Minor histocompatibility antigen (mHAg)-specific alloreactive donor T cells cause graft vs. host disease (GVHD) in matched related donor allogeneic hematopoietic cell transplantation (HCT). In a phase I trial, we expanded and infused (on day -2) mHAg-specific donor regulatory T cells (Treg) together with sirolimus-based pharmacologic prophylaxis to examine safety and preliminary efficacy of this GVHD prevention approach. We employed a 3+3 phase I design escalating Treg dose in 4 levels: 0.5 x 105/kg, 1 x 105/kg, 2 x 105/kg, and 4 x 105/kg. Dose-limiting toxicity (DLT) included grade 4-5 related infusion reaction, grade 4-5 unexpected organ toxicity, grade III-IV acute GVHD, or treatment-related death. Secondary and exploratory measures examined acute and chronic GVHD, survival outcomes, and Treg clone (TCR-Seq) expansion in culture, and in-vivo longevity and expansion post-HCT. 15 subjects were included (N=3 each per dose levels 1-3, and N=6 in dose level 4). No DLT were observed, and 4 x 105/kg Treg was identified as MTD. Median follow up for survivors was 41.7 months (range 14.5-72.8). The day 100 cumulative incidence of grade II-IV acute GVHD was 13% (95% CI 2-35%). NIH moderate/severe chronic GVHD by 1 year was 6.7% (95% CI 0.36-27%) and by 3 years was 20% (95%CI 4.4-44%). Overall survival was 73% (95% CI 54-100%). Treg clones expanded in culture, and demonstrated post-HCT lineage fidelity, persistence, and in-vivo expansion. This translational trial supports mHAg-specific expanded donor Treg as a novel GVHD prevention strategy, and demonstrates expanded donor Treg clones can persist and expand through one-year post-HCT. NCT01795573.

Watch & wait is the standard of care in asymptomatic early-stage chronic lymphocytic leukemia (CLL). The CLL12 trial investigated ibrutinib versus placebo in early-stage patients with intermediate to very high risk of progression, showing improved event-free survival (EFS) but no overall survival (OS) benefit10. Building on these findings, our analysis examined whether a significant benefit could be identified within distinct genetic subgroups. After a median follow-up of 69.3 months, there were 166 EFS and 32 OS events in 515 trial patients. In the placebo arm, del(17p), del(11q), +12, U-IGHV, and mutations in NOTCH1, ATM, NRAS/KRAS/BRAF, and NFKBIE correlated with shorter EFS. With ibrutinib, only del(17p) and TP53 and NFKBIE mutations significantly compromised EFS. Ibrutinib offered substantial EFS benefit in subgroups with U-IGHV, del(11q), +12, NOTCH1, ATM, and NFKBIE mutations. No EFS improvement was seen for asymptomatic early-stage patients with del(17p) or TP53 mutations. Ibrutinib provided no OS benefits in any genetic subgroup. Multivariable analysis revealed ibrutinib treatment as an independent favorable factor for EFS, while U-IGHV, del(17p), POT1, RAS/RAF, and NFKBIE mutations were adverse prognostic factors. The results confirm watch-and-wait as standard of care for early-stage CLL patients, especially in high-risk CLL characterized by del(17p) and/or mutated TP53. EudraCT Number: 2013-003211-22.

Treatment options for patients with immunoglobulin light chain (AL) amyloidosis and advanced cardiac involvement remain limited. The prospective, phase 2 EMN22 trial included previously untreated patients with AL amyloidosis, measurable hematologic disease, and Mayo2004/European cardiac stage IIIB to receive daratumumab monotherapy at the standard dose and schedule for up to two years (28-day cycles); patients with inadequate response after three cycles could additionally receive bortezomib weekly and dexamethasone. The primary endpoint was 6-month overall survival (OS) rate. Of 40 enrolled patients, ten (25.0%) received additional treatment with bortezomib and dexamethasone. The 6-month OS rate was 65.0% (95% CI, 48.2-77.6) and median OS was 10.4 months. The best hematologic response rate (partial response or better) up to six months was 75.0% (very good partial response or better: 47.5%; complete response: 12.5%), the median time to the first and best hematologic response being one week and 2.3 months, respectively. The cardiac response rate at six months was 30.0%. Common serious adverse events were cardiac failure (25.0%), sudden cardiac death (10.0%), and acute kidney injury (7.5%). The patients' quality of life remained stable throughout the trial treatment and observation. In patients with high-risk, advanced (stage IIIB) AL amyloidosis, daratumumab monotherapy was feasible and well-tolerated, achieving rapid hematologic responses and associated with prolonged survival relative to historical cohorts. Cardiac response rates at 6 months were significant, considering the advanced cardiac disease. These findings support daratumumab as the backbone of anti-clonal therapy in advanced cardiac AL amyloidosis. This trial was registered at www.clinicaltrials.gov as #NCT04131309.

Targeting ACKR3/CXCR7 regulates enzymatic generation of pro-thrombotic, while favoring anti-thrombotic lipids that inhibit platelets through AC-cAMP-PKA pathway in coordination with prostacyclin-IP receptor. This investigation validated the impact of CXCR7 in modulating non-enzymatic lipid (per)oxidation, platelet response to lipoproteins-(LDL, oxLDL), mitochondrial metabolism and procoagulatory functions. Pharmacological CXCR7-agonist-(VUF11207) preserved mitochondrial membrane integrity-(Δψm), counteracted activation-induced mitochondrial superoxide generation-(MitoSOXRed), and nonenzymatic lipid (per)oxidation. Additionally, CXCR7-agonist regulated lipoprotein-induced platelet adhesion on thrombogenic matrices, degranulation, αIIbβIII-integrin activation, aggregation and thrombotic response, by reducing lipoprotein uptake through scavenger receptors-(CD36, ApoER2). CXCR7-ligation triggered activation of metabolic energy sensor Adenosine MonoPhosphate-dependent Kinase-(AMPKSer-172), prompted AMPK-mediated inhibitory phosphorylation of Acetyl-CoA-Carboxylase-(ACC)Ser-79, to foster lipolysis over lipogenesis. Consequently AMPKSer-172-ACCSer-79 pathway increased anticoagulatory FXa-inhibitory long-chain acylcarnitine-(LC-CARs)-(16:0, 18:1, 18:2) generation in platelets from healthy subjects and CAD patients. Increased intraplatelet LC-CARs was not due to dysregulated mitochondrial respiration; since CXCR7-agonist improved maximal respiration, spare respiratory capacity, and ATP-linked respiration in thrombin-activated platelets, suggesting sustained mitochondrial metabolism. Exerting a two-pronged effect on procoagulant function, CXCR7-agonist downregulated phosphatidylserine exposure on activated platelets, reducing FX/FXa binding, while platelet-derived anticoagulatory-LC-CARs regulated thrombin generation. CXCR7-agonist administration reduced thrombus formation, platelet degranulation, αIIbβIII-integrin activation, procoagulant activity, circulatory platelet-leukocyte aggregates in murine venous thrombosis model; besides, decreased plasma procoagulant lipids-(platelet COX-1, 12-LOX, and leukocyte 5/15-LOX-derived) and thrombo-inflammatory mediators-(IL-1β, IL-6, IFN-γ, TNF-α, MCP-1), and increased plasma LC-CAR levels. Therefore, pharmacological targeting of CXCR7 could regulate (non)enzymatic lipid processing, and promote anticoagulatory LC-CAR generation to check platelet-directed thrombotic propensity, and hypercoagulation, moreover, replenish reduced levels of circulatory anticoagulant-LC-CARs in STEMI and venous thromboembolism-(VTE) patients.

Fas-associated phosphatase-1 (FAP-1), a nonreceptor protein tyrosine phosphatase, has been implicated in multiple signaling pathways, but its in vivo role remains unclear. Here, we show that FAP-1-deficient (FAP-1ΔP/ΔP) mice develop early megakaryocyte hyperplasia with defective platelet function and occasional hemorrhagic manifestations, accompanied by myelofibrosis-like features in aged animals. Bone marrow analysis revealed impaired demarcation membrane system (DMS) development with pre-DMS arrest in megakaryocytes, leading to defective proplatelet formation and impaired platelet function, with prolonged bleeding partly associated with reduced clot retraction. Mechanistically, FAP-1 deficiency induces sustained Src activation and cofilin inactivation, impairing perinuclear actin remodeling required for DMS expansion and resulting in pre-DMS arrest. With aging, approximately half of mice develop a symptomatic phenotype characterized by extramedullary hematopoiesis, hepatosplenomegaly, anemia, and thrombocytopenia; among these, most remain in a prefibrotic state, while a subset progresses to fibrosis-like changes. Bone marrow transplantation demonstrates that megakaryocyte abnormalities and fibrosis-associated changes are hematopoietic cell-intrinsic and partially transferable. Pharmacologic inhibition of Src with dasatinib attenuates these defects in FAP-1-deficient mice, supporting pathway specificity. In patients with primary myelofibrosis, reduced FAP-1 expression is associated with pre-DMS megakaryocyte accumulation, abnormal DMS and actin organization, and Src activation, supporting clinical relevance. Collectively, we identify a FAP-1-dependent mechanism governing Src-cofilin-mediated actin remodeling required for megakaryocyte maturation and platelet function, and suggest this pathway as a potential therapeutic target for platelet dysfunction, hemorrhagic complications, and fibrosis-associated disease.

Anbalcabtagene autoleucel (Anbal-cel) is a CD19-directed CAR T-cell therapy incorporating dual PD-1 and TIGIT knockdown to enhance antitumor function and durability. We report the results of a Phase 1/2 study in patients with relapsed or refractory large B-cell lymphoma (LBCL). In Phase 2, 79 patients received Anbal-cel, and efficacy was evaluated in 73 patients. The complete response (CR) and partial response (PR) rates were 67.1% and 8.2%, respectively. Median progression-free survival (PFS) was 6.04 months (95% CI, 4.34-16.46), and the 6-, 12-, and 18-month PFS rates were 50.9%, 41.1%, and 35.2%, respectively. Median overall survival (OS) was not reached, with 12- and 18-month OS rates of 66.6% and 57.3%. CAR T-cell expansion was significantly greater in responders than in non-responders (median Cmax: 20,403 vs. 8,580 copies/μg). Patients were categorized into long-term response (LR) group or non-LR group based on sustained CR at 6 months. Reduced PD-1 and TIGIT expression on CAR-positive T cells was observed in LR group. Most patients (97.5%) experienced grade ≥3 adverse events, most commonly neutropenia (93.7%), followed by thrombocytopenia (41.8%) and anemia (30.4%). Cytokine release syndrome and neurologic events occurred in 57.0% and 13.9% of patients, respectively. Grade 3 CRS occurred in 8.9% of patients, with no grade 4 events reported, and grade ≥3 neurologic events occurred in 3.8%. Serious infections occurred in 25.3% of patients, and grade 5 infection was reported in 3 patients. This trial was registered at Clinicaltrials.gov (NCT04836507).

Idecabtagene vicleucel (ide-cel) induces deep responses in relapsed/refractory multiple myeloma (RRMM), yet more than half of patients relapse within one year. The intrinsic features of CAR-T products that distinguish durable from non-durable responders are poorly defined, particularly at single-cell resolution, and defining drivers of durable response is critical to guide patient counseling and to inform strategies for optimizing CAR-T manufacturing and efficacy. To address this need, 40 ide-cel infusion products (184,398 cells) were profiled using single-cell RNA sequencing. These analyses revealed that a transcriptional program in CD4 CAR-T cells that led to durable responses is characterized by NF-κB signaling, pro-survival circuits, tonic/chemokine signaling, and elevated CAR transgene expression. These features were associated with prolonged progression-free and overall survival irrespective of baseline clinical characteristics. Further, analysis of paired apheresis and tumor microenvironment samples showed that elevated NF-κB activity is an intrinsic hallmark of T-cell fitness that is characterized by a central memory phenotype and the lack of checkpoint receptorligand expression, and that these features were manifest in marrow-derived and peripheral blood T cells prior to CAR-T manufacturing. Finally, validating functional relevance, pharmacologic inhibition of NF-κB abrogated CAR-T cytotoxicity and cytokine production in vitro. Our results support that NFKB in the ide-cel product marks a signaling axis impacting CAR-T function and NFKB activity represents a global marker of T cell fitness present prior to CAR-T manufacture.

Pharmacological plasminogen reduction enhanced liver regeneration experimentally and clinically. siRNA-induced plasminogen deficiency promoted hepatocyte proliferation after partial hepatectomy in mice, contrasting genetic deficiency models. In the HeLiX trial, tranexamic acid reduced post-hepatectomy liver failure odds, suggesting a novel therapeutic strategy.

Thrombosis is a major contributor to global morbidity and mortality. Current standards of care target the extrinsic and/or common pathways of coagulation, effectively inhibiting thrombosis but also increasing bleeding risk, highlighting the unmet need for additional treatment options. Genetic deficiency in factor XI (FXI), a component of the intrinsic pathway, reduces thrombosis risk without spontaneous bleeding. We generated 2 FXI monoclonal antibodies (mAbs) with distinct profiles to provide new approaches to anticoagulation. Cenvacibart (REGN7508Cat) targets the catalytic domain to completely block FXI activity (induced by FXIIa or FXIa in the intrinsic pathway or thrombin in an intrinsic/common pathway amplification loop), thereby maximizing anticoagulation; amrecibart (REGN9933A2) targets the apple 2 domain of FXI/FXIa to specifically prevent FXI activity induced by FXIIa-delivering perhaps less anticoagulation but with potentially lower bleeding risk. We evaluated the anticoagulant effects of both mAbs in vitro in human/non-human primate plasma, in vivo in non-human primates, and healthy volunteers. Both mAbs inhibited intrinsic pathway-triggered coagulation, assessed by activated partial thromboplastin time (aPTT); cenvacibart exhibited a greater increase in aPTT versus amrecibart or other FXI-targeted inhibitors. Neither amrecibart nor cenvacibart affected the extrinsic pathway, assessed by prothrombin time (PT). In non-human primates, both mAbs prevented thrombosis without increasing bleeding. In first-in-human studies, both mAbs were generally well tolerated and dose-dependently inhibited intrinsic pathway-triggered coagulation, with durable aPTT prolongation without affecting PT. Amrecibart and cenvacibart may offer tailored therapies for patients with different bleeding risk profiles. The trials are registered at www.clinicaltrials.gov as #NCT05102136 and #NCT05603195.