Outcomes of Relapsed/Refractory Patients with IDH1/2 Mutated AML Treated with Non-Targeted Therapy: Results from the NCRI AML Trials

Introduction: The increasing delineation of acute myeloid leukemia (AML) has identified a number of genetic mutations which may be amenable to targeted therapies. However, such mutations typically only occur in a minority of patients, and this relative paucity presents challenges in drug development. Even for more common mutations such as FLT3 ITD, randomised trials can take many years to complete, and there is the issue of how to deal with patients who are tested but not eligible. Earlier phase trials therefore tend to be single arm studies, and often recruit in the relapsed/refractory population, where eligibility is known up front, and it is possible to obtain an early read out for efficacy. Such is the case for the recent evaluations of enasidenib and ivosidenib in IDH1/2 mutated patients. However, with single-arm studies there a need to contextualise results. We therefore looked at outcomes from the United Kingdom NCRI trials of AML for patients with IDH1/IDH2 mutations who were relapsed or refractory to therapy.