Peax: Men With Metastatic Castrate-Resistant Prostate Cancer (Mcrpc) Treated With Either Sipuleucel-T (Sip-T), Enzalutamide (Enza) Or Abiraterone Acetate (Abi) Undergoing Cardiopulmonary Exercise Testing (Cpet).

281Background: Both ENZA and ABI are associated with significant toxicity to the cardiovascular-musculoskeletal system and physical side effects. However whether they cause a decline in cardiorespiratory fitness (CRF), as conventional ADT does, has not been studied. We hypothesized that men treated with ENZA or ABI would have a significant decline in CRF, whereas those treated with SIP-T would not. Methods: Men starting standard of care (SOC) ENZA or ABI for asymptomatic or minimally symptomatic mCRPC were treated per institutional standards. SIP-T (SOC) is the control arm. Primary endpoint is change in VO2peak from baseline to week 21 by CPET. Secondary endpoints include measurement of functional status by patient reported outcomes (FACT-P, FACIT-Fatigue) and physician reported outcomes (ECOG PS, AEs). Results: In this single-site, prospective, parallel group, observational study, 28 pts completed the baseline and week 21 CPET and secondary assessments. Median age was 68 years; 86% were white. Two-thirds...