Smoldering multiple myeloma (SMM) has long been viewed as an intermediate precursor state, monitored until symptoms or organ dysfunction signaled the transition to active multiple myeloma (MM). Over the past decade, however, major advances in molecular biology, modern imaging, and immunotherapy have reshaped our understanding of early plasma cell disorders. The recent FDA approval of daratumumab for high-risk SMM marks a historic turning point. For the first time, early intervention is not only feasible but clinically validated. This evolving framework challenges long-standing assumptions regarding diagnostic boundaries, risk stratification, and the traditional "watch-and-wait" paradigm. It is logical to conjecture that emerging and future technologies will redefine portions of today's SMM population as early myeloma, while others may ultimately be reclassified as benign monoclonal gammopathies. An interesting question is whether there will be any SMM patients left? This article reviews how the field has arrived at this new therapeutic era, outlines its limitations, and highlights key scientific and clinical questions that will shape the next generation of SMM research and care.

MDM2 is an E3 ubiquitin ligase that promotes p53 tumor suppressor degradation and has emerged as a therapeutic target in the treatment of wild-type (wt) TP53 tumors. In acute myeloid leukemia (AML), TP53 mutations are infrequent (15-20%), but wt-p53 is often inactivated through overexpression of MDM2. Thus, MDM2 inhibitors are currently in clinical trials for AML. However, p53 stabilization with inhibitors upregulates MDM2, which limits their clinical efficacy. Proteolysis-targeting chimeric (PROTAC) molecules that degrade MDM2 may overcome this feedback. MD-265 is a PROTAC that recruits CRBN, degrades MDM2, restores p53 and induces apoptosis. We tested MD-265 in ex vivo cultures of 105 primary leukemic stem cells (LSCs). The median cytotoxic IC50 for MD-265 was 16 nM, median IC50 for MI-1061 was 150-fold higher. LSCs with IC50 > 1 µM were classified as MD-265 resistant and harbored mutations in TP53. Normal hematopoietic stem cells showed 100-fold higher IC50 (818 nM) than LSCs. AML patient-derived xenograft (PDX) models in NSG-SGM3 mice were treated with MD-265 or an oral MDM2 inhibitor. In PDX models, MD-265 was not toxic and prolonged survival. MD-265 is a potent and specific MDM2 degrader with broad pre-clinical activity and a promising drug candidate for the treatment of leukemias.

Mantle cell lymphoma (MCL) is a biologically and clinically heterogeneous B-cell malignancy with a historically poor prognosis. Recent advances have substantially expanded treatment options, particularly through the integration of targeted therapies, chemotherapy-free regimens, and cellular approaches. Frontline treatment now incorporates Bruton's tyrosine kinase inhibitors (BTKi) in combination with chemotherapy and in chemotherapy-free regimens. For patients with relapsed or refractory disease, particularly those previously exposed to BTKi, chimeric antigen receptor T-cell (CAR T) therapies and third-generation BTKi like pirtobrutinib provide highly effective options while several novel agents, including bispecific antibodies (bsAbs), are under investigation. Nevertheless, achieving long-lasting remissions is still a major challenge, especially among high-risk patients. Future directions include optimizing sequencing, refining rational combination therapies, expanding the application of bsAbs, and integrating small molecules and novel immunoconjugates to enhance therapeutic efficacy and long-term outcomes. This review provides an overview of the current and emerging therapies for MCL, highlighting how the integration of biological agents, strategic combinations, and patient-centered approaches are driving the next phase of MCL treatment.

Protein arginine methyltransferase 5 (PRMT5) is overexpressed in B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL). While PRMT5 is known to regulate multiple oncogenic pathways, including PI3K-AKT signaling, its role in lipid metabolism and ferroptosis, a regulated, iron-dependent cell death driven by lipid peroxidation, remains poorly understood. Here, we identify a novel role for PRMT5 in suppressing ferroptosis in DLBCL and MCL cells through upregulation of SLC7A11, which imports cystine for glutathione (GSH) biosynthesis. This effect is mediated by the AKT-MYC-ATF5 signaling axis. ATF5, a MYC-regulated transcription factor overexpressed in these lymphomas, induces SLC7A11 expression. In addition, ATF5 promotes the expression of ATF4, another key regulator of the ferroptotic response, which forms heterodimers with ATF5 to further reinforce this regulatory network. PRMT5 inhibition sensitizes lymphoma cells to ferroptosis inducers such as dimethyl fumarate (DMF), an electrophile that irreversibly depletes GSH via succination. Notably, combined treatment with the PRMT5 inhibitor GSK3326595 and DMF synergistically enhances anti-tumor activity in a patient-derived xenograft (PDX) model. These findings reveal a previously unrecognized PRMT5-ATF5-SLC7A11 axis that drives ferroptosis resistance in B-cell lymphomas and provide a strong rationale for targeting PRMT5 to potentiate ferroptosis-based therapies in relapsed or refractory disease.

B-cell maturation antigen (BCMA)-targeting therapies provide a new approach to treating multiple myeloma (MM). Alnuctamab (ALNUC) is a 2 + 1 immunoglobulin G1-based bispecific antibody binding BCMA and CD3ε receptors on myeloma and T cells, respectively. CC-93269-MM-001 is a first-in-human, phase 1 dose escalation/expansion study investigating ALNUC in relapsed/refractory MM. Patients had ≥3 prior regimens, disease progression ≤60 days of last regimen, and were BCMA-directed therapy-naïve. ALNUC was administered intravenously (IV) and subcutaneously (SC); however, SC was selected for further evaluation due to the more favorable safety profile. Ninety-five patients received ALNUC SC; at data cutoff, 44.2% remained on treatment and median follow-up was 8.0 months. The recommended phase 2 dose was 30 mg. The most common treatment emergent adverse events (any grade/grade 3/4) were CRS (57.9%/0%), and neutropenia (53.7%/43.2%). Infections were also frequent (64.2%/14.7%). ORR was 58.9% for all ALNUC SC-treated patients and 71.4% for the 30-mg cohort; 47/95 (49.5%) were measurable residual disease (MRD) negative. Overall, the safety and efficacy of ALNUC SC were comparable to other BCMA-targeted therapies. These results support improved safety of SC versus IV, and corroborate a step-up dosing strategy to mitigate CRS. Importantly, a schedule that de-intensifies over time provides favorable toxicity that may be applicable to other bispecific engagers.