A Phase 2, Open-Label, Multicenter Study of PSMA ADC in Subjects with Metastatic Castration Resistant Prostate Cancer (mCRPC)

Summary

PSMa aDC 2301 is a Phase 2, open-label, multicenter study to assess the anti-tumor activity and
tolerability of PSMa aDC in up to 75 subjects with metastatic castration-resistant prostate cancer
(mCRPC). Subjects must have received at least one taxane-containing chemotherapy regimen (e.g.
docetaxel, cabazitaxel). if a subject has received more than two cytotoxic chemotherapy regimens, Sponsor
approval is required for study participation. Subjects must also have received and progressed on
abiraterone acetate and/or enzalutamide. if a subject is unable to receive abiraterone acetate and/or
enzalutamide, Sponsor approval is required for participation in the study. a second group will be comprised of approximately 35 subjects who are cytotoxic chemotherapy-naive. Both groups must have also received and progressed on abiraterone acetate and/or enzalutamide.
PSMa aDC 2.3 mg/kg will be administered as an iV infusion over approximately 60 minutes once every
three weeks (Q3W) for up to eight doses (unless dose delay or dose reduction is required). The subject will be weighed prior to each cycle and dosing will be calculated on a mg/kg basis prior to each dose. The dose for subjects weighing greater than 100 kg should be calculated based on a weight of 100 kg.
Dose delays and/or reductions within the scope of the titration guidelines do not require
Sponsor approval; however it is recommended that the clinical research associate (CRa) is contacted
regarding either dose delay or dose reduction. if the guidelines are not followed, both the Sponsor and
CRa must be notified. all changes and reasons for dose changes must be documented on the subject's
source documents. Dose reductions should be in steps of 0.2 mg/kg. Dosing may neither be less than 2.1
mg/kg nor more than the starting dose of 2.3 mg/kg.

Participant Eligibility

In order to be eligible for the study, subjects have to meet all of the following inclusion
criteria:
1. Males greater than or equal to age 18 years
2. < 150 kg
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2
(Appendix 2)
4. Life expectancy >= six months
5. Must have histologically or cytologically confirmed prostate adenocarcinoma.
6. CRMPC as determined by the results of imaging studies performed in either column
A or column B:
Column A
Bone Scan and Computed tomography (CT) of chest, pelvis, and upper/lower abdomen

OR
Column B
Bone Scan and Anatomical MRI of chest, pelvis, and upper/lower abdomen
(If clinically indicated a confirmatory bone scan at Cycle 7 should be considered after an initial sign of progression at Cycle 5. The confirmatory bone scan will differentiate true progression of bone metastasis from the flare phenomenon on bone scans due to healing of previous bone metastasis. Early progression events could be confounded by tumor flare phenomenon and implementation of a
confirmatory scan will reduce the number of false positive determinations of CRPC progression.)
7. A castrate level of serum testosterone (<50 ng/dL) at screening (testosterone should
be measured by the central laboratory by mass spectrometry if colorimetric assay is greater than 50).
8. Prior and/or ongoing androgen-deprivation therapy consisting of either orchiectomy or luteinizing hormone-releasing hormone (LHRH) agonists, with or without an antiandrogen. If chemically castrated, subjects must agree to stay on LHRH agonist medication for the duration of the study.
9. 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.
10. Central laboratory result requirements:
- White blood count (WBC) 3000/mm3
- Absolute neutrophil count (ANC) 1000/mm3
- Platelets (Plt) 100,000/mm3
- Hemoglobin (Hgb) 9.0 g/dL
- Total bilirubin 2.0 mg/dL
- Serum alanine aminotransferase (ALT) 2.5 the upper limit of normal (ULN)
- Serum aspartate aminotransferase (AST) 2.5 the upper limit of normal (ULN)
- Serum creatinine 2.0 mg/dL Calculated (Cockcroft-Gault, Appendix 3) glomerular filtration rate (GFR) of > 40 mL/min
- Pancreatic Amylase (p-amylase) the ULN
- Lipase the ULN
- 11. Prior history of treatment with at least one taxane-containing chemotherapy regimen (e.g. docetaxel, cabazitaxel). If a subject received more than two cytotoxic chemotherapy regimens, Sponsor approval is required for study participation or subjects with no prior history of treatment with a cytotoxic chemotherapy regimen.
12. Must have received and progressed on abiraterone acetate and/or enzalutamide and must wait a
minimum of 30 days from their last dose of abiraterone acetate and/or enzalutamide prior to receiving their first dose of PSMA ADC. If subject is unable to receive abiraterone acetate and/or enzalutamide, Sponsor approval is required for participation in the study.
13. Willing and able to provide written informed consent and written authorization for use and release of health and research information.