Measurable residual disease after CAR T-cell therapy

Testing for measurable residual disease (MRD) provides important prognostic and predictive implications on survival and management of many hematologic diseases. Among the many clinical uses of MRD is post-therapy response assessment and risk stratification. With the integration of precision medicine in routine clinical care and the development of novel and innovative therapies resulting in deeper responses, it is necessary to refine the role of MRD, standardize available methodologies and define its role as a surrogate endpoint for relapse and time-to-next treatment in clinical studies. Chimeric Antigen Receptor (CAR) T-cell therapy is an approved treatment for various hematologic malignancies. Even though it produces high rates of remission, the durability of response is still a consideration as almost 40% to 50% of patients eventually relapse. MRD testing as a prognostic and surrogate marker is being explored in patients after CAR T-cell therapy to predict early relapse. In this chapter, we review the various tools available for MRD detection and monitoring post-CAR T-cell therapy. We later discuss disease-specific MRD assessment and its application in recent studies in the post-CAR T setting.