Late complications and long-term care of adult CAR T-cell patients

The success of chimeric antigen receptor (CAR) T-cell therapy in adult patients with hematologic malignancies has resulted in a large number of long-term survivors who may experience late complications distinct from those in the early CAR T-cell treatment period. These late complications, defined as occurring more than 90 days after CAR T-cell infusion, include cytopenias, infections, secondary malignancies, and delayed neurotoxicities. Late cytopenias may be from prolonged recovery after lymphodepleting (LD) chemotherapy or arise anew, raising concerns for recurrent primary disease or a secondary malignancy. Cytopenias are treated with supportive care, hematopoietic cytokines, and, occasionally, hematopoietic stem cell support. LD chemotherapy profoundly affects B, T, and natural killer cells. CD19 and B-cell maturation antigen are expressed on normal B cells and plasma cells, respectively, and the targeting of these structures by CAR T-cell products can result in prolonged lymphopenias and hypogammaglobulinemia, making infection an ongoing risk. Late infections are predominantly due to respiratory viruses, reactivation of herpes viruses, and Pneumocystis jirovecii. Patients may require ongoing prophylaxis and immunoglobulin replacement therapy. Although responses may be blunted, vaccinations are generally recommended for most adult CAR T-cell patients. Both hematologic and solid secondary malignancies are a known risk of CAR T-cell therapy; retroviruses used to produce CAR T-cell products have resulted in T-cell cancers secondary to insertional oncogenesis. It is essential to monitor for late complications in adult patients receiving CAR T-cells by using a multidisciplinary approach between referring hematologist oncologists and cell therapy centers to improve the outcomes and quality of life for these patients.