Comparison of response using mRECIST versus RECIST 1.1 Criteria in advanced hepatocellular carcinoma: A retrospective analysis of multicenter clinical trials.

Abstract

4595 Background: mRECIST 2010 criteria for Hepatocellular Carcinoma (HCC) response assessment were focused on a concept of measuring viable tumor tissue showing enhancement in arterial phase of contrast enhanced CT/MRI, whereas RECIST 1.1 focuses mainly on the morphological measurements quantifying the tumor size irrespective of viability of the tumor and associated response to therapy. RECIST 1.1 does not address measures of antitumor activity other than tumor shrinkage, underestimating responses in HCC. Methods: We retrospectively analyzed multiple, phase III, multi-center clinical trials using both mRECIST and RECIST 1.1 criteria, read separately. The intent was to compare the overall responses at post-baseline assessments read independently by the two criteria. A total of 1682 subjects with 6159 post-baseline imaging timepoints were included in the analysis. The Overall response rate (ORR) as measured by sum of complete response (CR) and partial response(PR) and the Complete response rate (CRR) were evaluated. In addition, we also assessed the number of not evaluable (NE) time points by each criteria separately. We tested the following hypotheses 1. mRECIST may have better ORR and CRR compared to RECIST 1.1. 2. RECIST 1.1 may have more timepoints with Stable disease (SD) compared to mRECIST. 3. mRECIST may have more Not evaluable (NE) timepoints due to stringent imaging specifications. Results: The results are tabulated in the table below: Conclusions: The results above suggest that mRECIST shows more than double the CRR than RECIST 1.1, and the ORR is 62% higher using mRECIST than RECIST 1.1. Stable disease as expected was more commonly observed in RECIST 1.1 analysis. A NE response was 60% more common in mRECIST criteria evaluation. Our analysis confirms that reduction in viable tumor/enhancing area using contrast-enhanced radiologic imaging is the more optimal method to assess treatment response in HCC, and using RECIST 1.1 tumor measurement of a longest diameter as the sole measure of response, may not be adequate in response assessment for HCC. Our analysis validates and supports more widespread adoption of mRECIST in HCC tumor response assessment. Our results also indicate the need for uniform image acquisition and rigorous image quality control for a valid response in mRECIST criteria. [Table: see text]