(278) Linking Progression to Lines of Therapy in Triple Class Refractory Multiple Myeloma Patients: Experience from An Oncology Electronic Health Record Database

Publication Number: 952

Background: Multiple myeloma (MM) is a hematologic cancer. Patients with MM are considered triple class refractory (TCR) if they have been treated with at least one proteasome inhibitor, one immunomodulatory agent, and one anti-CD38 monoclonal antibody and experienced a progression or relapse while on these treatments or shortly after. In electronic health record (EHR) data, progression for MM patients can be derived using International Myeloma Working Group criteria and available laboratory data. However, using real-world data to identify refractory disease and appropriately link a progression event with a particular line of therapy (LOT) is often challenging.

Objectives: To assess whether the number of TCR patients identified and their characteristics differ when using three different time windows to link progressions to LOTs to determine refractory status.

Methods: A population-based retrospective cohort study was conducted using the nationwide de-identified EHR-derived Flatiron Health database (January 2011 – July 2021). MM patients were classified as refractory to treatment based on a progressive event that occurred after a certain period of time after starting a LOT (start of the window) through < 60 days after the last dose of that LOT (end of the window). To see the effect of modifying the time window, three different starting points were used: 30 days after LOT start, 45 days, and 60 days. The end of the time window remained the same for all definitions (ie, < 60 days of last dose of that LOT). Baseline characteristics for all three cohorts including demographic, clinical, and treatment characteristics were compared using descriptive statistics.

Results: Using the 30-day, 45-day, and 60-day time window, 189, 185, and 180 TCR patients were selected, respectively. No demographic, clinical, or treatment differences were observed in baseline characteristics across definitions (e.g. for 30d, 45d, and 60d, respectively: female (47.6%, 46.5%, 46.7%), ISS or R-ISS stage III MM at initial diagnosis ( 23.8%, 25.4%, 26.7%), receipt of stem cell transplant (41.2%, 41.6%, 41.7%)).

Conclusions: When linking progressions to LOTs to determine refractory status in EHR data, using a time window that starts 30 days after the commencement of a LOT to capture progressive events maximizes the number of TCR patients identified without affecting the distribution of patient characteristics.