Background
Phase 3, double-blind, placebo-controlled randomized controlled trial (VIALE-C). N=211 patients with newly diagnosed AML unfit for intensive induction chemotherapy (age ≥75, or age 18–74 with ECOG PS 2–3 or organ dysfunction precluding intensive therapy). Venetoclax is a selective BCL-2 inhibitor; BCL-2 is overexpressed in AML blasts and confers survival. Low-dose cytarabine (LDAC) is a legacy option for unfit AML patients with modest activity. VIALE-C tests whether venetoclax enhances LDAC efficacy, analogous to VIALE-A which tested venetoclax + azacitidine. Published Blood 2020.
Interventions and follow up
Arm A: Venetoclax 600 mg PO daily + low-dose cytarabine (LDAC) 20 mg/m² SC twice daily days 1–10 of each 28-day cycle
Arm B: Placebo PO daily + low-dose cytarabine 20 mg/m² SC twice daily days 1–10 of each 28-day cycle
Primary endpoint: OS
mFollow up: 12.0 month
Arm B: Placebo PO daily + low-dose cytarabine 20 mg/m² SC twice daily days 1–10 of each 28-day cycle
Primary endpoint: OS
mFollow up: 12.0 month
Results
mOS: 7.2 vs 4.1 months (venetoclax+LDAC vs placebo+LDAC), HR 0.75 (95% CI 0.52–1.07), P=.11 — NOT STATISTICALLY SIGNIFICANT
CR+CRi rate: 48% vs 13%, P<.001 — highly significant
mDOR (CR+CRi): 11.1 vs 4.4 months
12-month OS rate: 30.6% vs 20.2%
Updated analysis (12-mo follow-up): OS HR 0.70 — trend toward benefit, not significant
CR+CRi rate: 48% vs 13%, P<.001 — highly significant
mDOR (CR+CRi): 11.1 vs 4.4 months
12-month OS rate: 30.6% vs 20.2%
Updated analysis (12-mo follow-up): OS HR 0.70 — trend toward benefit, not significant
Adverse events
Overall: Grade ≥3 AEs 82.0% (ven+LDAC) vs 67.9% (placebo+LDAC); discontinuation due to AEs 11% vs 10%.
Hematologic: Neutropenia grade ≥3 46% vs 26% — greater myelosuppression with venetoclax.
Infectious: Febrile neutropenia grade ≥3 32% vs 29%; infections grade ≥3 38% vs 33%.
Gastrointestinal: Nausea 34% vs 21%; diarrhea 30% vs 18%.
Metabolic: TLS risk lower with LDAC than azacitidine; venetoclax 3-day ramp-up (100→200→600 mg) required.
Hematologic: Neutropenia grade ≥3 46% vs 26% — greater myelosuppression with venetoclax.
Infectious: Febrile neutropenia grade ≥3 32% vs 29%; infections grade ≥3 38% vs 33%.
Gastrointestinal: Nausea 34% vs 21%; diarrhea 30% vs 18%.
Metabolic: TLS risk lower with LDAC than azacitidine; venetoclax 3-day ramp-up (100→200→600 mg) required.
Conclusions
Venetoclax + LDAC significantly improved CR+CRi rates (48% vs 13%) but did not meet its primary endpoint of OS superiority (mOS 7.2 vs 4.1 months, HR 0.75, P=.11) in newly diagnosed unfit AML. FDA approved the combination based on CR+CRi response rates under accelerated approval pathway, despite non-significant OS at primary analysis.
Key Limitations
The primary OS endpoint was not met — approval of venetoclax + LDAC rests on response rate (CR+CRi), not OS benefit. This contrasts with VIALE-A (venetoclax + azacitidine), which showed clear OS benefit (HR 0.66, P<.001) — making ven+aza the preferred regimen when azacitidine is feasible. The HR of 0.75 for OS may represent true clinical benefit that the trial was underpowered to confirm. Venetoclax causes prolonged cytopenias and infection risk, requiring careful monitoring and dose holds. TLS prophylaxis and monitoring mandatory. In IDH-mutated or FLT3-mutated patients, targeted inhibitor combinations may be preferred over LDAC backbone.
Clinical Context
FDA approved venetoclax + LDAC for newly diagnosed AML ineligible for intensive induction in May 2021 (accelerated, CR+CRi-based). However, in practice, venetoclax + azacitidine (VIALE-A) is overwhelmingly preferred over venetoclax + LDAC when both are feasible, given the proven OS benefit of ven+aza. Venetoclax + LDAC is reserved for patients who cannot receive azacitidine. Glasdegib + LDAC (BRIGHT 1003) is an alternative for the same population. IDH1-mutated unfit AML patients may receive ivosidenib + aza (AGILE) as targeted frontline therapy. ESMO-MCBS: not assigned.