Apalutamide Compared with Darolutamide for the Treatment of Non-metastatic Castration-Resistant Prostate Cancer: Efficacy and Tolerability in a Matching-Adjusted Indirect Comparison

Introduction: Apalutamide and darolutamide are next-generation androgen receptor inhibitors that have demonstrated superior efficacy compared to placebo in men with non-metastatic castration-resistant prostate cancer (nmCRPC) receiving androgen deprivation therapy (ADT). In the absence of head-to-head studies, the present study sought to indirectly compare the efficacy and tolerability between these two treatments.

Methods: This anchored matching-adjusted indirect comparison (MAIC) used patient-level data from the phase 3, randomized, controlled SPARTAN study (apalutamide + ADT), weighted to match aggregate published data from the ARAMIS study (darolutamide + ADT) for clinically relevant baseline measures. Hazard ratios (HR) and 95% credible intervals (CrI) were estimated for efficacy endpoints: metastasis-free survival (MFS), prostate-specific antigen (PSA) progression, progression-free survival (PFS), and overall survival (OS). Odds ratios were estimated for tolerability outcomes: adverse events and serious adverse events.

Results: Before weighting, baseline characteristics from SPARTAN versus ARAMIS were different for median PSA (7.8 vs. 9.2 ng/mL), Eastern Cooperative Oncology Group performance status of 1 (23% vs. 31%), use of bone-targeted agents (10% vs. 4%), median time from initial diagnosis (94.9 vs. 85.4 months), and proportion of patients from North America (35% vs. 12%) and Europe (50% vs. 64%). After matching (n = 455), our analysis demonstrated that apalutamide + ADT had a Bayesian probability of being more effective than darolutamide + ADT for MFS [98.3%; HR 0.70 (95% CrI 0.51, 0.98)], PSA progression [~ 100%; HR 0.46 (95% CrI 0.33, 0.64)], and PFS [93.2%; HR 0.79 (95% CrI 0.59, 1.08)]. Results for OS and tolerability were similar between apalutamide + ADT and darolutamide + ADT.

Conclusion: This anchored MAIC analysis of pivotal phase 3 studies in patients with nmCRPC suggests that apalutamide + ADT is more effective than darolutamide + ADT for MFS, progression-free survival (PFS), and prostate-specific antigen (PSA) progression, with a similar OS benefit and tolerability profile.

Trial registration: ARAMIS ClinicalTrials.gov number: NCT02200614; SPARTAN ClinicalTrials.gov number: NCT01946204.