An Open-label Extension Study of PSMA ADC 2301 in mCRPC

Study Overview
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Brief Summary
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PSMA ADC 2301EXT is an open-label study to further assess the anti-tumor activity as measured by radiographic imaging and biomarkers, safety and tolerability of Prostate Specific Membrane Antigen Antibody Drug Conjugate (PSMA ADC) in subjects with mCRPC. Subjects who have participated in the PSMA ADC 2301 study and who, in the opinion of the Principal Investigator are likely to benefit from continued treatment with PSMA ADC are eligible for the PSMA ADC 2301 extension study. Subjects who are benefiting from treatment may be able to receive up to an additional eight to sixteen doses (every 3 weeks) of PSMA ADC.

Official Title
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An Open-label Treatment Extension of PSMA ADC in Subjects With Metastatic Castration-resistant Prostate Cancer (mCRPC)

Conditions
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Prostate Cancer

Intervention / Treatment
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* Drug: PSMA ADC


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subjects who have completed the PSMA ADC 2301 study and who, in the opinion of the investigator, are likely to benefit from continued treatment with PSMA ADC Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2 If chemically castrated, subjects must agree to stay on androgen-deprivation therapy for the duration of the study If applicable, men must agree to commit to the use of a medically acceptable method of birth control (e.g., spermicide in conjunction with a barrier such as a condom) or sexual abstinence for the duration of the study, including 30 days after the last dose of study drug Exclusion Criteria: An acute infection requiring ongoing antibiotic therapy (e.g., UTI, indwelling catheter or other potential site(s) of infection) History of significant hypersensitivity reactions to PSMA ADC or any of its components, or to any prior investigational or approved monoclonal antibodies (mAbs), immunoglobulin (Ig) fusion proteins (e.g., circulating neutralizing antibodies), or ADC Clinically significant cardiac disease or severe debilitating pulmonary disease Any recent or ongoing medical condition that may interfere with a subject's participation or compliance with the study or evaluation of PSMA ADC

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Arm 1: PSMA ADC<br>Subjects started the extension study at the same dose received upon completion of the core PSMA ADC 2301 study. Each Prostate Specific Membrane Antigen Antibody Drug Conjugate (PSMA ADC) dose was administered as an IV infusion over approximately 60 minutes once every three weeks (Q3W) for up to eight doses, unless a dose delay or dose reduction was required. | Drug: PSMA ADC<br>* Upon recommendation from the PI and after Sponsor approval, a subject benefiting from treatment could have received up to eight additional doses Q3W. Subjects were weighed prior to each cycle and dosing was calculated on a mg/kg basis prior to each dose, with a maximum weight of 100 kg for dosing calculations.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants With Total Serum PSA Response | Total serum PSA (prostate-specific antigen) was measured at baseline and had at least one post-baseline assessment. PSA response was examined at two levels: at least 30% decrease or at least 50% decrease in serum PSA. Response was assessed as the maximum decrease over the extension study. Response was defined as any decrease from baseline of at least 30% or 50%. | 25 Weeks | 
| CTC Response | Circulating tumor cells (CTC) response was measured at baseline and had at least one post-baseline assessment. Response was assessed as the maximum decrease over the extension study. Response was defined as any decrease from baseline of at least 50%. | 25 weeks | 
| Overall Radiologic Response | Overall radiologic response was measured at baseline and post-baseline. Imaging techniques used at screening were used throughout the study. The preferred imaging techniques include: bone scan, contrast enhanced CT of chest, contrast enhanced CT of pelvis, and contrast enhanced CT of upper & lower abdomen. Best overall radiologic response (confirmed), target and non-target lesions, was defined as responses in bone, visceral or nodal metastases according to the Modified Response Evaluation Criteria (RECIST 1.1). The best overall radiologic response is the best response recorded from the start of the treatment until disease progression/recurrence (taking, as reference for progressive disease, the smallest measurements recorded since the treatment started). The subject's best response assignment depended on the achievement of both measurement and confirmation criteria. | 25 weeks |