Patients with acute myeloid leukemia (AML) have a poor 5-year survival rate, highlighting the need for the identification of new approaches to target this disease. AML is highly dependent on glutathione (GSH) metabolism for survival. Although the metabolic role of GSH is well characterized in AML, the contribution of protein glutathionylation, a reversible modification that protects protein thiols from oxidative damage, remains largely unexplored. Therefore, we sought to elucidate the role of protein glutathionylation in AML pathogenesis. Here, we demonstrate that protein glutathionylation is essential for AML cell survival. Specifically, the loss of glutaredoxin 2 (GLRX2), an enzyme that removes GSH modifications, resulted in selective primary AML cell death while sparing normal human hematopoietic stem and progenitor cells. Unbiased proteomic analysis revealed increased mitochondrial protein glutathionylation upon GLRX2 depletion, accompanied by mitochondrial dysfunction, including impaired oxidative phosphorylation, reduced mitochondrial membrane potential, and increased opening of the mitochondrial permeability transition pore (mPTP). Further investigation identified adenosine triphosphate synthase subunit O (ATP5PO), a key regulator of mPTP opening and a component of the ATP synthase complex, as a critical GLRX2 target. Disruption of ATP5PO glutathionylation partially restored mPTP function and rescued AML cell viability after GLRX2 depletion. Moreover, both genetic and pharmacological inhibition of mPTP opening restored the leukemic potential of primary AML specimens in the absence of GLRX2. By disrupting glutathionylation-dependent mitochondrial homeostasis, this study reveals a novel vulnerability in AML that could inform future therapeutic strategies.

The regulation of the switch from fetal (HBG) to adult (HBB and HBD) β-globin gene expression has served as a paradigm for clinically relevant developmental transcriptional control. Mechanistic studies of this switch have predominantly focused on HBG repressors, with comparatively little attention paid to potential HBG activators. We found that in adult-type HUDEP2 erythroid cells, the ATP-dependent chromatin remodeler Brahma Related Gene 1 (BRG1) preferentially activates the HBG genes as well as the minor adult HBD gene. BRG1 is a core catalytic subunit of 3 BRG1/BRM-associated factor (BAF) complexes, canonical BAF, polybromo BAF, and noncanonical BAF (ncBAF) that regulate chromatin accessibility in distinct gene- and cell-type contexts. To dissect the specific BAF complex configuration mediating selective activation of HBG and HBD in erythroid cells, we performed CRISPR-mediated targeting of individual subunits and pinpointed the regulatory activity to the ncBAF complex. Loss of the ncBAF complex subunits BRD9 and BAF60A preferentially decreased HBG and HBD transcription while accelerating terminal erythroid differentiation and hemoglobinization. Acute pharmacological depletion of BRD9 in HUDEP2 and primary erythroid cells selectively reduced transcription of HBD and HBG, suggesting direct effects at these genes. Collectively, our unexpected findings demonstrate that the BAF complex, through distinct subcomplex configurations, can regulate selective gene expression within a multigene cluster. This expands the traditional view of BAF as a general coactivator, highlights its role in gene-specific regulation, and identifies a potential target for therapeutic manipulation of β-like globin genes in erythroid cell disorders.

We compared daunorubicin/cytarabine plus fractionated gemtuzumab ozogamicin (DAGO2) with CPX-351 (CPX; 1:2 randomization) in 439 patients with acute myeloid leukemia (AML) aged ≥60 years (median age, 68 years) without known adverse-risk cytogenetics. Median follow-up was 35 months. Patients not in measurable residual disease (MRD)-negative remission after course 1 could enter a second randomization between standard and intensified chemotherapy. Post-course 1, the overall response rate (complete remission [CR] + CR with incomplete hematological recovery) was greater after DAGO2 (60% vs 47.5%; odds ratio [OR], 0.61; P = .016). Following course 2, the overall response was not significantly different (85% for DAGO2 vs 78% for CPX; P = .095). More patients attained CR with MRD negativity after course 1 in the DAGO2 arm (47% vs 29% for CPX; OR, 0.46; P = .004). We observed better 3-year event-free survival (34% vs 27%; hazard ratio [HR], 0.73; P = .012) and overall survival (52% vs 35%; HR, 0.62; P = .001) with DAGO2. CPX did not provide a survival benefit in patients with myelodysplasia (MDS)-related mutations and was associated with poorer survival in patients with NPM1 (HR, 2.83) and FLT3 mutations (HR, 2.14). Overall, 37% of patients underwent transplantation in first remission, with no difference in transplantation frequency or survival after transplant between randomization groups. Among patients entering the course 2 randomization (n = 107), survival was equivalent between standard and intensified CPX doses (P = .565). In conclusion, in this population of older patients with AML without known adverse-risk cytogenetics, DAGO2 resulted in superior survival compared with CPX. CPX did not benefit patients with MDS-related mutations over DAGO2. This trial was registered at www.ClinicalTrials.gov as #NCT02272478.

Only 30% to 50% of patients with immune thrombocytopenia (ITP) exhibit a sustained response upon thrombopoietin receptor agonists (TPO-RA) withdrawal, underscoring the necessity for mechanistic elucidation. We enrolled 49 patients treated with TPO-RA for 4 months and performed a follow-up study for 3 months, classifying them into sustained responders (n = 21), and nonsustained responders (n = 28). Compared with total transforming growth factor β1 (TGF-β1) levels, activated TGF-β1 levels (3854 ± 4380 vs 943 ± 1500 pg/mL; P< .001) were significantly elevated in sustained responders, with integrin αvβ8 regulating TGF-β1 activation and restoring immune tolerance. We established a passive ITP model using platelet factor 4-TGF-β1 conditional knockout (CKO) mice, which exhibited a shorter duration of sustained response than wild-type (WT) mice. CKO mice demonstrated a reduced regulatory T-cell (Treg) population, an increased M1-to-M2 macrophage ratio, and more severe megakaryocyte destruction after anti-CD41 injection. Exogenous administration of αvβ8 (250 ng/kg) effectively activated TGF-β1 and prolonged remission after TPO discontinuation in WT mice. Additionally, CD4+ T cells were transfected with lentiviral small interfering RNA or short hairpin RNA to modulate integrin β8 expression and these were injected into severe combined immunodeficiency mice undergoing an active model of ITP. Results showed that β8 overexpression increased Tregs and reduced megakaryocyte damage. Mechanistically, TPO-RA modulated αvβ8-mediated TGF-β1 activation through the activator protein 1family and Smad family member 2 signaling pathways. Furthermore, D-mannose combined with TPO prolonged the response in ITP mice by upregulating αvβ8 and activating TGF-β1. Overall, the integrin αvβ8-mediated activation of TGF-β1 pathway represents a promising therapeutic target for ITP, with substantial potential for clinical application.

The major challenges of gene therapy for hemophilia A using adeno-associated virus (AAV) vectors are reducing vector doses and the long-term maintenance of stable factor VIII (FVIII). In this study, we developed engineered human B-domain-deleted FVIIIs (FVIIISQ) with enhanced secretion and coagulation potential. Intracellular accumulation was markedly reduced in some engineered FVIIISQ, resulting in reduced unfolded protein responses. The administration of AAV vectors carrying engineered FVIIISQ to hemophilia A mice resulted in ∼8-fold higher FVIII activity and 4-fold higher FVIII antigen levels compared with wild-type FVIIISQ administration. The specific FVIII activity of the engineered FVIIISQ was 3.6 times higher than that of the wild-type FVIIISQ, and its binding to activated coagulation factor IX was significantly enhanced, which is supported by the structural analysis. In macaques, the administration of AAV5 vector carrying the engineered FVIIISQ without CpG sequences resulted in a supraphysiological increase in plasma FVIII activity at a dose one-thirtieth that of valoctocogene roxaparvovec (2 × 1012 vector genome per kg). The engineered FVIIISQ may thus provide stable, long-term therapeutic efficacy in AAV-mediated hemophilia A gene therapy even at low doses.

Therapy resistance in acute myeloid leukemia (AML) remains a major clinical obstacle, particularly because of the persistence of leukemia stem cells (LSC) capable of metabolic adaptation. Although venetoclax (Ven) inhibits oxidative phosphorylation (OXPHOS), we found that Ven-resistant LSC undergo glycolytic reprogramming to bypass OXPHOS inhibition. This metabolic shift is supported by enhanced ribosome biogenesis, which is sustained by upregulated de novo guanine nucleotide biosynthesis. Abundant guanine nucleotides suppress the impaired ribosome biogenesis checkpoint (IRBC), leading to TP53 destabilization and persistent MYC expression. The inhibition of inosine monophosphate dehydrogenases (IMPDH1/2) depletes guanine nucleotides, activates IRBC, stabilizes TP53, represses MYC, and impairs the metabolic shift to glycolysis. This metabolic rewiring disrupts LSC stemness and suppresses the reconstitution of human AML cells in xenotransplantation experiments. Notably, the suppression of LSC stemness was observed regardless of Ven resistance or the TP53 mutational status of AML cells. These findings reveal that mutation-independent TP53 inactivation is involved in resistant AML and suggest that targeting guanine nucleotide biosynthesis may offer a clinically actionable strategy to eradicate therapy-resistant LSC.

We previously reported a chemogenomics screen that unexpectedly identified phosphatidylinositol-3-phosphate 5-kinase (PIKfyve) as a vulnerable target in multiple myeloma (MM). PIKfyve is an essential regulator of lysosomal function and autophagy. Given the high basal requirement for autophagy in MM for sustainable immunoglobulin synthesis, targeting autophagy holds clinical potential as a novel therapeutic avenue. Here, we report the development and characterization of PIK001 and analogs, potent and selective novel small-molecule inhibitors of PIKfyve. PIK001 demonstrated potent anti-MM activity in vitro, as well as synergistic activity with established anti-MM agents (including venetoclax and selinexor), while retaining efficacy in lenalidomide-resistant models. Multiomic characterization of isogenic cell lines sensitive and resistant to PIK001 identified a catalytic domain mutation (PIKFYVE N1939K) and heterogenous alterations in autophagy capabilities. Importantly, we noted that PIK001 exposure also resulted in significantly increased cholesterol metabolism and upregulation of major histocompatibility complex (MHC) class I expression, with potential implications in tumor immunity. Beyond MM, PIKfyve inhibition also shows selective cytotoxicity in acute myeloid leukemia, melanoma, and renal cancer, highlighting broader therapeutic potential. These findings establish PIKfyve inhibition as a valid target for MM and other hematologic malignancies, provide insights into mechanisms of sensitivity and resistance, and lay the foundation for further preclinical (particularly the role of cholesterol metabolism and tumor immunity) and clinical development.

Brexucabtagene autoleucel (brexu-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for adults with relapsed/refractory (R/R) mantle cell lymphoma (MCL) based on the ZUMA-2 cohort 1 (ClinicalTrials.gov identifier: NCT02601313) study in which brexu-cel demonstrated a 93% objective response rate (ORR) and 67% complete response (CR) rate in patients with R/R MCL and previous BTKi therapy (N = 60). Here, we report the primary results of ZUMA-2 cohort 3 (brexu-cel in patients with BTKi-naive R/R MCL). Adults received brexu-cel at 2 × 106 anti-CD19 CAR T cells per kilogram. The primary end point was ORR assessed by independent radiology review committee (IRRC). As of 26 November 2023, 95 patients were enrolled, and 86 received brexu-cel; median follow-up was 15.5 months. The primary end point was met, with a 91% ORR (95% confidence interval [CI], 82.5-95.9; P< .0001; N = 86) and a CR rate of 73% (95% CI, 62.6-82.2). Estimated 12-month progression-free survival (PFS), duration of response, and overall survival (OS) rates were 75%, 80%, and 90%, respectively. Among 95 enrolled patients, the ORR was 82%, the CR rate was 66%, and the 12-month PFS and OS rates (95% CI) were 73% (62.1-80.8) and 85% (75.6-90.7), respectively. Most patients (88%) experienced treatment-related grade ≥3 adverse events, including 4 treatment-related grade 5 events. Consistent with cohort 1, brexu-cel demonstrated a high ORR and similar safety profile. These results support the continued use of brexu-cel in patients with R/R MCL, and consideration in some patients without previous BTKi therapy who have high-risk disease. This trial was registered at clinicaltrials.gov as #NCT04880434.

Thrombin is generated from prothrombin through cleavage at 2 sites by the enzyme prothrombinase, composed of factor Xa (fXa) and fVa. The affinity of fXa for fVa is low, with assembly and function dependent on phospholipid (PL) membranes. Some snakes have evolved venom versions of fXa that bind to fVa with high affinity and efficiently activate prothrombin in the absence of PL. We created a similar high-affinity, PL-independent human prothrombinase with 17 mutations to human fXa (M17). The increase in affinity enabled cryogenic electron microscopy (cryo-EM) structure determination of M17-prothrombinase to a resolution of 3.3 Å. All protein domains were well resolved in the map, except for the γ-carboxyglutamic acid domain of fXa. The main contacts involve the serine protease and epidermal growth factor-like domain 2 (EGF2) domains of fXa and the A2 and A3 domains of fVa, resulting in the burying of a total surface area of 4900 Å2. The map is of sufficient quality to resolve side-chain interactions, including several key M17 mutations. To aid in the placement of the loop C-terminal to the A2 domain (a2-loop), we solved a high-resolution crystal structure of fXa in complex with a synthetic a2 peptide. The acidic a2-loop interacts with the basic heparin-binding site of fXa, involving a conserved antiparallel β-strand interaction. The M17-prothrombinase structure is compatible with data from biochemical and mutagenesis research and provides important new insights into the assembly and function of the prothrombinase complex.

The repair of pathological gene variants is an ultimate goal in treating genetic diseases; however, developing distinct therapeutic reagents for each of the numerous variants within a gene may not be scalable. Here, we investigated whether base editing to introduce a gain-of-function variant in blood coagulation factor IX (FIX) can increase FIX activity as a targeted therapeutic approach for hemophilia B. We engineered a G:C to A:T substitution at c.1151 of F9 by cytosine base editing to generate R338Q (the Shanghai F9 variant), which markedly increases coagulation factor activity. An adeno-associated virus vector harboring the base editor converted >60% of the target G:C to A:T and increased FIX activity in HEK293 cells harboring patient-derived F9 variants as well as in knock-in mice carrying a human F9 complementary DNA. Furthermore, administration of lipid nanoparticles containing the base-editor mRNA and guide RNA increased FIX activity in mice. These data indicate that cytosine base editing to generate R338Q in FIX is a broadly applicable genome-editing strategy for hemophilia B with residual FIX activity.

Myeloid leukemia of Down syndrome (ML-DS) is associated with an excellent prognosis but high treatment-related toxicity and mortality. The Phase 3 Clinical Trial for CPX-351 in ML-DS 2018 aimed to maintain the excellent event-free survival (EFS) achieved in the previous ML-DS 2006 trial while reducing the treatment intensity. Intensity-reduced induction and reinduction therapy with cytarabine and idarubicin with or without etoposide was replaced with CPX-351 (66 U/m2 on 3 days in course 1 and on 2 days in course 2). Risk stratification was based on flow cytometric measurable residual disease (MRD) after first induction. High-risk patients received high-dose cytarabine (3 g/m2 per 12 hour) in consolidation; standard-risk patients received cytarabine at a dose of 1 g/m2 per 12 hour. A total of 35 patients were enrolled until the trial was halted because of an unexpectedly high relapse rate. A per-protocol interim analysis revealed a significantly lower 24-month EFS when compared with the ML-DS 2006 trial (69% vs 90%; P< .001). In contrast with previous studies, most patients who relapsed responded to salvage therapy, leading to a comparable 24-month overall survival of 88% (vs 92%; P = .612). CPX-351 demonstrated a favorable toxicity profile with no treatment-related mortality. Positive MRD by error-corrected GATA1 next-generation sequencing, the presence of trisomy 8 or a complex karyotype were associated with an increased risk for relapse. In conclusion, replacing intensity-reduced induction therapy with CPX-351 in ML-DS led to a significantly lower EFS, highlighting the need for dose optimization to balance the efficacy and toxicity in this sensitive patient population. This trial was registered at https://www.clinicaltrialsregister.eu as EudraCT #2018-002988-25.

Oncogenic growth places great strain and dependence on protein homeostasis (proteostasis). This has made proteostasis pathways attractive therapeutic targets in cancer, but efforts to drug these pathways have yielded disappointing clinical outcomes. One exception is proteasome inhibitors, which are approved for the frontline treatment of multiple myeloma. However, proteasome inhibitors are largely ineffective for the treatment of other cancers at tolerable doses, including acute myeloid leukemia (AML), although reasons for these differences are unknown. Here, we determined that proteasome inhibitors are ineffective in AML due to their inability to disrupt proteostasis. In response to proteasome inhibition, AML cells activated HSF1 and increased autophagic flux to preserve proteostasis. Genetic inactivation of HSF1 sensitized AML cells to proteasome inhibition, marked by accumulation of unfolded protein, activation of the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK)-mediated integrated stress response, severe reductions in protein synthesis, proliferation and cell survival, and significant slowing of disease progression and extension of survival in vivo. Similarly, combined autophagy and proteasome inhibition suppressed proliferation, synergistically killed human AML cells, and significantly reduced AML burden and extended survival in vivo. Furthermore, autophagy and proteasome inhibition preferentially suppressed protein synthesis and colony formation and induced apoptosis in cells from patients with primary AML, including AML stem/progenitor cells, compared with normal hematopoietic stem/progenitor cells. Combined autophagy and proteasome inhibition activated a terminal integrated stress response, which was surprisingly PKR. These studies unravel how proteostasis pathways are coopted to promote AML growth, progression and drug resistance and reveal that disabling the proteostasis network is a promising strategy to therapeutically target AML.

Epstein-Barr virus (EBV) infects over 90% of the global population and drives multiple aggressive B-cell malignancies, including Burkitt lymphoma, diffuse large B-cell lymphoma, and Hodgkin lymphoma. Standard chemoimmunotherapy regimens can be highly effective, yet Epstein-Barr virus positive (EBV+) lymphomas sometimes exhibit poorer responses, higher resistance, and worse survival compared with Epstein-Barr virus-negative (EBV-) counterparts. This reflects the virus's ability to drive immune evasion, alter cell death pathways, and exploit host immune dysfunction, underscoring the potential value of EBV-directed strategies. Withaferin A (WA), a steroidal lactone with known anticancer and anti-inflammatory properties, was evaluated for its efficacy against EBV-associated B-cell non-Hodgkin lymphomas (B-NHL). Across a panel of lymphoma cell lines, WA demonstrated selective cytotoxicity toward EBV+ B-NHL, in part through proteasome-dependent degradation of EBNA1 (EBV nuclear antigen 1) and subsequent loss of viral episomes, alongside additional effects on cellular stress and survival pathways. Mechanistic studies revealed that WA collapses antioxidant defenses, drives oxidative stress, and suppresses NF-κB signaling, creating a multipronged disruption of viral and host survival pathways. In primary B-cell models and a cord blood-humanized mouse model of EBV-driven lymphomagenesis, WA inhibited B-cell transformation, reduced splenomegaly and tumor burden, and significantly prolonged survival without evidence of increased viral replication. These findings establish WA as a potent preclinical candidate that selectively targets vulnerabilities unique to EBV-transformed B cells, supporting further optimization and evaluation for EBV+ B-cell malignancies.

Tissue factor (TF), encoded by F3, binds factor VII (FVII)/activated factor VII (FVIIa) to initiate blood coagulation. Because standard clinical assays do not measure endogenous TF directly, the extent to which human F3 variants affect blood coagulation is unknown. We sought to determine the effect of the human TF missense variants with the highest allele frequency as well as additional rare variants occurring at sites predicted to perturb the initiation of blood coagulation. The variants with the highest allele frequency did not affect coagulation activation. By contrast, some rare human TF missense substitutions did profoundly affect TF-initiated plasma clotting time and the activation of FIX and FX by 2 distinct mechanisms: by precluding TF interaction with FVIIa, or by altering the TF exosite to prevent macromolecular but not amidolytic substrate cleavage. Individuals heterozygous for the rare p.Gly196Arg variant have reduced basal FVIIa-antithrombin complex and D-dimer levels but no major differences in TF or FVII levels. Gly196Arg supported impaired FVII autoactivation in vitro. These data demonstrate that rare missense variants in F3 can impair the activation of FVII, FIX, and FX, and suggest these variants impair the basal activation of blood coagulation in humans.

In multiple myeloma (MM), cell-specific antigens are valuable targets for developing effective T-cell-engaging therapeutics that can provide good immune responses. Achieving a sustained immune response in recurrent MM, however, remains challenging. Ramantamig (JNJ-79635322) is a trispecific antibody targeting BCMA (B-cell maturation antigen) and GPRC5D (G-protein-coupled receptor family C group 5 member D), both of which are highly expressed on plasmablasts and plasma cells in samples from patients with myeloma. Dual antigen recognition on malignant plasma cells by a trispecific T-cell-engaging antibody could potentially enhance tumor binding through increased avidity, resulting in efficient depletion of the malignant clonal populations, targeting of tumor heterogeneity, and prevention of tumor antigen loss-mediated resistance. At subnanomolar ranges, ramantamig induced potent cytotoxicity in cancer cell lines with concomitant T-cell activation. Ramantamig efficiently depleted both dual- and single-target-expressing MM cell lines. In addition, it induced dose-dependent depletion of malignant plasma cells in samples from patients with MM both in an ex vivo T-cell coculture assay and in healthy fresh whole blood cocultured with H929 MM cells to mimic physiological conditions. Ramantamig exhibited potent antitumor activity in a murine xenograft prevention model (single-target-expressing clonal cells) and 2 tumor regression models. The potent and selective antitumor activity of ramantamig, with a clonal-depleting ability in vitro, ex vivo, and in vivo, warrants clinical evaluation of its ability to induce durable responses in myeloma. Phase 1 clinical trials are ongoing for patients with relapsed/refractory MM. These trials are registered at www.clinicaltrials.gov as NCT05652335 and NCT06768489.