The safety and efficacy of combining the isocitrate dehydrogenase-1 (IDH1) inhibitor ivosidenib (IVO) with the BCL2 inhibitor venetoclax (VEN; IVO + VEN) ± azacitidine (AZA; IVO + VEN + AZA) were evaluated in four cohorts of patients with IDH1-mutated myeloid malignancies (n = 31). Most (91%) adverse events were grade 1 or 2. The maximal tolerated dose was not reached. Composite complete remission with IVO + VEN + AZA versus IVO + VEN was 90% versus 83%. Among measurable residual disease (MRD)-evaluable patients (N = 16), 63% attained MRD-negative remissions; IDH1 mutation clearance occurred in 64% of patients receiving ≥5 treatment cycles (N = 14). Median event-free survival and overall survival were 36 [94% CI, 23–not reached (NR)] and 42 (95% CI, 42-NR) months. Patients with signaling gene mutations appeared to particularly benefit from the triplet regimen. Longitudinal single-cell proteogenomic analyses linked cooccurring mutations, antiapoptotic protein expression, and cell maturation to therapeutic sensitivity of IDH1-mutated clones. No IDH isoform switching or second-site IDH1 mutations were observed, indicating combination therapy may overcome established resistance pathways to single-agent IVO. Significance: IVO + VEN + AZA is safe and active in patients with IDH1-mutated myeloid malignancies. Combination therapy appears to overcome resistance mechanisms observed with single-agent IDH-inhibitor use, with high MRD-negative remission rates. Single-cell DNA ± protein and time-of-flight mass-cytometry analysis revealed complex resistance mechanisms at relapse, highlighting key pathways for future therapeutic intervention. Watch the interview with Courtney D. DiNardo, MD, MSCE, recipient of the 2025 Blood Cancer Discovery Award for Outstanding Journal Article: https://vimeo.com/1100470320 This article is highlighted in the In This Issue feature, p. 247

Assessment of measurable residual disease (MRD) provides prognostic information in acute myeloid leukemia (AML). However, the utility of MRD with venetoclax-based lower intensity regimens is unknown. We analyzed the prognostic value of achieving a negative MRD in older/“unfit” patients with AML receiving first-line therapy with 10-day decitabine and venetoclax. MRD was evaluated in bone marrow specimens using multicolor flow cytometry (sensitivity 0.1%). Ninety-seven patients achieving either a complete remission (CR) or CR with incomplete hematologic recovery (CRi) or morphologic leukemia-free state were included. Median age was 72 years (interquartile range, 68-78 years), and 64% had adverse-risk AML. Eighty-three patients achieved CR/CRi, and 52 (54%) became MRD negative. Median time to becoming MRD negative was 2.0 months (interquartile range, 0.9-3.1 months). Patients becoming MRD negative by 2 months had longer relapse-free survival (RFS) compared with those remaining MRD positive (median RFS, not reached vs 5.2 months; hazard ratio [HR], 0.31; 95% confidence interval [CI], 0.12-0.78; P = .004), longer event-free survival (EFS) (median EFS, not reached vs 5.8 months; HR, 0.25; 95% CI, 0.12-0.55; P < .001), as well as longer overall survival (OS) (median OS, 25.1 vs 7.1 months; HR, 0.23; 95% CI, 0.11-0.51; P < .001). Patients achieving an MRD-negative CR had longer OS compared with those with an inferior response (median OS, 25.1 vs 11.6 months; HR, 0.33; 95% CI, 0.19-0.58; P < .0005). Patients becoming MRD negative within 1 month had an improved OS compared with MRD-positive patients (median OS, 25.1 vs 3.4 months; HR, 0.15; 95% CI, 0.03-0.64; P < .0001). Differential impact of MRD status on survival outcomes persisted at a later 4-month time point of evaluation. In conclusion, MRD-negative status at 1, 2, and 4 months after starting therapy confers significantly better survival in older/unfit patients with AML receiving first-line therapy with 10-day decitabine and venetoclax. This trial was registered at www.clinicaltrials.gov as #NCT03404193.

Ruxolitinib (RUX)-based combinations may provide benefit for patients with myelofibrosis (MF). In this open-label, nonrandomized, prospective phase 2 study, patients with MF initially received RUX twice per day continuously in 28-day cycles for the first 3 cycles. Azacitidine (AZA) 25 mg/m² (days 1-5) was added starting with cycle 4 and could be subsequently increased to 75 mg/m² (days 1-5). Forty-six patients were enrolled with a median follow-up of 28 months (range, 4-50+ months). An International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) response was achieved in 33 patients (72%), with a median time to response of 1.8 months (range, 0.7-19.0 months). One-fourth (7 of 33) of the IWG-MRT responses occurred after the addition of AZA. A reduction of >50% in palpable spleen length at 24 weeks and at any time on the study was achieved in 62% and 71% of the evaluable patients, respectively. Among patients who achieved a >50% reduction in spleen length at 24 weeks, 95% had maintained it at 48 weeks. Notably, improvements in bone marrow reticulin fibrosis grade occurred in 57% of the patients at 24 months. Treatment discontinuations as a result of drug-related toxicities occurred in 4 patients (9%), all as a result of cytopenias. New onset grade 3 to 4 anemia and thrombocytopenia occurred in 35% and 26% of patients, respectively. RUX and AZA were safe, with encouraging spleen response rates and improvement in bone marrow fibrosis in patients with MF. This trial was registered at www.clinicaltrials.gov as #NCT01787487. Key Points The combination of RUX and AZA was safe with encouraging spleen response rates at 24 weeks and any time on study. RUX and AZA demonstrated marked improvements in bone marrow fibrosis at 24 months when compared with RUX alone. Visual Abstract

The isocitrate dehydrogenase enzyme 2 (IDH2) gene is mutated in ∼5% of patients with myelodysplastic syndrome (MDS). Enasidenib is an oral, selective, mutant IDH2 inhibitor approved for IDH2-mutated (mIDH2) relapsed/refractory acute myeloid leukemia. We designed a 2-arm multicenter study to evaluate safety and efficacy of (A) the combination of enasidenib with azacitidine for newly diagnosed mIDH2 MDS, and (B) enasidenib monotherapy for mIDH2 MDS after prior hypomethylating agent (HMA) therapy. Fifty patients with mIDH2 MDS enrolled: 27 in arm A and 23 in arm B. Median age of patients was 73 years. The most common adverse events were neutropenia (40%), nausea (36%), constipation (32%), and fatigue (26%). Hyperbilirubinemia from off-target UGT1A1 inhibition occurred in 14% of patients (8%; grades 3 and 4), and IDH-inhibitor–associated differentiation syndrome (IDH-DS) in 8 patients (16%). In the combination arm, the overall response rate (ORR: complete remission [CR] + marrow CR [mCR] + partial remission) was 74%, including 70% composite CR (CRc: CR + mCR). Median time to best response was 1 month (range, 1-4), and a median of 4 cycles was received (1-32). The median overall survival (OS) was 26 months (range, 14 to not reached). In the enasidenib monotherapy cohort after HMA failure, ORR and CRc were both 35% (n = 8), with 22% CR (n = 5). Median time to first response was 27 days, and time to best response was 4.6 months (2.7-7.6 months). A median of 7 cycles was received (range, 1-29), and the median OS was 20 months (range, 11 to not reached). Enasidenib is an effective treatment option for mIDH2 MDS, both in combination with azacitidine for treatment-naïve high-risk MDS, and as a single agent after prior HMA therapy. This trial is registered at www.clinicaltrials.gov as #NCT03383575.

Mutations in Nucleophosmin 1 (NPM1) are associated with a favorable prognosis in newly diagnosed acute myeloid leukemia (AML), however, their prognostic impact in relapsed/refractory (R/R) settings are unknown. In a retrospective analysis, we identified 206 patients (12%) with mutated NPM1 (NPM1c) and compared their outcomes to 1516 patients (88%) with NPM1 wild-type (NPM1wt). NPM1c was associated with higher rates of complete remission or complete remission with incomplete count recovery compared with NPM1wt following each line of salvage therapy (first salvage, 56% vs 37%; P < .0001; second salvage, 33% vs 22%; P = .02; third salvage, 24% vs 14%; P = .02). However, NPM1 mutations had no impact on relapse-free survival (RFS) and overall survival (OS) with each salvage therapy with a median OS following salvage 1, 2 or 3 therapies in NPM1c vs NPM1wt of 7.8 vs 6.0; 5.3 vs 4.1; and 3.5 vs 3.6 months, respectively. Notably, the addition of venetoclax to salvage regimens in patients with NPM1c improved RFS and OS (median RFS, 15.8 vs 4.6 months; P = .05; median OS, 14.7 vs 5.9 months; P = .02). In conclusion, NPM1 mutational status has a minimal impact on prognosis in relapsed or refractory AML; therefore, novel treatment strategies are required to improve outcomes in this entity.

Key Points: IDH1/2-inhibitor–based combinations conferred significant clinical responses in patients with IDH1/2-mutated post–MPN AML. Complete remission was achieved in 3/7 patients (1 attaining MRD–) with new IDH1/2-mutated post–MPN AML treated with IDH1/2-i combinations.