Dr. Tagawa on Safety Profile of 225Ac-J591 in mCRPC

Scott T. Tagawa, MD, MS, Richard A. Stratton Associate Professor in Hematology and Oncology, associate professor of clinical medicine and urology at Weill Cornell Medicine, and associate attending physician, NewYork-Presbyterian/Weill Cornell Medical Center, discusses the safety profile of novel monoclonal antibody ²²⁵Ac-J591 in metastatic castration-resistant prostate cancer (mCRPC).

At the 2020 Genitourinary Cancers Symposium, results of a phase I dose-escalation trial (NCT03276572) showed that 63.6% of 22 men treated with ²²⁵Ac-J591 experienced prostate-specific antigen (PSA) decline.

There were no dose-limiting toxicities (DLTs) in the cohort of patients who received 93.3 KBq/Kg of ²²⁵Ac-J591, which was the highest dose that was evaluated, says Tagawa.

However, 1 of 6 patients in the cohort who received 80.0 KBq/Kg of ²²⁵Ac-J591 experienced a DLT of grade 4 anemia and grade 4 thrombocytopenia, says Tagawa.

No other grade 3 or 4 hematologic or non-hematologic adverse events were reported, says Tagawa. Grade 1/2 fatigue was noted in 77% of patients, but generally subsided after several weeks.

These results were in line with what was expected, says Tagawa. The short-range alpha-emitter ²²⁵Ac appears to reduce the rate of myelosuppression associated with beta emitters like ¹⁷⁷Lu, concludes Tagawa.