Patterns and Predictors of Failure in Recurrent or Refractory Large B-Cell Lymphomas After Chimeric Antigen Receptor T-Cell Therapy.

Purpose Chimeric antigen receptor T-cell (CAR T) therapy is capable of eliciting durable responses in patients with relapsed/refractory (R/R) lymphomas. However, most treated patients relapse. Patterns of failure after CAR T have not been previously characterized, and may provide insights into the mechanisms of resistance guiding future treatment strategies. Methods and Materials This is a retrospective analysis of patients with R/R large B-cell lymphoma who were treated with anti-CD19 CAR T at a National Cancer Institute-designated Comprehensive Cancer Center between 2015 and 2019. Pre- and posttreatment positron emission/computed tomography scans were analyzed to assess the progression of existing (local failures) versus new, nonoverlapping lesions (de novo failures) and identify lesions at a high risk for progression. Results A total of 469 pretreatment lesions in 63 patients were identified. At a median follow-up of 12.6 months, 36 patients (57%) recurred. Most (n = 31; 86%) had a component of local failure, and 13 patients (36%) exhibited strictly local failures. Even when progressing, 84% of recurrent patients continued to have a subset of pretreatment lesions maintain positron emission/computed tomography resolution. Lesions at a high risk for local failure included those with a diameter ≥5 cm (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.55-3.55; P Conclusions Most patients who recur after CAR T experience a component of local progression. Furthermore, lesions with high-risk features, particularly large size, were associated with inferior treatment efficacy and patient survival. Taken together, these observations suggest that lesion-specific resistance may contribute to CAR T treatment failure. Locally directed therapies to high-risk lesions, such as radiation therapy, may be a viable strategy to prevent CAR T failures in select patients.