Reliability of mRECIST criteria for HCC in the relationship between response and progression.

Abstract

e16645 Background: Response Evaluation Criteria in Solid Tumors (RECIST) guidelines consider the measurement of treatment response based on tumor shrinkage due to the antitumor activity of cytotoxic drugs. However, tumor response can be misleading when molecular-targeted therapies or locoregional therapies are used in Hepatocellular carcinoma (HCC). RECIST 1.1 does not specify for changes in tumor vascularity or necrosis. The modified RECIST (mRECIST) adapts the concept of viable (Enhancing) tumor and tumoral necrosis in the assessment of response. According to mRECIST, if a tumor that is solid at baseline becomes entirely necrotic, all the tumors are evaluated as complete response (CR). Edeline et al. evaluated the response of sorafenib in HCC and reported that 26.2% of the patients who were classified as having stable disease (SD) according to RECIST were reclassified as responding to treatment, according to the mRECIST. Takada et al. analyzed tumor responses with sorafenib in HCC according to RECIST 1.1 and mRECIST where 13.1 % of patients were assessed as responders by mRECIST and 7.8 % by RECIST 1.1. There was a significant difference in overall survival (OS) between responders and non-responders according to mRECIST ( p = 0.0117), but no significant difference in OS between responders and non-responders according to RECIST 1.1 ( p = 0.0722). Methods: A retrospective review of time points associated with HCC was performed for 3 clinical trials with a total of 1060 patients with 3998 time points and evaluated using RECIST and mRECIST guidelines. The responses: overall response rate (ORR), CR and partial response (PR) were compared using both guidelines and correlated with disease progression. Results: At a subject level, there are 128 responders by RECIST, of which 73 progressed (57%), 274 responders by mRECIST, of which 156 progressed (57%); while of 148 responders by mRECIST, which were non-responders by RECIST only 80 progressed (54%) within the stipulated study duration. At the visit level, there are 520 timepoints of response by both RECIST & mRECIST, while there are 509 timepoints of response by mRECIST, which are SD by RECIST due to necrosis related difference in criteria implementation. Conclusions: It can be concluded that subjects with response by mRECIST with response or no response by RECIST tend to have an excellent correlation with progression as well. The use of mRECIST improves the outcome of the response in HCC treatment. [Table: see text]