ORLANDO, FL, USA (UroToday.com) - Enzalutamide (ENZA) is a novel androgen receptor (AR) and AR signaling inhibitor. In the AFFIRM study, ENZA increased median overall survival (OS) by 4.8 months vs. placebo (pbo) in mCRPC post-docetaxel (HI Scher et al, NEJM 2012). There is a body of evidence that corticosteroids (CS) increases risk for prostate cancer, therefore it was hypothesized that CS may reduce survival in this study.
Patients were allowed, but not required, to take CS in the AFFIRM study, and 30% of patients entered the study on CS. The primary endpoint was OS and secondary endpoints included rPFS, time to PSA progression, and safety. On-study CS use was defined as oral CS use for ≥ 1 day concurrently with study medication. It included patients who entered the study on CS and those who began CS during study treatment. On-study CS use was 48% in ENZA and 45% in pbo patients. Prognostic factors were slightly better in the no-CS group compared to the CS group. Use of CS, regardless of treatment, was associated with median OS of 11.5 months for CS patients vs. median OS NM for no CS patients. ENZA improved OS, rPFS, and time to PSA progression independent of on-study CS use. Patients on CS had higher rates of grade 3-4 adverse events (AE) compared to no-CS patients, 63.3% vs. 34.4%. The inferior outcomes in CS patients may be due to either biologic factors of the tumor or unknown confounders.
Highlights of a presentation by Howard I. Scher, MD at the 2013 Genitourinary Cancers Symposium - February 14 - 16, 2013 - Rosen Shingle Creek - Orlando, Florida USA
Memorial Sloan-Kettering Cancer Center, New York, NY USA
Written by Anna Forsberg, medical reporter for UroToday.com
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