Antibody-Based Treatment Approaches in Multiple Myeloma

Lymphocyte profile in peripheral blood of patients with multiple myeloma

Multiple myeloma (MM) is a disease which remains incurable. One of the main reasons is a weakened immune system that allows MM cells to survive. Therefore, the current research is focused on the study of immune system imbalance in MM to find the most effective immunotherapy strategies. Aiming to identify the key points of immune failure in MM patients, we analysed peripheral lymphocytes subsets from MM patients (n = 57) at various stages of the disease course and healthy individuals (HI, n = 15) focusing on T, NK, iNKT, B cells and NK-cell cytokines. Our analysis revealed that MM patients exhibited immune alterations in all studied immune subsets. Compared to HI, MM patients had a significantly lower proportion of CD4 + T cells (19.55% vs. 40.85%; p < 0.001) and CD4 + iNKT cells (18.8% vs. 40%; p < 0.001), within B cells an increased proportion of CD21LCD38L subset (4.5% vs. 0.4%; p < 0.01) and decreased level of memory cells (unswitched 6.1% vs. 14.7%; p < 0.001 and switched 7.8% vs. 11.2%; NS), NK cells displaying signs of activation and exhaustion characterised by a more than 2-fold increase in SLAMF7 MFI (p < 0.001), decreased expression of NKG2D (MFI) and NKp46 (%) on CD16 + 56 + and CD16 + 56- subset respectively (p < 0.05), Effective immunotherapy needs to consider these immune defects and monitoring of the immune status of MM patients is essential to define better interventions in the future.

Targeting GPRC5D in multiple myeloma

INTRODUCTION

The prognosis of multiple myeloma (MM) continues to improve. Recent progress in therapies, using immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs), and anti-CD38 monoclonal antibodies, has greatly improved patients' outcomes. Despite these advancements, relapses still happen often, and patients can become resistant to the usual treatments. Newer treatments, such as chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies (BsAbs) targeting B-cell maturation antigen (BCMA), have resulted in excellent outcomes in patients with limited treatment options. G protein - coupled receptor, class C group 5 member D (GPRC5D) is considered a very promising target with early results from clinical trials showing high response rates in patients with relapsed or refractory multiple myeloma.

AREAS COVERED

This review covers the efficacy and safety of CAR-T and BsAbs targeting GPRC5D in MM, focusing on talquetamab - the inaugural FDA-approved BsAb targeting GPRC5D. Talquetamab has exhibited promising response rates alongside a distinctive side effect profile. Additionally, ongoing trials examining talquetamab in combination with agents like daratumumab and teclistamab are discussed.

EXPERT OPINION

We offer insights into the potential utilization of various GPRC5D-based therapies in the treatment paradigm for MM, either independently or in combination with established therapies.

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.

Embracing Myeloma Chimeric Antigen Receptor-T: From Scientific Design to Clinical Impact

Despite recent advancement of treatment strategies in multiple myeloma (MM), patients with relapsed/refractory MM disease, particularly after triple-class refractoriness, continue to have poor prognosis. Chimeric antigen receptor (CAR-T) cells were developed and applied to improve outcomes in this setting, and two products, idecabtagene vicleucel and ciltacabtagene autoleucel, both targeting B-cell maturation antigen, have been approved by the Food and Drug Administration in the United States and European Medicines Agency in Europe. Both have shown unprecedented clinical outcomes with high response rate and prolonged progression-free survival and overall survival in this patient population with grim prognosis. Currently, further investigations are ongoing for CAR-T targeting different tumor antigens such as G protein-coupled receptor, class C, group 5, member D or with different combinations of intracellular signaling domains, as well as fourth-generation CAR-T with antigen-unrestricted inducible cytokines. Although CAR-T therapies hold hopes and enthusiasm from the myeloma community, several hurdles remain before these treatments become available for all patients in need. These barriers include CAR-T-cell manufacturing availability, access to administering centers, financial cost, caregivers' availability, and socioeconomic and racial disparities. Expanding clinical trial eligibility criteria and real-world data collection and analysis is crucial to understand the efficacy and safety of CAR-T in the patient cohort who tends to be excluded from current trials.

Idecabtagene Vicleucel for Relapsed/Refractory Multiple Myeloma: Real-World Experience From the Myeloma CAR T Consortium

PURPOSE

Idecabtagene vicleucel (ide-cel) is an autologous B-cell maturation antigen-directed chimeric antigen receptor T-cell therapy approved for relapsed/refractory multiple myeloma (RRMM) on the basis of the phase II pivotal KarMMa trial, which demonstrated best overall and ≥ complete response rates of 73% and 33%, respectively. We report clinical outcomes with standard-of-care (SOC) ide-cel under the commercial Food and Drug Administration label.

METHODS

Data were retrospectively collected from patients with RRMM who underwent leukapheresis as of February 28, 2022, at 11 US institutions with intent to receive SOC ide-cel. Toxicities were graded per American Society for Transplantation and Cellular Therapy guidelines and managed according to each institution's policies. Responses were graded on the basis of the International Myeloma Working Group response criteria.

RESULTS

One hundred fifty-nine of 196 leukapheresed patients received ide-cel by data cutoff. One hundred twenty (75%) infused patients would have been ineligible for participation in the KarMMa clinical trial because of comorbidities at the time of leukapheresis. Any grade and grade ≥ 3 cytokine release syndrome and neurotoxicity occurred in 82/3% and 18/6%, respectively. Best overall and ≥ complete response rates were 84% and 42%, respectively. At a median follow-up of 6.1 months from chimeric antigen receptor T infusion, the median progression-free survival was 8.5 months (95% CI, 6.5 to not reached) and the median overall survival was 12.5 months (95% CI, 11.3 to not reached). Patients with previous exposure to B-cell maturation antigen-targeted therapy, high-risk cytogenetics, Eastern Cooperative Oncology Group performance status ≥ 2 at lymphodepletion, and younger age had inferior progression-free survival on multivariable analysis.

CONCLUSION

The safety and efficacy of ide-cel in patients with RRMM in the SOC setting were comparable with those in the phase II pivotal KarMMa trial despite most patients (75%) not meeting trial eligibility criteria.

Monoclonal Antibodies: The Greatest Resource to Treat Multiple Myeloma

Multiple myeloma (MM) is a currently incurable hematologic cancer. This disease is characterized by immunological alterations of myeloid cells and lymphocytes. The first-line therapy involves the use of classic chemotherapy; however, many patients have a relapsed form that could evolve into a refractory MM. The new therapeutic frontiers involve the use of new monoclonal antibodies (Mab) such as daratumumab, isatuximab, and elotuzumab. In addition to monoclonal antibodies, new immunotherapies based on modern bispecific antibodies and chimeric antigen receptor (CAR) T cell therapy have been investigated. For this reason, immunotherapy represents the greatest hope for the treatment of MM. This review intends to focus the attention on the new approved antibody targets. The most important are: CD38 (daratumumab and isatuximab), SLAM7 (elotuzumab), and BCMA (belantamab mafodotin) for the treatment of MM currently used in clinical practice. Although the disease is still incurable, the future perspective is to find the best therapeutic combination among all available drugs.

Therapeutic Monoclonal Antibody Interference in Monoclonal Gammopathy Monitoring: a Denosumab Experience

A 73-year-old woman was diagnosed with a lambda light chain myeloma. A follow-up immunofixation electrophoresis showed a monoclonal immunoglobulin (Ig)G kappa in addition to the regular lambda band. A monoclonal antibody therapy interference was suspected but her VRD (bortezomib, lenalidomide, dexamethasone) regimen did not include such a medication. Later it was learned that she was prescribed denosumab, a monoclonal human antibody agent to treat bone lesions. The IgG kappa band disappeared 7 months after the first and 4 months after the last dose of denosumab, confirming a case of interference. This case once again emphasizes the importance of delta check and close communication between clinicians to avoid a false result in electrophoresis. It also describes the migration pattern of denosumab. As therapeutic antibodies gain approval and enter into common clinical practice, drug interference will complicate electrophoresis testing in diagnosis and patient follow-up.

Kinase Inhibition in Multiple Myeloma: Current Scenario and Clinical Perspectives

Multiple myeloma (MM) is a blood cell neoplasm characterized by excessive production of malignant monoclonal plasma cells (activated B lymphocytes) by the bone marrow, which end up synthesizing antibodies or antibody fragments, called M proteins, in excess. The accumulation of this production, both cells themselves and of the immunoglobulins, causes a series of problems for the patient, of a systemic and local nature, such as blood hyperviscosity, renal failure, anemia, bone lesions, and infections due to compromised immunity. MM is the third most common hematological neoplasm, constituting 1% of all cancer cases, and is a disease that is difficult to treat, still being considered an incurable disease. The treatments currently available cannot cure the patient, but only extend their lifespan, and the main and most effective alternative is autologous hematopoietic stem cell transplantation, but not every patient is eligible, often due to age and pre-existing comorbidities. In this context, the search for new therapies that can bring better results to patients is of utmost importance. Protein tyrosine kinases (PTKs) are involved in several biological processes, such as cell growth regulation and proliferation, thus, mutations that affect their functionality can have a great impact on crucial molecular pathways in the cells, leading to tumorigenesis. In the past couple of decades, the use of small-molecule inhibitors, which include tyrosine kinase inhibitors (TKIs), has been a hallmark in the treatment of hematological malignancies, and MM patients may also benefit from TKI-based treatment strategies. In this review, we seek to understand the applicability of TKIs used in MM clinical trials in the last 10 years.

Expression of Cysteine-Rich Secreted Acidic Protein in Multiple Myeloma and Its Effect on the Biological Behavior of Cancer Cells

The multiple myeloma is a malignant clonal tumor of bone marrow plasma cells that is incurable and inevitably recurrent. The mechanisms of progression include tumor cell metastasis, immune escape, resistance to apoptosis, and malignant proliferation. The cysteine-rich secreted acidic protein is closely related to the growth, development, remodeling, and repair of cells and tissues. In our study, we divided myeloma patients and patients with other blood diseases into groups and measured the cysteine-rich secreted acidic protein (SPARC) content in the serum of different groups of patients as well as the prognostic differences. The U266 cells were transfected with interfering vectors and overexpressed SPARC vectors to determine the physiological functions of MM cells. Our results showed that SPARC was highly expressed in MM and the survival rate of the high SPARC expression group was lower than that of the low expression group. Interfering SPARC vectors inhibited cancer cell proliferation, migration, and invasion and promoted apoptosis. Overexpression of SPARC vectors promoted cancer cell development. SPARC affected the patient's disease development by regulating the biological behavior of the MM cells.

Mechanisms of Action of the New Antibodies in Use in Multiple Myeloma

Monoclonal antibodies (mAbs) directed against antigen-specific of multiple myeloma (MM) cells have Fc-dependent immune effector mechanisms, such as complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent cellular phagocytosis (ADCP), but the choice of the antigen is crucial for the development of effective immuno-therapy in MM. Recently new immunotherapeutic options in MM patients have been developed against different myeloma-related antigens as drug conjugate-antibody, bispecific T-cell engagers (BiTEs) and chimeric antigen receptor (CAR)-T cells. In this review, we will highlight the mechanism of action of immuno-therapy currently available in clinical practice to target CD38, SLAMF7, and BCMA, focusing on the biological role of the targets and on mechanisms of actions of the different immunotherapeutic approaches underlying their advantages and disadvantages with critical review of the literature data.

Harnessing the Physiological Functions of Cellular Prion Protein in the Kidneys: Applications for Treating Renal Diseases

A cellular prion protein (PrP^C) is a ubiquitous cell surface glycoprotein, and its physiological functions have been receiving increased attention. Endogenous PrP^C is present in various kidney tissues and undergoes glomerular filtration. In prion diseases, abnormal prion proteins are found to accumulate in renal tissues and filtered into urine. Urinary prion protein could serve as a diagnostic biomarker. PrP^C plays a role in cellular signaling pathways, reno-protective effects, and kidney iron uptake. PrP^C signaling affects mitochondrial function via the ERK pathway and is affected by the regulatory influence of microRNAs, small molecules, and signaling proteins. Targeting PrP^C in acute and chronic kidney disease could help improve iron homeostasis, ameliorate damage from ischemia/reperfusion injury, and enhance the efficacy of mesenchymal stem/stromal cell or extracellular vesicle-based therapeutic strategies. PrP^C may also be under the influence of BMP/Smad signaling and affect the progression of TGF-β-related renal fibrosis. PrP^C conveys TNF-α resistance in some renal cancers, and therefore, the coadministration of anti-PrP^C antibodies improves chemotherapy. PrP^C can be used to design antibody-drug conjugates, aptamer-drug conjugates, and customized tissue inhibitors of metalloproteinases to suppress cancer. With preclinical studies demonstrating promising results, further research on PrP^C in the kidney may lead to innovative PrP^C-based therapeutic strategies for renal disease.