Methods and compositions for enhancing radiation therapy with dopamine receptor (DRD2)‑binding compounds

Abstract

Provided are methods and compositions for enhancing radiotherapy in various cancers by administering dopamine receptor (DRD2)‐binding phenylpiperazine derivatives such as brexpiprazole, cariprazine, pipamperone, and perospirone. In vitro studies show that combining these agents with ionizing radiation (e.g., 5 Gy) significantly reduces cancer cell survival, suppresses metastatic and stemness markers (e.g., CD44, MMP‑2, Snail, Nanog), and promotes apoptosis. Fractionated or single‐fraction radiation regimens can be paired with DRD2 antagonists to lower treatment‐resistant phenotypes, decrease the likelihood of recurrence, and potentially reduce necessary radiation dosages. The approach applies to breast, prostate, lung, pancreatic, and brain cancers, among others. Depending on tumor characteristics, additional chemotherapeutic or immunotherapeutic agents may further improve outcomes.

Description

Atty Docket: 359410.04402METHODS AND COMPOSITIONS FOR ENHANCING RADIATION THERAPY WITH DOPAMINE RECEPTOR (DRD2)-BINDING COMPOUNDS CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is an International Application of and claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 760,787, filed on February 20, 2025, the entire contents of which are herein incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure relates generally to the treatment of cancer using dopamine receptor 2 (DRD2)-binding phenylpiperazine derivatives. More particularly, it is directed to methods of augmenting radiation therapy (e.g., X-ray or y-ray) via administration of DRD2-binding compounds such as brexpiprazole, cariprazine, pipamperone, or perospirone in combination with radiotherapy, to improve therapeutic outcomes in various cancer cell types.BACKGROUND OF THE DISCLOSURE

[0003] Cancer remains a leading cause of morbidity and mortality worldwide, prompting ongoing efforts to improve therapeutic outcomes and minimize adverse effects. Radiation therapy (e.g., y-ray, X-ray, proton beam, or electron beam) is one of the most widely utilized strategies for managing various cancers, owing to its ability to directly damage tumor cell DNA and induce cell death. Nonetheless, a subset of cancer cells adapts or acquires resistance mechanisms — such as enhanced DNA repair capabilities, altered redox states, or activation of pro-survival pathways — that diminish the efficacy of standard radiation doses. In recent years, research has increasingly emphasized the roles of dopamine receptors and related signaling pathways in tumor progression and metastasis, suggesting that these receptors may contribute to the development of radiation resistance.

[0004] Although advances in targeted therapeutics have improved certain treatment outcomes, novel approaches that integrate radiation with drugs modulating dopamine receptor pathways remain underexplored. By combining radiation therapy withDRD2-binding agents or other modulators of dopaminergic signaling, the potential arises toAtty Docket: 359410.04402overcome tumor resistance mechanisms and enhance radiation-induced cell death.Consequently, leveraging these pathways may lead to more robust and durable responses in treatment-resistant or aggressive cancers.SUMMARY OF THE DISCLOSURE

[0005] The present disclosure provides methods and compositions that utilize DRD2-binding compounds (e.g., brexpiprazole, cariprazine, pipamperone, perospirone, or aripiprazole) in combination with radiation therapy to more effectively suppress cancer cell proliferation, migration, invasion, and / or metastasis. In certain embodiments, these phenylpiperazine derivatives specifically enhance the susceptibility of tumor cells to radiation-induced DNA damage by modulating dopaminergic signaling pathways that regulate survival, DNA repair, and stress responses. As a result, tumor cells subjected to ionizing radiation (e.g., X-ray or y-ray) may experience higher rates of apoptosis, senescence, or growth arrest, ultimately leading to improved tumor control.

[0006] In some embodiments, the disclosure includes pharmaceutical compositions containing one or more DRD2-binding compounds, optionally in admixture with pharmaceutically acceptable carriers or excipients (e.g., diluents, stabilizers, or buffers). These formulations may be administered via various routes — oral, intravenous, or other parenteral methods — singly or in combination with standard chemotherapy agents, immunotherapies, or targeted drugs. In further aspects, the disclosure pertains to methods of administering these compositions to subjects undergoing radiation therapy (e.g., total doses of 1-75 Gy per fraction, or as clinically indicated) to enhance overall therapeutic efficacy and potentially reduce the required radiation dosage. Such strategies can mitigate normal tissue toxicity while maintaining or improving anti-cancer outcomes.

[0007] This approach is applicable to a wide range of malignancies, including but not limited to breast cancer, prostate cancer, lung cancer, pancreatic cancer, and brain tumors (such as glioblastoma). These particular malignancies have been selected due to their relatively high dopamine receptor 2 (DRD2) expression, as described in Li et al. (Oncotarget, 2015, PMID: 26477316), Dumitru et al. (Nat Rev Clin Oncol, PMID: 31822725), Li et al. (Am J Cancer Res, 2021, PMID: 33557912), Chen et al. (Cell Death Dis, 2021, PMID: 34952904), Wang et al. (Cancer Lett, 2022, PMID: 35372029), and Zhao et al. (Front Oncol, 2023, PMID:2182235113.1Atty Docket: 359410.0440238583575), as well as in The Human Protein Atlas (https: / / www.proteinatlas.org / ENSG00000149295-DRD2 / cell+line), all of which are incorporated herein by reference in their entirety, making these cancers prime candidates for the proposed combination therapy. In certain embodiments, administering DRD2-binding agents in conjunction with fractionated or single-fraction high-dose radiation contributes to reduced tumor growth and diminished metastatic spread. Specifically, treatment may lower epithelial-to-mesenchymal transition (EMT) markers (e.g., Snail, MMP-2) and decrease the proportion of cancer stem cell (CSC) subpopulations within the tumor microenvironment. Such effects can translate to fewer recurrences, less aggressive tumor phenotypes, and enhanced long-term patient survival.

[0008] In some embodiments, a method of treating cancer in a patient in need thereof comprises administering a dopamine receptor (DRD2)-binding phenylpiperazine derivative to the patient and exposing the patient to ionizing radiation, thereby treating the cancer.

[0009] This method may provide a synergistic effect in reducing tumor cell viability or proliferation.

[0010] The DRD2-binding phenylpiperazine derivative may be selected from the group consisting of brexpiprazole, cariprazine, pipamperone, and perospirone.

[0011] The cancer may be selected from breast cancer, prostate cancer, lung cancer, pancreatic cancer, brain cancer, bone cancer, skin cancer, head and neck cancer, uterine cancer, ovarian cancer, rectal cancer, small intestinal cancer, colon cancer, gastric cancer, endometrial cancer, cervical cancer, thyroid cancer, parathyroid cancer, renal cancer, bladder cancer, hepatic cancer, or combinations thereof. In certain embodiments, the cancer is a solid tumor, including gastrointestinal cancers (e.g., pancreatic, gastric, small intestinal, colon, or rectal cancer), head and neck cancers, and ovarian cancer.

[0012] The ionizing radiation may be administered as a single fraction of about 5 Gy to about 75 Gy.

[0013] The ionizing radiation may be administered in fractionated doses of about 1-3 Gy per fraction over multiple sessions, with the phenylpiperazine derivative co-administered prior to or during each fraction.3182235113.1Atty Docket: 359410.04402

[0014] An additional anti-cancer agent may be included, selected from a chemotherapeutic agent, a targeted therapy, or an immunotherapy.

[0015] The chemotherapeutic agent may be selected from paclitaxel, doxorubicin, cisplatin, 5 -fluorouracil (5-FU), or combinations thereof.

[0016] The phenylpiperazine derivative may be administered orally or intravenously at a dosage of about 2 mg / kg to about 10 mg / kg.

[0017] In some embodiments, a method of reducing cancer metastasis in a patient comprises administering a dopamine receptor (DRD2)-binding phenylpiperazine derivative and exposing the patient to ionizing radiation, thereby reducing metastatic potential.

[0018] This method may provide a synergistic effect in decreasing metastatic spread.

[0019] The DRD2-binding phenylpiperazine derivative may be selected from brexpiprazole, cariprazine, pipamperone, and perospirone.

[0020] The cancer may be selected from breast cancer, prostate cancer, lung cancer, pancreatic cancer, brain cancer, or combinations thereof.

[0021] The ionizing radiation may be administered as a single fraction of about 5 Gy to about 10 Gy.

[0022] The ionizing radiation may be administered in fractionated doses of about 1-2 Gy per fraction over multiple sessions, with the phenylpiperazine derivative co-administered prior to or during each fraction.

[0023] An additional anti-cancer agent may be included, selected from a chemotherapeutic agent, a targeted therapy, or an immunotherapy.

[0024] The chemotherapeutic agent may be selected from paclitaxel, doxorubicin, cisplatin, 5 -fluorouracil (5-FU), or combinations thereof.

[0025] The phenylpiperazine derivative may be administered orally or intravenously at a dosage of about 2 mg / kg to about 10 mg / kg.

[0026] In some embodiments, a method of enhancing cancer cell apoptosis in a patient comprises administering a dopamine receptor (DRD2)-binding phenylpiperazine derivative4182235113.1Atty Docket: 359410.04402to cancer cells in the patient and exposing the cancer cells to ionizing radiation, thereby enhancing cancer cell apoptosis.

[0027] This method may provide a synergistic effect that increases apoptotic cell populations relative to radiation alone.BRIEF DESCRIPTION OF DRAWINGS

[0028] FIG. 1 illustrates bar graph data showing the surviving cell populations of various cancer cell lines (MDA-MB-231, DU145, T98G, U87, PANC-1, A549) treated with brexpiprazole or cariprazine in combination with 5 Gy radiation. The graphs highlight the synergistic reduction in viability compared to radiation alone or drug alone.

[0029] FIG. 2 shows representative fluorescence microscopy images (Calcein AM / PI staining) for PANC-1 (pancreatic), A549 (lung), MDA-MB-231 (breast), and DU145 (prostate) cells, illustrating enhanced cell death when DRD2-binding compounds are co-administered with 5 Gy radiation.

[0030] FIG. 3 depicts representative transwell invasion assays in MDA-MB-231 and DU145 cells and corresponding changes in gene / protein expression (e.g., MMP-2, Snail, CD44, DRD2, TGFP-RII, Nanog), together indicating that co-administration of DRD2-binding compounds with 5 Gy radiation reduces tumor invasiveness and pro-metastatic marker levels.

[0031] FIG. 4 depicts qPCR data in MCF-7 breast cancer cells, showing reduced Nanog, Snail, MMP-2, MMP-9, Oct3 / 4, and Sox2 expression when brexpiprazole or cariprazine is combined with 5 Gy radiation.

[0032] FIG. 5 shows qPCR analysis in MDA-MB-231 and DU145 cancer cells, indicating a significant decrease in MMP-2, Snail, and CD44 upon co-treatment with DRD2-binding compounds plus 5 Gy radiation.

[0033] FIG. 6 presents Western blot data in MDA-MB-231 and DU145 cells, demonstrating lowered DRD2, TGFP-RII, CD44, MMP-2, Snail, and Nanog protein levels following co-treatment with brexpiprazole or cariprazine and 5 Gy radiation.182235113.1Atty Docket: 359410.04402

[0034] The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS

[0035] The following disclosure is presented to enable any person skilled in the art to make and use the disclosure. Various modifications to the embodiments described will be readily apparent, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. The present disclosure is intended to be illustrative and not restrictive.

[0036] Briefly summarized, the disclosure provides methods and compositions for enhancing the treatment of cancer by utilizing dopamine receptor (DRD2)-binding compounds in conjunction with radiation therapy. The following Detailed Description offers various embodiments and examples intended to demonstrate the disclosure’s scope and utility, without limiting the disclosure to any specific configuration or concentration range.

[0037] Unless otherwise noted, the following terms shall be understood as follows:

[0038] The term “patient” or “subject” herein refers to any mammal (e.g., human, canine, feline, rodent) in need of treatment for a disease or condition related to aberrant cell proliferation, including but not limited to cancer.

[0039] The term “DRD2-binding compounds” herein refers to phenylpiperazine derivatives (e.g., brexpiprazole, cariprazine, pipamperone, perospirone, aripiprazole) that exhibit measurable affinity for dopamine D2 receptors.

[0040] The term “therapeutically effective amount” herein refers to an amount sufficient to yield a desired clinical or biological response, such as tumor growth inhibition, reduction in metastasis, or enhanced radiotherapy responsiveness.

[0041] The term “radiation therapy” herein includes ionizing radiation treatments (e.g., X-ray, y-ray, proton therapy) delivered at dosages optimized for anti-tumor efficacy, typically on a fractionated or single-fraction basis as determined by clinical protocols.6182235113.1Atty Docket: 359410.04402

[0042] The term “pharmaceutically acceptable carrier or excipient” herein refers toa substance suitable for the formulation, stabilization, and administration of active agents (e.g., buffers, diluents, or other inert ingredients) without causing undue adverse effects in the subject.

[0043] The term “chemotherapeutic agent” herein refers to a compound or formulation that is conventionally recognized as having anti-cancer efficacy, including but not limited to alkylating agents, antimetabolites, anthracyclines, taxanes, platinum-based drugs, topoisomerase inhibitors, and other cytotoxic or cytostatic agents.

[0044] The term “synergistic effect” herein refers to an effect achieved by the combined administration of two or more therapeutic modalities (e.g., DRD2-binding compounds and radiation) that is greater than the sum of the effects observed when each modality is administered separately under comparable conditions.

[0045] The term “biomarker-driven selection” herein refers to a treatment strategy wherein patients or subjects are identified as likely responders based on the presence or level of one or more specific biological markers (e.g., DRD2, TGFP-RII, Nanog, etc.), enabling personalized or precision medicine approaches.

[0046] The term “maintenance dose” herein refers to a dose of a therapeutic agent administered after the primary treatment course has ended, for the purpose of sustaining therapeutic benefit, preventing tumor regrowth, or inhibiting metastatic progression.

[0047] In the present disclosure, DRD2-binding compounds refers to phenylpiperazine derivatives such as brexpiprazole, cariprazine, pipamperone, perospirone, and aripiprazole, which exhibit measurable affinity for dopamine D2 receptors. A therapeutically effective amount indicates an amount sufficient to produce a desired clinical or biological effect, including but not limited to tumor size reduction, inhibition of tumor growth, or enhanced radiation-induced cancer cell death. Radiation therapy encompasses ionizing radiation treatments such as X-ray, y-ray, or proton therapy administered at doses optimized for anti-tumor efficacy.

[0048] A representative pharmaceutical composition contains at least one DRD2-binding phenylpiperazine derivative, for example brexpiprazole or cariprazine, in combination with a pharmaceutically acceptable carrier or excipient. Such formulations may optionally include additional anti-cancer agents or radio-sensitizing chemicals and can be provided as oral 7182235113.1Atty Docket: 359410.04402tablets, capsules, injectable solutions, or suspensions. In certain embodiments, the DRD2-binding compound is administered before, during, and / or after a fractionated course of radiation therapy, with in vitro concentrations ranging from about 1 pM to 50 pM or corresponding clinical doses in mg / kg body weight. Target cancers include, but are not limited to, breast tumors (e.g., MDA-MB-231, MCF-7), prostate cancer (DU145), lung cancer (A549), pancreatic cancer (PANC-1), and brain cancer (glioblastoma cell lines such as T98G and U87). The underlying mechanism is believed to involve the downregulation of pathways associated with epithelial-to-mesenchymal transition (EMT) and cancer sternness, including SNAIL, NANOG, OCT3 / 4, SOX2, MMP-2, MMP-9, and CD44. Thisco-administration can block or counteract radiation-induced prosurvival signals and enhance tumor cell kill.Example 1 (In Vitro Radiation Sensitization in Breast and Prostate Cancer Cells)

[0049] Various cancer cell lines reported to have elevated DRD2 expression — MDA-MB-231 (breast), DU145 (prostate), T98G (glioblastoma), U87 (brain tumor), PANC-1 (pancreatic), and A549 (lung) — were utilized to investigate the anti-cancer effects of brexpiprazole or cariprazine in combination with ionizing radiation. Each cell line was seeded into 6-well plates (SPL, Cat. No. 030006) at a density of approximately 1-2 x io5cells / well in 2 mL of the appropriate growth media. MDA-MB-231 and PANC-1 cells were maintained in DMEM (Welgene, Cat. No.LM011-51), DU145 in RPMI (LM011-01), T98G and U87 in DMEM (LM001-05), and A549 in HAM’s F12-K (LM010-52). In all cases, FBS (Gibco, Cat.No. 26140079) was added at a suitable concentration (e.g., 10%), and the cultures were incubated at 37 °C in a humidified atmosphere containing 5% CO2 for about 24 hours to allow cell attachment and stabilization.

[0050] After this initial incubation, either brexpiprazole or cariprazine was added to each well in 2 mL of fresh medium at the concentrations specified in the table:• MDA-MB-231 : 5 pM (both brexpiprazole and cariprazine), 48 hours total exposure • DU145: 5 pM (both), 48 hours• T98G: 10 pM brexpiprazole or 20 pM cariprazine, 72 hours• U87: 10 pM brexpiprazole or 20 pM cariprazine, 72 hours8182235113.1Atty Docket: 359410.04402• PANC-1 : 5 pM brexpiprazole or 10 pM cariprazine, 72 hours• A549: 5 pM brexpiprazole or 10 pM cariprazine, 72 hours

[0051] Within 2 hours after adding the drug, each culture was irradiated with a single dose of 5 Gy y-rays using a BioBeam 8000 irradiator (Gamma-Service Medical GmbH). Control wells (i.e., no drug) were included for each cell line, with or without the same 5 Gy radiation dose. Plates were then returned to the incubator for the remainder of each experiment’s specified time (e.g., 48 or 72 hours), taking into account the approximate doubling times of the respective cell lines.

[0052] At the end of each experiment, cells were harvested to quantify remaining viable populations. First, the culture media were collected in 15 mL conical tubes, and adherent cells were briefly rinsed with DPBS (Welgene, Cat. No. LB001-01). Cells were detached using Trypsin-EDTA (Thermo or Welgene brand, per lab protocols) so that any loosely adherent or floating cells could be combined with the previously collected media. The cell suspension was centrifuged at approximately 300 * g for 2 minutes, and the supernatant was discarded. The pellet was gently resuspended in fresh medium or DPBS for viability assessment. A 0.4% Trypan blue solution (Invitrogen, Cat. No. 15250061) was then added at a suitable ratio, and 10 pL of this mixture was loaded onto a cell counting chip (used with an Invitrogen Countess 3 automated cell counter) to measure total and viable cell numbers.

[0053] As shown in FIG. 1, bar graphs derived from these cell counts depict the surviving cell populations under each condition:• 0 Gy Control vs. 0 Gy + Drug (no radiation)• 5 Gy Control vs. 5 Gy + Brexpiprazole• 5 Gy Control vs. 5 Gy + Cariprazine

[0054] In general, unirradiated (0 Gy) cells grew robustly, with or without drug, showing only minimal reductions in cell number in the drug-treated groups. By contrast, 5 Gy alone reduced cell counts relative to unirradiated control wells across all tested lines. However, the 5 Gy + Brexpiprazole or 5 Gy + Cariprazine groups frequently exhibited an even more pronounced decline in cell numbers, indicating a synergistic or at least additive effect. For example, MDA-MB-231 (breast) and DU145 (prostate) cells showed a roughly 20-40% further drop in viability under combination therapy compared to 5 Gy alone, whereas T98G and U87 (both brain tumor lines) likewise demonstrated a marked increase in radiation9182235113.1Atty Docket: 359410.04402sensitivity. PANC-1 (pancreatic) and A549 (lung) cells displayed a similar pattern, underscoring the applicability of DRD2-binding phenylpiperazine derivatives as radiosensitizers across a variety of solid tumor types.

[0055] Further analyses, including transwell invasion assays (not shown in these particular bar graphs) and qPCR of genes such as MMP-2, Snail, and CD44, revealed that co-treatment with brexpiprazole or cariprazine plus 5 Gy downregulated key mediators of invasiveness and metastasis. This suggests that these agents, beyond reducing overall cell survival, may also suppress tumor aggressiveness or metastatic potential. Mechanistically, partial disruption of dopaminergic signaling may impair prosurvival and proinvasive pathways, including those involved in epithelial-to-mesenchymal transition (EMT).

[0056] Certain embodiments involve customizing the concentrations of brexpiprazole or cariprazine — ranging, for instance, from 5 pM to 20 pM — based on the specific doubling times and drug sensitivities of different tumor lines. Another approach is fractionated radiotherapy, in which 1-2 Gy fractions are administered over multiple sessions, each accompanied by DRD2-binding drugs, to progressively inhibit tumor growth while potentially minimizing normal tissue toxicity. A further embodiment contemplates combination therapies by incorporating chemotherapeutic agents (e.g., paclitaxel or doxorubicin) or immunotherapies (e.g., checkpoint inhibitors) alongside DRD2-binding compounds and radiation, thereby targeting multiple cancer survival pathways concurrently. In addition, timing variations may be explored, such as administering DRD2-binding compounds several hours prior to irradiation to enhance radiosensitivity, or extending drug treatment post-radiation to prevent recovery and re-population of resistant tumor cells.

[0057] Taken together, these integrated procedures and bar-graph data show that brexpiprazole and cariprazine, when used at concentrations aligned with each cell line’s growth characteristics, markedly enhance the effect of a 5 Gy radiation dose across multiple cancer models. This synergistic activity is reflected in reduced cell survival and diminished invasiveness, highlighting the promise of DRD2-binding phenylpiperazine derivatives as potent adjuncts to radiation therapy in diverse oncological contexts.Example 2 (Live / Dead Staining for PANC-1 and A549 Cells)10182235113.1Atty Docket: 359410.04402

[0058] In this study, four cancer cell lines — PANC-1 (pancreatic), A549 (lung),MDA-MB-231 (breast), and DU145 (prostate) — were evaluated to determine whether DRD2-binding compounds (brexpiprazole, cariprazine) in combination with ionizing radiation induce cell death without causing nonspecific cytotoxicity. Each cell line was seeded in 6-well plates (1-2 * 105cells / well) with 2 mL of the appropriate phenol red-free medium (Welgene). For PANC-1 and A549, brexpiprazole was used at 10 pM and cariprazine at 15 pM, each over a 72-hour incubation; for MDA-MB-231 and DU145, brexpiprazole at 7.5 pM and cariprazine at 10 pM were tested over a 48-hour incubation. After a 24-hour preincubation to let cells attach and stabilize, the respective test compound was added to each well. Within 2 hours of drug addition, cells were irradiated with 5 Gy of y-rays (or X-rays), and culture was continued for the remaining incubation period (48 hours forMDA-MB-231 / DU145, 72 hours for PANC-1 / A549).

[0059] To confirm that growth inhibition was not merely due to nonspecific toxicity, Calcein AM (Invitrogen, Cat. No. C1430) and propidium iodide (PI; Invitrogen, Cat. No. P3566) were applied according to the following procedure: (1) spent media were gently removed from each well, and the monolayer was briefly rinsed with DPBS to eliminate debris; (2) 20 pL of Calcein AM solution (1 mM stock) plus 30 pL of 1 pg / mL PI were mixed in 1-2 mL of fresh media or DPBS, then vortexed lightly; (3) this staining solution was added back to each well and incubated at 37 °C for 30-60 minutes; (4) afterwards, the staining medium was removed, wells were rinsed with DPBS, and 1 mL of 1 % FBS media was replenished to prevent cell dehydration. Cells were then observed under a NEXCOPE NIB900-FL fluorescent microscope at magnifications up to xlOO, capturing green fluorescence (Calcein AM) indicative of live cells and red fluorescence (PI) indicative of dead ormembrane-compromised cells.

[0060] FIG. 2 shows representative images of PANC-1 and A549, illustrating the following trends. Under control (0 Gy) conditions, cells displayed robust green fluorescence with almost no red staining, indicating minimal cytotoxicity. The addition of 5 Gy radiation alone produced a slight reduction in green signal and a modest rise in Pi-positive (red) cells, consistent with moderate radiation-induced cell death. However, when 5 Gy was combined with brexpiprazole or cariprazine at the specified concentrations, the fraction of red-stained cells rose substantially, and green fluorescence diminished more dramatically. While a mild increase in apoptosis was observed — evidenced by some cells appearing rounded or11182235113.1Atty Docket: 359410.04402fragmented — the principal anticancer effect was predominantly due to growth inhibition rather than robust cytotoxicity.

[0061] Quantitative analysis further confirmed that the co-treatment groups (radiation plus DRD2-binding agents) exhibited greater cell death than either radiation alone or drug alone, thus demonstrating radiosensitizing properties of brexpiprazole and cariprazine. Parallel tests in MDA-MB-231 and DU145 showed a similar pattern, including reduced invasiveness and downregulated metastatic markers (e.g., MMP-2, Snail, CD44) upon combination therapy. These outcomes suggest that brexpiprazole and cariprazine not only potentiate radiation-induced killing but may also suppress pathways related to epithelial-to-mesenchymal transition (EMT) and metastasis.

[0062] In certain embodiments, the drug concentration can be adjusted — for example, from 5 pM to 15 or 20 pM — based on cell line-specific doubling times and radiosensitivity. In certain embodiments, fractionated radiotherapy (1-2 Gy / fraction) can be adopted, each fraction paired with DRD2-binding agents, to steadily impede tumor progression while controlling toxicity to normal tissue. Yet another embodiment involves co-administration of these agents with established chemotherapeutics or immunomodulators, potentially harnessing multiple anticancer pathways simultaneously. Additionally, timing can be varied — administering the compounds hours before irradiation or continuing treatment postradiation — to sustain pro-apoptotic signaling and prevent surviving tumor cells from recovering.

[0063] In conclusion, the Calcein AM / PI live / dead assay images — along with the complementary data from other tumor cell lines and gene expression analyses — strongly indicate that brexpiprazole and cariprazine, at carefully selected doses, can serve as effective radiosensitizers against a range of malignancies including pancreatic, lung, breast, and prostate cancers. By targeting dopaminergic pathways that influence cell survival and invasive behavior, these DRD2-binding phenylpiperazine derivatives offer a promising avenue for enhancing radiotherapy efficacy and potentially improving clinical outcomes in patients with diverse solid tumors.Example 3 (Transwell Invasion and DRD2 Pathway Analysis in MDA-MB-231 and DU145)12182235113.1Atty Docket: 359410.04402

[0064] Cell Lines, Drug Treatment and Radiation

[0065] MDA-MB-231 (breast) and DU145 (prostate) cells — both known for high DRD2 expression — were selected to investigate how brexpiprazole or cariprazine, in combination with ionizing radiation, impacts tumor cell invasion. Each cell line was plated at about 2 x 105cells per 60 mm dish in 2 mL of suitable growth medium (e.g., DMEM for MDA-MB-231 or RPMI for DU145), then incubated for 24 hours at 37 °C / 5 % CO2 to allow attachment. Cells from a 60 mm dish were detached and then seeded into Transwell inserts. The lower chamber was filled with medium containing 5 pM brexpiprazole or 5 pM cariprazine. After allowing a two-hour stabilization period, the samples were subjected to y-irradiation, and the cells were subsequently incubated under standard culture conditions, r Subsequently, brexpiprazole (5 pM) or cariprazine (5 pM) was added to the culture. Within 2 hours of adding the drug, cells were irradiated with 5 Gy of X rays (or y rays). A control set treated with DMSO (vehicle only) and single-treatment sets (drug only or 5 Gy only) were included. After a 2d hour incubation post radiation, cells were prepared for transwell invasion assays and protein analyses, as detailed below.

[0066] Matrigel Coating and Transwell Invasion Assay

[0067] To evaluate cell invasion under these treatment conditions, 24-well transwell inserts (Corning, Cat. No. 3422) were coated with Matrigel Matrix (Coming, Cat. No. 354230) at 1 / 10 dilution in serum-free media and kept at 4 °C to solidify. Approximately 25 pL of this chilled Matrigel solution was spread evenly on the transwell membrane. Meanwhile, MDA-MB-231 or DU145 cells were trypsinized (Trypsin-EDTA), pelleted by gentle centrifugation, and resuspended in 1 mL of serum-free medium to achieve a final density of about 2 x 104cells per insert. T The lower chamber of each well was filled with 750 pL of medium containing 5% FBS as a chemoattractant. After seeding cells in the transwell inserts, the drug was added to the lower chamber. Following a 2-hour incubation, cells were irradiated and then maintained at 37 °C for an additional 24 hours. Following the invasion assay, the Matrigel-coated membrane was fixed, stained (e.g., with H&E or crystal violet), and gently wiped with a cotton swab to remove non-invaded cells on the top surface. The membrane was then allowed to dry before being examined under a microscope.

[0068] Microscopic Observations and Quantification of Invasion13182235113.1Atty Docket: 359410.04402

[0069] FIG. 3 shows representative micrographs of MDA-MB-231 and DU145 transwell filters. Under control (0 Gy) conditions, both cell lines exhibit substantial invasion through the Matrigel, reflected by numerous purple-stained cells on the underside of the insert. When irradiated with 5 Gy alone, the number of invading cells is modestly reduced compared to unirradiated controls. However, in the presence of brexpiprazole (5 pM) or cariprazine (5 pM) plus 5 Gy, the invaded cell population is significantly lower, with many fewer stained cells visible. Bar graphs quantifying invasion as a percentage of control (set to 100 %) confirm that radiation + DRD2-binding compound achieves the greatest reduction, typically cutting invasion by 50-70 % relative to control. This underscores the enhanced anti-invasive effect of brexpiprazole or cariprazine when combined with ionizing radiation.

[0070] Western Blot Analysis of DRD2 Pathway and Metastasis Markers

[0071] To examine the underlying molecular mechanisms, whole-cell lysates from identically treated MDA-MB-231 samples were subjected to SDS-PAGE, followed by immunoblotting against DRD2, TGFP-RII, CD44, MMP-2, Snail, Nanog, and GAPDH (loading control). The resulting blots revealed a partial suppression of DRD2, along with a substantial reduction in the levels of key metastasis- and sternness-associated proteins (TGFP-RII, CD44, MMP-2, Snail, Nanog) in the combination groups compared to either the single-agent or radiation-only controls. Notably, a similar decrease in these metastasis- andsternness-associated proteins was also observed in DU-145 cells. This pattern suggests that blocking dopaminergic signaling, in tandem with radiation-induced stress, diminishes not only invasion but also multiple aspects of cancer stem cell biology and EMT-driven metastatic capacity.

[0072] In certain embodiments, dosing can be optimized by administering higher or lower concentrations of DRD2-binding drugs (e.g., 2-10 pM) depending on the tumor type and patient tolerance. In other embodiments, fractionated radiation may be employed, for example by combining daily or weekly low-dose fractions of 1-2 Gy with repeated doses of DRD2-binding compounds to gradually diminish tumor aggressiveness. In still other embodiments, triple-combination approaches are considered, such as adding metalloproteinase blockers or immunotherapeutic agents (e.g., checkpoint inhibitors) to further restrict metastatic and invasive pathways. Finally, in additional embodiments, temporal variations in treatment may be explored, for instance by administering14182235113.1Atty Docket: 359410.04402DRD2-binding agents before radiation to prime tumor cells for damage, or continuing therapy post-radiation to prevent the recovery of residual, stem-like cells.

[0073] Hence, brexpiprazole and cariprazine appear to block crucial signaling nodes involved in both tumor cell survival and invasion, especially when combined with ionizing radiation. By attenuating DRD2 signaling and thereby influencing downstream effectors (e.g., TGFP-RII, MMP-2, Snail, CD44, Nanog), these phenylpiperazine derivatives have the potential to reinforce radiotherapy outcomes, reducing metastatic risk and perhaps improving overall prognosis in breast and prostate cancers.Example 4 (qPCR Analysis in MCF-7)

[0074] qPCR Analysis in MCF-7 (Breast Cancer) Cells

[0075] In a complementary set of in vitro experiments, MCF-7 breast cancer cells — also featuring elevated DRD2 expression — were employed to dissect the molecular mechanisms by which brexpiprazole or cariprazine, in conjunction with radiation, curtail invasive and stem cell-like properties. Cells were seeded in 6-well plates (2 x io5cells / well in 2 mL DMEM containing 10 % FBS, penicillin [100 U / mL], and streptomycin [100 pg / mL]) and incubated at 37 °C with 5 % CO2. After 24 hours, the culture medium was replaced with fresh DMEM containing either brexpiprazole (5 pM) or cariprazine (5 pM). Within 2 hours of drug addition, the cells received 5 Gy of y-ray(or X-ray) irradiation, and incubation continued for a total of 48 hours post-irradiation.

[0076] Total RNA was then isolated using an mRNA extract kit (Qiagen, Cat. No. 74104), and its concentration / purity was measured on a Thermo NANOdrop spectrophotometer (ONEUV-VIS). First-strand cDNA was synthesized using a Bio-Rad cDNA synthesis kit (Cat. No. 1708891), followed by qPCR with a Promega qPCR Master mix (Cat. No. A6002) on a Bio-Rad T100 Thermal Cycler or Invitrogen QuantStudio 5 system. The resulting cDNA samples were subjected to SYBR Green-based real-time PCR targeting Nanog, Snail, Oct3 / 4, Sox2, MMP-2, and MMP-9, with GAPDH as an internal housekeeping gene.

[0077] FIG. 4 shows the relative mRNA expression levels for these genes in MCF-7 cells under different treatment conditions: control (0 Gy), 0 Gy + drug, 5 Gy alone, and 5 Gy + drug (brexpiprazole or cariprazine). Notably, 5 Gy alone significantly decreased some targets 15182235113.1Atty Docket: 359410.04402(e.g., MMP-2), but the 5 Gy + DRD2-binding compound groups exhibited an even more pronounced downregulation of these sternness (Nanog, Oct3 / 4, Sox2) and invasion / metastasis (Snail, MMP-2, MMP-9) markers. This result underscores a synergistic effect in suppressing aggressive tumor phenotypes, consistent with the observations in the MDA-MB-231 cell line.

[0078] Taken together, these in vitro findings indicate that brexpiprazole or cariprazine can enhance the anti-tumor efficacy of radiation both by reducing tumor volume in anMDA-MB-231 cells and by attenuating key molecular drivers of metastasis and sternness (e.g., Nanog, Snail, MMP-2, MMP-9, Oct3 / 4, Sox2) in MCF-7 cells. This dual approach — simultaneously lowering tumor growth and inhibiting invasive or stem-like properties — suggests that DRD2-binding phenylpiperazine derivatives may provide a comprehensive therapeutic advantage when combined with standard radiotherapy.

[0079] In certain embodiments, expanded dose ranges can be explored, for example by adjusting drug levels (e.g., 2-10 mg / kg in vivo or 1-15 pM in vitro) and altering the radiation dose / frequency to optimize anti-tumor synergy. In other embodiments, extended treatment cycles can be adopted by prolonging the number of weekly drug / radiation sessions or administering a maintenance dose of DRD2 inhibitors post-radiation to avert tumor recurrence. In still other embodiments, combination with other agents may be used, incorporating chemotherapeutics or targeted immunotherapies (e.g., anti-PD-l / PD-Ll checkpoint inhibitors) alongside DRD2 antagonists to mount a multi-pronged attack on tumors. Additionally, biomarker-driven selection can be implemented by stratifying patients based on DRD2 expression or elevated stemness / metastasis markers, thereby identifying those most likely to benefit from DRD2 blockade in conjunction with radiation.

[0080] Overall, these data furnish a robust rationale for DRD2-targeting phenylpiperazine derivatives as potent radiosensitizers, capable of curbing both tumor growth and aggressiveness in breast cancer models. Given the broad relevance of EMT / stemness pathways in other malignancies, such strategies may extend beyond breast cancer, offering improved therapeutic outcomes and potentially reducing metastatic risk in a wide array of solid tumors.Example 5 (Dose Escalation Study and qPCR Analyses in MDA-MB-231 and DU145)

[0081] Dose Escalation with Fractionated Radiation in MDA-MB-23116182235113.1Atty Docket: 359410.04402

[0082] A dose escalation protocol was conducted in vitro using MDA-MB-231 breast cancer cells to investigate the combined effects of brexpiprazole and fractionated radiation. Cells were seeded into 6-well plates at approximately 2 * 105cells / well, cultured for 24 hours in DMEM supplemented with 10 % fetal bovine serum (FBS) and 1 % penicillin-streptomycin, then exposed to varying concentrations of brexpiprazole (2.5, 5, 10, or 15 pM). Within 2 hours of drug addition, a single radiation dose of 5 Gy was administered. However, it will be understood by those skilled in the art that the total radiation dose (e.g., from about 1 Gy to about 10 Gy) and the fractionation schedule (single or multiple fractions) may be varied as needed based on experimental or clinical considerations. Throughout this protocol, the medium containing the designated brexpiprazole concentration was replenished daily to maintain a consistent drug environment.

[0083] qPCR Analyses in MDA-MB-231 and DU145

[0084] In parallel experiments, MDA-MB-231 (breast) and DU145 (prostate) cells were subjected to 5 Gy radiation combined with either brexpiprazole (7.5 or 10 pM) or cariprazine (10 or 15 pM), each for a total exposure time of 48 hours. After treatment, total RNA was isolated (e.g., via Qiagen kits) and 1 pg of purified RNA was reverse-transcribed into cDNA (Bio-Rad kit). qPCR was then carried out (e.g., with SYBR Green mix from Promega) to quantify MMP-2, Snail, and CD44 mRNA levels, with GAPDH as an internal reference.

[0085] FIG. 5 presents the relative mRNA expression profiles for MMP-2, Snail, and CD44 in MDA-MB-231 and DU145 under the following conditions:• Control (0 Gy): Baseline expression of each marker.• Radiation only (5 Gy): Moderate reduction in MMP-2, Snail, and CD44 relative to control.• Drug only (brexpiprazole or cariprazine): Minor to moderate decreases in some markers, depending on dose.

[0086] Combination (5 Gy + DRD2-binding compound): Marked downregulation of MMP-2, Snail, and CD44 at higher drug concentrations (e.g., 10 pM brexpiprazole or 15 pM cariprazine), highlighting a dose-dependent synergy between DRD2 blockade and radiation.

[0087] Statistically, the largest reductions in invasion / metastasis (as inferred from MMP-2, Snail) and sternness or tumor aggressiveness (as inferred from CD44) were apparent in cells receiving 5 Gy plus the higher DRD2-binding doses. These results closely align with the17182235113.1Atty Docket: 359410.04402clonogenic data from the fractionated radiation study in MDA-MB-231, reinforcing the concept that elevated concentrations of brexpiprazole or cariprazine can amplify the cytotoxic and anti-metastatic effects of radiation.

[0088] Overall, the dose escalation study confirms that brexpiprazole potentiates fractionated radiation in a concentration-dependent manner, and the qPCR results in MDA-MB-231 and DU145 demonstrate synergistic suppression of key metastatic and sternness markers (MMP-2, Snail, CD44). Taken together, these findings suggest that DRD2-binding phenylpiperazine derivatives can be optimized to achieve maximum radiosensitizing benefits with minimal off-target toxicity.

[0089] In certain embodiments, dynamic dose adjustments can be implemented, for example by gradually increasing DRD2 -binding compound concentrations over multiple radiation fractions to match evolving tumor sensitivity. In other embodiments, combination with immunotherapy can be employed, such as introducing immune checkpoint blockers (e.g., anti-PD-Ll) at later fractions of radiation once DRD2 antagonism has weakened tumor defenses. In further embodiments, extended observation can be adopted to continue monitoring clonogenic survival and gene expression changes beyond the initial fractionation cycle, thereby assessing long-term adaptive responses. Additionally, alternate dosing schedules can be explored, for instance administering higher drug concentrations intermittently (e.g., every other day) rather than continuously, to allow normal tissue recovery while maintaining tumor suppression.

[0090] Hence, the dose-dependent synergy between DRD2-binding agents and radiation provides a promising avenue for refining treatment regimens in breast and prostate cancers, with the potential for broader application to other DRD2-positive malignancies.Example 6 (Combined Therapy with DRD2-Binding Compounds and Chemotherapeutics)

[0091] Synergy with Standard Chemotherapy in MCF-7

[0092] To investigate potential synergy with conventional chemotherapeutic agents, MCF-7 breast cancer cells were treated with either paclitaxel (10 nM) or doxorubicin (0.5 pM) in combination with 5 Gy radiation, in the presence or absence of brexpiprazole (5 pM). Cells 18182235113.1Atty Docket: 359410.04402were seeded in 6-well plates at 2* IO5cells / well, grown for 24 hours in DMEM supplemented with 10 % FBS and 1 % penicillin-streptomycin, and then incubated with the chosen chemotherapy drug. Within 1-2 hours of chemotherapy addition, they received a single 5 Gy dose of X-ray (or y-ray), and subsequently, brexpiprazole (5 pM) was introduced to the appropriate combination group.

[0093] After 48 hours, AlamarBlue viability assays revealed that adding brexpiprazole to the chemo-radiation regimen improved cell killing by an additional 20-30 % compared to chemotherapy plus radiation alone. qPCR of EMT (Snail, Zebl) and sternness (Nanog, Sox2) markers showed further downregulation in the triple-combination group, underscoring a multimodal synergy wherein dopaminergic pathway blockade, standard chemotherapy, and ionizing radiation collectively hindered tumor cell survival and aggressiveness.

[0094] Western Blot Analysis in MDA-MB-231 and DU-145 (DRD2 and Related Proteins)

[0095] In parallel experiments, MDA-MB-231 breast cancer cells (10 % FBS, 1 % antibiotics in DMEM) and DU-145 prostate cancer cells(10 % FBS, 1 % antibiotics in RPMI), were plated in 6-well plates (~1 * 105' 2* 105cells / well, 2 mL medium each) and incubated at 37 °C / 5 % CO2 for 24 hours. At that point, for MDA-MB-231 cells, brexpiprazole (7.5 pM) or cariprazine (10 pM) was added to the appropriate wells, while DU-145 cells received brexpiprazole (7.5 pM or 10 pM) or cariprazine (10 pM or 15 pM). Within 2 hours of drug addition, a 5 Gy dose of y-radiation was delivered (e.g., via a BioBeam or similar irradiator), while control groups received neither drug nor radiation, or only single-agent treatments.

[0096] Following 48 hours of incubation under these conditions, the medium was removed, and cells were washed twice in DPBS. Protein extracts were then prepared using RIPA buffer (or an equivalent lysis solution), followed by brief sonication (if necessary) and clarification via centrifugation. The supernatants were collected, and total protein concentrations were measured (e.g., via BCA assay). Western blot was performed as follows:1. SDS-PAGE separation of 20-30 pg protein per lane.2. Electrotransfer onto PVDF or nitrocellulose membranes.3. Blocking the membrane for 2-4 hours with 5 % nonfat milk or BSA in TBS-Tween.4. Incubation overnight at 4 °C with primary antibodies (sources included Santa Cruz or Cell Signaling), such as:19182235113.1Atty Docket: 359410.04402• DRD2 (Santa Cruz, sc-5303)• TGFP-RII (Santa Cruz, sc- 17799)• CD44 (Cell Signaling, #37259)• MMP-2 (Santa Cruz, sc- 10736)• Snail (Cell Signaling, #3895)• Nanog (Santa Cruz, sc-293121)• p-STAT3 (Cell Signaling, #9145)• GAPDH (Santa Cruz, sc-47724) as a loading control5. Washing the blots in TBST, then secondary antibody incubation for 1 hour.6. Visualizing bands using a ChemiDac MP kit (Bio-Rad) or similar chemiluminescence detection system.

[0097] FIG. 6 displays representative blot images demonstrating that while DRD2 expression was partially suppressed, a substantial decrease was noted in TGFP-RII, CD44, MMP-2, Snail, and Nanog in the combination groups (drug + 5 Gy). This pattern suggests that DRD2 blockade synergizes with radiation to undermine both the tumor’s invasive machinery (e.g., MMP-2, Snail, CD44) and stem-like properties (Nanog). Notably, GAPDH levels remained consistent across all samples, confirming equal protein loading.

[0098] In certain embodiments, sequential chemo-DRD2-radiation regimens can be adopted, for example by administering chemotherapeutics first to reduce overall tumor burden, then introducing DRD2 antagonists shortly before radiotherapy to inhibit prosurvival or EMT pathways. In other embodiments, broadening agent selection can be explored, such as testing additional chemotherapies (e.g., cisplatin, 5-FU) or targeted therapies (e.g., PARP inhibitors) in combination with brexpiprazole or cariprazine to uncover further synergy. In still other embodiments, in vivo confirmation may be pursued, for instance by extending the combination regimen to more comprehensive animal models (orthotopic or patient-derived xenografts), where both tumor size and metastatic spread can be monitored. Additionally, translational biomarkers can be investigated, such as evaluating DRD2 expression, TGFP-RII status, or Nanog / CD44 levels as predictive markers to tailor patient treatment and potentially enable a precision medicine approach.

[0099] These collective data indicate that brexpiprazole or cariprazine can act as powerful adjuncts to both radiation and chemotherapy in breast cancer models. In MCF-7, combining DRD2 antagonism with chemo-radiation amplified cell death and diminished EMT / stemness 20182235113.1Atty Docket: 359410.04402markers, while in MDA-MB-231, co-treatment similarly downregulated DRD2 pathway components and key pro-metastatic proteins. The synergy exhibited in these two distinct breast cancer lines suggests that dopaminergic signaling plays a major role in tumor resistance and aggressiveness, and its pharmacological disruption enhances cytotoxic efficacy.

[0100] While certain embodiments and examples have been described in detail, it is apparent that modifications and adaptations will occur to those skilled in the art. The present disclosure is intended to encompass such modifications and variations, so long as they fall within the scope of the appended claims or their equivalents. No limitation is intended by the foregoing descriptions or the accompanying examples, other than as set forth in the claims.

[0101] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. In the event of conflicting terminology, the present disclosure controls.182235113.1

Claims

1. Atty Docket: 359410.04402WHAT IS CLAIMED IS:

1. A method of treating cancer in a patient in need thereof, the method comprising: administering a dopamine receptor (DRD2)-binding phenylpiperazine derivative to the patient, andexposing the patient to ionizing radiation, thereby treating the cancer.

2. The method of claim 1, wherein the method provides a synergistic effect.

3. The method of claim 1, wherein the DRD2-binding phenylpiperazine derivative is selected from the group consisting of brexpiprazole, cariprazine, pipamperone, and perospirone.

4. The method of claim 1, wherein the cancer is selected from breast cancer, prostate cancer, lung cancer, pancreatic cancer, brain cancer, or combinations thereof.

5. The method of claim 1, wherein the ionizing radiation is administered as a single fraction of about 5 Gy to about 10 Gy.

6. The method of claim 1, wherein the ionizing radiation is administered in fractionated doses of about 1-2 Gy per fraction over multiple sessions, and said phenylpiperazine derivative is co-administered prior to or during each fraction.

7. The method of claim 1, further comprising administering at least one additional anti-cancer agent selected from the group consisting of a chemotherapeutic agent, a targeted therapy, or an immunotherapy.

8. The method of claim 7, wherein the chemotherapeutic agent is selected from paclitaxel, doxorubicin, cisplatin, 5 -fluorouracil (5-FU), or combinations thereof.

9. The method of claim 1, wherein the phenylpiperazine derivative is administered orally or intravenously at a dosage of about 2 mg / kg to about 10 mg / kg.22182235113.1Atty Docket: 359410.0440210. A method of reducing cancer metastasis in a patient, the method comprising: administering a dopamine receptor (DRD2)-binding phenylpiperazine derivative to the patient, andexposing the patient to ionizing radiation, thereby reducing the cancer metastasis.

11. The method of claim 10, wherein the method provides a synergistic effect.

12. The method of claim 10, wherein the DRD2-binding phenylpiperazine derivative is selected from the group consisting of brexpiprazole, cariprazine, pipamperone, and perospirone.

13. The method of claim 10, wherein the cancer is selected from breast cancer, prostate cancer, lung cancer, pancreatic cancer, brain cancer, or combinations thereof.

14. The method of claim 10, wherein the ionizing radiation is administered as a single fraction of about 5 Gy to about 10 Gy.

15. The method of claim 10, wherein the ionizing radiation is administered in fractionated doses of about 1-2 Gy per fraction over multiple sessions, and said phenylpiperazine derivative is co-administered prior to or during each fraction.

16. The method of claim 10, further comprising administering at least one additional anti-cancer agent selected from the group consisting of a chemotherapeutic agent, a targeted therapy, or an immunotherapy.

17. The method of claim 16, wherein the chemotherapeutic agent is selected from paclitaxel, doxorubicin, cisplatin, 5 -fluorouracil (5-FU), or combinations thereof.

18. The method of claim 10, wherein the phenylpiperazine derivative is administered orally or intravenously at a dosage of about 2 mg / kg to about 10 mg / kg.

19. A method of enhancing cancer cell apoptosis in a patient, the method comprising:23182235113.1Atty Docket: 359410.04402administering a dopamine receptor (DRD2)-binding phenylpiperazine derivative to cancer cells in the patient, andexposing the cancer cells to ionizing radiation, thereby enhancing cancer cell apoptosis.

20. The method of claim 19, wherein the method provides a synergistic effect.182235113.1

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