[Clinical Characteristics of Acute Leukemia Patients with PICALM∷MLLT10 Fusion Gene Positivity and Prognostic Analysis of Combined Venetoclax Targeted Therapy].

Abstract

Objective: To investigate the clinical characteristics and prognostic of venetoclax (VEN) combined targeted therapy in acute leukemia (AL) patients with PICALM∷MLLT10 fusion gene positivity.

Methods: A retrospective analysis was conducted on 16 PICALM∷MLLT10-positive AL patients treated at the First Affiliated Hospital of Soochow University from January 2021 to August 2024. These patients were diagnosed by targeted RNA sequencing (RNA-seq) or reverse transcription multiplex PCR, including newly diagnosed and relapsed/refractory (R/R) cases. The immunophenotypes, genetic features, gene mutations, and the efficacy of VEN combination targeted therapy of patients were evaluated.

Results: Among the 16 cases, 3 were confirmed by reverse transcription multiplex PCR, and 13 were detected through targeted RNA-seq among 528 AL patients, with a detection rate of 2.46%. The averge age of patients was (28.0±8.58) years. Patients exhibited diverse immunophenotypes, including 7 cases of acute myeloid leukemia, 5 of acute T-lymphoblastic leukemia, 1 of acute B-lymphoblastic leukemia, 1 of acute undifferentiated leukemia, and 2 of mixed-phenotype acute leukemia. Among them, 11 had extramedullary disease (EMD), 14 expressed CD7, and 12 expressed CD33. Major co-occurring mutations included PHF6 (6 cases), NOTCH1 (5 cases), and 7 cases with complex karyotypes. Of the 12 patients who received standard induction therapy, 7 did not achieve remission (PR+NR). All 4 patients treated with VEN combination therapy achieved complete remission (CR). Among the 7 induction failure cases, 4 achieved CR upon re-induction with VEN, while the remaining 3 re-induced with standard therapy, did not achieve CR. Thirteen patients received allogeneic hematopoietic stem cell transplantation, including 6 who received maintenance therapy with hypomethylating agents (HMA) alone or in combination with VEN, and seven were followed up. Survival analysis showed that the overall survival was better in the maintenance therapy group (P =0.044).

Conclusion: PICALM∷MLLT10-positive AL involves multiple lineages and demonstrates poor response to conventional chemotherapy. VEN combination therapy shows promising efficacy in both newly diagnosed and R/R patients. Post-transplant maintenance therapy with HMA alone or combined with VEN may extend survival; however, further clinical validation is required.