Case Report: Sonrotoclax in combination with azacitidine for acute undifferentiated leukemia

Acute undifferentiated leukemia (AUL) is a rare, highly aggressive hematologic malignancy with a dismal prognosis and no standardized first-line treatment. Conventional acute myeloid leukemia (AML)-type or acute lymphoblastic leukemia (ALL)-type chemotherapy yields low remission rates, and most patients fail to achieve sufficient disease control to bridge to curative allogeneic hematopoietic stem cell transplantation. Herein, we report a 56-year-old male with newly diagnosed AUL harboring TET2, DNMT3A and U2AF1 mutations, who received induction therapy with the novel B-cell lymphoma-2 (BCL-2) inhibitor sonrotoclax combined with azacitidine. Morphological complete remission with incomplete hematologic recovery (CRi) was achieved after one induction cycle, and deep remission with negative measurable residual disease was confirmed at post-treatment reassessment. The primary adverse events were myelosuppression and febrile neutropenia, both of which were well controlled with supportive care. This case suggests that sonrotoclax plus azacitidine represents a promising therapeutic strategy for AUL, particularly in patients with epigenetic driver mutations. Further large-scale studies are required to verify the long-term efficacy and safety of this regimen.