Targeted immunotherapeutic approaches represent highly effective novel therapies that can treat chemotherapy resistant or relapsed high-risk ALL. Blinatumomab, a bispecific T-cell engager (BiTE), creates an immune synapse between a cytolytic T cell and the CD19 lymphoblast, 1 that once engaged, activates T cells inducing caspase activation and apoptosis of blast cells. Expansion of T cells then occurs, leading to a more than doubling of baseline within 2 to 3 weeks of therapy initiation. 2,3 Blinatumomab has recently shown a positive effect on overall survival in a phase 1-2 pediatric clinical trial in patients with ALL, with a 39% complete remission rate at the recommended phase 2 dose. 4,5 Chimeric antigen receptor (CAR) T cells have emerged as a powerful class of anti-cancer therapeutics, particularly for B-cell ALL, where unprecedented rates of remission have been achieved in the multiply relapsed and refractory population. 6-10 CARs have the specificity of a monoclonal antibody combined with the intracellular signaling domain of T cells, which results in a recombinant receptor that can recognize and bind to tumor cells, which leads to activation and expansion of CAR-T cells, and apoptosis of blasts. 6-10
AbstractTargeted immunotherapeutic approaches have become an attractive, novel therapy in the treatment of chemotherapy resistant or relapsed high-risk acute lymphoblastic leukemia (ALL). Many of these therapies, chimeric antigen receptor (CAR) T cells, and bispecific T-cell engagers (BiTE) in particular, rely on surface expression of the antigen for activity and efficacy. As such, antigen loss is a growing problem in this relapsed population. We present a case of relapsed, refractory B-ALL that has immunophenotypic variability in the leukemia blasts in response to the sequential targeted immunotherapies received. This case additionally describes a bolstered CAR-T cell expansion after the patient received subsequent blinatumomab therapy, suggesting a potential strategy for utilization of multiagent immunotherapies to have synergistic approaches to eradicate disease and prolong remission in patients with relapsed hematologic malignancies (Anti-CD22 chimeric receptor T cells in pediatric and young adult patients with recurrent or relapsed CD22-expressing B-cell malignancies. clinicaltrials.gov NCT02315612).
K E Y W O R D Schimeric antigen receptor T cell, immunotherapy, leukemia