822PPreliminary safety results of the randomized phase II ABIDO-SOGUG trial: Toxicity profile of concomitant abiraterone acetate + docetaxel treatment in comparison to docetaxel

Background: Abiraterone acetate (AA) improves OS and rPFS in asymptomatic/minimally symptomatic mCRPC patients (pts) who are chemotherapy (CT) naïve. Upon progression to this strategy, Docetaxel (D) is currently one of standard treatments. However, the value of maintaining AA along with D despite progression to the former has not been tested yet. ABIDO is a randomized-phase II trial that evaluates efficacy and safety of D + AA vs. D after disease progression to first line AA in mCRPC. Methods: mCRPC CT naïve pts with no visceral metastases, ECOG PS 0-1, testosterone < 50 ng/dL and adequate, hematologic, hepatic, and renal function were included. The study has two stages. In stage I pts receive AA at the approved regime (AA 1000mg/day+prednisone (P) 5 mgbid) until progressive disease determined by PSCWG2 criteria. Upon progression, in stage II, pts are randomized to receive either three-weekly D + daily AA+P (Arm A) or three-weekly D alone (Arm B). Results: So far 148 pts have been included and 88 were randomized already. Of those 77 have completed D and have been analyzed (39 in arm A and 38 in Arm B). Median age was 72 y/o, 43% had ECOG 0 and 88% had bone metastases and 16% visceral metastases. Patients received 255 and 274 cycles of D in Arm A and B respectively with a median number of cycles of 7 and 8. Docetaxel median dose intensity was 90% and 92% for each arm and 94% for AA. Nine pts discontinued treatment due to toxicity, 5 in arm A and 4 in arm B. Most frequent G3-4 toxicities per arm (A/B) were: neutropenia (56%; 29%), febrile neutropenia (21%; 8%), diarrhea (10%; 8%), and asthenia (13%; 11%). Most common toxicities all grades per arm were: asthenia (74%; 66%), neutropenia (59%; 34%), alopecia (44%; 45%), nail toxicity (49%; 34%), diarrhea (46%; 42%), neurotoxicity (39%; 42%), nauseas (28%; 26%), mucositis (26%; 29%) and anemia (23%;11%). Conclusions: In the AA maintenance cohort, more frequent and severe hematological treatment related adverse events (neutropenia, febrile neutropenia and anemia) were observed. No other differences were relevant. Prophylactic G-CSF use is encouraged in all patients. These preliminary data require confirmation once the study is completed. Clinical trial identification: NCT02036060; EudraCT: 2013-003811-23. Editorial acknowledgement: Juan Luis Sanz, APICES. Legal entity responsible for the study: SOGUG: Spanish Oncology Genitourinary Group. Funding: Janssen-Cilag, S.A. Disclosure: J. Puente: Honoraria: Astellas, Bayer, Janssen, Roche, Ipsen; Consulting or advisory role: Astellas, Roche, Ipsen, Pfizer, Bristol-Myers Squibb, Merck sharp & Dohme; Research funding: Astellas. M.J. Mendez Vidal: Consulting: Janssen, Pfizer, Astellas, Sanofi, Bayer, Bristol-Myers Squibb, Novartis, Roche. I. Duran: Honoraria: Bristol-Myers Squibb, Ipsen, Roche; Advisory role: Roche, MSD, Bayer, Bristol-Myers Squibb. A. Sanchez-Hernandez: Honoraria: Sanofi, Astellas, Janssen, Bayer, Roche, Boehringer Ingelheim, Pierre-Fabre, Bristol-Myers Squibb, MSD; Consulting: Sanofi, Astellas, Janssen, Bayer, Roche, Boehringer Ingelheim, Pierre-Fabre, Bristol-Myers Squibb, MSD; Spikers bureau: Sanofi, Astellas, Janssen, Bayer, Roche, Boehringer Ingelheim, Pierre-Fabre, Bristol-Myers Squibb, MSD. T. Alonso: Consulting: Sanofi. M.A. Gonzalez del Alba Baamonde: Consulting: Astellas, Sanofi, Bayer, Janssen, Pfizer, Bristol-Myers Squibb, Eisai, Pierre Fabre. M. Lazaro: Expert testimony: Janssen, Pfizer, Roche. M.A. Climent Duran: Honoraria: Janssen, Astellas, Sanofi, Bayer; Consulting: Janssen, Sanofi, Bayer. All other authors have declared no conflicts of interest.