Individual patient data analysis to assess modifications to the RECIST criteria

Assessment of 5 lesions per patient led to a difference in best overall response assignment for an estimated 209 (3.2%) patients as compared to RECIST version 1.0. However, these changes did not affect the overall response rate. Progression-free survival was only minimally affected by measuring fewer lesions. In contrast, removing the requirement for response confirmation led to a significant increase in the numbers of patients classified as responders, resulting in a relative increase of approximately 19% in response rate. An algorithm using a maximum of three target lesions shows high concordance with the 10 lesions requirement in terms of response and TTP assignment. Concern that appropriate assessment of disease within an organ requires two lesions to be followed per organ suggests the approach of following two target lesions per organ, up to a maximum of five target lesions overall. Both strategies seem reasonable based on the data warehouse. The requirement of response confirmation in trials where this is a primary end-point is recommended to be maintained as its removal would substantially increase reported response rates.