Cytopenia Management in Patients With Newly Diagnosed Acute Myeloid Leukemia Treated With Venetoclax Plus Azacitidine in the VIALE-A Study

Background: Patients with acute myeloid leukemia (AML) who are older or ineligible for intensive induction chemotherapy have limited treatment options and poor survival. In the VIALE-A study, venetoclax (Ven) + azacitidine (Aza) improved overall survival and response rates compared with placebo (Pbo) + Aza in older or unfit patients with newly diagnosed AML (DiNardo et al. N Engl J Med. 2020). Although cytopenia is common in AML, Ven+Aza was associated with hematologic adverse events in 83% of patients in the VIALE-A study (vs 69% in the Pbo+Aza arm). Here, the frequency and management of cytopenia are analyzed in patients achieving a best response of complete remission (CR) or CR with partial hematologic recovery (CRh) in the VIALE-A study.

Methods: This double-blind, Pbo-controlled, multicenter Phase 3 study (NCT02993523) enrolled patients with newly diagnosed AML who were ineligible for intensive chemotherapy due to age ≥75 years or comorbidities. Patients were randomized 2:1 to receive 75 mg/m² Aza (Days 1-7 of each 28-day cycle) plus either daily 400 mg Ven (Ven+Aza) or Pbo (Pbo+Aza). Disease response was assessed via bone marrow aspirate and biopsy at the end of Cycle 1 and at least every 3 cycles thereafter. After patients achieved blast clearance (bone marrow blasts <5%), various dosing modifications were implemented to manage cytopenia (Table 1). Cytopenia, defined here as Grade 4 neutropenia (absolute neutrophil count <500/μL) or Grade 4 thrombocytopenia (platelet count <25×10³/μL) lasting ≥7 days, was assessed using laboratory data.

Results: In total, 186 of 283 (66%) Ven+Aza-treated patients and 33 of 144 (23%) Pbo+Aza-treated patients achieved a best response of CR or CRh (CR/CRh). Of patients with a best response of CR/CRh in the Ven+Aza arm, 77% achieved blast clearance by the end of Cycle 1, 88% by the end of Cycle 2, 92% by the end of Cycle 3, and 98% by the end of Cycle 4. Of patients with a best response of CR/CRh in the Pbo+Aza arm, 33% achieved blast clearance by the end of Cycle 1, 55% by the end of Cycle 2, 76% by the end of Cycle 3, and 91% by the end of Cycle 4. After achieving blast clearance, 75% and 67% of patients in the Ven+Aza and Pbo+Aza arms, respectively, had a delay of the next cycle, with a median duration per cycle delay post–blast clearance (range) of 9.0 (1–39) and 5.5 (1–21) days.

Among CR/CRh patients, more patients receiving Ven+Aza versus Pbo+Aza had post-remission cytopenia (87% vs 45%; Table 2). A similar percentage of CR/CRh patients in both arms (Ven+Aza, 26%; Pbo+Aza, 24%) had in-cycle dose interruptions (ie, days without Ven/Pbo exposure between a cycle’s first and last Ven/Pbo dose), with a median duration (range) of 2.0 days (1–20) for Ven+Aza and 1.0 (1–13) for Pbo+Aza. A greater proportion of CR/CRh patients experienced post-remission cycle delays due to cytopenia in the Ven+Aza arm (77%) than in the Pbo+Aza arm (30%). Furthermore, a higher percentage of CR/CRh patients had post-remission cycles with a reduction in Ven/Pbo dosing days and/or cycle delays totaling ≥7 days due to cytopenia in the Ven+Aza arm (75%) than in the Pbo+Aza arm (27%). Among these patients, the median percentage of days without Ven/Pbo administration while in remission (out of the total number of days in remission) was 18% (range, 1–69) in the Ven+Aza arm and 13% (3–44) in the Pbo+Aza arm. Ultimately, 129 CR/CRh patients (69%) in the Ven+Aza arm and 10 (30%) in the Pbo+Aza arm received ≤21-day Ven/Pbo dosing post-remission, with a median time from remission to first ≤21-day cycle (range) of 92.0 days (1–480) for Ven+Aza and 74.0 days (6–405) for Pbo+Aza.

Conclusion: In the VIALE-A study of older or unfit patients with newly diagnosed AML, the majority of responding patients in the Ven+Aza arm required dosing modifications to manage cytopenia, of which delays between cycles or within-cycle reductions of Ven dosing days were most common. Post-remission cytopenia and dosing modifications were more frequent with Ven+Aza versus Pbo+Aza treatment. The impact of cytopenia and dosing modifications on patient outcomes with Ven+Aza is currently being analyzed and will be reported at a future date.