Apalutamide Decreases Metastases in Men with nmCRPC: SPARTAN Trial Results

Chicago—In the SPARTAN trial, men with nonmetastatic castration-resistant prostate cancer (nmCRPC) were treated with apalutamide, an orally administered next generation androgen receptor inhibitor. Results of the SPARTAN trial were reported during a poster session at the ASCO 2018 Annual Meeting in a poster titled Relationship of Time to Metastasis (TTM) and Site of Metastases in Patients (pts) with Nonmetastatic Castration-Resistant Prostate Cancer (nmCRPC): Results from the Phase 3 SPARTAN Trial.

SPARTAN, a phase 3 randomized placebo-controlled study, was designed to examine the effect of apalutamide on men with nmCRPC with rapidly rising prostate-specific antigen level.  Results demonstrated a 73% relative risk reduction of distant metastasis with apalutamide. The analysis reported by Matthew Raymond Smith, MD, at the ASCO meeting assessed the relationship between time to metastasis and site of metastases following androgen deprivation therapy (ADT) plus apalutamide versus ADT plus placebo.

A total of 1207 patients with nmCRPC and PSA doubling time ≤10 months were randomized in a 2:1 ratio to receive 250 mg apalutamide or placebo; both arms also received concurrent ADT. Time to metastasis was defined as the time from randomization to the first evidence of blinded central review-confirmed radiographically detectable distant metastasis, and was determined by site of metastases, nodal versus bone versus visceral. Time to metastasis was analyzed using the Kaplan-Meier method. Hazard ratios (HRs) and confidence intervals (CIs) were estimated using a stratified proportional hazards model with treatment group as a factor, stratified by PSA doubling time, bone-sparing use, and loco-regional disease.

Of the patients with metastases, 30% of the apalutamide group (52/175) and 40% of the placebo group (76/175) developed nodal metastases; 57% of the apalutamide group (100/175) and 52% of the placebo group (100/191) developed bone metastases; and 13% of the apalutamide group (23/175) and 8% of the placebo group (15/191) developed visceral metastases. In the intent-to-treat population, for apalutamide versus placebo, the HRs for time to metastasis were 0.19 (95% CI, 0.13-0.27) and 0.31 (0.23-0.41) for nodal and bone metastases, respectively (P<.0001).

In conclusion, the researchers said, “Treatment with apalutamide markedly decreased the risk of metastases, regardless of the site of metastasis. The consistency of these results provides further evidence for the clinical benefit of apalutamide in nmCRPC.”

Clinical trial information: NCT01946204.

Source: Smith MR, Saad F, Rathkopf DE, et al. Relationship of time to metastasis (TTM) and site of metastases in patients (pts) with nonmetastatic castration-resistant prostate cancer (nmCRPC): Results from the phase 3 SPARTAN trial. Abstract of a poster presented at the American Society of Clinical Oncology 2018 Annual Meeting, June 2, 2018, Chicago, Illinois.