OA11.01 Prolonged OS of Patients Exposed to Weekly Paclitaxel and Bevacizumab: Impact of the Cross-Over in the IFCT-1103 ULTIMATE Study

Overall survival (OS) is considered as the gold standard for evaluating efficacy of antineoplastic treatments, including chemotherapy and targeted therapies. In randomized trials, allowing patients to cross-over to the other arm usually prevents demonstration of a survival benefit. However, it may provide important information with clinical relevance. The phase III IFCT-1503 ULTIMATE study compared weekly paclitaxel and bevacizumab (wPB) vs. docetaxel (DOC) as second- or third-line therapy in non-squamous NSCLC. At progression, patients were allowed to cross over to the other arm. Date of progression was collected for patients who crossed over to the other arm and for those who did not cross over but received a post-discontinuation treatment within 60 days following progression. Post-discontinuation progression-free survival (PFS2) and OS2 were calculated from day 1 of post-discontinuation treatment. The study met its primary endpoint, PFS, which was significantly improved in the wPB arm (medians 5.4 vs. 3.9 mo, hazard ratio (HR) 0.62, p=0.006). No overall survival was observed (medians 9.9 vs. 11.4 mo, HR 1.18, p=0.4). Out of patients treated with DOC (n=55), those who crossed over to wPB (n=21, 38.2%) had a median PFS2 of 4.9 mo [3.1-6.2] and a median OS2 of 12.5 mo (7.0-NR), whereas those who did not cross over but received a post-discontinuation treatment (n=13, 23.7%) had a median PFS2 of 1.7 mo [1.1-2.2] and a median OS2 of 4.1 mo [2.1-5.9]. Out of patients treated with wPB (n=111), median PFS2 was 1.9 mo [1.2-2.2] for those who crossed over to DOC (n=9, 8.3%) and median PFS2 and OS2 were 1.9 mo [1.7-2.6] and 5.0 m [3.4-9.0] for those who did not cross over but received a post-discontinuation treatment (n=57, 52.3%). Allowing patients to cross over to the other arm demonstrated benefit of wPB following progression on docetaxel and explains the absence of OS benefit.