T-cell redirecting bispecific and trispecific antibodies in multiple myeloma beyond BCMA

Expert Opinion on Multiple Myeloma Treatment in Brazil in the Bispecific Antibody Era

Multiple myeloma treatment has evolved rapidly with the development of novel targeted therapies. The paper outlines multiple myeloma epidemiology, current treatments, and recent advances, highlighting the role of bispecific antibodies. Brazilian authorities have approved 3 bispecific antibodies (teclistamab, elranatamab, and talquetamab) for relapsed/refractory multiple myeloma patients who have received at least three prior therapies. These therapies have shown promising efficacy in clinical trials, with 61%-74% overall response rates. However, access to these treatments varies significantly between Brazil's private and public healthcare systems. A panel of 6 Brazilian experts in multiple myeloma and bispecific antibody therapy convened for a three-day virtual conference organized and moderated by Americas Health Foundation. They addressed key questions regarding bispecific antibody therapy in multiple myeloma and developed consensus recommendations. While bispecific antibodies offer new hope for multiple myeloma patients, challenges remain in ensuring equitable access to these therapies. The paper discusses the sequencing of bispecific antibodies with other treatments, the management of adverse events, and the need for real-world data. It also highlights the disparities in multiple myeloma treatment between Brazil's public and private healthcare systems, emphasizing the need for targeted efforts to bridge this gap and improve outcomes for all multiple myeloma patients.

Pathogenesis, Diagnosis, and Management of Cytokine Release Syndrome in Patients with Cancer: Focus on Infectious Disease Considerations

Background: Cytokine Release Syndrome (CRS) is a hyperinflammatory state triggered by immune therapies like CAR T-cell therapy and bispecific T-cell engagers (BiTEs). Characterized by excessive cytokine release, CRS often mimics infectious and inflammatory conditions, complicating diagnosis and treatment. Immunosuppressive therapies used for CRS further elevate the risk of secondary infections. Methods: A systematic search of PubMed and EMBASE was conducted using terms related to "cytokine release syndrome", "cytokine storm", "infections", and "management". Studies were included if they described infectious complications, diagnostic mimics, or therapeutic approaches related to CRS. Results: Of 19,634 studies, 2572 abstracts were reviewed. Infections occurred in up to 23% of patients post-CAR T therapy and 24% post-BiTE therapy. Pathogens included gram-positive and gram-negative bacteria, herpesviruses (e.g., CMV, HSV), fungi (e.g., Candida, Aspergillus), and parasites (e.g., Toxoplasma gondii). CRS mimics also included non-infectious inflammatory syndromes. Differentiation remains challenging, but cytokine profiling and biomarkers (e.g., ferritin, CRP, sIL-2Rα) may aid in diagnosis. Treatments included tocilizumab, corticosteroids, and empiric antimicrobials. Prophylactic strategies were inconsistently reported. Conclusions: Effective CRS management requires early recognition, differentiation from infectious mimics, and collaboration between oncology and infectious disease (ID) specialists. A multidisciplinary, collaborative, and structured approach, including dedicated ID input and pre-treatment evaluation, is essential for optimizing CRS management and patient outcomes.

Talquetamab in Multiple Myeloma: Efficacy, Safety, and Future Directions

Relapsed and refractory multiple myeloma (RRMM) remains a challenging condition despite advances in immunotherapies. Novel bispecific antibodies (BsAbs), including talquetamab, have shown promising efficacy in heavily pretreated patients, even those with triple- and penta-refractory disease. Talquetamab, recently approved by the FDA and EMA, is indicated for patients who have progressed after at least three or four prior lines of therapy (LOTs). Administered following a step-up dosing phase to manage cytokine release syndrome (CRS), talquetamab demonstrated a high overall response rate (ORR) of approximately 70%, including in patients previously treated with T-cell redirecting therapies. Its safety profile is consistent with other BsAbs, with hematologic adverse events such as anemia and neutropenia commonly reported, alongside unique on-target off-tumor toxicities like dysgeusia and skin-related events. Infections were less frequent compared to other BsAbs. The optimal sequencing of talquetamab and other therapies, including CAR-T cell treatments, remains an area of active research, as resistance to anti-BCMA therapies presents ongoing clinical challenges. Current trials are exploring the use of talquetamab in combination therapies, as well as therapeutic strategies post-treating progression. The real-world data further support talquetamab's efficacy, making it a valuable addition to the RRMM treatment landscape.

Antibody-Based Immunotherapies for the Treatment of Hematologic Malignancies

Despite the great advancements in treatment strategies for hematological malignancies (HMs) over the years, their effective treatment remains challenging. Conventional treatment strategies are burdened with several serious drawbacks limiting their effectiveness and safety. Improved understanding of tumor immunobiology has provided novel anti-cancer strategies targeting selected immune response components. Currently, immunotherapy is counted as the fourth pillar of oncological treatment (together with surgery, chemo- and radiotherapy) and is becoming standard in the treatment regimen, alone or in combination therapy. Several categories of immunotherapies have been developed and are currently being assessed in clinical trials for the treatment of blood cancers, including immune checkpoint inhibitors, antigen-targeted antibodies, antibody-drug conjugates, tumor vaccines, and adoptive cell therapies. However, monoclonal antibodies (mAbs) and their derivatives have achieved the most notable clinical outcome so far. Since the approval of rituximab for treating B-cell malignancies, the availability of mAbs against tumor-specific surface molecules for clinical use has flourished. Antibody-based therapy has become one of the most successful strategies for immunotherapeutic cancer treatment in the last few decades, and many mAbs have already been introduced into standard treatment protocols for some hematologic malignancies. To further increase the efficacy of mAbs, they can be conjugated to radioisotopes or cytostatic drugs, so-called antibody-drug conjugates. Moreover, with the growing recognition of T-cell immunity's role in cancer development, strategies aimed at enhancing T cell activation and inhibiting mechanisms that suppress T cell function are actively being developed. This review provides a comprehensive overview of the current status of immunotherapeutic strategies based on monoclonal antibodies and their derivatives, including antibody-drug conjugates, bispecific T-cell engagers, and checkpoint inhibitors, approved for the treatment of various HMs.

Are we there yet? CAR-T therapy in multiple myeloma

The last few years have seen a revolution in cellular immunotherapies for multiple myeloma (MM) with novel antigen targets. The principle new target is B-cell maturation antigen (BCMA). Autologous chimeric antigen receptor T-cell (CAR-T) therapy directed against BCMA was first approved by the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) in 2021, although approval by the National Institute for Health and Care Excellent (NICE) is awaited. Initial response rates in patients with heavily pretreated MM have been impressive, but patients are still relapsing. Furthermore, CAR-T manufacturing is expensive and time-consuming, and T-cell fitness is impaired by prior MM treatment. Numerous strategies to improve outcomes and delivery of cellular immunotherapy are under investigation, including next-generation CARs, allogeneic 'off-the-shelf' CARs and targeting of other MM antigens including G protein-coupled receptor, class C, group 5, member D (GPRC5D), Fc receptor homologue 5 (FcRH5), cluster of differentiation (CD)19, signalling lymphocyte activation molecule family member 7 (SLAMF7) and several others. In this exciting and rapidly evolving treatment landscape, this review evaluates the most recent clinical and preclinical data pertaining to these new cellular immunotherapies and explores strategies to overcome resistance pathways. On the protracted journey to a long-term cure, we outline the challenges that lie ahead and ask, 'Are we there yet?'

Enhancing Fc-mediated effector functions of monoclonal antibodies: The example of HexaBodies

Since the approval of the CD20-targeting monoclonal antibody (mAb) rituximab for the treatment of lymphoma in 1997, mAb therapy has significantly transformed cancer treatment. With over 90 FDA-approved mAbs for the treatment of various hematological and solid cancers, modern cancer treatment relies heavily on these therapies. The overwhelming success of mAbs as cancer therapeutics is attributed to their broad applicability, high safety profile, and precise targeting of cancer-associated surface antigens. Furthermore, mAbs can induce various anti-tumor cytotoxic effector mechanisms including antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC), all of which are mediated via their fragment crystallizable (Fc) domain. Over the past decades, these effector mechanisms have been substantially improved through Fc domain engineering. In this review, we will outline the different approaches to enhance Fc effector functions via Fc engineering of mAbs, with a specific emphasis on the so-called "HexaBody" technology, which is designed to enhance the hexamerization of mAbs on the target cell surface, thereby inducing greater complement activation, CDC, and receptor clustering. The review will summarize the development, preclinical, and clinical testing of several HexaBodies designed for the treatment of B-cell malignancies, as well as the potential use of the HexaBody technology beyond Fc-mediated effector functions.

Mechanism of Action and Pharmacokinetics of Approved Bispecific Antibodies

Bispecific antibodies represent a significant advancement in therapeutic antibody engineering, offering the ability to simultaneously target two distinct antigens. This dual-targeting capability enhances therapeutic efficacy, especially in complex diseases, such as cancer and autoimmune disorders, where drug resistance and incomplete target coverage are prevalent challenges. Bispecific antibodies facilitate immune cell engagement and disrupt multiple signaling pathways, providing a more comprehensive treatment approach than traditional monoclonal antibodies. However, the intricate structure of bispecific antibodies introduces unique pharmacokinetic challenges, including issues related to their absorption, distribution, metabolism, and excretion, which can significantly affect their efficacy and safety. This review provides an in-depth analysis of the structural design, mechanisms of action, and pharmacokinetics of the currently approved bispecific antibodies. It also highlights the engineering innovations that have been implemented to overcome these challenges, such as Fc modifications and advanced dimerization techniques, which enhance the stability and half-life of bispecific antibodies. Significant progress has been made in bispecific antibody technology; however, further research is necessary to broaden their clinical applications, enhance their safety profiles, and optimize their incorporation into combination therapies. Continuous advancements in this field are expected to enable bispecific antibodies to provide more precise and effective therapeutic strategies for a range of complex diseases, ultimately improving patient outcomes and advancing precision medicine.

ISB 2001 trispecific T cell engager shows strong tumor cytotoxicity and overcomes immune escape mechanisms of multiple myeloma cells

Despite recent advances in immunotherapies targeting single tumor-associated antigens, patients with multiple myeloma eventually relapse. ISB 2001 is a CD3+ T cell engager (TCE) co-targeting BCMA and CD38 designed to improve cytotoxicity against multiple myeloma. Targeting of two tumor-associated antigens by a single TCE resulted in superior cytotoxic potency across a variable range of BCMA and CD38 tumor expression profiles mimicking natural tumor heterogeneity, improved resistance to competing soluble factors and exhibited superior cytotoxic potency on patient-derived samples and in mouse models. Despite the broad expression of CD38 across human tissues, ISB 2001 demonstrated a reduced T cell activation profile in the absence of tumor cells when compared to TCEs targeting CD38 only. To determine an optimal first-in-human dose for the ongoing clinical trial ( NCT05862012 ), we developed an innovative quantitative systems pharmacology model leveraging preclinical data, using a minimum pharmacologically active dose approach, therefore reducing patient exposure to subefficacious doses of therapies.

Fast and furious: Changing gears on the road to cure with chimeric antigen receptor T cells in multiple myeloma

Based on the pivotal KarMMa-1 and CARTITUDE-1 studies, Idecabtagene vicleucel (Ide-cel) and Ciltacabtagene autoleucel (Cilta-cel) have been approved to treat multiple myeloma patients, who have been exposed to at least 1 proteasome inhibitor, immunomodulatory drug and anti-CD38 antibody after 4 or 3 lines of therapy, respectively. The unprecedented rates of deep and long-lasting remissions have been meanwhile confirmed in multiple real-world analyses and more recently, the KarMMa-3 and CARTITUDE-4 studies lead to the approval in earlier lines of therapy. It is currently believed that ultimately all patients with relapsed/refractory multiple myeloma experience relapse after anti-BCMA CAR T-cell therapies. There is a plethora of CAR T-cell therapies targeting novel antigens, with the aim to overcome current CAR T-cell resistance. In this review, we will summarize current evidence of novel antigens and their clinical potential. Together with current CAR T-cell therapy and T-cell engagers, these approaches might lead us to the next frontier in multiple myeloma: total immunotherapy and the road to chemotherapy-free cure.

IL-15/IL-15Rα-Fc-Fusion Protein XmAb24306 Potentiates Activity of CD3 Bispecific Antibodies through Enhancing T-Cell Expansion

An insufficient quantity of functional T cells is a likely factor limiting the clinical activity of T-cell bispecific antibodies, especially in solid tumor indications. We hypothesized that XmAb24306 (efbalropendekin alfa), a lymphoproliferative interleukin (IL)-15/IL-15 receptor α (IL-15Rα) Fc-fusion protein, may potentiate the activity of T-cell dependent (TDB) antibodies. The activation of human peripheral T cells by cevostamab, an anti-FcRH5/CD3 TDB, or anti-HER2/CD3 TDB resulted in the upregulation of the IL-2/15Rβ (CD122) receptor subunit in nearly all CD8+ and majority of CD4+ T cells, suggesting that TDB treatment may sensitize T cells to IL-15. XmAb24306 enhanced T-cell bispecific antibody-induced CD8+ and CD4+ T-cell proliferation and expansion. In vitro combination of XmAb24306 with cevostamab or anti-HER2/CD3 TDB resulted in significant enhancement of tumor cell killing, which was reversed when T-cell numbers were normalized, suggesting that T-cell expansion is the main mechanism of the observed benefit. Pretreatment of immunocompetent mice with a mouse-reactive surrogate of XmAb24306 (mIL-15-Fc) resulted in a significant increase of T cells in the blood, spleen, and tumors and converted transient anti-HER2/CD3 TDB responses to complete durable responses. In summary, our results support the hypothesis that the number of tumor-infiltrating T cells is rate limiting for the activity of solid tumor-targeting TDBs. Upregulation of CD122 by TDB treatment and the observed synergy with XmAb24306 and T-cell bispecific antibodies support clinical evaluation of this novel immunotherapy combination.

T-cell redirecting bispecific antibody treatment in multiple myeloma: current knowledge and future strategies for sustained T-cell engagement

INTRODUCTION

T-cell redirecting bispecific antibodies (BsAbs), targeting B-cell maturation antigen (BCMA) or G-protein - coupled receptor class C group 5 member D (GPRC5D), are efficacious new agents for the treatment of patients with relapsed or refractory MM.

AREAS COVERED

This review discusses the pharmacokinetic properties, efficacy, and safety profile of T-cell redirecting BsAbs in MM, with a special focus on their optimal dosing schedule, resistance mechanisms and future strategies to enhance efficacy, reduce toxicity, and maximize duration of response.

EXPERT OPINION

To further improve the efficacy of BsAbs, ongoing studies are investigating whether combination therapy can enhance depth and duration of response. An important open question is also to what extent response to BsAbs can be improved when these agents are used in earlier lines of therapy. In addition, more evidence is needed on rational de-intensification strategies of BsAb dosing upon achieving a sufficient response, and if (temporary) treatment cessation is possible in patients who have achieved a deep remission (e.g. complete response or minimal residual disease-negative status).

Updates on Therapeutic Strategies in the Treatment of Relapsed/Refractory Multiple Myeloma

Multiple myeloma is a heterogeneous condition characterized by the proliferation of monoclonal B-cells, for which there is currently no curative treatment available. Relapses are, unfortunately, common after first-line treatment. While the prognosis for relapsed refractory multiple myeloma is generally poor, advances in the treatment of relapsed or refractory multiple myeloma offer hope. However, the expansion of effective options in targeted treatment offers renewed optimism and hope that patients who fail on older therapies may respond to newer modalities, which are often used in combination. We review currently approved and novel investigational agents classified by mechanisms of action, efficacy, approved setting, and adverse events. We delve into future directions of treatment for relapsed/refractory multiple myeloma, reviewing novel agents and therapeutic targets for the future.

In vivo mRNA expression of a multi-mechanistic mAb combination protects against Staphylococcus aureus infection

Single monoclonal antibodies (mAbs) can be expressed in vivo through gene delivery of their mRNA formulated with lipid nanoparticles (LNPs). However, delivery of a mAb combination could be challenging due to the risk of heavy and light variable chain mispairing. We evaluated the pharmacokinetics of a three mAb combination against Staphylococcus aureus first in single chain variable fragment scFv-Fc and then in immunoglobulin G 1 (IgG1) format in mice. Intravenous delivery of each mRNA/LNP or the trio (1 mg/kg each) induced functional antibody expression after 24 h (10-100 μg/mL) with 64%-78% cognate-chain paired IgG expression after 3 days, and an absence of non-cognate chain pairing for scFv-Fc. We did not observe reduced neutralizing activity for each mAb compared with the level of expression of chain-paired mAbs. Delivery of the trio mRNA protected mice in an S. aureus-induced dermonecrosis model. Intravenous administration of the three mRNA in non-human primates achieved peak serum IgG levels ranging between 2.9 and 13.7 μg/mL with a half-life of 11.8-15.4 days. These results suggest nucleic acid delivery of mAb combinations holds promise and may be a viable option to streamline the development of therapeutic antibodies.

Bispecific and multispecific antibodies in oncology: opportunities and challenges

Research into bispecific antibodies, which are designed to simultaneously bind two antigens or epitopes, has advanced enormously over the past two decades. Owing to advances in protein engineering technologies and considerable preclinical research efforts, bispecific antibodies are constantly being developed and optimized to improve their efficacy and to mitigate toxicity. To date, >200 of these agents, the majority of which are bispecific immune cell engagers, are in either preclinical or clinical evaluation. In this Review, we discuss the role of bispecific antibodies in patients with cancer, including history and development, as well as innovative targeting strategies, clinical applications, and adverse events. We also discuss novel alternative bispecific antibody constructs, such as those targeting two antigens expressed by tumour cells or cells located in the tumour microenvironment. Finally, we consider future research directions in this rapidly evolving field, including innovative antibody engineering strategies, which might enable more effective delivery, overcome resistance, and thus optimize clinical outcomes.

Stepping forward: T-cell redirecting bispecific antibodies in cancer therapy

T cell-redirecting bispecific antibodies are specifically designed to bind to tumor-associated antigens, thereby engaging with CD3 on the T cell receptor. This linkage between tumor cells and T cells actively triggers T cell activation and initiates targeted killing of the identified tumor cells. These antibodies have emerged as one of the most promising avenues within tumor immunotherapy. However, despite success in treating hematological malignancies, significant advancements in solid tumors have yet to be explored. In this review, we aim to address the critical challenges associated with T cell-redirecting bispecific antibodies and explore novel strategies to overcome these obstacles, with the ultimate goal of expanding the application of this therapy to include solid tumors.

Beyond BCMA: the next wave of CAR T cell therapy in multiple myeloma

Chimeric antigen receptor (CAR) T cell therapy has transformed the treatment landscape of relapsed/refractory multiple myeloma. The current Food and Drug Administration approved CAR T cell therapies idecabtagene vicleucel and ciltacabtagene autoleucel both target B cell maturation antigen (BCMA), which is expressed on the surface of malignant plasma cells. Despite deep initial responses in most patients, relapse after anti-BCMA CAR T cell therapy is common. Investigations of acquired resistance to anti-BCMA CAR T cell therapy are underway. Meanwhile, other viable antigenic targets are being pursued, including G protein-coupled receptor class C group 5 member D (GPRC5D), signaling lymphocytic activation molecule family member 7 (SLAMF7), and CD38, among others. CAR T cells targeting these antigens, alone or in combination with anti-BCMA approaches, appear to be highly promising as they move from preclinical studies to early phase clinical trials. This review summarizes the current data with novel CAR T cell targets beyond BCMA that have the potential to enter the treatment landscape in the near future.

Editorial: Multiple Myeloma: Molecular Mechanism and Targeted Therapy

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