The committee discussed the company's approach to crossover using the more mature overall survival data from PROFILE 1007. The mature data were based on median follow-up of 51 and 53 months, by which time 67% and 73% of patients had died in the crizotinib and chemotherapy arms respectively. This compared with the company's original submission based on a median follow-up of 12.2 months in each arm, when 28% and 27% of patients had died in the crizotinib and chemotherapy arms respectively. The committee noted that in the mature dataset there was a higher proportion of patients who switched to other treatments when their disease progressed. In the chemotherapy arm (n=174), 87% and 64% of patients in the mature and the previous dataset, respectively, switched from chemotherapy to crizotinib or other drugs. The committee was aware that the company had revisited the most appropriate method for modelling overall survival when using the mature data. The company argued that because of the high degree of crossover, the small number of patients remaining on chemotherapy in the control arm, and the variation in post-progression therapies, the IPTCW method was no longer appropriate. The company therefore adjusted the survival data using the RPSFT method. Unlike IPTCW, the RPSFT method relies on the assumption of a 'common treatment effect', meaning that a therapy is as effective when given later (for example, at progression) as it would be earlier (before progression). The committee asked the company whether it had tested this assumption. The company was unable to satisfactorily answer the committee. The ERG agreed that the RPSFT method was a better choice than the IPTCW approach, but it noted that the company had not explored other methods, for example the iterative parameter estimation and 2-stage methods. Noting that in the analyses the hazard ratio declined from 0.79 (adjusted for crossover, less mature data) to 0.38 (adjusted for crossover, more mature data), the ERG highlighted that the more mature data suggested that crizotinib (compared with docetaxel) appeared to be much more effective than in the company's original submission. The committee agreed that irrespective of the method of crossover adjustment used, and despite the longer follow-up, the size of the overall survival estimate associated with crizotinib is uncertain.