A prognostic model for survival after salvage treatment with FLAG‐Ida +/− gemtuzumab‐ozogamicine in adult patients with refractory/relapsed acute myeloid leukaemia

The combination of fludarabine, cytarabine, idarubicin, and granulocyte colony‐stimulating factor (FLAG‐Ida) is widely used in relapsed/refractory acute myeloid leukaemia (AML). We retrospectively analysed the results of 259 adult AML patients treated as first salvage with FLAG‐Ida or FLAG‐Ida plus Gentuzumab‐Ozogamicin (FLAGO‐Ida) of the Programa Español de Tratamientos en Hematología (PETHEMA) database, developing a prognostic score system of survival in this setting (SALFLAGE score). Overall, 221 patients received FLAG‐Ida and 38 FLAGO‐Ida; 92 were older than 60 years. The complete remission (CR)/CR with incomplete blood count recovery (CRi) rate was 51%, with 9% of induction deaths. Three covariates were associated with lower CR/CRi: high‐risk cytogenetics and t(8;21) at diagnosis, no previous allogeneic stem cell transplantation (allo‐SCT) and relapse‐free interval <1 year. Allo‐SCT was performed in second CR in 60 patients (23%). The median overall survival (OS) of the entire cohort was 0·7 years, with 22% OS at 5‐years. Four independent variables were used to construct the score: cytogenetics, FLT3‐internal tandem duplication, length of relapse‐free interval and previous allo‐SCT. Using this stratification system, three groups were defined: favourable (26% of patients), intermediate (29%) and poor‐risk (45%), with an expected 5‐year OS of 52%, 26% and 7%, respectively. The SALFLAGE score discriminated a subset of patients with an acceptable long‐term outcome using FLAG‐Ida/FLAGO‐Ida regimen. The results of this retrospective analysis should be validated in independent external cohorts.