PCN5 Real-World Incidence and Management of Adverse Events (AE) in Patients with NON-Metastatic Castrate-Resistant Prostate Cancer Receiving Apalutamide or Enzalutamide

Second generation androgen receptor inhibitors (SGARIs) apalutamide and enzalutamide have been associated with adverse events (AE) such as fatigue, falls, fracture and rash, among others, in non-metastatic castrate resistant prostate cancer (nmCRPC) patients as identified in clinical trials. Objectives of this real-world study were to describe nmCRPC patients and their treatment patterns, and to estimate incidence and management of AEs in patients receiving apalutamide and enzalutamide. This was a retrospective chart review study conducted in 43 nmCRPC-treating sites in the US. In Phase-1, all patients starting an SGARI between February 2018 and December 2018 and any AEs they experienced were recorded. In Phase-2, detailed chart data were collected in a subset of patients with ≥1 AEs to better understand AE severity and management. Descriptive results were summarized. 699 patients were recorded by 36 medical oncologists and 6 urologist/urologist-oncologists in Phase-1. Among these, 75.1% experienced ≥1 AE and 44.2% experienced ≥1 central nervous system AE (defined as fatigue, asthenia, headache, fracture, falls, seizures, dizziness, cognitive impairment). Most common AEs were fatigue (23.5%), hot flush (13.9%), and arthralgia (13.6%). Phase-2 patient (apalutamide, 125; enzalutamide, 125) demographics were: Caucasian 72%, mean age 71 years; 0-1 ECOG score 86.0%. PSA-doubling time (PSA-DT) <10 months was chosen as reason to initiate treatment in 40% of patients, while 2 consecutive PSA levels that would allow for assessment of PSA-DT were recorded in only 16% of patient-charts. Grade 3-4 and Grade 5 AEs occurred in 14.4% and 0.4% patients, respectively. Actions to manage AEs included treatment of the AE (38.0%), SGARI discontinuation (10.4%), dose reduction (7.6%), and AE-related hospitalization (4.8%). Using real-world data, we found that nmCRPPC patients treated with SGARIs have high susceptibility to AEs, with nearly 40% requiring treatment. These results highlight the continued need to improve tolerance of SGARI-based therapies in nmCRPC.