Three mutation-specific targeted therapies have recently been approved by the FDA for the treatment of acute myeloid leukemia (AML): midostaurin for FLT3 mutations, enasidenib for relapsed or refractory cases with IDH2 mutations, and ivosidenib for cases with an IDH1 mutation.
Acute myeloid leukemia with isolated del(5q) was less likely therapy-related (p = 0.037), more likely to have IDH1/IDH2 mutations (p = 0.009), and less likely to have TP53 mutations (p = 0.005) when compared to acute myeloid leukemia with complex karyotype including del(5q).
The therapeutic landscape is rapidly changing, with eight new drugs approved by the Food and Drug Administration within the last 2 years, including midostaurin and gilteritinib for FLT3 mutant newly diagnosed and relapsed/refractory (R/R) acute myeloid leukemia (AML), respectively; CPX-351 (liposomal cytarabine and daunorubicin) for therapy-related AML and AML with myelodysplasia-related changes; gemtuzumab ozogamicin (anti-CD33 monoclonal antibody conjugated with calicheamicin) for newly diagnosed and R/R CD33-positive AML; enasidenib and ivosidenib for IDH2 and IDH1 mutant R/R AML, respectively.
Although the first reports have also already emerged describing acquired resistance for these mutant IDH inhibitors, combination treatment might overcome this problem, which could drastically change the treatment landscape of AML over the next few years.
Among 39 patients with newly diagnosed mutant-IDH2AML who received enasidenib monotherapy in this phase I/II trial, median age was 77 years (range 58-87) and 23 patients (59%) had had an antecedent hematologic disorder.
The analysis of these mutations in AML patients is of great importance as a prognostic factor due to their impact on survival and their use as potential therapeutic targets or as targets of inhibitors of IDH1(Ivosidenib, Tibsovo) and IDH2 (Enasidenib, Idhifa).
Here we describe two patients with IDH2-mutant AML who had a clinical response to enasidenib followed by clinical resistance, disease progression, and a recurrent increase in circulating levels of 2HG.
The molecular subclassification was as follows: 34.6% patients (n = 136) with AML with the <i>NPM1</i> mutation, 10.7% (n = 42) with AML with mutated chromatin or RNA-splicing genes or both, 1.5% (n = 6) with AML with <i>TP53</i> mutations, 13.5% (n = 53) with AML with biallelic <i>CEBPA</i> mutations, 2.0% (n = 8) with AML with <i>IDH2-R1</i>72 mutations and no other class-defining lesion, 29.5% (n = 116) with AML with driver mutations but no detected class-defining lesion, 4.3% (n = 17) with AML with no detected driver mutation, and 3.8% (n = 15) patients with AML who met the criteria for ≥2 genomic subgroups.
In August 2017, the United States Federal Drug Administration (FDA) approved enasidenib (Idhifa, Celgene/Agios) for adults with relapsed and refractory acute myelogenous leukemia (AML) with an IDH2 mutation.
Mutations in IDH1 or IDH2 are detected in approximately 20% of patients with acute myeloid leukemia (AML) and induce amino acid changes in conserved residues resulting in neomorphic enzymatic function and production of an oncometabolite, 2-hydroxyglutarate (R-2-HG).
Additionally, targeted therapies are now becoming available for patients with mutations in FMS-like tyrosine kinase 3 (FLT3) or isocitrate dehydrogenase 2 (IDH2), ushering in an era of personalized medicine in the treatment of AML.
Recent studies indicate that in malignancies such as acute myeloid leukemia (AML), measurements of 2HG in serum provide useful diagnostic and prognostic information and improve patient selection and monitoring of IDH-targeted treatments.
Enasidenib (formerly AG-221) is an oral small molecule selective targeted inhibitor of the mutant IDH2 enzyme, approved in August 2017 by the United States Food and Drug Administration for the treatment of patients with relapsed or refractory (R/R) <i>IDH2</i>-mutated AML.
Enasidenib, a specific small-molecule inhibitor of IDH2, recently gained FDA approval for the treatment of patients with relapsed/refractory <i>IDH2</i>-mutated AML.
Further studies addressing its biology and clinical significance may be especially relevant in the era of IDH inhibitors and recent work showing efficacy of ATRA therapy in NPM1 and IDH1-mutated AML.
Isocitrate dehydrogenase differentiation syndrome is a recognizable and potentially lethal clinical entity, occurring in approximately 12% of enasidenib-treated patients with mutant-IDH2 R/R AML.