Multiple myeloma is a hematologic malignancy characterized by the clonal proliferation of plasma cells within the bone marrow. The tumor microenvironment plays a crucial role in multiple myeloma pathogenesis, progression, and drug resistance. Traditional two-dimensional cell culture models have been instrumental in multiple myeloma research. However, they fail to recapitulate the complex in vivo bone marrow microenvironment, leading to limited predictive value for clinical outcomes. Three-dimensional cell culture models emerged as more physiologically relevant systems, offering enhanced insights into multiple myeloma biology. Scaffold-based systems (e.g., hydrogels, collagen, and Matrigel), scaffold-free spheroids, and bioprinted models have been developed to simulate the bone marrow microenvironment, incorporating key components like mesenchymal stromal cells, osteoblasts, endothelial cells, and immune cells. These models enable the functional assessment of cell adhesion-mediated drug resistance, cytokine signaling networks, and hypoxia-induced adaptations, which are often lost in 2D cultures. Moreover, 3D platforms demonstrated improved predictive value in preclinical drug screening, facilitating the evaluation of novel agents and combination therapies in a setting that better mimics the in vivo tumor context. Hence, 3D cultures represent a pivotal step toward bridging the gap between basic myeloma research and translational applications, supporting the development of more effective and patient-specific therapies.

Multiple myeloma profoundly remodels the bone marrow microenvironment, causing osteolytic bone disease through a persistent uncoupling of bone resorption and formation. Beyond the canonical roles of the receptor activator of nuclear factor kappa-B ligand/receptor activator of nuclear factor kappa-B/osteoprotegerin triad and Wnt antagonism, three interdependent stress programs orchestrate the osteolytic niche. These include oxidative stress driven by mitochondrial and nicotinamide adenine dinucleotide phosphate oxidase-derived reactive oxygen species; sterile inflammation sustained by damage-associated molecular patterns, pattern-recognition receptors, and pro-inflammatory cytokines; and autophagy–lysosomal remodeling governed by transcription factor EB and the coordinated lysosomal expression and regulation network. These axes intersect with iron handling and lipid peroxidation to regulate sensitivity to ferroptotic cell death, thereby shaping osteoclast priming, osteoblast suppression, and matrix turnover. Building on these mechanistic insights, we outline a translational framework that aligns standardized bone turnover markers of formation and resorption with composite panels of oxidative and nitrosative stress. This framework also integrates modern imaging to capture structural injury and metabolically active marrow disease. We further propose a therapeutic roadmap layered on antiresorptive foundations that targets selective inhibition of nicotinamide adenine dinucleotide phosphate oxidase 4 and calibrated modulation of nuclear factor erythroid 2–related factor 2, disrupts damage-associated molecular pattern and cytokine circuits, and applies lineage- and timing-specific tuning of autophagy together with restoration of ferroportin-1 or iron chelation. This integrated strategy is designed to recouple bone remodeling and improve clinically meaningful skeletal outcomes in multiple myeloma.

Systemic mastocytosis comprises a group of clonal mast cell disorders characterized by multisystem involvement. Bone involvement represents a major source of morbidity, particularly in young men affected by indolent systemic mastocytosis. This review provides an integrated and up-to-date overview of SM-related bone disease. We dissect the dual and context-dependent role of mast cells in bone remodeling, detailing how they promote osteoclastogenesis, suppress osteoblast function, and, in advanced disease, drive osteosclerosis. We critically appraise available treatments, including classic anti-resorptive therapy and emerging anabolic strategies. We further discuss the transformative impact of KIT-directed tyrosine kinase inhibitors, particularly avapritinib, which has demonstrated for the first time the ability to reverse not only osteoporosis but also osteosclerosis. Finally, we explore the emerging role of machine learning models in SM, proposing their application to individualized prediction of osteoporosis and fracture risk in SM. By bridging clinical care, bone biology, and therapeutic advances, this review underscores the need for a paradigm shift in which SM-related bone disease is recognized as a dynamic process requiring early identification, integrated risk stratification, and coordinated use of anti-resorptive, disease-modifying, and data-driven precision approaches to prevent fractures and improve long-term outcomes and quality of life in this delicate category of patients.

Relapsed and refractory multiple myeloma remains the principal cause of myeloma-related mortality despite major advances in therapeutic options, including proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, and T-cell-based immunotherapies. Conventional resistance models based on linear genetic clonal evolution inadequately explain reversible drug resistance, heterogeneous responses, and relapse after deep remissions. Emerging data from longitudinal genomics, single-cell analyses, and functional studies support a paradigm in which relapsed and refractory multiple myeloma is driven by adaptive plasticity rather than irreversible genetic change alone. Myeloma cells undergo reversible cell state transitions through transcriptional, epigenetic, metabolic, and proteostatic reprogramming, shaped by bone marrow microenvironmental cues and immune pressure. This narrative review integrates current evidence supporting adaptive plasticity as a central driver of therapeutic failure in relapsed and refractory multiple myeloma and discusses clinical and translational implications, highlighting adaptive treatment strategies and approaches targeting phenotypic flexibility to improve durability of response.

Myelodysplastic syndromes are clonal hematopoietic neoplasms in which ineffective hematopoiesis arises within the context of chronic inflammation and immune dysregulation. Growing evidence indicates that aging-associated inflammaging and inflammation-driven remodeling of the bone marrow microenvironment are not secondary phenomena, but active forces that shape clonal selection, lineage commitment, and disease evolution. This narrative review integrates recent insights from translational immunology, stem cell biology, multi-omics analyses, and clinical studies to examine the reciprocal interplay between inflammation and myelodysplastic syndrome pathogenesis. Chronic inflammatory stress imposes selective pressure on hematopoietic stem cells, favoring the expansion of mutation-bearing clones characteristic of clonal hematopoiesis and overt disease. As inflammation persists, immune dysfunction, together with stromal alterations, progressively reinforce ineffective hematopoiesis and clonal dominance. Genetic lesions, including TP53 and spliceosome mutations, further amplify inflammatory signaling and reshape the marrow niche, conferring clonal fitness and genomic instability. Clinically, readily accessible peripheral blood inflammatory indices reflect these biological processes and correlate with prognosis and therapeutic response. Collectively, these observations position inflammation as a unifying determinant of myelodysplastic syndrome initiation, progression, and treatment sensitivity. Integrating inflammatory signatures with genomic profiling may refine risk stratification and support the development of therapeutic strategies aimed at restoring marrow homeostasis and limiting inflammation-driven clonal evolution.

Myelodysplastic syndromes are clonal hematopoietic neoplasms in which ineffective hematopoiesis arises within the context of chronic inflammation and immune dysregulation. Growing evidence indicates that aging-associated inflammaging and inflammation-driven remodeling of the bone marrow microenvironment are not secondary phenomena, but active forces that shape clonal selection, lineage commitment, and disease evolution. This narrative review integrates recent insights from translational immunology, stem cell biology, multi-omics analyses, and clinical studies to examine the reciprocal interplay between inflammation and myelodysplastic syndromes pathogenesis. Chronic inflammatory stress imposes selective pressure on hematopoietic stem, favoring the expansion of mutation-bearing clones characteristic of clonal hematopoiesis and overt disease. As inflammation persists, immune dysfunction, together with stromal alterations, progressively reinforce ineffective hematopoiesis and clonal dominance. Genetic lesions, including TP53 and spliceosome mutations, further amplify inflammatory signaling and reshape the marrow niche, conferring clonal fitness and genomic instability. Clinically, readily accessible peripheral blood inflammatory indices reflect these biological processes and correlate with prognosis and therapeutic response. Collectively, these observations position inflammation as a unifying determinant of myelodysplastic syndromes initiation, progression, and treatment sensitivity. Integrating inflammatory signatures with genomic profiling may refine risk stratification and support the development of therapeutic strategies aimed at restoring marrow homeostasis and limiting inflammation-driven clonal evolution.