Biosimilars used in hematology have been at the forefront of biosimilar development since the first US approval in 2015 of a filgrastim product, with over 80 now FDA-licensed. Developers traditionally submitted data from...Biosimilars used in hematology have been at the forefront of biosimilar development since the first US approval in 2015 of a filgrastim product, with over 80 now FDA-licensed. Developers traditionally submitted data from a comparative analytical assessment (CAA) and clinical studies, often including a comparative efficacy study (CES), to support demonstrating their product is "highly similar" to and has "no clinically meaningful differences" from its reference product (RP). However, growing scientific confidence in the analytical comparisons between biosimilars and their RP included in the CAA has prompted FDA and global regulators to reconsider the utility of CES. Recently, FDA published updated recommendations on the need for a CES in biosimilar programs. As approvals for hematologic biosimilars span the entire history of FDA biosimilar development across a breadth of patient ages and diseases, reexamining these programs provides valuable insights into the evolving role of the CES in the past and its role in the future. In this review, we present a historical overview of the development programs for all FDA-approved hematologic biosimilars in the context of an emerging global consensus recognizing the CAA is more sensitive than CES for predicting biosimilarity.
Xu C, Lv X, Yang S
… +19 more, Lv Y, Zheng Y, Wang YX, Hui Y, Sun G, Zhao X, Ma LY, Duan H, Zhang L, Pu S, Sun L, Li X, He Y, Fang W, Yang M, Suda T, Chen Q, Cheng T, Cheng H
Hematopoietic stem cells (HSCs) rely on specialized niche cells for maintenance, yet how these regulators functionally integrate to preserve hematopoiesis remains unknown. Here, we identified a subset of Procr+ endotheli...Hematopoietic stem cells (HSCs) rely on specialized niche cells for maintenance, yet how these regulators functionally integrate to preserve hematopoiesis remains unknown. Here, we identified a subset of Procr+ endothelial cells (ECs) with progenitor-like properties in bone marrow (BM), which is critical for vascular homeostasis and injury regeneration. Endothelial-specific ablation of Procr severely compromises BM vascular integrity and function. Beyond serving as a stem cell marker, Procr serves dual biological functions as a functional signaling receptor in multicellular communication. Mechanistically, Procr binds HSPA8 to promote Foxc2 nuclear translocation, upregulating Dll4 transcription to sustain Dll4/Notch3 activation in mesenchymal stem cells (MSCs), revealing a Procr/HSPA8/Foxc2/Dll4 axis essential for EC and MSC crosstalk. Through the HSPA8/Foxc2/Dll4/Notch3 axis, Procr+ ECs instruct MSCs Notch signaling, coordinating their adipogenic-osteogenic differentiation to maintain HSC self-renewal and myeloid output. Building on this mechanism, we demonstrated conserved functionality of Procr+ EPCs in human BM. Human PROCR+ ECs were found to similarly enhance DLL4/Notch3 signaling in MSCs, consequently preserving HSC function, confirming their therapeutic relevance. Our work highlights Procr⁺ EPCs sustain vascular integrity and govern MSC-dependent HSC maintenance, offering targeted clinical strategies for niche regeneration.
T cell dysfunction is an important contributor to both multiple myeloma (MM) disease progression and failure of anti-myeloma chimeric antigen receptor (CAR) T cell and bispecific T cell engager (TCE) therapies. Overcomin...T cell dysfunction is an important contributor to both multiple myeloma (MM) disease progression and failure of anti-myeloma chimeric antigen receptor (CAR) T cell and bispecific T cell engager (TCE) therapies. Overcoming T cell dysfunction is therefore key to improving MM patient outcomes. Immunomodulatory drugs (IMiDs) and cereblon E3 ligase modulatory drugs (CELMoDs) have been observed to activate T cells, and more recently reduce T cell dysfunction, however the underlying mechanisms behind this are incompletely understood. Here, using bone marrow samples from MM patients, we demonstrate a significant reduction in dysfunctional T cell populations expressing exhaustion markers such as TIGIT, upon treatment with Mezigdomide. We further demonstrate the ability of Mezigdomide to improve T cell function and cytotoxicity in primary T cell models of T cell dysfunction and bispecific TCE therapy in vitro. Using concurrent ATAC-seq, ChIP-seq, HiC and RNA-seq in primary T cells treated with Mezigdomide, we demonstrate the novel role of transcription factor Ikaros in regulating an important T cell exhaustion gene TIGIT. Finally, we demonstrate the ability of Mezigdomide to enhance survival outcomes from anti-BCMA CAR-T therapy in vivo. Overall, our data show that Mezigdomide treatment improves anti-myeloma T cell therapy efficacy and reduces T cell dysfunction by abrogating Ikaros-mediated upregulation of exhaustion genes.
Heparin-induced thrombocytopenia (HIT) is characterized by the production of pathogenic antibodies that bind to complexes of platelet factor 4 (PF4) and heparin, causing platelet activation and a hypercoagulable state. A...Heparin-induced thrombocytopenia (HIT) is characterized by the production of pathogenic antibodies that bind to complexes of platelet factor 4 (PF4) and heparin, causing platelet activation and a hypercoagulable state. A significant proportion of heparin-treated patients develop nonpathogenic anti-PF4/heparin antibodies that do not activate platelets but interfere with routine screening tests causing frequent false-positive results. We recently showed that pathogenic HIT antibodies are monoclonal and bind to an overlapping PF4 binding site, which could be exploited to identify clinically significant antibodies in patients. This study aimed to develop epitope-specific inhibitors based on the HIT-like murine monoclonal antibody (KKO) that recognizes a binding site overlapping with patient-derived pathogenic HIT antibodies on PF4. We developed a wild-type single-chain variable fragment (scFv) derived from KKO and performed site-directed mutagenesis to create a library of mutant anti-PF4/heparin scFv sequences. Five candidate scFvs were selected based on sequence enrichment after phage biopanning. We confirmed the high affinity and specific binding of these scFv fragments to PF4/heparin complexes using enzyme immunoassays (EIAs) and biolayer interferometry and demonstrated that KKO and all scFvs bind to an overlapping heparin-dependent site on PF4 by epitope mapping. Using patient sera, we demonstrated that our scFv candidates selectively inhibit the binding of pathogenic anti-PF4/heparin HIT antibodies and prevented platelet activation of some samples in the serotonin release assay. Importantly, the binding of nonpathogenic antibodies to PF4/heparin was unperturbed. These findings support the use of scFvs targeting a shared pathogenic region on PF4 to improve the diagnostic accuracy of anti-PF4/heparin EIAs for HIT.
Hematopoietic regeneration requires coordinated activation of hematopoietic stem and progenitor cells (HSPCs) and adaptive remodeling of the bone marrow (BM) microenvironment to meet extreme metabolic and oxidative deman...Hematopoietic regeneration requires coordinated activation of hematopoietic stem and progenitor cells (HSPCs) and adaptive remodeling of the bone marrow (BM) microenvironment to meet extreme metabolic and oxidative demands imposed by cytotoxic injury, transplantation, and inflammation. While soluble factors and cytokine signaling are central to this process, emerging evidence identifies direct intercellular communication as a critical regulatory layer in stress hematopoiesis. Connexins, particularly Connexin-43 (Cx43), form an evolutionarily conserved communication network that integrates metabolic coupling, redox buffering, and organelle dynamics across hematopoietic and stromal compartments. Beyond canonical gap junction channel activity, connexins exert non-junctional, compartment-specific functions through cytoplasmic, nuclear, and mitochondrial pools that regulate signaling scaffolds, transcriptional programs, cytoskeletal organization, mitochondrial dynamics, calcium homeostasis, and bioenergetics. In HSPCs, mitochondrial Cx43 functions as a metabolic checkpoint that preserves regenerative capacity by supporting oxidative phosphorylation, limiting chronic AMPK activation, maintaining fusion-fission balance, and preventing mitochondrial Ca²⁺ overload. In parallel, Cx43 enables mitochondrial transfer from donor HSPCs to stromal niche cells, restoring stromal metabolic competence and promoting effective niche repair and engraftment. Dysregulation of connexin networks contributes to marrow failure, clonal evolution, leukemic niche remodeling, and chemoresistance, highlighting their context-dependent roles in health and disease. This review synthesizes advances in connexin biology in hematopoiesis, reframes connexins as integrators of metabolic and regenerative signaling rather than passive conduits, and defines emerging translational opportunities. Isoform- and compartment-specific targeting of connexin pathways offers a therapeutic strategy to enhance hematopoietic recovery, preserve long-term stem cell function, and disrupt pathological niche support in hematologic malignancies.
Hypocellular bone marrow failure (BMF) may be acquired due to immune-mediated disease, the prototype being immune aplastic anemia (IAA), or inherited, due to germline defects in genes important for hematopoietic stem cel...Hypocellular bone marrow failure (BMF) may be acquired due to immune-mediated disease, the prototype being immune aplastic anemia (IAA), or inherited, due to germline defects in genes important for hematopoietic stem cells' function and maintenance (inherited bone marrow failure syndromes [IBMFS]). Proper diagnosis of the underlying etiology of hypocellular bone marrow failure, particularly distinguishing immune AA, myelodysplastic syndrome (MDS) (most relevant in this setting, hypoplastic MDS [MDS-h]), and the IBMFS, is important given the differences in clinical management. Clonal hematopoiesis (CH), in this context comprising somatic mutations or chromosomal abnormalities, is incorporated into standard algorithms for classification, risk stratification, and treatment decisions for hematologic malignancies, but the clinical significance in BMF is not well established. Disease-specific clonal signatures have been reported across the BMF spectrum, and here we show how distinct patterns of CH can aid in distinguishing different etiologies of hypocellular BMF. Additionally, detection of somatic alterations in many BMF disorders can estimate risk for secondary myeloid neoplasms, guide surveillance and, in some instances, allow for early therapeutic intervention.
Heparin-induced thrombocytopenia (HIT) is a common drug-induced immune disorder occurring in a subset of heparin-treated patients. Immune complexes comprising heparin, platelet factor 4 (PF4), and PF4/heparin-reactive an...Heparin-induced thrombocytopenia (HIT) is a common drug-induced immune disorder occurring in a subset of heparin-treated patients. Immune complexes comprising heparin, platelet factor 4 (PF4), and PF4/heparin-reactive antibodies are central to its pathogenesis. However, the role of epigenetic modification in HIT remains unexplored. Our study identified JMJD1C, a member of the lysine-specific histone demethylase 3 subfamily, as an essential regulator of PF4/heparin-specific antibody production. While JMJD1C was expressed throughout B-cell development and was dispensable for normal B-cell development, its deficiency disrupted immune tolerance and promoted production of self-reactive antibodies in systemic autoimmune diseases, including PF4/heparin-specific platelet-activating antibodies, a hallmark of pathogenic HIT antibodies. JMJD1C-deficient B cells were hyperresponsive, characterized by enhanced B-cell receptor (BCR)-induced proliferation. Transcriptomic analysis (RNA-Seq) revealed upregulation of pathways associated with BCR signaling, NF-kB activation, the cell cycle, and systemic lupus erythematosus (SLE). CUT&Tag profiling demonstrated that JMJD1C deficiency increased H3K36me1 modification at gene start sites in these pathways, indicating that epigenetic dysregulation drives B-cell hyperactivation. Importantly, transcriptional profiling and regulon analysis of B cells from HIT patients showed enrichment of BCR signaling, cell-cycle, NF-κB, and SLE-associated pathways, closely mirroring those in JMJD1C-deficient B cells. Epigenetic analyses further revealed enhanced promoter chromatin accessibility and elevated H3K36me1 deposition at promoter-TSS regions in HIT B cells. Together, these findings establish a strong molecular overlap between JMJD1C deficiency and human HIT B cells and reveal a previously unrecognized epigenetic mechanism underlying HIT pathogenesis. Our study provides the first evidence linking epigenetic regulation to HIT, offering new insights into its pathophysiology.
Hematopoiesis is a tightly regulated process through which a small pool of stem cells sustains the lifelong production of all blood cell types in response to physiological demand. Understanding how this process is contro...Hematopoiesis is a tightly regulated process through which a small pool of stem cells sustains the lifelong production of all blood cell types in response to physiological demand. Understanding how this process is controlled and how hematopoietic stem cells commit to specific lineages is essential to understand blood and immune health and to treat their disorders. In this review, we examine the major conceptual frameworks that have been proposed to describe hematopoiesis and the underlying data that informed them, ranging from the classical discrete hierarchy to the continuous model, the punctuated continuum, and the multitrack model. Evidence from clonal lineage-tracing studies in mouse, nonhuman primates, and humans supports the idea that lineage fate is largely predetermined rather than stochastically acquired, and we highlight the importance of clonal multiomics approaches for identifying the molecular predictors of fate. We then discuss the computational models that have been developed to study hematopoietic development. Finally, we outline key challenges, including resolving native hematopoiesis in vivo, in both mouse and humans, and identifying the molecular programs that encode fate trajectories and how they are altered in disease. Looking at the hematopoietic process through a clonal lens is paramount to find the molecular signatures that truly can predict fate.
Inflammation and coagulation are intricately linked. Although some studies have documented pro-inflammatory drivers of coagulation, the role of anti-inflammatory cytokines and the underlying mechanisms in the modulation...Inflammation and coagulation are intricately linked. Although some studies have documented pro-inflammatory drivers of coagulation, the role of anti-inflammatory cytokines and the underlying mechanisms in the modulation of coagulation, platelet function, and thrombosis remain poorly characterized. In this study, we demonstrated that interleukin-4 (IL-4), an anti-inflammatory cytokine, plays a crucial role in regulating platelet function and thrombus formation. IL-4 inhibited collagen-induced intracellular calcium mobilization, P-selectin expression, ATP release, integrin αIIbβ3 activation, platelet spreading, and platelet aggregation. IL-4 binds to residues 38-46 within GPVI's extracellular collagen-binding domain and suppresses downstream signaling by inhibiting phosphorylation of phospholipase Cγ2 and protein kinase C. A GPVI-derived interfering peptide (RR9) binding to IL-4 disrupted the IL-4-GPVI complex and reversed the inhibitory effects of IL-4 on platelets. In vivo, IL-4 overexpression or intravenous administration inhibited platelet intracellular calcium mobilization, ATP release, and aggregation, prolonged bleeding time, and attenuated both arterial and venous thrombosis. Conversely, IL-4 knockout, anti-IL-4 antibody treatment, or RR9 treatment enhanced platelet reactivity, promoted hemostasis, and aggravated thrombosis. Our findings reveal that IL-4 negatively regulates platelet function through direct interaction with GPVI, thereby facilitating crosstalk among inflammation, hemostasis, and thrombosis. Therefore, modulating IL-4 levels provides a novel strategy for treatment of thrombotic disorders.
Ribera JM, Torrent A, Morgades M
… +51 more, Barrena S, Ribera J, Genesca E, González-Campos J, Martínez-Cibrian N, Montesinos P, Hernández Sánchez A, Barba P, Zapico E, Sánchez R, Novo A, Sitges M, Maluquer Artigal C, Such E, Botella C, Queipo de Llano MP, Cabrero M, Vicent A, Lopez de Ugarriza P, Tormo M, González-González BJ, Garcia-Cadenas I, Rodríguez-Medina C, Martinez Sanchez P, Bermúdez A, Gómez-Centurión I, Herrero-Garcia M, Ciudad J, Navas-Acosta J, Hermosín L, Serrano J, Raposo-Puglia JÁ, Solan L, Roldán-Galiacho V, de Laiglesia A, Gómez-Pérez L, Solé-Rodríguez M, Casado MS, Llorente Gonzalez L, Barrios Decoud D, Vall-Llovera F, Algarra JL, Amador L, García-Boyero R, Cladera A, Bergua Burgues JM, Calasanz MJJ, Granada I, Feliu E, Hernández-Rivas JM, Orfao A
In adults with Philadelphia chromosome-negative (Ph-) acute lymphoblastic leukemia (ALL) genetic risk is usually combined with measurable residual disease (MRD) assignment to consolidation therapy. However, this combinat...In adults with Philadelphia chromosome-negative (Ph-) acute lymphoblastic leukemia (ALL) genetic risk is usually combined with measurable residual disease (MRD) assignment to consolidation therapy. However, this combination is not uniform across trials and centralized assessment is not always performed. This study analyzed patients' outcomes using centrally assessed MRD and genetics. Patients with high genetic risk (HGR), those who required two induction cycles for complete remission (CR), and CR patients with end-of-induction (EOI) MRD ≥0.01% were assigned to allogeneic hematopoietic stem cell transplant (alloHSCT), while the remaining patients were assigned to delayed consolidation and maintenance. HGR for B-ALL included KMT2A rearrangements, low hypodiploidy and age >35 years, homozygous TP53 mutations/deletions, or concomitant IKZF1 and CDKN2A/B deletions. HGR in T-ALL included absence of NOTCH1/FBXW7 mutations and/or K/NRAS or PTEN alterations. Patients with early T-ALL (ETP) received a different induction regimen, and all were assigned to alloHSCT. Median (range) age of 436 patients was 39 (18-60) years, 332 with B-lineage ALL and 104 T-ALL. By intention to treat, 243 non-ETP patients (61%) were assigned to alloHSCT and 157 (39%) to CT. The 3-year overall survival (OS) probability (95% CI) was 64% (58%-69%). For patients with CR and EOI MRD<0.01% without HGR (n=109), the OS probability was 81% (70%-89%), compared with 50% (34%-63%) for MRD-negative patients with HGR (n=64). In patients with ETP-ALL the probability of 3-year OS was 61% (37%-79%). The combination of genetics and MRD allows accurate identification of adult Ph- ALL patients candidates to alloHSCT or chemotherapy. The trial was registered at www.ClinicalTrials.gov: NCT04179929.
Plasma cell leukemia (PCL) represents an exceptionally aggressive plasma cell malignancy defined by ≥5% circulating plasma cells in peripheral blood of patients otherwise meeting diagnostic criteria for multiple myeloma...Plasma cell leukemia (PCL) represents an exceptionally aggressive plasma cell malignancy defined by ≥5% circulating plasma cells in peripheral blood of patients otherwise meeting diagnostic criteria for multiple myeloma (MM), per International Myeloma Working Group consensus. This ultra-high-risk disease exhibits distinctive clinical features including frequent extramedullary involvement, severe cytopenias, hypercalcemia, renal insufficiency, and/or significantly elevated β2-microglobulin and lactate dehydrogenase levels. The molecular landscape includes high-risk cytogenetic abnormalities and mutations that promote accelerated proliferation, apoptotic resistance, immune evasion, and bone marrow microenvironmental independence through dysregulated adhesion molecule and chemokine receptor expression. While autologous stem cell transplantation, proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies improved historical outcomes, the therapeutic paradigm continues to evolve. Novel therapeutic approaches including B-cell maturation antigen (BCMA)-directed therapies (bispecific antibodies and chimeric antigen receptor T-cell therapy), GPRC5D-targeted therapy, and BCL-2 inhibition demonstrate promise in treating both primary and secondary PCL. Despite these advances, PCL remains inadequately studied, with treatment approaches predominantly extrapolated from MM trials where PCL patients have largely been excluded. This review synthesizes current evidence and presents illustrative clinical cases demonstrating practical treatment approaches, while highlighting critical knowledge gaps requiring dedicated prospective clinical trials to meaningfully improve outcomes in this challenging disease entity.