We analyzed 217 patients with KMT2A-rearranged acute myeloid leukemia (AML) in 2 large sequential randomized trials. Those randomized to FLAG-Ida (fludarabine, cytarabine, granulocyte colony-stimulating factor, idarubucin) had markedly lower rates of relapse than other chemotherapy regimens. Molecular measurable residual disease assessment after cycle 2 was strongly prognostic for relapse and death. The trials were registered at the ISRCTN Registry as AML17 ISRCTN55675535 and AML19 ISRCTN78449203.

In 1974, Van den Berghe et al described a distinct hematologic disorder associated with acquired, interstitial deletion of part of the long arm of chromosome 5. This condition is now classified as myelodysplastic syndrome (MDS) with isolated deletion 5q, or MDS-del(5q). The common deletion region 5q32-5q33 contains several genes and microRNAs whose expression levels are reduced in hematopoietic cells, consistent with the loss of 1 allele. Haploinsufficiency production of multiple gene transcripts, primarily involving CSNK1A1, RPS14, MIR145, and MIR146A, results in myelodysplastic hematopoiesis. Lenalidomide can selectively suppress the del(5q)-mutant clone by promoting proteasomal degradation of casein kinase 1A1 and inducing mutant stem cell failure. However, lenalidomide is not a curative treatment, as almost all patients relapse. Molecular profiling studies have significantly improved our understanding of MDS-del(5q). Only a minority of patients have interstitial deletion 5q as their sole genetic lesion, a condition that is associated with an indolent clinical course. Most patients have co-occurring somatic mutations in myeloid genes, including DNMT3A, TET2, ASXL1, SF3B1, TP53, RUNX1, and CSNK1A1. These comutations have independent effects on leukemic transformation and survival, so genomic profiling is required for implementing a precision management approach to MDS-del(5q) in a clinical setting. Accurate assessment of the TP53 allelic state is crucial for distinguishing MDS-del(5q) from TP53-mutant MDS, a myeloid malignancy characterized by TP53 multihit state and very aggressive clinical course. Genomic profiling is also critical for therapeutic decision-making in patients with MDS-del(5q), particularly for assessing a patient's eligibility for allogeneic transplantation, which remains the only curative treatment.

Understanding the roles of myeloid cells in the tumor microenvironment (TME) has emerged as a promising strategy to identify novel targets to counteract the immunosuppressive barriers protecting multiple myeloma (MM). Neutrophils are a new cancer research focus due to their potential to reduce the efficacy of immune-based therapies. This study aimed to deepen understanding of neutrophil function in MM by analyzing freshly isolated myeloid cells from paired focal lesions (FLs) and bone marrow using single-cell RNA sequencing, immunofluorescence imaging, and functional assays. We describe 3 distinct CXCR2+ mature neutrophil subsets: TREM1+CD10+, RETN+LCN2+, and TNFAIP3+CXCL8+, each exhibiting unique phenotypes within the TME. Notably, the TREM1+CD10+ subset was highly prevalent, particularly in FLs, demonstrating potent immunosuppressive effects on T cells. This subset's gene signature was correlated with shorter overall survival (OS) in a large data set of patients with MM, underscoring its clinical significance. Targeted inhibition of neutrophil activity through CXCR2 blockade, alone or combined with standard anti-MM therapies, significantly reduced tumor burden, improving OS in preclinical MM models. These insights into neutrophil-mediated immunosuppression in MM provide valuable knowledge regarding mechanisms driving immune evasion, and reveal new therapeutic approaches to enhance the efficacy of MM treatment.

Chronic myeloid leukemia (CML) represents a paradigm of success in targeted therapy, with tyrosine kinase inhibitors (TKIs) revolutionizing patient outcomes. This progress has extended to the management of pregnancy in women with CML, a complex scenario requiring a balance between disease control and fetal safety. Since TKIs are contraindicated during the first trimester due to their teratogenic potential, treatment must be stopped as soon as pregnancy is confirmed, necessitating careful pre-conception planning and alternative management strategies. This article uses illustrative clinical cases to explore key aspects of CML pregnancy management, including the timing of TKI discontinuation, the feasibility of treatment-free remission, and the role of alternative therapies such as interferon-alpha. Additionally, we discuss the challenges of restarting treatment during pregnancy, the TKI selection in subsequent trimesters, and postpartum disease management, including breastfeeding considerations. Through the analysis of real-world cases, we provide insights into the evolving landscape of CML and pregnancy, offering practical guidance on optimizing maternal and fetal outcomes in this unique setting.

Ciltacabtagene autoleucel (cilta-cel) and idecabtagene vicleucel (ide-cel), 2 B-cell maturation antigen (BCMA)-directed chimeric antigen receptor T-cell (CAR-T) therapies, have transformed outcomes for relapsed/refractory multiple myeloma; however, the 6 to 8 weeks manufacturing time risks disease progression or death in up to 10% of patients. Talquetamab, a G-protein-coupled receptor, family C, group 5, member D (GPRC5D)-targeting bispecific antibody, represents a promising option. We performed a multi-institutional retrospective analysis across 20 centers (18 United States, 2 Germany) evaluating talquetamab as a bridging therapy prior to cilta-cel or ide-cel. Among 134 patients receiving talquetamab, 119 proceeded to CAR-T (n = 98 cilta-cel, n = 21 ide-cel). Reasons for not proceeding (n = 15) included progression (n = 7), manufacturing failure (n = 6), or patient decision (n = 2). Median age was 65 years and had median 5 prior lines of therapy. Notably, 85% would not have met CARTITUDE-1/KarMMa eligibility criteria. Talquetamab was administered for a median 23 days. Toxicity was manageable: no grade ≥3 cytokine release syndrome (CRS), 2% grade 3 immune effector cell-associated neurotoxicity syndrome (ICANS) and grade 1 to 2 talquetamab unique toxicities (70% oral, 38% skin, and 17% nail; 60% resolved). Talquetamab achieved 71% response rate. After CAR-T, 88% responded (54% complete response), with low-grade toxicities (2 grade ≥3 CRS, 1 grade 3 ICANS, and 5% grade ≥3 infections). Two cases of facial palsy and 1 acute myeloid leukemia occurred. Talquetamab correlated with sustained soluble BCMA decline and peak CAR-T expansion around day 14. Talquetamab bridging appears safe, enabling the majority of difficult-to-treat patients to successfully proceed to BCMA CAR-T therapy.

Hematopoietic stem cells (HSCs) exhibit a distinctive antioxidant profile during steady-state and stress hematopoiesis. HSCs and multipotential progenitors (MPPs) are metabolically coupled to bone marrow mesenchymal stromal cells through mitochondrial transfer, a process dependent on hematopoietic connexin 43 (Cx43) and low adenosine monophosphate-activated protein kinase (AMPK) activity. However, the mechanism by which Cx43 preserves mitochondrial functionality in HSCs remains elusive. Here, through integrated transcriptomic, proteomic, metabolomic, phenotypic, and functional analyses of HSCs and their isolated mitochondria, we identified that Cx43 is present on the inner and outer mitochondrial membranes of HSCs/MPPs, in which it primarily regulates mitochondrial metabolism and adenosine triphosphate synthesis by preserving the mitochondrial cristae, activation of mitochondrial AMPK, and 2-oxoglutarate dehydrogenase, a rate-liming enzyme in tricarboxylic acid cycle and electron transfer chain. During replicative stress, Cx43-deficient HSCs/MPPs fail to adapt metabolically and accumulate mitochondrial Ca2+, leading to increased mitochondrial AMPK activity, mitochondrial fission, mitophagy, and production of reactive oxygen species, thereby limiting HSC/MPP regeneration potential. Disruption of hyperfragmentation of mitochondria and mitophagy by Drp1 dominant-negative mutant (Drp1K38A) or restoration of mitochondrial function through ex vivo heteroplasmy prevents the harmful effects of Cx43 deficiency on mitochondrial metabolism and restore HSC activity in serial transplantation experiments. Re-expression analysis of Cx43 structure-function mutants indicates that Cx43 hemichannels are sufficient to reset HSC mitochondrial metabolism, dynamics, Ca2+ levels, and regeneration capacity. This report defines the cell-autonomous mechanism of action behind the role of Cx43 in HSC activity and opens a venue to translational applications in transplantation.

The current approach to minimize transplant-associated complications, including graft-versus-host disease (GVHD) includes long-term pharmacological immune suppression frequently accompanied by unwanted side effects. Advances in targeted immunotherapies regulating alloantigen responses in the recipient continue to reduce the need for pan-immunosuppression. Here, in vivo targeting of the TNF superfamily receptor TNFRSF25 and the high affinity IL-2 receptor with a TL1A-Ig fusion protein and low dose IL-2, respectively was used to pre-treat recipient mice prior to allogeneic-HSCT (aHSCT). Pre-treatment induced Treg expansion persisting 1-2 weeks post-HSCT leading to diminished GVHD and improved transplant outcomes. Expansion was accompanied by an increase in the frequency of stable and active Tregs creating a suppressive tissue environment in the colon, liver and eye. Importantly, pre-treatment supported epithelial cell function/integrity, a diverse microbiome including reduction of pathologic bacteria outgrowth and promotion of butyrate producing bacteria, while maintaining physiologic levels of obligate/facultative anaerobes. Notably, using a sphingosine 1-phosphate receptor agonist to sequester T cells in lymphoid tissues, it was found that the increased tissue Treg frequency included resident CD69+CD103+FoxP3+ hepatic Tregs. In contrast to infusion of donor Treg cells, the strategy developed here resulted in the presence of immunosuppressive target tissue environments in the recipient prior to the receipt of donor allo-reactive T cells and successful perseveration of GVL responses. We posit strategies that circumvent the need of producing large numbers of Tregs ex-vivo through manipulating this recipient compartment in vivo, can provide translational approaches to improve aHSCT outcomes.

T-cell engagers (TCEs) are transformative therapeutics in hematologic malignancies, including non-Hodgkin lymphoma. Initially approved for relapsed/refractory disease settings, TCEs are now explored in first-line and second-line settings, often combined with standard-of-care (SOC) treatments, including chemotherapy and antibody-drug conjugates. This study investigates glofitamab (CD20×CD3 TCE) combinations in preclinical humanized lymphoma models, addressing heterogeneity of tumor antigen expression, immune evasion, and T-cell exhaustion. Combining glofitamab with R-CHP-Pola (rituximab, cyclophosphamide, doxorubicin, prednisone, and polatuzumab vedotin) chemotherapy or Pola demonstrated strong synergistic antitumor efficacy with rapid tumor regression and reduced tumor cell proliferation. Glofitamab combination with gemcitabine/oxaliplatin also demonstrated strong efficacy, enhancing intratumor T-cell number, activation, and reduced exhaustion. These combinations were particularly advantageous in models with low and heterogeneous CD20 expression, facilitating rapid tumor debulking and elimination of CD20-low/CD20- cells. Translational studies with patient-derived peripheral blood mononuclear cells receiving glofitamab combination with chemotherapies demonstrated sustained T-cell functionality throughout extended treatment cycles. Novel chemotherapy-free combinations, including CD19-targeted 4-1BBL and CD19-CD28, amplified glofitamab activity, especially in CD20 high- and homogenous-expressing tumor models, with dual costimulatory approaches revealing synergy. In addition, the combination with checkpoint inhibitors (programmed cell death protein 1/Lag3-bispecific antibody) and regulatory T-cell depletion (α-CD25) emerged as promising approaches for enhanced efficacy and to sustain T-cell functionality. These findings highlight the versatility of glofitamab when integrated with SOC and innovative combinations, addressing resistance and improving patient outcomes. The preclinical investigations provide a strong foundation for ongoing and future clinical trials, emphasizing the need to tailor TCE-based combination therapies to maximize efficacy while minimizing toxicity in lymphoma treatment. These trials were registered at www.clinicaltrials.gov as #NCT04408638 and NCT03467373.

Dysregulated RNA modifications contribute to cancer progression and therapy resistance, yet the underlying mechanism often remains unknown. Here, we perform CRISPR-based synthetic lethality screens to systematically explore the role of RNA modifications in mediating resistance to antileukemic drugs. We identify the tRNA methyltransferase 5 (TRMT5)-mediated formation of N1-methylguanosine (m1G) in the transfer RNA (tRNA) anticodon loop as essential for mediating drug tolerance to cytarabine and venetoclax (Ven) in acute myeloid leukemia (AML). TRMT5 methylates nearly all mitochondrial and nuclear tRNAs with a guanosine at position 37, but its role in promoting drug tolerance specifically depends on its mitochondrial function. TRMT5 is essential for the dynamic upregulation of mitochondrial messenger RNA translation and oxidative phosphorylation, which are critical for sustaining drug tolerance in leukemia cells. This mitochondrial dependency correlates with therapy outcomes in patients with leukemia: lower expression of electron transport chain genes is linked to poorer outcomes in a cohort of nearly 100 patients with AML undergoing first induction therapy. Finally, we demonstrate that targeted depletion of the TRMT5 protein using a conditional degron, in conjunction with cytarabine and Ven treatment, synergistically induces cell death in drug-tolerant AML cells. Thus, our study reveals TRMT5 as a promising drug target for therapy-resistant leukemia.