The phase 3 ENESTPath study investigated treatment-free remission (TFR) rates in patients with chronic Philadelphia chromosome-positive (Ph+) and/or BCR::ABL1+ chronic myeloid leukemia who had not achieved deep molecular response (DMR) after >2 years of imatinib treatment and were switched to nilotinib 300 mg twice daily (BID). After 24 months of treatment, patients with a stable DMR were randomized to either enter the TFR phase (Arm 1) or continue nilotinib consolidation for an additional 12 months and then enter the TFR phase if in stable DMR (Arm 2). The primary endpoint was the proportion of patients who remained in TFR (≥MR4.0 [BCR::ABL1IS ≤ 0.01%]) without molecular relapse at the end of 12 months. Of the 620 patients enrolled, 239 (38.5%) achieved stable MR4.0 and were randomized to Arm 1 (n = 120) or Arm 2 (n = 119). In the TFR phase, MR4.0 rates at 12 months (Arm 1: 31.9%, Arm 2: 37.5%; p = 0.383) and 24 months (Arm 1: 29.4%, Arm 2: 30.8%) revealed no differences in TFR success between 2 and 3 years of nilotinib. Irrespective of the consolidation duration, switching to nilotinib 300 mg BID provided the opportunity to achieve TFR if patients were unable to reach stable DMR with first-line imatinib.

Aberrant activation of NF-κB transcription factors is a hallmark of human lymphomas. Most lymphoma-intrinsic as well as microenvironment-induced NF-κB activation occurs upstream of the key kinase IKK2, therefore affecting additional pathways. Here, we show that canonical NF-κB signaling in mouse B cells, induced through the expression of one or two copies of a constitutively active IKK2 variant, dose-dependently drives lymphomagenesis. The observed phenotype and stereotypic B cell receptor clonality resemble human small lymphocytic lymphoma (SLL) and chronic lymphocytic leukemia (CLL). Stronger IKK2 signaling drives early B1a cell expansion and uniform SLL/CLL-like lymphomagenesis, while intermediate signals cause more heterogeneous malignancies. Mechanistically, constitutive IKK2 signals provide a profound cell-intrinsic competitive advantage to B1a cells and dose-dependently synergize with TCL1 overexpression in driving aggressive CLL. Further, strong constitutive NF-κB activation overcomes critical microenvironmental dependencies of TCL1-driven lymphomas. Our findings establish canonical NF-κB as an oncogenic driver in lymphoma and reveal reduced microenvironment dependency as a key NF-κB-mediated mechanism, thus highlighting its therapeutic relevance.

KMT2A-rearranged infant leukaemia is one of the most severe malignancies in infants and children, and is characterised by a very aggressive phenotype and lineage plasticity. KMT2A::MLLT3 is among the most common translocations initiating leukaemia in infants, where it can manifest with a myeloid or lymphoid leukaemia phenotype. The cell-of-origin and the mechanisms driving lineage choice in KMT2A::MLLT3+ infant leukaemia are poorly understood. In this study, we show that a subset of foetal lymphoid-primed multipotent progenitors (LMPPs) expressing the Colony-Stimulating Factor 1 receptor (CSF1R) gives rise to acute myeloid leukaemia (AML) upon KMT2A::MLLT3 induction in a mouse model, with the myeloid phenotype, at least in part, being dependent on CSF1R signalling. In line with their leukaemia-propagating properties, KMT2A::MLLT3 + CSF1R+ LMPPs possess a stemcell-like and myeloid-biased expression signature and require autophagy to expand and form blast-like colonies in methylcellulose. Interrogation of public datasets confirms the existence of a human foetal-restricted CSF1R+ LMPP population at early stages of embryonic development. Finally, CSF1R inhibition on a KMT2A::MLLT3+ paediatric leukaemia cell line resulted in significant cell death, suggesting that CSF1R could be therapeutically targeted in these patients. Our findings suggest that KMT2A::MLLT3+ infant AML may originate from foetal liver CSF1R+ LMPPs, and that these patients may benefit from anti-CSF1R-CAR-T cell therapy.

Abstract NPM1 -mutated ( NPM1 -mut) acute myeloid leukemia (AML) is generally associated with a more favorable outcome, although the presence of additional gene mutations can influence patient prognosis. We analyzed intensively-treated adult NPM1 -mut AML patients included in the HARMONY Alliance database. A newly developed risk classification, which included combinations of co-mutations in FLT3 -ITD, DNMT3A , IDH1/IDH2 , and TET2 genes, was applied to a training cohort of NPM1 -mut AML patients included in clinical trials ( n = 1001), an internal validation cohort more representative of real-world settings ( n = 762), and an external validation cohort enrolled in UK-NCRI trials ( n = 585). The HARMONY classification considered 51.8% of the NPM1 -mut AML training cohort patients as favorable, 24.8% as intermediate, and 23.4% as adverse risk, with median overall survival (OS) of 14.4, 2.2, and 0.9 years, respectively; p < 0.001), thereby reclassifying 42.7% of NPM1 -mut patients into a different European LeukemiaNet (ELN) 2022 risk category. These results were confirmed both in an internal and external validation cohort. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR1) showed the highest benefit in the NPM1 -mut adverse-risk subgroup. The HARMONY classification provides the basis for a refined genetic risk stratification for adult NPM1 -mut AML with potential clinical impact on allo-HSCT decision-making.

Individuals with history of chemo- or radiotherapy frequently exhibit somatic mosaicism in the blood, often involving mutations in genes responsible for DNA damage responses (DDR), such as CHEK2. However, the mechanisms by which CHEK2 mutations promote the expansion of mutant cells following chemo- or radiotherapy remain poorly understood. Here, we demonstrate that loss of CHEK2 confers resistance to chemotherapy in hematopoietic stem and progenitor cells (HSPCs). Through a CRISPR-based screen, we identified CHEK2 as a gene whose loss enhances resistance to cytotoxic chemotherapies. A complementary drug screen revealed that CHEK2-mutant cells are also resistant to DNA hypomethylating agents. Chek2-deficient HSPCs persist in vivo following chemotherapy exposure and exhibit elevated levels of DNA damage compared to wild-type cells. Our findings establish that CHEK2 loss promotes chemoresistance in HSPCs, offering new insights into the role of CHEK2 in therapy-related clonal hematopoiesis observed in cancer patients.

Treatment-free remission (TFR) after discontinuation of ABL tyrosine kinase inhibitors (TKIs) is an important therapeutic goal in chronic myeloid leukemia (CML). Interferon-α (IFN) has been suggested to promote durable TFR. The phase 3 ENDURE trial (NCT03117816; EUDRA-CT 2016-001030-94) prospectively tested this hypothesis in patients with stable deep molecular remission after TKI therapy. A total of 203 patients were randomised 1:1 to receive ropeginterferon alfa-2b (ropeg-IFN; 100 µg subcutaneously every two weeks for 15 months, n = 95) or observation alone (n = 108) after TKI discontinuation. The primary endpoint was molecular relapse-free survival (MRFS), defined as time to loss of major molecular response (MMR) or death. At a median follow-up of 36 months, 25-month MRFS was 56% (95% confidence interval (CI), 45-66) with ropeg-IFN and 59% (95% CI, 49-68) with observation (hazard ratio (HR), 1.02; 95% CI, 0.68-1.55; P = 0.91). Among 83 patients with molecular data after TKI restart, 79 (95%) regained at least MMR, 78 within 12 months (median 3 months, interquartile range: 2-4 months). Ropeg-IFN was well tolerated (median administered dose of 92 µg, range 3-104), and no new safety signals were observed. Ropeg-IFN maintenance did not improve the probability of sustained TFR after TKI discontinuation.

The prevailing fixed-hierarchy approach to donor selection for allogeneic hematopoietic cell transplantation (HCT) fails to capture critical interactions between donor age and type. We addressed this by analyzing 1713 adult recipients of matched related (MRD), matched unrelated (MUD), or haploidentical donors, receiving post-transplantation cyclophosphamide, using both regularized-Cox and XGBoost machine learning models. Our analysis revealed that the overall, independent association of donor age with survival was modest; however, its importance became pivotal within specific, context-dependent trade-offs. For example, while age-matched MRD and MUD were equivalent, a younger MUD was superior to an older MRD for elderly recipients. The survival advantage of MUD over haploidentical donors was consistent and magnified with increasing recipient age. We identified a non-linear relationship between baseline risk and the benefit of a matched versus a haploidentical donor; with the gain being maximal for intermediate-risk patients but attenuated in the highest-risk stratum. Our framework quantifies the gap that persists even between HLA-favorable haploidentical donors and matched donors. These findings provide a quantitative framework -the principles of which we have made explorable via an interactive web application -for a personalized, risk-adapted approach to donor selection. The clinical utility of this model must be confirmed in future validation studies.

Existing treatments for lower-risk myelodysplastic syndromes/neoplasms (LR-MDS) focus on symptom relief. Until recently, altering the disease course was rarely considered a therapeutic objective. The first-in-class, direct, competitive telomerase inhibitor, imetelstat, demonstrated significantly higher rates of red blood cell (RBC) transfusion independence (TI) versus placebo in patients with non-del(5q), RBC transfusion-dependent LR-MDS who were relapsed/refractory to or ineligible for erythropoiesis-stimulating agents in the Phase 3 IMerge study (NCT02598661). In this exploratory analysis of IMerge, patients treated with imetelstat had greater sustained reductions in variant allele frequency of multiple mutations versus placebo recipients, which was positively associated with RBC-TI duration. Subsequent analyses showed that 70% of patients with a cytogenetic response with imetelstat achieved ≥1-year RBC-TI. Additionally, higher rates of ≥1-year RBC-TI were observed in patients with maximum variant allele frequency reduction of ≥50% in SF3B1 (58% vs. 7%), TET2 (90% vs. 9%), DNMT3A (100% vs. 13%), or ASXL1 (50% vs. 0%) and patients with ≥50% bone marrow ring sideroblast reduction (46% vs. 0%) versus patients who did not. Lastly, 60% of patients with ≥1-year RBC-TI had ≥50% reduction in telomerase activity/human telomerase reverse transcriptase RNA. These results suggest that imetelstat targets clonal progenitor cells and may modify LR-MDS biology.

CBFA2T3::GLIS2-positive pediatric acute myeloid leukemia (AML) remains one of the worst prognostic AML subgroups. To uncover innovative targeted therapy approaches in this disease subtype we performed genome-scale CRISPR-Cas9 screening that highlighted a strong, selective dependency on JAK2 compared to other types of cancer. Using a doxycycline-inducible JAK2 knockout (KO) system, we validated JAK2 dependency in CBFA2T3::GLIS2 cell lines, observing impaired proliferation in vitro and in vivo and apoptosis induction in vitro. Both type I (ruxolitinib) and type II (CHZ868) JAK2 inhibitors showed selective in vitro activity in CBFA2T3::GLIS2-positive AML models. To identify resistance and sensitizer mechanisms to JAK2 inhibitors, we used CRISPR-Cas9 ruxolitinib anchor screening in CBFA2T3::GLIS2 AML. sgRNAs targeting negative regulators of the MAPK pathway were enriched in the ruxolitinib-treated cells. Similarly, CBFA2T3::GLIS2 AML sublines grown to resistance under chronic ruxolitinib treatment expressed pathogenic NRAS mutations. Both approaches converged on MAPK pathway activation as a resistance mechanism to ruxolitinib treatment. Combining ruxolitinib with MEK inhibitors showed a synergistic effect in cell lines and patient-derived xenograft (PDX) cells expressing the fusion and in vivo activity in a CBFA2T3::GLIS2 AML PDX, suggesting a potential approach to target this signaling circuitry in this poor outcome AML subtype.