Matching-Adjusted Indirect Comparison of the Efficacy of Apalutamide and Enzalutamide with ADT in the Treatment of Non-Metastatic Castration-Resistant Prostate Cancer
Advances in Therapy, 2020
Apalutamide and enzalutamide are next-generation androgen receptor inhibitors that demonstrated efficacy in placebo-controlled studies (SPARTAN for apalutamide; PROSPER for enzalutamide) when used in combination with androgen deprivation therapy (ADT) for treatment of non-metastatic castration-resistant prostate cancer (nmCRPC). In the absence of comparative studies between these agents, the present study sought to indirectly compare metastasis-free survival (MFS) and overall survival (OS) in patients with nmCRPC who received these therapies.
Individual patient-level data from SPARTAN (apalutamide plus ADT) and published data from PROSPER (enzalutamide plus ADT) were utilized. An anchored matching-adjusted indirect comparison (MAIC) was conducted by weighting the patients from the SPARTAN study to match baseline characteristics reported for PROSPER. Hazard ratios (HRs) for MFS and OS were re-estimated for SPARTAN using weighted Cox proportional hazards models and indirectly compared with those of PROSPER using a Bayesian network meta-analysis.
From the SPARTAN population (N = 1207), a total of 1171 patients were matched to the PROSPER population (N = 1401). The recalculated HRs (95% confidence interval) for apalutamide versus ADT based on the reweighted SPARTAN data to mimic the PROSPER patient population were 0.26 (0.21; 0.33) for MFS and 0.62 (0.41; 0.94) for OS. MAIC-based HRs (95% credible interval) for apalutamide versus enzalutamide were 0.91 (0.68; 1.22) for MFS and 0.77 (0.46; 1.30) for OS. The Bayesian probabilities of apalutamide being more effective than enzalutamide were 73.6% for MFS and 83.5% for OS.
MAIC results suggest that nmCRPC patients treated with apalutamide have a higher probability of a more favorable MFS and OS compared with those treated with enzalutamide.
Chowdhury S, Oudard S, Uemura H, Joniau S, Pilon D, Ladouceur M, Behl AS, Liu J, Dearden L, Sermon J, Van Sanden S, Diels J, Hadaschik BA