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ASCO 2019 Annual Meeting

ASCO 2019: Age-related Efficacy and Safety of Apalutamide Plus Ongoing ADT in Subgroups of Patients with nmCRPC: Post hoc Analysis of SPARTAN - Medical Oncologist Perspective

Chicago, IL (UroToday.com) SPARTAN is double-blind, placebo-controlled, phase 3 trial involving men with nonmetastatic castration-resistant prostate cancer and a prostate-specific antigen doubling time of 10 months or less.1 In the 2018 NEJM publication, Smith et al showed that apalutamide improved metastasis-free survival (MFS) over placebo (40.5 months vs. 16.2 months, hazard ratio (HR) for metastasis or death = 0.28) and apalutamide was well tolerated with only 10.6% of patients discontinuing due to adverse events (AEs). Also approved in this space is enzalutamide, which demonstrated very similar improvements in MFS over placebo.

Apalutamide has been compared with enzalutamide and no significant differences have been observed, although apalutamide has fewer reports of hypertension compared with enzalutamide.2 This abstract provides age-related efficacy and safety of apalutamide, a critical question given that many patients with nmCRPC are over the age of 75 (median age in SPARTAN = 74).

ASCO2019_SPARTAN.png

This abstract provides data on patients from three different cohorts of SPARTAN: patients aged < 65, 65-74, and ≥ 75 years old. Regardless of the age of the patient, apalutamide improved metastasis-free survival and symptomatic progression.

ASCO2019_SPARTAN_KM_curve.png
ASCO2019_SPARTAN_KM_curve2.png

Time to second progress free survival (PFS) was also improved in all age groups, which was the time from randomization to disease progression on their first anti-cancer therapy after apalutamide. In terms of treatment-emergent adverse events, 50% of patients ≥75 yo experienced a grade 3/4 event compared to 37% of patients under 65 yo in the apalutamide group. Detailed adverse events (AEs) are shown below.

ASCO2019_adverse_events.png

This abstract demonstrates that apalutamide was effective in all age groups in SPARTAN and improves metastases-free survival, PFS2, and symptomatic progression regardless of age. However, patients >75 are more likely to experience grade 3 or 4 toxicity compared to those <65. This data is useful when counseling older patients who are considering therapy for non-metastatic castration-resistant prostate cancer. Given the numerous options now available in nmCRPC (Apalutamide, Enzalutamide, Darolutamide), discussion of AEs is critical in the clinic.

ASCO2019_safety_tolerability.png

Presented by: Julie Nicole Graff, MD, Medical Oncology, VA Portland Health Care System, Portland and Knight Cancer Institute, Oregon Health & Science University, Portland, OR

Written by: Jason Zhu, MD. Fellow, Division of Hematology and Oncology, Duke University, @TheRealJasonZhu, at the 2019 ASCO Annual Meeting #ASCO19, May 31- June 4, 2019, Chicago, IL USA

References:
  1. Smith MR, Saad F, Chowdhury S, et al. Apalutamide Treatment and Metastasis-free Survival in Prostate Cancer. New England Journal of Medicine 2018;378:1408-18.
  2. Riaz IB, Bhattacharjee S, Malik S, et al. Apalutamide (APA) or enzalutamide (ENZA) in men with nonmetastatic castration-resistant prostate cancer (CRPC): A systematic review and network meta-analysis of randomized clinical trials (RCTs). J Clin Onc (2019) 263-263.