For patients with metastatic castration-resistant prostate cancer (mCRPC), prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) is increasingly being included in the treatment plan. For a study, researchers sought to better understand how early biochemical reaction predicts overall survival (OS).

They included 184 mCRPC patients who received 177Lu-PSMA RLT in the bicentric study. A drop in PSA levels 8 weeks following the beginning of RLT was considered a response to therapy (any decline or >50%, according to Prostate Cancer Working Group 3). The OS of respondents and nonresponders were compared using Kaplan-Meier curves and log-rank comparison after that.

An overall PSA drop was seen in 114/184 individuals (62.0%) (PSA response more than 50%, 55/184 [29.9%]). OS of 19 months was substantially longer than nonresponders’ (13 months; hazard ratio of death [HR] = 0.64, 95% CI=0.44-0.93; P=0.02) for people with a PSA decrease of greater than 50%. For any PSA drop, the difference was much more apparent, with responders having an OS of 19 months and nonresponders having just 8 months (HR=0.39, 95% CI=0.25-0.60; P<0.001).

Regardless of the degree of PSA drop, the early biochemical response was strongly associated with longer life in mCRPC patients scheduled for RLT. RLT should thus continue, even in individuals whose PSA decline is less than 50%.

Reference: onlinelibrary.wiley.com/doi/10.1002/pros.24414