Multiple myeloma: a model for scientific and clinical progress

Current status of bispecific antibodies and CAR-T therapies in multiple myeloma

Multiple myeloma (MM), a malignancy of plasma cells, is an incurable disease that is characterized by the neoplastic proliferation of plasma cells leading to extensive skeletal destruction. This includes osteolytic lesions, osteopenia, and pathologic fractures. MM is clinically manifested through bone pain, renal insufficiency, hypercalcemia, anemia, and recurrent infections. Its prevalence and the need for effective treatment underscore the importance of this research. Recent advancements in MM therapy have been significant, particularly with the integration of daratumumab into first-line treatments. The use of daratumumab in regimens such as DRD (Daratumumab, Revlimid, Dexamethasone) and D-RVd (Daratumumab, Lenalidomide, Bortezomib, Dexamethasone) represents a paradigm shift in the treatment landscape. GRIFFIN and CASSIOPEIA trials have highlighted the efficacy of these regimens, particularly in prolonging progression-free survival and deepening patient responses. The shift from older regimens like MPV (Melphalan, Prednisone, Velcade) to more effective ones like DRD and RVD has been pivotal in treatment strategies. This review also focuses on the potential of Chimeric Antigen Receptor T-cell therapy and bispecific antibodies in MM. CAR-T therapy, which has shown success in other hematological malignancies, is being explored for its ability to specifically target MM cells. The latest clinical trials and research findings are analyzed to evaluate the efficacy and challenges of CAR-T therapy in MM. Additionally, the role of bispecific antibodies, which are designed to bind both cancer cells and T cells, is explored. These antibodies offer a unique mechanism that could complement the effects of CAR-T therapy.

Orthogonal targeting of osteoclasts and myeloma cells for radionuclide stimulated dynamic therapy induces multidimensional cell death pathways

Rationale: Multiple myeloma (MM) is a multifocal malignancy of bone marrow plasma cells, characterized by vicious cycles of remission and relapse that eventually culminate in death. The disease remains mostly incurable largely due to the complex interactions between the bone microenvironment (BME) and MM cells (MMC). In the “vicious cycle” of bone disease, abnormal activation of osteoclasts (OCs) by MMC causes severe osteolysis, promotes immune evasion, and stimulates the growth of MMC. Disrupting these cancer-stroma interactions would enhance treatment response.

Methods: To disrupt this cycle, we orthogonally targeted nanomicelles (NM) loaded with non-therapeutic doses of a photosensitizer, titanocene (TC), to VLA-4 (α4ß1, CD49d/CD29) expressing MMC (MM1.S) and αvß3 (CD51/CD61) expressing OC. Concurrently, a non-lethal dose of a radiopharmaceutical, ¹⁸F-fluorodeoxyglucose ([¹⁸F]FDG) administered systemically interacted with TC (radionuclide stimulated therapy, RaST) to generate cytotoxic reactive oxygen species (ROS). The in vitro and in vivo effects of RaST were characterized in MM1.S cell line, as well as in xenograft and isograft MM animal models.

Results: Our data revealed that RaST induced non-enzymatic hydroperoxidation of cellular lipids culminating in mitochondrial dysfunction, DNA fragmentation, and caspase-dependent apoptosis of MMC using VLA-4 avid TC-NMs. RaST upregulated the expression of BAX, Bcl-2, and p53, highlighting the induction of apoptosis via the BAK-independent pathway. The enhancement of multicopper oxidase enzyme F5 expression, which inhibits lipid hydroperoxidation and Fenton reaction, was not sufficient to overcome RaST-induced increase in the accumulation of irreversible function-perturbing α,ß-aldehydes that exerted significant and long-lasting damage to both DNA and proteins. In vivo, either VLA-4-TC-NM or αvß3-TC-NMs RaST induced a significant therapeutic effect on immunocompromised but not immunocompetent MM-bearing mouse models. Combined treatment with both VLA-4-TC-NM and αvß3-TC-NMs synergistically inhibited osteolysis, reduced tumor burden, and prevented rapid relapse in both in vivo models of MM.

Conclusions: By targeting MM and bone cells simultaneously, combination RaST suppressed MM disease progression through a multi-prong action on the vicious cycle of bone cancer. Instead of using the standard multidrug approach, our work reveals a unique photophysical treatment paradigm that uses nontoxic doses of a single light-sensitive drug directed orthogonally to cancer and bone cells, followed by radionuclide-stimulated generation of ROS to inhibit tumor progression and minimize osteolysis in both immunocompetent murine and immunocompromised human MM models.

Physical activity is associated with less comorbidity, better treatment tolerance and improved response in patients with multiple myeloma undergoing stem cell transplantation

OBJECTIVES

Multiple myeloma (MM) is the second most common hematological malignancy. Progression free survival (PFS) and overall survival (OS) have substantially improved, nonetheless MM usually remains incurable. Patients with active disease may be affected by numerous comorbidities, including fatigue, depression and osteolytic lesions, which influence their quality of life (QoL). Albeit, it is known that exercising is beneficial for patients' QoL, few clinical trials are available in patients with MM. We therefore aimed to compare comorbidities and clinical outcome in physically active and inactive patients with MM.

MATERIAL AND METHODS

We defined physical activity according to WHO criteria (150 min of moderate activity and two sessions of resistance training/week). We matched 53 physically active patients with 53 controls (for age, gender, cytogenetics, disease stage, and therapy) and compared the cohorts for incidence of comorbidities/MM symptoms (osteolytic lesions, anemia, infections, fatigue, depression, Revised-Myeloma Comorbidity Index [R-MCI]) and clinical outcome (treatment tolerance, responses to therapy, PFS and OS) in a retrospective audit. All patients were newly diagnosed with MM and received autologous stem cell transplantations (ASCT) between 2001 and 2017.

RESULTS

Physically active patients showed superior outcomes in R-MCI (p = 0.0005), fatigue (p = 0.0063), treatment tolerance (p = 0.0258) and hospital stays (p = 0.0072). Furthermore, they showed better treatment responses (p = 0.0366), especially complete remission (CR; p = 0.0018) as well as better OS and PFS.

CONCLUSION

Physical activity in patients with MM undergoing ASCT seemed associated with better overall clinical outcome. Randomized clinical trials are required to understand the benefits and devise strategies for improving exercising among patients with MM.

Chromatin activation as a unifying principle underlying pathogenic mechanisms in multiple myeloma

Multiple myeloma (MM) is a plasma cell neoplasm associated with a broad variety of genetic lesions. In spite of this genetic heterogeneity, MMs share a characteristic malignant phenotype whose underlying molecular basis remains poorly characterized. In the present study, we examined plasma cells from MM using a multi-epigenomics approach and demonstrated that, when compared to normal B cells, malignant plasma cells showed an extensive activation of regulatory elements, in part affecting coregulated adjacent genes. Among target genes up-regulated by this process, we found members of the NOTCH, NF-kB, MTOR signaling, and TP53 signaling pathways. Other activated genes included sets involved in osteoblast differentiation and response to oxidative stress, all of which have been shown to be associated with the MM phenotype and clinical behavior. We functionally characterized MM-specific active distant enhancers controlling the expression of thioredoxin (TXN), a major regulator of cellular redox status and, in addition, identified PRDM5 as a novel essential gene for MM. Collectively, our data indicate that aberrant chromatin activation is a unifying feature underlying the malignant plasma cell phenotype.

Monitoring the cytogenetic architecture of minimal residual plasma cells indicates therapy-induced clonal selection in multiple myeloma

Recent attempts have focused on identifying fewer magnitude of minimal residual disease (MRD) rather than exploring the biological and genetic features of the residual plasma cells (PCs). Here, a cohort of 193 patients with at least one cytogenetic abnormalities (CA) at diagnosis were analyzed, and interphase fluorescence in situ hybridization (iFISH) analyses were performed in patient-paired diagnostic and posttherapy samples. Persistent CA in residual PCs were observed for the majority of patients (63%), even detectable in 28/63 (44%) patients with MRD negativity (<10^-4). The absence of CA in residual PCs was associated with prolonged survival regardless of MRD status. According to the change of the clonal size of specific CA, patients were clustered into five groups, reflecting different patterns of clone selection under therapy pressure. Therapy-induced clonal selection exerted a significant impact on survival (HR = 4.0; P < 0.001). According to the longitudinal cytogenetic studies at relapse, sequential cytogenetic dynamics were observed in most patients, and cytogenetic architecture of residual PCs could to some extent predict the evolutional pattern at relapse. Collectively, the repeat cytogenetic evaluation in residual PCs could not only serves as a good complementary tool for MRD detection, but also provides a better understanding of clinical response and clonal evolution.

Minimal Residual Disease in Multiple Myeloma: Impact on Response Assessment, Prognosis and Tumor Heterogeneity

Multiple Myeloma (MM) therapy has evolved rapidly over the past decade. With current multidrug combinations and autologous transplant, rates of overall response exceed 90% and complete response (CR) more than 50% in some studies. Unfortunately, despite higher rates of CR, relapse rates remain high suggesting that persistent disease may not be measured by current techniques. Traditionally, response rates were defined by urine and serum protein electrophoresis, immunofixation and histopathological absence of clonal plasma cells in the bone marrow. Currently, there are several validated sensitive assays to evaluate for MRD (minimal residual disease); multiparameter flow cytometry (MFC) including nextgeneration flow cytometry (NGF), next-generation sequencing (NGS), and allele specific oligonucleotide quantitative polymerase chain reaction (ASO-qPCR). These methods have provided a means to quantitatively assess residual disease and accurately prognosticate PFS and OS in myeloma. In this chapter, we will discuss the current techniques for MRD detection as well as describe techniques that are emerging for improved characterization of drug resistant residual populations that could be adapted for MRD monitoring in the future. While improved therapies are able to eradicate the dominant clone, resistant sub-clones persist and remain undetectable even by MRD techniques. Characterization of these clones will help design therapies against drug-resistant clones and move us closer to a cure in MM.

Nanotherapeutics for multiple myeloma

Multiple myeloma (MM) is an age-related hematological malignancy with an estimated 30,000 new cases and 13,000 deaths per year. A disease of antibody-secreting malignant plasma B-cells that grow primarily in the bone marrow (BM), MM causes debilitating fractures, anemia, renal failure, and hypercalcemia. In addition to the abnormal genetic profile of MM cells, the permissive BM microenvironment (BMM) supports MM pathogenesis. Although advances in treatment options have significantly enhanced survival in MM patients, transient perfusion of small-molecule drugs in the BM does not provide sufficient residence to enhance MM cell-drug interaction, thus allowing some myeloma cells to escape the first line of treatment. As such, there remains a crucial need to develop advanced drug delivery systems that can navigate the complex BMM and effectively reach the myeloma cells. The high vascular density and spongy nature of bone structure suggest that nanoparticles (NPs) can serve as smart drug-delivery systems capable of extravasation and retention in various BM compartments to exert a durable therapeutic effect. In this focus article, we first summarize the pathophysiology of MM, emphasizing how the BM niche presents serious challenges for effective treatment of MM with small-molecule drugs. We then pivot to current efforts to develop NP-based drug carriers and intrinsically therapeutic nanotherapeutics. The article concludes with a brief perspective on the opportunities and challenges in developing and translating nanotherapeutics to improve the treatment outcomes of MM patients. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

The insulin-like growth factor system in multiple myeloma: diagnostic and therapeutic potential

Multiple myeloma (MM) is a highly heterogeneous plasma cell malignancy. The MM cells reside in the bone marrow (BM), where reciprocal interactions with the BM niche foster MM cell survival, proliferation, and drug resistance. As in most cancers, the insulin-like growth factor (IGF) system has been demonstrated to play a key role in the pathogenesis of MM. The IGF system consists of IGF ligands, IGF receptors, IGF binding proteins (IGFBPs), and IGFBP proteases and contributes not only to the survival, proliferation, and homing of MM cells, but also MM-associated angiogenesis and osteolysis. Furthermore, increased IGF-I receptor (IGF-IR) expression on MM cells correlates with a poor prognosis in MM patients. Despite the prominent role of the IGF system in MM, strategies targeting the IGF-IR using blocking antibodies or small molecule inhibitors have failed to translate into the clinic. However, increasing preclinical evidence indicates that IGF-I is also involved in the development of drug resistance against current standard-of-care agents against MM, including proteasome inhibitors, immunomodulatory agents, and corticoids. IGF-IR targeting has been able to overcome or revert this drug resistance in animal models, enhancing the efficacy of standard-of-care agents. This finding has generated renewed interest in the therapeutic potential of IGF-I targeting in MM. The present review provides an update of the impact of the different IGF system components in MM and discusses the diagnostic and therapeutic potentials.

Proteome complexity and the forces that drive proteome imbalance

The cellular proteome is a complex microcosm of structural and regulatory networks that requires continuous surveillance and modification to meet the dynamic needs of the cell. It is therefore crucial that the protein flux of the cell remains in balance to ensure proper cell function. Genetic alterations that range from chromosome imbalance to oncogene activation can affect the speed, fidelity and capacity of protein biogenesis and degradation systems, which often results in proteome imbalance. An improved understanding of the causes and consequences of proteome imbalance is helping to reveal how these systems can be targeted to treat diseases such as cancer.

Hematological approaches to multiple myeloma: trends from a Brazilian subset of hematologists. A cross-sectional study

CONTEXT AND OBJECTIVE

For the last nine years, hematologists and oncologists have gathered annually at an educational symposium organized by a Brazilian and an American hospital. During the 2015 Board Review, a survey among the attendees evaluated the differences in management and treatment methods for multiple myeloma (MM).

DESIGN AND SETTING

Cross-sectional study during an educational hematology symposium in São Paulo, Brazil.

METHODS

Hematologists present at the symposium gave responses to an electronic survey by means of mobile phone.

RESULTS

Among the 350 attendees, 217 answered the questionnaire. Most of the participants believed that immunotargeting agents (iTA) might be effective for slowing MM progression in heavily pretreated patients (67%) and that continued exposure to therapy might lead to emergence of resistant clones in patients with MM (76%). Most of the physicians use maintenance therapy after hematopoietic stem cell transplantation (95%) and 45% of them would further restrict it to post-transplantation patients with underlying high-risk disease. The first-line drugs used for transplantation-ineligible patients (TI-MM) were bortezomib-thalidomide-dexamethasone (31%), bortezomib-dexamethasone (28%), lenalidomide-dexamethasone (Rd; 17%) and melphalan-based therapy (10%). Lenalidomide was the drug of choice for post-transplantation maintenance for half of the participants. No significant differences were observed regarding age or length of experience.

CONCLUSION

The treatment choices for TI-MM patients were highly heterogenous and the melphalan-based regimen represented only 10% of the first-line options. Use of maintenance therapy after transplantation was a common choice. Some results from the survey were divergent from the evidence in the literature.

Phenotypic and genomic analysis of multiple myeloma minimal residual disease tumor cells: a new model to understand chemoresistance

We report for the first time the biological features of MRD cells in MM and unravel that clonal selection is already present at the MRD stage. MRD cells show a singular phenotypic signature that may result from persisting clones with different genetic and gene expression profiles.

Sorafenib for the treatment of multiple myeloma

INTRODUCTION

Sorafenib is an orally available compound that acts predominantly by targeting the Ras/Raf/MEK/ERK pathway and by inhibiting the vascular endothelial growth factor (VEGF). Since the Ras/Raf/MEK/ERK pathway is implicated in the proliferation of multiple myeloma (MM) cells and VEGF in bone marrow neovascularization, sorafenib is a drug offering the potential for targeting two important pathogenetic mechanisms involved in MM. Thus, sorafenib is being proposed for use in MM.

AREAS COVERED

In this review, the authors discuss the rationale for the use of sorafenib in MM. They then summarize the clinical development of sorafenib in MM, from initial Phase I to Phase II studies. A systematic literature review of the trials was performed using PubMed.

EXPERT OPINION

Preliminary data from phase I/II trials showed that sorafenib had a good safety profile but minimal anti-myeloma activity as a single agent in relapsed/refractory patients. Results of phase II trials, evaluating sorafenib combined with new drugs, such as bortezomib and lenalidomide are eagerly awaited.

Flow cytometry remission by Ig light chains ratio is a powerful marker of outcome in multiple myeloma after tandem autologous transplant: a real-life study

BACKGROUND

The achievement of complete response (CR) significantly correlates with a better clinical outcome in multiple myeloma (MM) patients treated with autologous stem cell transplant (ASCT). The depth of response is one of the most relevant factors to predict patient's outcome, however the definition of CR through standard criteria has shown several limitations.

METHODS

In this study we evaluated the minimal residual disease (MRD) in 50 consecutive MM patients who underwent an up-front tandem ASCT in our center, using a single-tube six-colors flow cytometry assay (FC) based on intra-cytoplasmic immunoglobulin (cy-Ig) light chains ratio evaluated on patient-specific plasma cells (PC) immune profile, in a real-life setting.

RESULTS

With a sensitivity up to 10(-5), clonal-PC were documented by FC in 36.4% (12/33) of patients in conventional CR after second transplant. The number of flow MRD-negative patients significantly increased after induction and first ASCT, but not between first and second transplant. The 5-years progression-free survival (5ys-PFS) of flow MRD-negative patients after second transplant was significantly better than patients who remained MRD-positive considering both all patients (5ys-PFS: 70% vs 5%) and patients in CR according to standard criteria (5ys-PFS: 67% vs 0%).

CONCLUSIONS

FC remission through cy-Ig light ratio on PC sub-populations is a sensitive, highly informative, low-cost and routinely applicable MRD assay, a powerful tool in treatment response evaluation and a crucial marker of outcome in MM.