Background:

As mCRPC is driven by activated androgen receptors and elevated intratumoral androgens, androgen annihilation may require dual inhibition. APA and AA are approved prostate cancer therapies that have distinct receptor inhibition and ligand suppression actions, respectively. ACIS compared radiographic progression-free survival (rPFS) of APA + AAP vs PBO + AAP in chemo-naive mCRPC.

Methods:mCRPC pts with ongoing androgen deprivation therapy (ADT) but no other life-prolonging treatment since diagnosis were randomized 1:1 to APA (240 mg po QD) + AA (1000 mg po QD) + P (5 mg po BID) or PBO + AAP (stratified by presence or absence of visceral metastases, Eastern Cooperative Oncology Group performance status 0 or 1, and geographic region). The primary end point was rPFS (investigator assessed; defined from randomization date to radiographic progression date or death). Secondary/other end points included prostate-specific antigen (PSA) response, overall survival (OS), safety, time to PSA progression, chronic opioid use, initiation of cytotoxic chemotherapy, and pain progression.

Results:982 pts were enrolled (Dec 2014 to Aug 2016). Median rPFS was extended 6 mos with APA + AAP (22.6 mos) vs AAP (16.6 mos) (HR 0.69 [95% CI 0.58-0.83]; p < 0.0001) at the final analysis for rPFS, coinciding with the first interim analysis of OS (median follow-up time 25.7 mo). At final analysis, treatment with APA + AAP vs AAP showed a significantly higher rate of confirmed ≥ 50% PSA decline. Although not statistically significant, treatment with APA + AAP vs AAP showed a longer median OS. Time to PSA progression, chronic opioid use, initiation of cytotoxic chemotherapy, and pain progression did not differ statistically significantly between arms. The safety profile was consistent with prior drug experience, with no new safety concerns. Grade 3/4 treatment-emergent adverse events (TEAEs) were reported in 63.3% (310/490) of APA + AAP–treated pts vs 56.2% (275/489) of AAP-treated pts, with more grade 3 (56.1%, 275/490 vs 45.6%, 223/489) and less grade 4 (7.1%, 35/490 vs 10.6%, 52/489) TEAEs, respectively. Results based on biomarker subpopulations and quality of life will be presented.

Conclusions:

The ACIS final analysis met the primary end point and demonstrated a 31% reduction in risk of radiographic progression or death in chemo-naive mCRPC pts treated with the combination of APA + AAP with ADT vs AAP with ADT. Funding: Janssen Research & Development. Trial registration: NCT02257736. Clinical trial information:

aRelative response.