Background: Only 2 chemotherapies have shown an overall survival (OS) benefit in mCRPC: docetaxel (DOC) and CABA. In patients (pts) previously treated with a new hormonal therapy (NHT: enzalutamide or abiraterone), DOC and CABA, therapeutic options are limited. We previously reported some activity of DOC rechallenge in good responders to first-line DOC. We present here the results of a retrospective study evaluating the efficacy and safety of CABA rechallenge. Methods: Records of 70 mCRPC pts rechallenged with CABA were collected in 17 centers (France, Italy, UK, Austria). To be included, pts should have previously received DOC, NHT and CABA with a good response to CABA. Results: Of these 70 pts, 52 received DOC-NHT-CABA, 15 DOC-CABA-NHT and 3 NHT-DOC-CABA. At rechallenge, 83% had a high-volume disease (CHAARTED definition), 10% had visceral mets, 66% consumed narcotic analgesics, 68 % were ECOG 0-1 and median neutrophil/lymphocyte ratio (NLR) was 3.1. CABA was rechallenged for a median of 6 cycles (25 mg/m² q3w, 59%; 20 mg/m², 27%; 16 mg/m²q3w 11%) with prophylactic G-CSF in 47%. Median time from last CABA cycle was 8.6 months (mo). CABA rechallenge had an acceptable tolerability: 7 pts (10%) had grade 3-4 toxicity (neutropenia). Data on efficacy are reported in Table 1. Median progression-free survival (PFS) was 11.3 mo with DOC, 12 mo with NHT, 11.9 mo with first CABA (median 8 cycles), and 7.8 mo with CABA rechallenge. Median OS calculated from the first life-extending therapy was 59.9 mo (95% CI 47.8; 66.4). Conclusions: This retrospective cohort of heavily treated mCRPC pts suggests that CABA rechallenge has a good activity with a manageable toxicity. CABA rechallenge might be an option in heavily treated pts still fit to receive chemotherapy.

*Based on ECOG performance status, pain and analgesic consumption