Dose-Escalation Study of Cabozantinib in Combination With Lutetium-177 (177Lu)-PSMA-617 in Patients With Metastatic Castration-Resistant Prostate Cancer

This is an open-label, phase 1b dose-escalation study of cabozantinib in combination with 177Lu-PSMA-617 in subjects with mCRPC. The primary hypothesis is that cabozantinib with 177Lu-PSMA will be safe and have efficacy in patients with mCRPC. The dose-escalation phase (Part 1) will assess the rate of dose-limiting toxicities (DLTs) during the DLT evaluation period and identify the MTD and/or recommended dose and schedule for the subsequent expansion phase (Part 2).

Inclusion Criteria: * Male subject aged ≥ 18 years. * Histologically or cytologically confirmed adenocarcinoma of the prostate without small cell histology. * Prior orchiectomy and/or ongoing androgen-deprivation therapy and a castrate level of serum testosterone (\ 0.5 teaspoon (2.5 ml) of red blood, or other history of significant bleeding (e.g., pulmonary hemorrhage) within 12 weeks before first dose of study treatment. * Cavitating pulmonary lesion(s) or known endotracheal or endobronchial disease manifestation. * Lesions invading or encasing any major blood vessels * Other clinically significant disorders that would preclude safe study participation. * Serious non-healing wound/ulcer/bone fracture. * Uncompensated/symptomatic hypothyroidism. * Moderate to severe hepatic impairment (Child-Pugh B or C). * Known history of COVID-19 unless the subject has clinically recovered from the disease at least 30 days prior to first dose of study treatment. * Major surgery (e.g., laparoscopic nephrectomy, GI surgery, removal or biopsy of brain metastasis) within 2 weeks before first dose of study treatment or minor surgeries within 10 days before first dose of study treatment. * Subjects must have complete wound healing from major surgery or minor surgery before first dose of study treatment. --Subjects with clinically relevant ongoing complications from prior surgery are not eligible. * Corrected QT interval calculated by the Fridericia formula (QTcF) \> 500 ms per electrocardiogram (ECG) within 28 days before first dose of study treatment. --Note: If a single ECG shows a QTcF with an absolute value \> 500 ms, two additional ECGs at intervals of approximately 3 min must be performed within 30 min after the initial ECG, and the average of these three consecutive results for QTcF will be used to determine eligibility. * Inability to swallow tablets * Previously identified allergy or hypersensitivity to components of the study treatment formulations. * Known HIV infection with a detectable viral load within 6 months of the anticipated start of treatment. --Note: Subjects on effective antiretroviral therapy with an undetectable viral load within 6 months of the anticipated start of treatment are eligible for this trial. * Active infection including tuberculosis (clinical evaluation that includes clinical history, physical examination, radiographic findings, and TB testing in line with local practice), hepatitis B (known positive HBV surface antigen (HBsAg) result), or hepatitis C. * Note: Subjects with a past or resolved HBV infection (defined as the presence of hepatitis B core antibody \[anti-HBc\] and absence of HBsAg) are eligible. Subjects positive for hepatitis C (HCV) antibody are eligible only if polymerase chain reaction is negative for HCV RNA. * Medical, psychiatric, cognitive, or other conditions that may compromise the subject's ability to understand the subject information, give informed consent, comply with the study protocol or complete the study. * Subjects taking prohibited medications as described in Section 6.8.2. A washout period of prohibited medications for a period of at least five half-lives or as clinically indicated should occur before the start of treatment.