177Lu-PSMA-617 (LuPSMA) is associated with improved safety, higher response rates, and similar overall survival (OS) vs cabazitaxel in metastatic castration–resistant prostate cancer, according to an updated analysis from the TheraP trial presented at the 2022 ASCO Annual Meeting.

“We previously reported that in men with mCRPC progressing after docetaxel randomly assigned LuPSMA vs. cabazitaxel (Lancet 2021), those assigned LuPSMA has significant improvements in PSA response rate (66% vs. 37%), RECIST response rate (49% vs. 24%), progression-free survival (HR 0.63), less G3-4 toxicities (33% vs. 53%) and better patient-reported outcomes,” wrote Michael Hoffman, MD, Peter MacCallum Cancer Centre and Sire Peter MacCallum Department of Oncology, University of Melbourne, Australia, and colleagues.

This follow-up analysis provides an update on OS in this trial with a more mature follow-up. OS was analyzed by intention-to-treat and summarized by restricted mean survival time (RMST) to account for non-proportional hazards.

The TheraP trial enrolled 200 eligible patients with metastatic castration–resistant prostate cancer progressing after docetaxel. Patients had high PSMA-expression and no sites of disease of FDG-positive and PSMA-negative, determined via PET imaging.

Patients were randomized to receive either LuPSMA (n = 99) or with cabazitaxel (n = 101). Of the additional 80 patients that had been initially registered and then excluded due to PET imagining standards, 61 were available for follow-up.

Median follow-up was 36 months at the data cut-off of December 31, 2021. Deaths reported were 70 (69.3%) in the cabazitaxel arm, 77 (77.8%) in the LuPSMA arm, and 55/61 (90.2%) that had been excluded. Of those who had been assigned cabazitaxel, 21 patients received subsequent treatments including cabazitaxel. In the LuPSMA arm, 5 patients received additional LuPSMA, and 32 received additional cabazitaxel.

The OS was similar in both the LuPSMA and the cabazitaxel arm (RMST to 36 months was 19.1 vs. 19.6 months). For those patients who had been excluded from the trial, RMST to 36 months was 11 months, following treatment that included cabazitaxel in 29 patients, and LuPSMA in 3. In this longer follow-up analysis, no additional safety signals were reported.

“LuPSMA is a suitable option for men with mCRPC progressing after docetaxel, with lower adverse events, higher response rates, improved patient-reported outcomes, and similar OS compared with cabazitaxel,” concluded Dr Hoffman and colleagues.

Source:

Hofman MS, Emmett L, Sandhu S, et al. TheraP: 177Lu-PSMA-617 (LuPSMA) versus cabazitaxel in metastatic castration-resistant prostate cancer (mCRPC) progressing after docetaxel—Overall survival after median follow-up of 3 years (ANZUP 1603). Presented at: ASCO Annual Meeting; June 3-7, 2022. Chicago, IL; and virtual. Abstract 5000.