San Francisco, CA USA (UroToday.com) Dr. Carla Cavaliere and colleagues presented their data on a novel use of PSA kinetics as a predictive factor for treatment response to abiraterone in today’s poster session at the 2016 GU ASCO conference. The investigators studied PSA kinetics in 87 mCRPC patients treated with abiraterone, focusing on 15-day, 90-day, and monthly time points. Clinical and pathological covariates were entered into a multivariable model to identify the independent prognostic ability of very early PSA response to abiraterone, defined as a decline of >50% at 15 days.
PSA decline was identified in 78.6% (59/75 with complete data) of the patients studied. Early response was demonstrated in 42 (56%) patients, while 17 (22.7%) had <50% response, and 16 (21.3%) progressed. This effect was durable at the 90 day time point in 29 (69%) of the early responders. Early responders had a survival advantage at 1 year (PFS: HR=0.28, CI 0.12-0.65, and OS: HR=0.21, CI 0.06-0.72). Among the early responders, the study demonstrated a correlation between OS and duration of abiraterone use (>7 months), previous chemotherapy received (>2 lines received), cumulative docetaxel dose received (<675 mg/m2), and previous hormone therapy (>2.5 months).
The authors concluded that early PSA decline can provide clinically useful information, as it is prognostic for survival advantage in terms of both PFS and OS.
Reported By:
Nikhil Waingankar, MD at the 2016 Genitourinary Cancers Symposium - January 7 - 9, 2016 – San Francisco, CA
Fox Chase Cancer Center, Philadelphia, PA