400 mg / m IV on day 1 2 IV loading dose, then 250 mg / m IV every week 2 IV (pretreatment with dexamethasone, diphenhydramine, and ranitidine); carboplatin AUC 5 mg / mL IV on day 1 every 3 weeks for 6 cycles * IV and 5-FU 1000 mg / m by continuous IV infusion on days 1 to 4 every 3 weeks for 6 cycles 2 / day and cetuximab 400 mg / m IV on day 1 2 IV loading dose, then 250 mg / m IV every week 2 IV (pretreatment with dexamethasone, diphenhydramine, and ranitidine); cisplatin 75 mg / m IV on day 1 every 3 weeks 2 IV and docetaxel 75 mg / m IV on day 1 2 IV; cisplatin 75 mg / m IV on day 1 every 3 weeks 2 IV and paclitaxel 175 mg / m IV on day 1 2 IV; carboplatin AUC 6 IV on day 1 every 3 weeks and docetaxel 65 mg / m IV on day 1 2 IV; carboplatin AUC 6 IV on day 1 every 3 weeks and paclitaxel 200 mg / m IV on day 1 2IV; Cisplatin 75 - 100 mg / m² on day 1 every 3 - 4 weeks 2 IV and Cetuximab 400 mg / m² on day 1 2 IV loading dose, then 250 mg / m² weekly 2 IV (pretreatment with dexamethasone, diphenhydramine, and ranitidine); Cisplatin 100 mg / m² on day 1 every 3 weeks 2 IV and 5 - FU 1000 mg / m² by continuous IV infusion on days 1 - 4 2 / day; Methotrexate 40 mg / m² weekly 2 IV (3 weeks is equivalent to 1 cycle); Paclitaxel 200 mg / m² every 3 weeks 2 IV; Docetaxel 75 mg / m² every 3 weeks 2 IV; Cetuximab 400 mg / m² on day 1 2 IV loading dose, then 250 mg / m² weekly until disease progression 2 IV (pretreatment with dexamethasone, diphenhydramine, and ranitidine); Cisplatin 100 mg / m² on days 1, 22, and 43 every 4 weeks along with radiation therapy for 3 cycles 2 IV, then Cisplatin 80 mg / m² on day 1 2 IV and 5 - FU 1000 mg / m² by continuous IV infusion on days 1 - 4 2 / day; Cisplatin 75 mg / m² on day 1 every 3 weeks 2 IV and Docetaxel 75 mg / m² on day 1 2 IV; Cisplatin 75 mg / m² on day 1 every 3 weeks 2 IV and Paclitaxel 175 mg / m² on day 1 2 IV; Carboplatin AUC 6 IV and Docetaxel 65 mg / m² on day 1 every 3 weeks 2 IV; Carboplatin AUC 6 IV and Paclitaxel 200 mg / m² on day 1 every 3 weeks 2 IV; Cisplatin 100 mg / m² on day 1 every 3 weeks 2 IV and 5 - FU 1000 mg / m² by continuous IV infusion on days 1 - 4 2 / day; Cisplatin 50 - 70 mg / m² on day 1 every 4 weeks 2 IV and Gemcitabine 1000 mg / m² on days 1, 8, and 152 IV; On the 1st, 8th, and 15th days every 4 weeks, gemcitabine 1000 mg / m 2 IV or on the 1st and 8th days every 3 weeks, gemcitabine 1250 mg / m 2 IV; Methotrexate 40 mg / m weekly 2 IV (equivalent to 1 cycle in 3 weeks); Paclitaxel 200 mg / m every 3 weeks 2 IV; Docetaxel 75 mg / m every 3 weeks 2 IV; Cisplatin 75 mg / m on the 1st day every 3 weeks 2 IV and docetaxel 75 mg / m on the 1st day 2 IV; Cisplatin 75 mg / m on the 1st day every 3 weeks 2 IV and paclitaxel 175 mg / m on the 1st day 2 IV; Carboplatin AUC 6 IV on the 1st day and docetaxel 65 mg / m on the 1st day every 3 weeks 2 IV; Carboplatin AUC 6 IV on the 1st day and paclitaxel 200 mg / m on the 1st day every 3 weeks 2 IV; Cisplatin 100 mg / m on the 1st day every 3 weeks 2 IV and 5-FU 1000 mg / m by continuous IV infusion on the 1st to 4th days 2 / day; Cisplatin 50 - 70 mg / m on the 1st day every 4 weeks 2 IV and gemcitabine 1000 mg / m on the 1st, 8th, and 15th days 2 IV; On the 1st, 8th, and 15th days every 4 weeks, gemcitabine 1000 mg / m 2 IV or on the 1st and 8th days every 3 weeks, gemcitabine 1250 mg / m 2 IV; Methotrexate 40 mg / m weekly 2 IV (equivalent to 1 cycle in 3 weeks); Paclitaxel 200 mg / m every 3 weeks 2 IV; And docetaxel 75 mg / m every 3 weeks 2It can be used in combination with IV. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0195] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor in several standard treatment chemotherapy regimens, such as, 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, then dose-dense paclitaxel (Taxol (trademark)) 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 each, then paclitaxel (Taxol (trademark)); and Adriamycin / cyclophosphamide every two weeks for four cycles each, then paclitaxel (Taxol (trademark)). 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0196] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with several standard treatment chemotherapy treatment regimens, such as, but not limited to, CDK4 / 6 replication-independent bladder cancer treatment protocols, such as, but not limited to, postoperative 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 one dose or 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 / m2 on days 1, 8, and 15 every 28 days for a total of 4 cycles and cisplatin 70 mg / m 2 for 2 cycles; methotrexate 30 mg / m 2 IV on days 1, 15, and 22 every 28 days for a total of 3 cycles and vinblastine 3 mg / m 2 IV and doxorubicin 30 mg / m 2 IV on day 2 and cisplatin 70 mg / m 2 IV administration cycles; and the above-mentioned dose-dense regimens administered with growth factor stimulants. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0197] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor in several standard therapeutic chemotherapy treatment regimens, such as, but not limited to, the CDK4 / 6 replication-independent retinoblastoma treatment protocol, such as, but not limited to, the administration of carboplatin, vincristine, or etoposide with surgery, radiotherapy, cryotherapy, thermotherapy, or other local therapy 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0198] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor in several standard therapeutic chemotherapy treatment regimens, such as, but not limited to, the CDK4 / 6 replication-independent cervical cancer treatment protocol, such as, but not limited to, 40 mg / m of cisplatin weekly 2 IV; 50 - 75 mg / m of cisplatin on day 1 2 IV and 1000 mg / m of 5-fluorouracil (5-FU) as a continuous IV infusion on days 2 - 5 and days 30 - 33 2 ; every 3 weeks for 3 - 4 cycles, 50 - 75 mg / m of cisplatin on day 1 2 IV and 1000 mg / m of 5-FU over 24 hours on days 1 - 4 2IV infusion; every three weeks, bevacizumab 15 mg / kg IV over 30 - 90 minutes, cisplatin on day 1 or 2, and paclitaxel on day 1; every three weeks, bevacizumab and paclitaxel on day 1, and topotecan on days 1 - 3; every three weeks, paclitaxel on day 1, then cisplatin; every three weeks, topotecan on days 1 - 3, then cisplatin on day 1; and can be used in combination with the administration of paclitaxel on day 1 every three weeks. In another embodiment, the cervical cancer therapy protocol is performed in addition to radiation, surgery, or another method 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0199] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some of the standard treatment chemotherapy regimens for triple-negative breast cancer (TNBC). TNBC is defined as having no staining for estrogen receptor, progesterone receptor, and HER2 / neu. TNBC is insensitive to some of the most effective therapies available for breast cancer treatment, including HER2-directed therapies such as trastuzumab and endocrine therapies such as tamoxifen or aromatase inhibitors. Dose-dense or metronomic schedules of combination cytotoxic chemotherapy, as known to those skilled in the art, remain the standard therapy for early TNBC. Platinum agents have recently emerged as drugs of interest for the treatment of TNBC, in addition to paclitaxel and doxorubicin and cyclophosphamide chemotherapy in neoadjuvant therapy. Poly(ADP-ribose) polymerase (PARP) inhibitors, including niraparib (Tesaro), are under development as promising therapeutic agents for TNBC treatment. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

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

[0201] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for CLL and other lymphomas. Purine analogs such as fludarabine (Fludara (trademark)), pentostatin (Nipent (trademark)), and cladribine (2-CdA, Leustatin (trademark)), as well as alkylating agents including chlorambucil (Leukeran (trademark)), cyclophosphamide (Cytoxan (trademark)), and bendamustine (Treanda (trademark)) are included in the treatment of CLL. Other drugs that may be used in CLL include doxorubicin (Adriamycin (trademark)), methotrexate, oxaliplatin, vincristine (Oncovin (trademark)), etoposide (VP-16), and cytarabine (ara-C). Other drugs include rituximab (Rituxan (trademark)), obinutuzumab (Gazyva (trademark)), ofatumumab (Arzerra (trademark)), alemtuzumab (Campath (trademark)), and ibrutinib (Imbruvica (trademark)). 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0202] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard treatment chemotherapy regimens for CML. Treatments for CML include interferon, imatinib (Gleevec (trademark)), the chemotherapeutic agent hydroxyurea (Hydrea (trademark)), cytarabine (Ara-C), busulfan, cyclophosphamide (Cytoxan (trademark)), and vincristine (Oncovin (trademark)). Omacetaxine (Synribo (trademark)) is a chemotherapeutic agent approved for treating CML that is resistant to some currently used TKIs. In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0203] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some of the standard therapeutic chemotherapy regimens for CMML. CMML treatments include deferasirox (Exjade (trademark)), cytarabine and idarubicin, cytarabine and topotecan, and cytarabine and fludarabine, hydroxyurea (hydroxycarbamide, Hydrea (trademark)), azacitidine (Vidaza (trademark)) and decitabine (Dacogen (trademark)). In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0204] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard chemotherapy treatment regimens for multiple myeloma. Treatments for multiple myeloma include pomalidomide (Pomalyst™), carfilzomib (Kyprolis™), everolimus (Afinitor™), dexamethasone (Decadron™), prednisone, 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, 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.

[0205] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard chemotherapy treatment regimens for Hodgkin's disease. Treatments for Hodgkin's disease include brentuximab vedotin (Adcetris™): anti-CD-30, rituximab, doxorubicin (Adriamycin™), bleomycin, vinblastine, 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, 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.

[0206] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard treatment chemotherapy regimens for non-Hodgkin's disease. Treatments for non-Hodgkin's disease include rituximab (Rituxan (trademark)), ibritumomab (Zevalin (trademark)), tositumomab (Bexxar (trademark)), alemtuzumab (Campath (trademark)) (CD52 antigen), ofatumumab (Arzerra (trademark)), brentuximab vedotin (Adcetris (trademark)), and lenalidomide (Revlimid (trademark)). 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0207] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for diffuse large B-cell lymphoma (DLBCL). Treatments for DLBCL include CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) and the monoclonal antibody rituximab (Rituxan (trademark)). This regimen, known as R-CHOP, is typically administered for about six months. In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0208] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy treatment regimens for primary mediastinal B-cell lymphoma. Treatment of primary mediastinal B-cell lymphoma includes R-CHOP. In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0209] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for follicular lymphoma. Treatments for follicular lymphoma include rituximab (Rituxan (trademark)) in combination with chemotherapy using a single-agent chemotherapy drug (e.g., bendamustine or fludarabine) or a combination of drugs such as the CHOP or CVP (cyclophosphamide, vincristine, prednisone) regimens. Radioactive monoclonal antibodies, ibritumomab (Zevalin (trademark)) and tositumomab (Bexxar (trademark)) are also possible treatment options. For patients who cannot tolerate rituximab monotherapy, a more mild chemotherapy drug (e.g., chlorambucil or cyclophosphamide) is 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0210] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for chronic lymphocytic leukemia / small cell lymphocytic lymphoma. R-CHOP is included in the treatment of chronic lymphocytic leukemia / small cell lymphocytic lymphoma. In one embodiment, the therapy for chronic lymphocytic leukemia / small cell lymphocytic lymphoma 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0211] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for mantle cell lymphoma. Treatments for mantle cell lymphoma include fludarabine, cladribine, or pentostatin; bortezomib (trade name Velcade), lenalidomide (trade name Revlimid), and ibrutinib (trade name Imbruvica). In one embodiment, the 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 (trade name Yervoy), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (trade name Opdivo), pembrolizumab (trade name Keytruda), and pidilizumab.

[0212] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for mucosa-associated lymphoid tissue type extranodal marginal zone B-cell lymphoma (MALT). Treatments for mucosa-associated lymphoid tissue type extranodal marginal zone B-cell lymphoma (MALT) include rituximab; chlorambucil or fludarabine or combinations such as CVP often with rituximab. In one embodiment, the mucosa-associated lymphoid tissue type extranodal marginal zone B-cell lymphoma (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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0213] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard chemotherapy treatment regimens for follicular marginal zone B-cell lymphoma. Treatments for follicular marginal zone B-cell lymphoma include rituximab (Rituxan (trademark)) in combination with chemotherapy using a single-agent chemotherapy drug (e.g., bendamustine or fludarabine) or a combination of drugs such as the CHOP or CVP (cyclophosphamide, vincristine, prednisone) regimens. Also possible treatment options are the radioactively labeled monoclonal antibodies ibritumomab (Zevalin (trademark)) and tositumomab (Bexxar (trademark)). For patients who cannot tolerate the more intensive chemotherapy regimen of rituximab alone, milder chemotherapy drugs (e.g., chlorambucil or cyclophosphamide) can be used. In one embodiment, follicular 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0214] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for splenic marginal zone B-cell lymphoma. Rituximab is included in the treatment of splenic marginal zone B-cell lymphoma. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0215] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some of the standard therapeutic chemotherapy regimens for Burkitt lymphoma. Treatments for Burkitt lymphoma 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; etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone (EPOCH). In one embodiment, the 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, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some of the standard chemotherapy treatment regimens for lymphoplasmacytic lymphoma. Rituximab is included in the treatment of lymphoplasmacytic lymphoma. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0217] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for hairy cell leukemia. Treatments for hairy cell leukemia include cladribine (2-CdA) or pentostatin; rituximab; interferon-α. In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0218] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard chemotherapy treatment regimens for precursor T lymphoblastic lymphoma / leukemia. For the treatment of precursor T lymphoblastic lymphoma / leukemia, cyclophosphamide, doxorubicin (Adriamycin (trademark)), vincristine, L-asparaginase, methotrexate, prednisone, and optionally cytarabine (ara-C) are included. Due to the risk of spreading to the brain and spinal cord, chemotherapeutic drugs such as methotrexate are also administered into the cerebrospinal fluid. In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0219] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy treatment regimens for cutaneous lymphoma. For the treatment of cutaneous lymphoma, gemcitabine, liposomal doxorubicin (Doxil (trademark)); methotrexate; chlorambucil; cyclophosphamide; pentostatin; etoposide; temozolomide; pralatrexate; R-CHOP are included. 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0220] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard chemotherapy treatment regimens for angioimmunoblastic T-cell lymphoma. Treatment of angioimmunoblastic T-cell lymphoma 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0221] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy treatment regimens for extranodal natural killer / T-cell lymphoma, nasal type. Treatment of extranodal natural killer / T-cell lymphoma, nasal type, includes CHOP. In one embodiment, the treatment of extranodal natural killer / T-cell lymphoma, nasal type, 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0222] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for anaplastic large cell lymphoma. Treatments for anaplastic large cell lymphoma include CHOP; pralatrexate (Folotyn (trademark)), a targeted drug, for example, bortezomib (Velcade (trademark)) or romidepsin (Istodax), or an immunotherapy drug, for example, alemtuzumab (Campath (trademark)) and denileukin diftitox (Ontak (trademark)). In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0223] In one embodiment, the CDK4 / 6 inhibitor can be combined with an immune checkpoint inhibitor and used in combination with some standard therapeutic chemotherapy regimens for primary central nervous system (CNS) lymphoma. Treatments for primary central nervous system (CNS) lymphoma include methotrexate; rituximab. In one embodiment, the 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0224] In one embodiment, the subject has small cell lung cancer and is administered a chemotherapeutic agent selected from the group consisting of carboplatin, cisplatin, oxaliplatin, etoposide, and topotecan, or combinations 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), and pidilizumab.

[0225] In one embodiment, the chemotherapeutic agent is etoposide, the CDK4 / 6 inhibitor is a compound, 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 chemotherapeutic agent selected from the group consisting of dacarbazine, temozolomide, nab-paclitaxel, paclitaxel, cisplatin, oxaliplatin, carboplatin, vinblastine, or combinations 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), 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 chemotherapeutic agent selected from the group consisting of vinblastine, floxuridine, 5-fluorouracil, capecitabine, and gemcitabine, or combinations 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), 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 chemotherapeutic agent selected from the group consisting of carboplatin, oxaliplatin, cisplatin, fluorouracil, mitomycin, methotrexate, vinblastine, doxorubicin, gemcitabine, paclitaxel, or combinations 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), 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 chemotherapeutic 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 chemotherapeutic 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 chemotherapeutic agent is 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 chemotherapeutic agent is 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 chemotherapeutic agent is 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 chemotherapeutic 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 chemotherapeutic agent selected from the group consisting of carboplatin, cisplatin, oxaliplatin, fluorouracil, mitomycin, methotrexate, vinblastine, doxorubicin, gemcitabine, paclitaxel, or combinations 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademark)), 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 chemotherapeutic 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 chemotherapeutic 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 chemotherapeutic agent is 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 chemotherapeutic agent is 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 chemotherapeutic agent is 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 chemotherapeutic 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 chemotherapeutic agent selected from the group consisting of carboplatin, oxaliplatin, cisplatin, doxorubicin, 5-fluorouracil, paclitaxel, cyclophosphamide, gemcitabine, or combinations 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 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 (trademark)), tremelimumab, AGEN1884, and AGEN2041. In one embodiment, the immune checkpoint inhibitor is a PD-1 inhibitor selected from the group consisting of nivolumab (Opdivo (trademark)), pembrolizumab (Keytruda (trademar...

Claims

1. i) An effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor of the following structure or a pharmaceutically acceptable salt thereof: 【Chemical 1】 ii) An effective amount of carboplatin, iii) An effective amount of etoposide, and iv) An effective amount of a programmed cell death-ligand 1 (PD-L1) inhibitor A pharmaceutical composition for the treatment of a human having small cell lung cancer, comprising: wherein the CDK4 / 6 inhibitor is administered only within 24 hours before the administration of carboplatin and / or etoposide, both etoposide and carboplatin are administered on day 1 of a 21-day chemotherapy cycle, and etoposide is administered on days 2 and 3 of a 21-day chemotherapy cycle, and the CDK4 / 6 inhibitor is administered on day 1 of a 21-day chemotherapy cycle before the administration of etoposide and carboplatin, and the CDK4 / 6 inhibitor is administered on days 2 and 3 of a 21-day chemotherapy cycle before the administration of etoposide.

2. The pharmaceutical composition according to claim 1, wherein the PD-L1 inhibitor is selected from the group consisting of atezolizumab, durvalumab, and avelumab.

3. The pharmaceutical composition according to claim 1, wherein the PD-L1 inhibitor is administered on day 1 of a 21-day chemotherapy cycle.

4. The pharmaceutical composition according to claim 1, wherein the pharmaceutical composition is administered during first-line treatment for small cell lung cancer.

5. The pharmaceutical composition according to claim 3, further comprising administering an effective amount of the PD-L1 inhibitor one or more times during a maintenance period after a break in the administration of carboplatin, etoposide, and the CDK4 / 6 inhibitor.

6. The pharmaceutical composition according to claim 1, wherein the CDK4 / 6 inhibitor is administered only within 4 hours before the administration of carboplatin and / or etoposide.

7. The pharmaceutical composition according to claim 6, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide.

8. i) An effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor of the following structure or a pharmaceutically acceptable salt thereof: 【Chemical formula 2】 ii) An effective amount of carboplatin, iii) An effective amount of etoposide, and iv) An effective amount of atezolizumab, A pharmaceutical composition for the treatment of a human having small cell lung cancer, comprising: Here, the CDK4 / 6 inhibitor is administered only within 24 hours before the administration of carboplatin and / or etoposide, both etoposide and carboplatin are administered on day 1 of a 21-day chemotherapy cycle, and etoposide is administered on days 2 and 3 of a 21-day chemotherapy cycle, and a pharmaceutical composition, wherein the CDK4 / 6 inhibitor is administered on day 1 of a 21-day chemotherapy cycle before the administration of etoposide and carboplatin, and the CDK4 / 6 inhibitor is administered on days 2 and 3 of a 21-day chemotherapy cycle before the administration of etoposide. **Claim 9**: The pharmaceutical composition according to claim 8, wherein atezolizumab is administered on day 1 of a 21-day chemotherapy cycle. **Claim 10** The pharmaceutical composition according to claim 8, wherein the pharmaceutical composition is administered during first-line treatment for small cell lung cancer. **Claim 11** The pharmaceutical composition according to claim 8, further comprising administering an effective amount of atezolizumab one or more times during a maintenance period after a break in the administration of carboplatin, etoposide, and the CDK4 / 6 inhibitor. **Claim 12** The pharmaceutical composition according to claim 8, wherein the CDK4 / 6 inhibitor is administered only within 4 hours before the administration of carboplatin and / or etoposide. **Claim 13** The pharmaceutical composition according to claim 8, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide. **Claim 14** i) An effective amount of a selective CDK4 / 6 inhibitor of the following structure or a pharmaceutically acceptable salt thereof: 【Chemical Formula 3】 wherein the CDK4 / 6 inhibitor is administered on days 1, 2, and 3 of a 21-day chemotherapy cycle, ii) An effective amount of carboplatin administered on day 1 of a 21-day chemotherapy cycle, iii) An effective amount of etoposide administered on days 1, 2, and 3 of a 21-day chemotherapy cycle, and iv) An effective amount of atezolizumab A pharmaceutical composition for the treatment of a human having small cell lung cancer, comprising and administered according to a treatment plan including a 21-day chemotherapy cycle, wherein the CDK4 / 6 inhibitor is administered only on day 1 of a 21-day chemotherapy cycle within 4 hours before the administration of carboplatin and etoposide, A pharmaceutical composition, wherein the CDK4 / 6 inhibitor is administered only on days 2 and 3 of a 21-day chemotherapy cycle within 4 hours before the administration of etoposide.

15. The pharmaceutical composition according to claim 14, wherein atezolizumab is administered on day 1 of a 21-day chemotherapy drug cycle.

16. The pharmaceutical composition according to claim 14, wherein the pharmaceutical composition is administered during first-line treatment for small cell lung cancer.

17. The pharmaceutical composition according to claim 14, further comprising administering an effective amount of atezolizumab one or more times during a maintenance period after a break in the administration of carboplatin, etoposide, and a CDK4 / 6 inhibitor.

18. The pharmaceutical composition according to claim 14, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide.

19. The pharmaceutical composition according to claim 2, wherein the PD-L1 inhibitor is atezolizumab.

20. A pharmaceutical composition for the treatment of a human having small cell lung cancer, administered according to a treatment plan, wherein the treatment plan a) an induction period comprising one or more 21-day chemotherapy drug cycles, wherein the 21-day chemotherapy drug cycle i) an effective amount of a selective CDK4 / 6 inhibitor of the following structure, or a pharmaceutically acceptable salt thereof, administered on days 1, 2, and 3 of a 21-day chemotherapy drug cycle; [Chemical Formula 4] ii) an effective amount of carboplatin administered on day 1 of a 21-day chemotherapy drug cycle; iii) an effective amount of etoposide administered on days 1, 2, and 3 of a 21-day chemotherapy drug cycle; and iv) an effective amount of atezolizumab administered on day 1 of a 21-day chemotherapy drug cycle comprising, the CDK4 / 6 inhibitor is administered only on day 1 of a 21-day chemotherapy drug cycle within 4 hours before the administration of carboplatin and etoposide, the CDK4 / 6 inhibitor is administered only on days 2 and 3 of a 21-day chemotherapy drug cycle within 4 hours before the administration of etoposide, an induction period, and b) a maintenance period comprising one or more treatment cycles comprising administering an effective amount of atezolizumab, the maintenance period being administered after a break in the induction period comprising, a pharmaceutical composition.

21. The pharmaceutical composition according to claim 20, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide.

22. The pharmaceutical composition according to claim 20, wherein atezolizumab is administered every 21 days during the maintenance period.

23. A combination product for the treatment of a human having small cell lung cancer, separately comprising at least one of the following agents i) to iv): i) An agent comprising an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor of the following structure or a pharmaceutically acceptable salt thereof: [Chemical Formula 5] ii) An agent comprising an effective amount of carboplatin, iii) An agent comprising an effective amount of etoposide, and iv) An agent comprising an effective amount of a programmed cell death-ligand 1 (PD-L1) inhibitor wherein the CDK4 / 6 inhibitor is administered only within 24 hours before the administration of carboplatin and / or etoposide, both etoposide and carboplatin are administered on day 1 of a 21-day chemotherapy drug cycle, and etoposide is administered on days 2 and 3 of a 21-day chemotherapy drug cycle, and the CDK4 / 6 inhibitor is administered on day 1 of a 21-day chemotherapy drug cycle before the administration of etoposide and carboplatin, and the CDK4 / 6 inhibitor is administered on days 2 and 3 of a 21-day chemotherapy drug cycle before the administration of etoposide, a combination product.

24. The combination product according to claim 23, wherein the PD-L1 inhibitor is selected from the group consisting of atezolizumab, avelumab, and durvalumab.

25. The combination product according to claim 24, wherein the PD-L1 inhibitor is atezolizumab.

26. The combination product according to claim 23, wherein the PD-L1 inhibitor is administered on day 1 of a 21-day chemotherapy drug cycle.

27. The combination product according to claim 24, which is administered during first-line treatment for small cell lung cancer.

28. The combination product according to claim 26, further comprising administering an effective amount of a PD-L1 inhibitor one or more times during a maintenance period after the discontinuation of the administration of carboplatin, etoposide, and the CDK4 / 6 inhibitor.

29. The combination product according to claim 24, wherein the CDK4 / 6 inhibitor is administered only within 4 hours before the administration of carboplatin and / or etoposide.

30. The combination product according to claim 28, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide.

31. A combination product for the treatment of a human having small cell lung cancer, separately comprising at least one of the following agents i) to iv): i) An agent comprising an effective amount of a selective cyclin-dependent kinase 4 / 6 (CDK4 / 6) inhibitor of the following structure or a pharmaceutically acceptable salt thereof: 【Chemical Formula 6】 ii) An agent comprising an effective amount of carboplatin, iii) An agent comprising an effective amount of etoposide, and iv) An agent comprising an effective amount of atezolizumab, wherein the CDK4 / 6 inhibitor is administered only within 24 hours before the administration of carboplatin and / or etoposide, both etoposide and carboplatin are administered on day 1 of a 21-day chemotherapy cycle, and etoposide is administered on days 2 and 3 of a 21-day chemotherapy cycle, and the CDK4 / 6 inhibitor is administered on day 1 of a 21-day chemotherapy cycle before the administration of etoposide and carboplatin, and the CDK4 / 6 inhibitor is administered on days 2 and 3 of a 21-day chemotherapy cycle before the administration of etoposide, a combination product. **Claim 32**: The combination product according to claim 31, wherein carboplatin, etoposide, and atezolizumab are administered at standard therapeutic doses and schedules. **Claim 33**: The combination product according to claim 31, wherein the pharmaceutical composition is administered during first-line treatment for small cell lung cancer. **Claim 34**: The combination product according to claim 31, further comprising administering an effective amount of atezolizumab one or more times during the maintenance period after the discontinuation of the administration of carboplatin, etoposide, and the CDK4 / 6 inhibitor. **Claim 35**: The combination product according to claim 31, wherein the CDK4 / 6 inhibitor is administered only within 4 hours before the administration of carboplatin and / or etoposide. **Claim 36**: The combination product according to claim 31, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide. **Claim 37**: A combination product for the treatment of a human having small cell lung cancer, administered according to a treatment plan comprising a 21-day chemotherapy cycle, separately comprising at least one of the following agents i) - iv): i) An agent comprising an effective amount of a selective CDK4 / 6 inhibitor of the following structure or a pharmaceutically acceptable salt thereof: 【Chemical Formula 7】 wherein the CDK4 / 6 inhibitor is administered on days 1, 2, and 3 of a 21-day chemotherapy cycle, ii) An agent comprising an effective amount of carboplatin administered on day 1 of a 21-day chemotherapy cycle, iii) An agent comprising an effective amount of etoposide administered on days 1, 2, and 3 of a 21-day chemotherapy cycle on the 21st day, and iv) An agent comprising an effective amount of atezolizumab wherein the CDK4 / 6 inhibitor is administered only on day 1 of a 21-day chemotherapy cycle within 4 hours before the administration of carboplatin and etoposide, A combination product wherein the CDK4 / 6 inhibitor is administered only on days 2 and 3 of a 21-day chemotherapy cycle within 4 hours before the administration of etoposide.

38. The combination product according to claim 37, wherein atezolizumab is administered on day 1 of a 21-day chemotherapy cycle.

39. The combination product according to claim 37, which is administered during first-line treatment for small cell lung cancer.

40. The combination product according to claim 37, further comprising administering an effective amount of atezolizumab one or more times during the maintenance period after the discontinuation of the administration of carboplatin, etoposide, and the CDK4 / 6 inhibitor.

41. The combination product according to claim 37, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide.

42. A combination product for the treatment of a human having small cell lung cancer, administered according to a treatment plan, separately comprising at least one of the following agents i) to iv): wherein the treatment plan is a) An induction period comprising one or more 21-day chemotherapy cycles, wherein the 21-day chemotherapy cycle is i) An effective amount of a selective CDK4 / 6 inhibitor of the following structure or a pharmaceutically acceptable salt thereof, administered on days 1, 2, and 3 of a 21-day chemotherapy cycle; 【Chemical Formula 8】 ii) An effective amount of carboplatin administered on day 1 of a 21-day chemotherapy cycle; iii) An effective amount of etoposide administered on days 1, 2, and 3 of a 21-day chemotherapy cycle, and iv) An effective amount of atezolizumab administered on day 1 of a 21-day chemotherapy cycle comprising The CDK4 / 6 inhibitor is administered only on day 1 of a 21-day chemotherapy cycle within 4 hours before the administration of carboplatin and etoposide, An induction period wherein the CDK4 / 6 inhibitor is administered only on days 2 and 3 of a 21-day chemotherapy cycle within 4 hours before the administration of etoposide, b) a maintenance period comprising one or more treatment cycles including administration of an effective amount of atezolizumab, the maintenance period being administered after the rest of the induction period and comprising a combination product.

43. The combination product according to claim 42, wherein the CDK4 / 6 inhibitor is administered only within 30 minutes before the administration of carboplatin and / or etoposide.

44. The combination product according to claim 42, wherein atezolizumab is administered every 21 days during the maintenance period.

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