How I treat relapsed or refractory AML

Abstract

Treatment of relapsed or refractory acute myeloid leukemia (AML) has presented challenges for hematologists for decades. Despite numerous clinical studies, outcomes are consistently disappointing with 5-year overall survival rates of ∼10%. Allogeneic hematopoietic cell transplantation at the time of second complete remission remains the only reliable option with curative potential. However, recent approval of several new agents has transformed treatment paradigms that had been in place for almost half a century in AML. This new therapeutic landscape provides the opportunity to revisit the approach to relapsed or refractory AML. Through illustrative cases, we describe our approach, which increasingly relies on specific disease biology. We focus on treatment outside of the context of clinical trials because such trials are not available in most parts of the world. Primarily, we consider age, fitness to tolerate intensive chemotherapy, remission duration, and presence of a targetable mutation to guide treatment. The coming years will inevitably bring new targets and agents that may prove most effective when combined with each other and/or chemotherapy. Future studies are needed to determine how best to implement this evolving armamentarium of treatment options, to elucidate mechanisms of resistance, and to continue the pursuit of novel drug discovery.

Graphical abstract

Figure 1.

OS from relapse. Stratified by (A) age (<55 years or ≥55 years) and (B) duration of first CR (≤12 months or >12 months) from ECOG-ACRIN trials from 1984 to 2008. Reprinted from Ganzel et al with permission. CNSR, censor.

Figure 2.

Schematic capturing our current general approach for relapsed or refractory patients with AML with some factors guiding the clinical decision process. Risk stratification by 2017 ELN criteria. Approved targeted inhibitors include gilteritinib (FLT3), ivosidenib (IDH1), enasidenib (IDH2). *Assuming patient has already received intensive consolidation. **Randomized phase 3 data are only currently available for gilteritinib, not ivosidenib or enasidenib. †HMA alone if venetoclax unavailable. FLAG-IDA, fludarabine/cytarabine/granulocyte colony-stimulating factor/idarubicin; HiDAC, high-dose cytarabine; HMA, hypomethylating agent; IDH, isocitrate dehydrogenase; LoDAC, low-dose cytarabine; MEC, mitoxantrone/etoposide/cytarabine; PIF, primary induction failure.