Survival outcomes of apalutamide as a starting treatment: impact in real-world patients with metastatic hormone sensitive prostate cancer (OASIS)

BACKGROUND: Androgen receptor pathway inhibitors (apalutamide APA, enzalutamide ENZ, abiraterone acetate plus prednisone AAP) combined with androgen-deprivation therapy (ADT) are effective life-prolonging treatment options for metastatic hormone-sensitive prostate cancer (mHSPC). We evaluated the impact of upfront therapy for mHSPC on outcomes in real-world clinical practice in the United States. METHODS: This retrospective, observational cohort study used electronic healthcare records from the ConcertAI RWD 360 Prostate Cancer Dataset. All patients with newly diagnosed mHSPC from January 2018 to June 2023 were enrolled and followed-up until death, end of follow-up, or January 2024, whichever occurred first. Kaplan-Meier methods were used to estimate overall survival (OS), time to PSA50/PSA90 (50%/90% decline in PSA from baseline, respectively), time to undetectable PSA ( ≤ 0.2 ng/ml), and time to castration resistance (TTCR). Adjusted hazard ratios (aHR) were estimated using inverse probability of treatment weighted multivariate Cox proportional models adjusted for age, comorbidities, BMI, and baseline PSA. RESULTS: 4937 patients with mHSPC were included in the analysis: 315 received upfront APA + ADT, 1181 ENZ + ADT, 1760 AAP + ADT, 432 docetaxel (DTX) + ADT, and 1249 ADT alone. Percentages of patients reaching PSA50, PSA90, and undetectable PSA at 3 months were significantly higher for APA + ADT (70%/49%/44%, respectively) compared to ENZ + ADT (60%/38%/32%), AAP + ADT (59%/37%/33%) and ADT alone (32%/15%/32%). OS and TTCR were also significantly longer for APA + ADT (66%/77% respectively at 24 months) vs ENZ + ADT (55%/63%) AAP + ADT (59%/67%) and ADT alone (54%/57%). Starting treatment with APA + ADT was associated with a significantly reduced risk of death compared with ENZ + ADT (aHR, 95%CI) (0.66, 0.51-0.87), AAP + ADT (0.72, 0.55-0.94), and ADT alone (0.64, 0.49-0.84). CONCLUSIONS: Numerous patients were not treated with intensified therapies despite their increased effectiveness. First-line APA + ADT in mHSPC was associated with statistically significantly longer OS, longer TTCR, and faster and deeper PSA responses than other life-prolonging treatments in real-world clinical practice in the US.