Background
Phase 3, open-label, randomized controlled trial (ALFA-0701). N=280 patients with newly diagnosed AML (excluding APL), age 50–70 years, eligible for intensive chemotherapy. Gemtuzumab ozogamicin (GO) is a humanized anti-CD33 antibody conjugated to calicheamicin — an antibody-drug conjugate targeting CD33, expressed on >80% of AML blasts. GO was initially approved in 2000 (accelerated, non-randomized data), voluntarily withdrawn in 2010 due to a negative phase 3 trial (SWOG S0106, full dose GO), and re-evaluated using fractionated lower doses in this trial. ALFA-0701 used fractionated GO (3 mg/m² × 3 doses per induction cycle) to reduce sinusoidal obstruction syndrome (SOS/VOD) risk. Published Lancet 2012.
Interventions and follow up
Arm A: Daunorubicin 60 mg/m² IV days 1–3 + cytarabine 200 mg/m² CI days 1–7 + gemtuzumab ozogamicin 3 mg/m² IV days 1, 4, 7 (induction); followed by consolidation cytarabine ± GO + daunorubici
Arm B: Daunorubicin 60 mg/m² IV days 1–3 + cytarabine 200 mg/m² CI days 1–7 (standard 7+3 induction without GO); consolidation without GO
Primary endpoint: EFS
mFollow up: 34 month
Arm B: Daunorubicin 60 mg/m² IV days 1–3 + cytarabine 200 mg/m² CI days 1–7 (standard 7+3 induction without GO); consolidation without GO
Primary endpoint: EFS
mFollow up: 34 month
Results
EFS: 17.1 vs 9.7 months (GO+DA vs DA), HR 0.56, P=.0002
RFS (CR patients): 28.0 vs 11.3 months, HR 0.52, P=.0003
2-yr OS: 53.2% vs 41.9% (HR 0.69; became significant at longer follow-up, landmark P=.05)
CR rate: 81% (GO+DA) vs 74% (DA) — similar
Benefit by cytogenetics: EFS benefit in favorable (CBF-AML) and intermediate risk; no significant benefit in adverse cytogenetics
RFS (CR patients): 28.0 vs 11.3 months, HR 0.52, P=.0003
2-yr OS: 53.2% vs 41.9% (HR 0.69; became significant at longer follow-up, landmark P=.05)
CR rate: 81% (GO+DA) vs 74% (DA) — similar
Benefit by cytogenetics: EFS benefit in favorable (CBF-AML) and intermediate risk; no significant benefit in adverse cytogenetics
Adverse events
Overall: No increase in early deaths with GO; treatment discontinuation 4% vs 2%.
Hepatic: AST/ALT elevation 15–20% (manageable); sinusoidal obstruction syndrome (SOS/VOD) 3% (fractionated GO) vs 0% — much lower than the original 9 mg/m² single-dose regimen.
Hematologic: Prolonged grade ≥3 thrombocytopenia in GO arm (median platelet recovery delayed ~5 days).
Infectious: Febrile neutropenia grade ≥3 77% vs 73%.
Infusion: Infusion reactions (GO) 1–2%.
Hepatic: AST/ALT elevation 15–20% (manageable); sinusoidal obstruction syndrome (SOS/VOD) 3% (fractionated GO) vs 0% — much lower than the original 9 mg/m² single-dose regimen.
Hematologic: Prolonged grade ≥3 thrombocytopenia in GO arm (median platelet recovery delayed ~5 days).
Infectious: Febrile neutropenia grade ≥3 77% vs 73%.
Infusion: Infusion reactions (GO) 1–2%.
Conclusions
Fractionated gemtuzumab ozogamicin added to standard 7+3 significantly improved EFS (17.1 vs 9.7 months) and RFS in newly diagnosed AML age 50–70, with particular benefit in favorable and intermediate cytogenetic risk — establishing fractionated GO as a standard-of-care addition to induction for CD33-positive, non-adverse-risk AML.
Key Limitations
CD33 expression was not prospectively required — benefit presumably greater in CD33-high tumors. No benefit demonstrated in adverse cytogenetics (monosomy 7, TP53-mutated, complex) — identifying the subgroup where GO adds nothing. Fractionated (3 mg/m² ×3) dosing is essential; the original 9 mg/m² single-dose regimen was associated with excessive SOS and was the reason GO was withdrawn in 2010. Allo-SCT eligibility and transplant conditioning regimens must account for prior GO exposure (hepatic risk). GO is expensive and not universally available. This trial informed FDA re-approval in combination regimens but GO monotherapy data are more limited in newly diagnosed AML.
Clinical Context
ALFA-0701 was a key trial supporting FDA re-approval of GO (Mylotarg) in September 2017 for newly diagnosed CD33-positive AML (fractionated dosing) and R/R AML. GO is now incorporated into induction regimens for de novo AML with favorable (CBF-AML: inv16, t(8;21)) and intermediate cytogenetics. For adverse cytogenetics/secondary AML, CPX-351 (liposomal daunorubicin+cytarabine) is preferred. GO is NOT recommended in adverse cytogenetics (per ALFA-0701 subgroup data) or in patients planned for allo-SCT with myeloablative conditioning (SOS/VOD risk). ESMO-MCBS: not assigned.