Background: Apa-RP is a multicenter, open-label, single-arm Phase 2 study of adjuvant treatment with apalutamide and androgen deprivation therapy (ADT) in treatment-naïve patients with high-risk localized prostate cancer who underwent radical prostatectomy (NCT04523207). A rash management guide was implemented to improve dermatologic adverse events (AEs) that included proactive patient education on appropriate skin care and monitoring for rash, and frequent outreach through patient phone calls. We present rash-related safety data from Apa-RP compared with data from 2 Phase 3 apalutamide registrational studies. Methods: 108 patients were treated with apalutamide 240 mg once daily with ADT for 12 28-day cycles. Rash occurrence was monitored and skin-related AEs were defined by Common Terminology Criteria for Adverse Events (CTCAE) v5.0 grading scale. These factors were collated and compared with data from the North American population from SPARTAN (non-metastatic castration-resistant prostate cancer; NCT01946204) and TITAN (metastatic castration-sensitive prostate cancer; NCT02489318). Results: Of 108 patients in Apa-RP, 21.3% developed rash vs 28.3% in SPARTAN and 33.3% in TITAN. Information on rash severity, median time to onset of first rash, the proportion of patients with rash resolution, median time to resolution and the treatment administered for rash are provided in the Table. Conclusions: The Apa-RP rash management protocol demonstrates a proactive and patient-empowered approach to monitoring and managing patients on apalutamide who develop skin rash. With increased vigilance from the care team and appropriate patient education, it may be possible to reduce the incidence, severity and median time to resolution of skin rash. Clinical trial information: NCT04523207.

*Rash is a grouped term including MedDRA Preferred Terms related to general term ‘rash’. ^†Proportion of patients with any Grade rash (n/N). ^‡Regardless of Grade. Starting time for median calculation is the date of first dose of study drug. ^¶Defined as all skin rashes being reported as resolved (regardless of initial or worst Grade). Starting time for median calculation is the date of first skin rash.