RW2 RETROSPECTIVE REAL-WORLD ASSESSMENT OF RESPONSE OUTCOMES IN ONCOLOGY

Abstract

Clinical trial efficacy endpoints for treatments in oncology traditionally include Response Evaluation Criteria in Solid Tumors (RECIST) response assessments, including objective response rate (ORR), best overall response (BOR), and duration of response (DOR). This requires precise measurement of tumor sizes from imaging tests. Increasingly, there is value in assembling these endpoints using real-world data and study designs particularly in rare tumor types or where a randomized controlled trial (RCT) design is not viable. Our objective is to describe methodologic considerations and factors affecting interpretation of response outcomes in prospective RCTs versus real-world retrospective studies. Data from electronic health records were collected to calculate response endpoints for retrospective observational studies. Operational definitions were used to classify treatment response based on data type and whether assessments were clinical, physician-assessed response, or radiographic tumor measurements similar to RECIST. Educational materials and case report forms were developed. Sensitivity analysis were performed to assess how data variations affected results. Collection and interpretation of real-world treatment response was influenced by the number of patients with available data; frequency of assessments including office visits or imaging tests; types of imaging tests; availability of baseline and follow-up tests; and reporting of target lesion sizes. Difference in response rates were observed depending on availability and timing of data. Real-world response data can provide valuable information. Unlike standardized assessments in clinical trials, variability exists in clinical practice. Response measurements may be influenced by factors including physician or patient preferences, disease severity, payer coverage, and scheduling. Results may differ from RCTs, underscoring the importance of standardized operational definitions and timing of assessments to aid interpretation of results. This is also important as immunotherapies and new methods such as Immune-Modified Response Evaluation Criteria In Solid Tumors (imRECIST) are developed.