Effect of venetoclax plus chemotherapy on treatment-naive acute myeloid leukemia patients with moderate to poor cytogenetic profiles and the combination's influence on the expression of proteins of the anti-apoptoic family

Abstract

Objective: This was an open-label observational assessment aimed to evaluate whether venetoclax (VEN) plus chemotherapy could enhance the therapeutic benefits for treatment-naive acute myeloid leukemia (AML) patients with adverse cytogenetic profiles. Methods: A total of 38 adult patients (including 11 patients with moderate risk stratification and 27 patients with high risk stratification) who were treated at the Affiliated Hospital of Inner Mongolia Medical University from April 2019 to May 2022 were enrolled in this study. Patients were randomized into two cohorts according to the random number method to receive single intensive chemotherapy (18/38) alone or VEN+intensive chemotherapy (20/38), respectively. The chemotherapy cohort received 2 cycles of induction chemotherapy (idarbicin or daunorubicin plus cytarabine), followed by 6 cycles of consolidation chemotherapy (cytarabine), while the treatment for the VEN + chemotherapy cohort consisted of the same chemotherapy as above plus oral VEN. Heparinized bone marrow samples were obtained from patients at enrollment de novo and post chemotherapy. The expressions of MCL-1 and BCL-2 were detected by Western blot analysis. Results: Patients with VEN+chemotherapy showed an objective response rate (ORR) of 90.0% (18/20), compared with 55.6% (10/18, P=0.012) of the chemotherapy group. Meanwhile, the VEN + chemotherapy cohort gained more benefits in progression-free survival (PFS) and overall survival (OS) than the chemotherapy cohort (mean PFS: 27.1 months versus 17.9 months, P=0.038; mean OS: 32.2 months versus 21.3 months, P=0.004). For patients with moderate risk stratification, there were no differences in the ORR and PFS between the chemotherapy cohort and the VEN + chemotherapy cohort: the ORR was 80.0% (4/5) versus 100% (6/6, P=0.251), and the PFS was 27.9 months versus 32.0 months (P=0.582). Moreover, the ORR was 85.7% (12/14) for the VEN+chemotherapy cohort and 46.2% (6/13) for the chemotherapy cohort in the high risk profile (P=0.029). The PFS of the VEN+chemotherapy cohort was superior to the chemotherapy cohort in the high risk profile (mean PFS: 23.7 months versus 11.1 months, P=0.002). Meanwhile, in the chemotherapy cohort, there were no difference in the PFS between FAB-M5 patients and non-FAB-M5 patients; the mean PFS was 20.0 months versus 15.5 months (P=0.298) for the two groups. Nevertheless, FAB-M5 patients were inferior to non-FAB-M5 patients in PFS in the VEN + chemotherapy arm (mean PFS: 19.6 months versus 30.2 months, P=0.031). The most frequent grade 4 hematological toxicities (therapy related) were leukopenia and thrombopenia. Grade 3/4 hematological adverse events in patients treated with VEN+chemotherapy were not increased compared with those who received chemotherapy. Western blot showed VEN continuously decreased the expression of BCL-2 proteins in both FAB-M5 and non-FAB-M5 patients, but obviously increased the expression of MCL-1 proteins only in FAB-M5 patients. Conclusions: VEN combined with intensive chemotherapy have yielded high ORR and survival advantages for de novo AML patients with poor cytogenetics profiles. The high-expression of MCL-1 may drive resistance to VEN.