This study reveals the central regulatory role of S100A9 in myelodysplastic neoplasms, suggesting that blocking S100A9 could serve as a combination therapeutic strategy to ameliorate the comorbidity of anemia and bone loss, providing a mechanistic basis for microenvironment-targeted therapy in myelodysplastic neoplasms.
Literature Overview
The article titled 'Preclinical efficacy of tasquinimod in myelodysplastic neoplasms: Restoring erythropoiesis and mitigating bone loss,' published in the journal HemaSphere, systematically investigates the therapeutic potential of the small-molecule inhibitor tasquinimod (TASQ) in myelodysplastic neoplasms (MDS). The study focuses on how the S100A9-mediated inflammatory signaling axis disrupts the bone marrow microenvironment and evaluates whether TASQ can reverse this pathological process. Using human sample analyses, in vitro co-culture systems, and the NHD13 transgenic mouse model, the authors systematically validated the multifaceted regulatory effects of TASQ on MSC function, erythroid differentiation, and bone metabolism, offering novel insights into treating the comorbidity of anemia and osteoporosis in low-risk MDS patients.Background Knowledge
Myelodysplastic neoplasms (MDS) are clonal hematologic disorders characterized by ineffective hematopoiesis, cytopenias, and a risk of progression to acute myeloid leukemia (AML). Patients often suffer from severe anemia and depend on red blood cell transfusions, significantly reducing their quality of life. Recent studies have shown that MDS is not solely driven by hematopoietic stem cell mutations; chronic inflammation within the bone marrow microenvironment also plays a critical role. Among these, the damage-associated molecular pattern molecules S100A8/A9 are widely recognized as core inflammatory mediators that activate TLR4 and RAGE receptors, triggering the NF-κB signaling pathway and promoting the release of cytokines such as IL-1β and IL-18, leading to apoptosis and differentiation blockage of hematopoietic stem and progenitor cells (HSPCs). Moreover, osteoporosis is frequently observed in MDS patients, indicating tight crosstalk between bone metabolism and hematopoiesis. However, simultaneously improving anemia and bone loss remains an unmet clinical need. Although anti-inflammatory therapies such as IRAK4 inhibitors have been attempted, their efficacy is limited. Therefore, targeting upstream S100A9 may offer broader anti-inflammatory effects. Tasquinimod, an oral small-molecule inhibitor of S100A9, has shown immunomodulatory activity in prostate cancer and myelofibrosis models, but its role in MDS remains unclear. This study explores whether TASQ can achieve dual protective effects by reshaping the bone marrow microenvironment.
Research Methods and Experiments
The study employed multiple technical approaches for systematic validation. First, multiplex immunofluorescence staining was used to analyze cell origins in bone marrow sections from MDS patients and healthy donors, identifying the primary cell types expressing S100A9. Subsequently, in vitro experiments isolated human MSCs and stimulated them with recombinant S100A9 to simulate the inflammatory state of the MDS microenvironment, with TASQ intervention. Western blotting was used to detect downstream signaling molecules of TLR4 (e.g., IRAK1, NF-κB-p65), while qPCR assessed changes in inflammatory factors (e.g., IL-1β, IL-18, caspase-1) and immune checkpoint PD-L1 expression. Functionally, CFU-F and CAF-C assays evaluated the MSCs' ability to support HSPCs, and co-culture systems analyzed HSC differentiation into erythroid (CFU-E) and granulocyte-monocyte (CFU-GM) lineages. For in vivo models, NHD13 transgenic mice were used as a preclinical model of MDS and treated orally with TASQ for 12 weeks, monitoring peripheral blood red cell parameters. Flow cytometry analyzed erythroid precursor distribution in the bone marrow, while micro-CT and bone histomorphometry assessed changes in bone microstructure, including bone volume, trabecular number, and osteoclast count.Key Conclusions and Perspectives
Research Significance and Prospects
This study presents a novel dual-effect strategy for MDS treatment—simultaneously improving anemia and bone loss. Traditional therapies such as ESAs or transfusions only alleviate symptoms, whereas TASQ fundamentally modulates the bone marrow microenvironment by targeting S100A9, restoring normal hematopoietic support function. This mechanism is particularly relevant for low-risk MDS patients, who experience slow disease progression but severely compromised quality of life due to anemia. Additionally, osteoporosis is often overlooked, and this study suggests S100A9 may be a common node linking inflammation, hematopoietic dysfunction, and bone disease, making TASQ a potential multi-system protective agent.
From a drug development perspective, TASQ has entered multiple clinical trials with substantial safety data, potentially accelerating its translation into MDS treatment. Future studies should explore its combination with other agents (e.g., luspatercept or hypomethylating agents) to enhance efficacy. Furthermore, it is essential to clarify whether TASQ affects clonal evolution or immune surveillance to avoid potential pro-leukemic risks. Additionally, this study underscores the importance of MSCs as a therapeutic target, suggesting that stromal components should be incorporated into disease modeling to build more physiologically relevant co-culture systems.
Conclusion
This study systematically elucidates the central role of S100A9 in myelodysplastic neoplasms, revealing that its activation of the TLR4/NF-κB pathway leads to dysfunction of bone marrow mesenchymal stem cells, thereby causing ineffective hematopoiesis and bone loss. The small-molecule inhibitor TASQ effectively blocks this pathway, restoring the hematopoietic support capacity of MSCs and improving erythroid differentiation and bone microstructure. These findings not only deepen our understanding of MDS pathogenesis but, more importantly, propose a new therapeutic paradigm that addresses both hematologic and skeletal health. For MDS patients who rely on long-term transfusions and suffer from osteoporosis, TASQ holds promise as the first targeted therapy to deliver dual clinical benefits. Future research should advance its clinical trials to validate efficacy and safety in patients, while exploring its potential in other inflammation-related hematologic disorders, ultimately realizing its translational value from bench to bedside.
