Multiple myeloma (MM) is a hematologic malignancy caused by the clonal expansion of immunoglobulin-producing plasma cells in the bone marrow and/or extramedullary sites. Common manifestations of MM include anemia, renal dysfunction, infection, bone pain, hypercalcemia, and fatigue. Despite numerous recent advancements in the MM treatment paradigm, current therapies demonstrate limited long-term effectiveness and eventual disease relapse remains exceedingly common. Myeloma cells often develop drug resistance through clonal evolution and alterations of cellular signaling pathways. Therefore, continued research of new targets in MM is crucial to circumvent cumulative drug resistance, overcome treatment-limiting toxicities, and improve outcomes in this incurable disease. This article provides a comprehensive overview of the landscape of novel treatments and emerging therapies for MM grouped by molecular target. Molecular targets outlined include BCMA, GPRC5D, FcRH5, CD38, SLAMF7, BCL-2, kinesin spindle protein, protein disulfide isomerase 1, peptidylprolyl isomerase A, Sec61 translocon, and cyclin-dependent kinase 6. Immunomodulatory drugs, NK cell therapy, and proteolysis-targeting chimera are described as well.

Current treatment guidelines of myeloma cast nephropathy (MCN) recommend the institution of plasma cell‐directed therapy and consideration of therapeutic plasma exchange (TPE), with the goal of rapid reduction of the serum free light chain (sFLC). However, the role of TPE continues to remain a subject of debate. The goal of this retrospective bi‐institutional study was to evaluate the clinical outcomes of TPE in combination with systemic therapy. Eighty patients were included in this analysis, of whom 72.5% had ≥50% drop in their initial involved sFLC. At 3 months from TPE initiation, the overall hematologic response rate (ORR) was 67.5% with a very good partial response or better (≥VGPR) rate of 40%. At 6 months, ORR was 57.5%, with ≥VGPR rate of 49%. The renal response rate at 3 and 6 months was 47.5% and 43.75%, respectively; the overall renal response rate was 48.75%. On multivariable analysis, every one unit increase in baseline creatinine (odds ratio [OR] 0.76, p = 0.006), and achievement of ≥VGPR (OR 21.7 p < 0.0001) were significantly associated with renal response. Also, a ≥50% drop in sFLC was favorably associated with renal response (OR 3.39, p = 0.09). With a median follow‐up of 36.4 months, the median overall survival (OS) was 11 months. On multivariable analysis, achievement of renal response (hazard ratio [HR] 0.3, p < 0.0001) and newly diagnosed disease (NDMM; HR 0.43, p = 0.0055) were associated with improved OS. Among NDMM patients, those treated with daratumumab‐based regimens had a trend for better OS (p = 0.15), compared to other regimens, but the difference was not significant. At the end of follow‐up, an estimated 40.4% of patients who were on dialysis were able to become dialysis independent. In conclusion, our study highlights the poor survival of patients with MCN. Achievement of early renal response is crucial for prolonged OS, with daratumumab‐based therapies showing promise.

Extramedullary disease (EMD)—the proliferation of clonal plasma cells in soft tissues without direct bone connection—represents one of the most challenging manifestations of multiple myeloma, associated with aggressive biology, treatment resistance, and poor outcomes. EMD is driven by distinct pathophysiologic mechanisms including downregulation of adhesion molecules, acquisition of high-risk cytogenetic abnormalities (del(17p), gain(1q)), activation of the RAS–MAPK pathway, epigenetic dysregulation such as EZH2 upregulation, and remodeling of the immune microenvironment toward an immunosuppressive, T-cell-depleted phenotype. Conventional therapies, including anti-CD38-based regimens, yield limited efficacy in EMD, with pooled overall response rates of approximately 20% in triple-class-exposed relapsed/refractory disease. T-cell-redirecting therapies have emerged as the most promising treatment strategy. Both chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies have demonstrated clinically meaningful activity in soft tissue EMD, with CAR T-cell therapy providing the deepest and most durable responses, and dual-targeting bispecific combinations showing particularly encouraging efficacy. Central nervous system (CNS) myeloma, the most devastating form of EMD, has historically carried a dismal prognosis. Emerging retrospective data suggest that both CAR T-cell therapy and bispecific antibodies can achieve meaningful CNS responses with acceptable safety profiles, as part of multimodal approaches incorporating CNS-directed therapies. Despite these advances, EMD remains associated with inferior outcomes even in the immunotherapy era, underscoring the need for strategies targeting the immunosuppressive microenvironment, novel therapeutic approaches, and prospective EMD-focused clinical trials. This review provides a comprehensive overview of the biology, classification, and evolving treatment landscape of both non-CNS and CNS EMD in the era of T-cell-redirecting immunotherapy.