This clinical trial will evaluate the safety and efficacy of \[161Tb\]Tb -PSMA-I\&T in men with metastatic castration-resistant prostate cancer (mCRPC).
Patient has provided written informed consent.
Male patients must be 18 years of age or older at the time of written informed consent.
Histologically or cytologically confirmed adenocarcinoma of the prostate, OR unequivocal diagnosis of metastatic prostate cancer (i.e., involving bone or pelvic lymph nodes or para-aortic lymph nodes) with an elevated serum prostate specific antigen (PSA).
Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2.
Prior treatment with another radioisotope (i.e. PSMA radioligands, radium-223, strontium-89, samarium-153).
Site(s) of discordant disease on PET imaging (Fluorodeoxyglucose [FDG]-positive and minimal PSMA-uptake).
Other malignancies (in addition to the prostate cancer being treated on this study) within the previous 2-years prior to registration other than basal cell or squamous cell carcinomas of skin or other cancers that are unlikely to recur within 24 months.
Symptomatic brain metastases or leptomeningeal metastases.
Single group
[ 161 Tb]Tb PSMA I&T
Drug\[161Tb\]Tb PSMA I\&T commencing as specified for cycle 1, with administered activity reduced by 0.4 GBq for each cycle (2 to 6). The first 3 patients of each dose level or modified schedule of treatment will be subject to safety review prior to dose expansion phase.
Maximum Tolerated dose (MTD)
The MTD is defined as the highest dose level at which the incidence of DLT was less than 1/3 or 2/6.
Adverse Events (AEs) and Serious Adverse Events (SAEs) measured using National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) v5.0
Safety of the combination will be measured by AEs and SAEs.
Dose Limiting toxicities (DLTs)
A DLT is defined as a toxicity that prevents further administration of the trial treatment at that dose level. Each cohort of 3 patients will be assessed for DLTs after 6 weeks from administration of cycle 1.
Recommended Phase 2 Dose (RP2D)
After the MTD is established, additional patients will be treated at the MTD. Safety and efficacy data from the study will be used to define the RP2D.
Absorbed radiation dose
Absorbed radiation dose will be determined using the SPECT/CT imaging after administration of the first dose of \[161Tb\]Tb-PSMA-I\&T
50% Prostate-Specific Antigen Response Rate (PSA-RR)
PSA will be assessed at baseline and every 3 weeks from Cycle 1 Day 1 during treatment, and every 6 weeks during follow-up. PSA response will be defined as a 50% or greater decrease in PSA from baseline to the lowest post-baseline PSA result.
Radiographic Progression-Free Survival (rPFS)
rPFS is defined as the time from registration to the first date of documented radiographic progression using conventional imaging or death due to any cause, whichever occurs first. Radiographic progression will be assessed by the Investigator per RECIST 1.1 for soft tissue and PCWG3 for bone lesions
PSA progression free survival (PSA-PFS)
PSA progression is defined as a rise in PSA by more than 25% AND more than 2ng/mL above the nadir (lowest PSA point). This needs to be confirmed by a repeat PSA performed at least 3 weeks later. Early rises in PSA prior to 12 weeks will be disregarded in determining PSA progression.
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