PS1043 OUTCOMES OF PATIENTS WITH RELAPSED OR REFRACTORY ACUTE MYELOID LEUKEMIA: A POPULATION‐BASED REAL‐WORLD STUDY

Background: Patients (pts) with acute myeloid leukemia (AML) may be treated with intensive or non‐intensive chemotherapy. While some pts achieve complete remission (CR) after initial treatment, a significant proportion become refractory to initial treatment or relapse after the initial response. Aims: To understand treatment patterns and outcomes in pts with relapsed or refractory AML (RR‐AML) in a real‐world setting. Methods: The Alberta Cancer Registry and local databases of the University of Alberta Hospital and the Tom Baker Cancer Centre were interrogated to identify AML pts with RR‐AML aged ≥18 years treated from January 2013 to December 2016. Pts were considered to have refractory AML if they failed to achieve CR or achieved CR with incomplete count recovery (CRi) after 2 cycles of intensive chemotherapy, 6 cycles of azacytidine, or 4 cycles of low‐dose cytarabine. Based on the treatment regimen received following the diagnosis of RR‐AML, pts were grouped as receiving either intensive therapy (IT), non‐intensive therapy (NIT), or best supportive care (BSC) and were followed from relapse to date of death or last follow‐up. Results: Overall, 572 pts with AML were identified from the database search, 199 (124 males, 75 females) of whom met the eligibility criteria for RR‐AML and were included in this analysis. The median age at diagnosis of RR‐AML was 66.8 years; median follow‐up was 4.7 months. According to the European LeukemiaNet (ELN) 2010 classification, 34 pts (17%) had a favorable risk, 102 (51%) intermediate (Int) risk, 59 (30%) adverse risk profile and 4 (2%) with unknown status. After relapse or refractoriness (RR), 88 pts (44%) received BSC, 46 (23%) received IT with fludarabine, cytarabine + granulocyte colony‐stimulating factor (FLAG) (n = 5), FLAG + idarubicin (n = 29), or another regimen (n = 12), while 65 (33%) received NIT with azacitidine ± another agent (n = 49), low‐dose cytarabine ± another agent (n = 12), or an alternative regimen (n = 4). The unadjusted median overall survival (mOS) for the overall study cohort was 5.3 months from the time of RR with a 12‐month OS rate of 29.6% (95% CI 29.0–30.3). The mOS was 13.8, 9.4, and 2.1 months for IT, NIT, and BSC groups, respectively ( P  < 0.001) (Figure). The mOS for pts aged <60 years was 8.3 vs 4.5 months for those ≥60 years ( P  = 0.009). Following RR, 16 (8%) pts received an allogeneic stem cell transplant (ASCT), for whom median survival was not reached, vs 4.5 months in pts who did not undergo transplantation. The mOS for pts with an ELN favorable, Int‐I, Int‐II, and adverse risk profile was 12.4, 4.5, 4.7, and 4.0 months, respectively ( P  = 0.002). In a multivariable Cox regression model incorporating age, ELN risk group, treatment intensity pre‐RR, number of treatment lines pre‐RR, best response pre‐RR, treatment intensity post‐RR, and ASCT post‐RR, treatment intensity post‐RR (NIT vs BSC: hazard ratio [HR] for mortality 0.32; 95% CI 0.23–0.48; IT vs BSC: HR for mortality 0.26; 95% CI 0.16–0.43) and best response pre‐RR (CR/CRi <12 months vs all others: HR for mortality 0.55, 95% CI 0.33–0.92) were significantly associated with OS. Summary/Conclusion: In a real‐world setting, a high proportion of pts only receive BSC, which is associated with very short survival. Treatment regimen post‐RR is the major predictor of survival, with non‐intensively and intensively treated pts having better outcomes compared to pts who received BSC. However, the overall outcomes of pts with RR‐AML remain poor regardless of treatment, and new therapies are urgently needed.