AML-396 Venetoclax-Containing Regimens Improve Outcomes of Intensive Treatment and Allogeneic Hematopoietic Stem Cell Transplantation in Patients With Extramedullary Acute Myeloid Leukemia

Abstract

The optimal treatment strategy for patients with extramedullary acute myeloid leukemia (eAML) is questionable, especially as applied to extramedullary tumor persistence while bone marrow response is achieved. To determine whether venetoclax-containing regimens, intensive treatment, and allogeneic hematopoietic stem cell transplantation (alloHSCT) can improve outcomes in patients with eAML. Overall, 27 patients with verified eAML were included: 14 were male and 13 were female with a median age of 40 years (13-84). Standard ("7+3"), high-intensity ("HiDAC", "FLAG±Ida"), and low-intensity chemotherapy regimens were administered to all patients. Ten patients (37%) received venetoclax with 5-azacytidine (VEN-AZA) because of comorbidities or refractory disease. AlloHSCT was performed in 17 patients (63%). According to the 2017 ELN risk stratification system, 18.5% (5/27) were favorable risk, 25.9% (7/27) were intermediate risk, and 55.6% (15/27) were adverse risk. Patients with favorable genetic alterations achieved bone marrow remission more frequently (100% vs. 44%, P=0.044) but did not have advantages in the rate of complete extramedullary response (75% vs. 68%, P>0.05). Using HiDAC enabled eradication of extramedullary lesions in case of failure of standard and low-intensity regimens (85% vs. 0%, P=0.044) and decreased the rate of early (during the first 12 months) relapse (38% vs. 100%, P=0.019). The overall response rate to VEN-AZA was 70% (7/10). Five patients (50%) achieved complete eradication of extramedullary tumor after venetoclax; among them, 3 still had persistent extramedullary disease after HiDAC. Performing alloHSCT in first complete remission decreased the risk of early relapse (12% vs. 80%, P=0.015) and demonstrated better median overall survival (38.85 vs. 7.57 months, P=0.013) and relapse-free survival (38.85 vs. 3.78 months, P=0.0021) compared to alloHSCT performed in second and subsequent complete remissions. Favorable genetic aberrations do not increase the frequency of extramedullary response. Intensive treatment helps to achieve complete eradication of extramedullary tumor and reduces early relapse rate. Using VEN-AZA is effective among patients with eAML, including patients who were refractory to intensive treatment, and allows complete response achievement before alloHSCT. The best time to perform the alloHSCT among patients with eAML is the first complete remission.