Immunotherapy of Multiple Myeloma: Promise and Challenges

Exploring the role of histone deacetylase and histone deacetylase inhibitors in the context of multiple myeloma: mechanisms, therapeutic implications, and future perspectives

Histone deacetylase inhibitors (HDACis) are a significant category of pharmaceuticals that have developed in the past two decades to treat multiple myeloma. Four drugs in this category have received approval from the U.S. Food and Drug Administration (FDA) for use: Panobinonstat (though canceled by the FDA in 2022), Vorinostat, Belinostat and Romidepsin. The efficacy of this group of drugs is attributed to the disruption of many processes involved in tumor growth through the inhibition of histone deacetylase, and this mode of action leads to significant anti-multiple myeloma (MM) activity. In MM, inhibition of histone deacetylase has many downstream consequences, including suppression of NF-κB signaling and HSP90, upregulation of cell cycle regulators (p21, p53), and downregulation of antiapoptotic proteins including Bcl-2. Furthermore, HDACis have a variety of direct and indirect oxidative effects on cellular DNA. HDAC inhibitors enhance normal immune function, thereby decreasing the proliferation of malignant plasma cells and promoting autophagy. The various biological effects of inhibiting histone deacetylase have a combined or additional impact when used alongside other chemotherapeutic and targeted drugs for multiple myeloma. This helps to decrease resistance to treatment. Combination treatment regimens that include HDACis have become an essential part of the therapy for multiple myeloma. These regimens incorporate drugs from other important classes of anti-myeloma agents, such as immunomodulatory drugs (IMiDs), conventional chemotherapy, monoclonal antibodies, and proteasome inhibitors. This review provides a comprehensive evaluation of the clinical efficacy and safety data pertaining to the currently approved histone deacetylase inhibitors, as well as an explanation of the crucial function of histone deacetylase in multiple myeloma and the characteristics of the different histone deacetylase inhibitors. Moreover, it provides a concise overview of the most recent developments in the use of histone deacetylase inhibitors for treating multiple myeloma, as well as potential future uses in treatment.

Editorial: Multiple Myeloma: Molecular Mechanism and Targeted Therapy

Multiple myeloma (MM) is a plasma cell disorder representing the second most common blood cancer [...].

Efficacy of elotuzumab for multiple myeloma deteriorates after daratumumab: a multicenter retrospective study

Elotuzumab-based regimens are sometimes selected for multiple myeloma treatment after daratumumab-based regimens. However, there has been insufficient discussion on the efficacy of elotuzumab after daratumumab. We used Kansai Myeloma Forum registration data in a multicenter retrospective evaluation of the efficacy of elotuzumab after daratumumab. Overall survival (OS) rate and time to next treatment (TTNT) were significantly worse in the cohort given elotuzumab after daratumumab (Dara cohort, n = 47) than in the cohort with no history of daratumumab administration before elotuzumab (No-Dara cohort, n = 80, OS: P = 0.03; TTNT: P = 0.02; best response: P < 0.01). In the Dara cohort, OS and TTNT rates were worse with sequential elotuzumab use after daratumumab than with non-sequential (OS: P = 0.02; TTNT: P = 0.03). In patients given elotuzumab < 180 days after daratumumab, OS (P = 0.08) and best response (P = 0.21) tended to be worse, and TTNT was significantly worse (P = 0.01), than in those given elotuzumab after ≥ 180 days. These findings were confirmed by subgroup analyses and multivariate analyses. Monoclonal-antibody-free treatment might be preferable after daratumumab-based regimens. If possible, elotuzumab-based regimens should be considered only ≥ 180 days after daratumumab use.

Teclistamab-cqyv in multiple myeloma

Multiple myeloma (MM) is an incurable neoplasm characterized by significant morbidity and mortality. Despite advances in treatment, MM patients eventually experienced a relapse of the disease. Penta-drug refractory patients continue to be the hard core of relapsed/refractory (RR) settings. Teclistamab-cqyv is a humanized IgG4 antibody and a bispecific BCMA-director CD3 T-cell engager. It recruits endogenous T cells, by targeting CD3 receptors expressed on their surface, resulting in their activation against BCMA, an antigen expressed by plasma cells. US Food and Drug Administration (FDA) and European Medicines Agency (EMA) have approved Teclistamab-cqyv in monotherapy for the treatment of RRMM patients who have received at least three prior therapies, including immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs), and anti-CD38 monoclonal antibodies (MoAbs) and have demonstrated disease progression during the last therapy. Its effectiveness was demonstrated in a pivotal clinical trial where the overall response rate (ORR) reached 60%. Other clinical studies are currently ongoing to investigate the association of the bispecific antibody with novel drugs with encouraging preliminary results, especially in the setting of heavily pretreated patients. In this review, the authors will provide a comprehensive overview of the drug, including its mechanism of action, major clinical trials, and future perspectives.

Editorial for the IJMS Special Issue on Molecular Pathogenesis and Molecular Therapy of Lymphoid Malignancies

In the era of targeted therapies, researchers have aimed to uncover the molecular drivers of malignant pathogenesis in lymphoid malignancies in an endeavor to develop effective therapeutic strategies [...].

Advances in research on potential inhibitors of multiple myeloma

Multiple myeloma (MM) is a common hematological malignancy. Although recent clinical applications of immunomodulatory drugs, proteasome inhibitors and CD38-targeting antibodies have significantly improved the outcome of MM patient with increased survival, the incidence of drug resistance and severe treatment-related complications is gradually on the rise. This review article summarizes the characteristics and clinical investigations of several MM drugs in clinical trials, including their structures, mechanisms of action, structure-activity relationships, and clinical study progress. Furthermore, the application potentials of the drugs that have not yet entered clinical trials are also reviewed. The review also outlines the future directions of MM drug development.

Efficacy and safety of anti-CD38 monoclonal antibodies in patients with relapsed/refractory multiple myeloma: a systematic review and meta-analysis with trial sequential analysis of randomized controlled trials

Objectives

The current study aims to evaluate the safety and efficacy of anti-CD38 monoclonal antibodies (mAbs) among patients with relapsed/refractory multiple myeloma (RRMM) through meta-analysis.

Methods

As of June 2023, we searched PubMed, Web of Science, Embase and the Cochrane Library. Randomized controlled trials (RCTs) which compared the clinical outcomes of anti-CD38 mAbs plus immunomodulatory drugs (IMiDs) or proteasome inhibitors (PIs) plus dexamethasone and IMiDs (or PIs) and dexamethasone alone for RRMM patients were included. Efficacy outcomes were mainly evaluated with progression-free survival (PFS) and overall survival (OS). The safety was analyzed with hematologic and nonhematologic treatment-emergent adverse events (TEAEs). All results were pooled using hazard ratio (HR), relative risk (RR), and their 95% confidence interval (CI) and prediction interval (PI).

Results

This meta-analysis included 11 RCTs in total. Compared with IMiDs (or PIs) and dexamethasone alone, anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone significantly prolonged PFS (HR: 0.552, 95% CI = 0.461 to 0.659, 95% PI = 0.318 to 0.957) and OS (HR: 0.737, 95% CI = 0.657 to 0.827, 95% PI = 0.626 to 0.868) in patients with RRMM. Additionally, RRMM patients receiving anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone achieved higher rates of overall response (RR: 1.281, 95% CI = 1.144 to 1.434, 95% PI = 0.883 to 1.859), complete response or better (RR: 2.602, 95% CI = 1.977 to 3.424, 95% PI = 1.203 to 5.628), very good partial response (VGPR) or better (RR: 1.886, 95% CI = 1.532 to 2.322, 95% PI = 0.953 to 3.731), and minimum residual disease (MRD)-negative (RR: 4.147, 95% CI = 2.588 to 6.644, 95% PI = 1.056 to 16.283) than those receiving IMiDs (or PIs) and dexamethasone alone. For TEAEs, the rates of hematologic and nonhematologic TEAEs, including thrombocytopenia, neutropenia, upper respiratory tract infection (URTI), pneumonia, bronchitis, dyspnea, diarrhea, pyrexia, back pain, arthralgia, fatigue, insomnia, and hypertension, were higher in the anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone group than in the IMiDs (or PIs) and dexamethasone group.

Conclusion

Our study showed that anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone improved PFS and OS, and achieved higher rates of overall response, complete response or better, VGPR or better, and MRD-negative, as well as higher rates of thrombocytopenia, neutropenia, URTI, pneumonia, bronchitis, dyspnea, diarrhea, pyrexia, back pain, arthralgia, fatigue, insomnia, and hypertension in RRMM patients.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023431071.

Targeting the Isoprenoid Biosynthetic Pathway in Multiple Myeloma

Multiple myeloma (MM) is a plasma cell malignancy for which there is currently no cure. While treatment options for MM have expanded over the last two decades, all patients will eventually become resistant to current therapies. Thus, there is an urgent need for novel therapeutic strategies to treat MM. The isoprenoid biosynthetic pathway (IBP) is responsible for the post-translational modification of proteins belonging to the Ras small GTPase superfamily, such as Ras, Rho and Rab family members. Given the important roles these GTPase proteins play in various cellular processes, there is significant interest in the development of inhibitors that disturb their prenylation and consequently their activity in MM cells. Numerous preclinical studies have demonstrated that IBP inhibitors have anti-MM effects, including the induction of apoptosis in MM cells and inhibition of osteoclast activity. Some IBP inhibitors have made their way into the clinic. For instance, nitrogenous bisphosphonates are routinely prescribed for the management MM bone disease. Other IBP inhibitors, including statins and farnesyltransferase inhibitors, have been evaluated in clinical trials for MM, while there is substantial preclinical investigation into geranylgeranyl diphosphate synthase inhibitors. Here we discuss recent advances in the development of IBP inhibitors, assess their mechanism of action and evaluate their potential as anti-MM agents.

Emerging Role of Antibody-Drug Conjugates and Bispecific Antibodies for the Treatment of Multiple Myeloma

Multiple myeloma (MM) is characterized by malignant proliferation of malignant plasma cells; it is the second most common hematological malignancy associated with significant morbidity. Genetic intricacy, instability, and diverse clinical presentations remain a barrier to cure. The treatment of MM is modernized with the introduction of newer therapeutics agents, i.e., target-specific monoclonal antibodies. The currently available literature lacks the benefits of newer targeted therapy being developed with an aim to reduce side effects and increase effectiveness, compared to conventional chemotherapy regimens. This article aims to review literature about the current available monoclonal antibodies, antibody-drug conjugates, and bispecific antibodies for the treatment of MM.