EFFICACY OF ANTI-CD19 CAR T THERAPY AFTER BISPECIFIC MONOCLONAL ANTIBODY (CD19/CD3) THERAPY IN A PATIENT WITH RELAPSED Ph-POSITIVE ACUTE LYMPHOBLASTIC LEUKEMIA WITH A MASSIVE EXTRAMEDULLARY COMPONENT

Introduction. Patients with relapsed/refractory (r/r) Ph-positive acute lymphoblastic leukemia (ALL) have a poor prognosis and limited treatment options. New promising immunotherapies using CAR T cells or monoclonal antibodies (blinatumomab, inotuzumab/ozogamicin) in combination with tyrosine kinase inhibitors are being used for this group of patients. However, long-term results have not been studied when relapse or refractoriness develops after the use of one of these methods. Aim: to present a clinical observation of the use of anti-CD19 CAR T therapy after blinatumomab therapy in a patient with a relapsed course of Ph-positive acute lymphoblastic leukemia. Main findings. A 28-year-old patient was first diagnosed with Ph-positive B-ALL (transcript p210) in 2014. In the 1st line of treatment he was treated with therapy according to the protocol 'ALL-2009' with imatinib and allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, 2 months later the first molecular relapse was detected, and imatinib was replaced by dasatinib. In November 2016, a second relapse was diagnosed. In 2017, a third relapse with testicular involvement and T315I mutation was diagnosed, and therapy with ponatinib was initiated. In 2022, a 4th medullary relapse developed, and therapy with blinatumomab (5 courses) in combination with ponatinib was performed. After the 5th course of therapy, the appearance of leukaemides was noted, and asciminib was added to the therapy. However, no clinical effect was noted. The patient was treated with anti-CD19 CAR T therapy. A complete response to CAR T-cell therapy was confirmed on day 28 after CAR T administration. Further follow-up, over the course of one year, demonstrated stable clinical response and persistence of CD3-positive CAR T-cells. This case report of anti-CD19 CAR T cell therapy in a patient with CD19-positive combined relapse with massive extramedullary component after blinatumomab therapy demonstrated long-term efficacy with a 1-year follow-up.