Current assessment and management of measurable residual disease in patients with acute lymphoblastic leukemia in the setting of CAR-T-cell therapy

Chimeric antigen receptor (CAR)-modified T-cell therapy has achieved remarkable success in the treatment of acute lymphoblastic leukemia (ALL). Measurable/minimal residual disease (MRD) monitoring plays a significant role in the prognostication and management of patients undergoing CAR-T-cell therapy. Common MRD detection methods include flow cytometry (FCM), polymerase chain reaction (PCR), and next-generation sequencing (NGS), and each method has advantages and limitations. It has been well documented that MRD positivity predicts a poor prognosis and even disease relapse. Thus, how to perform prognostic evaluations, stratify risk based on MRD status, and apply MRD monitoring to guide individual therapeutic decisions have important implications in clinical practice. This review assesses the common and novel MRD assessment methods. In addition, we emphasize the critical role of MRD as a prognostic biomarker and summarize the latest studies regarding MRD-directed combination therapy with CAR-T-cell therapy and allogeneic hematopoietic stem cell transplantation (allo-HSCT), as well as other therapeutic strategies to improve treatment effect. Furthermore, this review discusses current challenges and strategies for MRD detection in the setting of disease relapse after targeted therapy.