T-cell Engager Research Articles

Delineating MYC-Mediated Escape Mechanisms from Conventional and T Cell-Redirecting Therapeutic Antibodies

In B-cell malignancies, the overexpression of MYC is associated with poor prognosis, but its mechanism underlying resistance to immunochemotherapy remains less clear. In further investigations of this issue, we show here that the pharmacological inhibition of MYC in various lymphoma and multiple myeloma cell lines, as well as patient-derived primary tumor cells, enhances their susceptibility to NK cell-mediated cytotoxicity induced by conventional antibodies targeting CD20 (rituximab) and CD38 (daratumumab), as well as T cell-mediated cytotoxicity induced by the CD19-targeting bispecific T-cell engager blinatumomab. This was associated with upregulation of the target antigen only for rituximab, suggesting additional escape mechanisms. To investigate these mechanisms, we targeted the MYC gene in OCI-LY18 cells using CRISPR-Cas9 gene-editing technology. CRISPR-Cas9-mediated MYC targeting not only upregulated CD20 but also triggered broader apoptotic pathways, upregulating pro-apoptotic PUMA and downregulating anti-apoptotic proteins BCL-2, XIAP, survivin and MCL-1, thereby rendering tumor cells more prone to apoptosis, a key tumor-lysis mechanism employed by T-cells and NK-cells. Moreover, MYC downregulation boosted T-cell activation and cytokine release in response to blinatumomab, revealing a MYC-mediated T-cell suppression mechanism. In conclusion, MYC overexpressing tumor cells mitigated the efficacy of therapeutic antibodies through several non-overlapping mechanisms. Given the challenges associated with direct MYC inhibition due to toxicity, successful modulation of MYC-mediated immune evasion mechanisms may improve the outcome of immunotherapeutic approaches in B-cell malignancies.

Unlocking Intracellular Oncology Targets: The Unique Role of Antibody-Based T-Cell Receptor Mimic (TCRm) Therapeutics in T-Cell Engagers (TCEs) and Antibody-Drug Conjugates (ADCs)

Effectively targeting intracellular tumor-associated proteins presents a formidable challenge in oncology, as they are traditionally considered inaccessible to conventional antibody-based therapies and CAR-T cell therapies. However, recent advancements in antibody engineering have revolutionized this field, offering promising new strategies to combat cancer. This review focuses on the innovative use of T-cell receptor mimic (TCRm) antibodies within the therapeutic frameworks of T-cell engagers (TCE) and antibody-drug conjugates (ADCs). TCRm antibodies, designed to recognize peptide-MHC complexes rather than cell surface proteins, integrate the capacity of T-cells to reach intracellular targets with the unique strengths of antibodies. When incorporated into T-cell engaging therapeutics, TCRms redirect T cells to cancer cells, facilitating direct cytotoxicity. In ADCs, TCRm antibodies deliver cytotoxic agents with highly specific targeting to cancer cells, sparing healthy tissues. Together, these antibody-based strategies represent a significant leap forward in oncology, opening new avenues for the treatment of cancers previously deemed untreatable, with other potential applications in autoimmune diseases. This review discusses the mechanisms, clinical advancements, and future prospects of these cutting-edge therapies, highlighting their potential to transform the landscape of cancer treatment.

A B7-H3–Targeted CD28 Bispecific Antibody Enhances the Activity of Anti–PD-1 and CD3 T-cell Engager Immunotherapies

Abstract T-cell activation is a multistep process requiring T-cell receptor engagement by peptide–MHC complexes (Signal 1) coupled with CD28-mediated costimulation (Signal 2). Tumors typically lack expression of CD28 ligands, so tumor-specific Signal 1 (e.g., neoepitope presentation) without costimulation may be ineffective or even induce T-cell anergy. We designed the bispecific antibody XmAb808 to co-engage the tumor-associated antigen B7-H3 with CD28 to promote T-cell costimulation within the tumor microenvironment. XmAb808 costimulation was measured by its ability to activate and expand T cells and enhance T cell–mediated cancer cell killing in cocultures of human peripheral blood mononuclear cells and cancer cells and in mice engrafted with human peripheral blood mononuclear cells and tumor xenografts. XmAb808 avidly bound cancer cells and stimulated IL2 and IFNγ secretion from T cells cocultured with cancer cells engineered to deliver Signal 1 to T cells via a surface-expressed anti-CD3 antibody. XmAb808 enhanced expression of the antiapoptotic factor Bcl-xL and CD25, promoting survival and IL2-dependent expansion of T cells coupled with increased T cell–mediated cytotoxicity in vitro. XmAb808 combined with an EpCAM×CD3 bispecific antibody to enhance target cell killing through IL2-dependent expansion of CD25+ T cells. This combination also suppressed pancreatic tumor xenograft growth in mice. Furthermore, XmAb808 combined with an anti–programmed cell death protein 1 antibody to suppress breast tumor xenograft growth in mice. XmAb808 as monotherapy and in combination with an anti–programmed cell death protein 1 antibody is currently in clinical development in patients with advanced solid tumors. Our results suggest that XmAb808 may also combine with tumor antigen–targeted anti-CD3 (Signal 1) T-cell engagers.

Beyond ADCs: harnessing bispecific antibodies to directly induce apoptosis for targeted tumor eradication

Abstract Bispecific apoptosis triggers (BATs) are innovative bispecific antibodies designed to simultaneously target both a tumor-associated antigen and a cancer cell’s death receptor, thereby directly activating the extrinsic apoptotic pathway to induce death of cancer cells. This unique mechanism distinguishes BATs from antibody-drug conjugates (ADCs), which rely on cytotoxic drugs, and bispecific immune cell engagers such as bispecific T-cell engagers (BiTEs) and bispecific natural killer cell engagers (NKCEs), which recruit immune cells to eliminate target cancer cells. BATs offer significant potential advantages in clinical efficacy and safety over ADCs and BiTEs. Although the field is still emerging, recent advancements are highly promising, and analysis of preclinical and clinical data of DR5-targeting antibodies have been pivotal in outlining the criteria for the next generation of effective and safe medicines. Antibodies found inactive in preclinical testing were also found to be clinically ineffective, whereas antibodies with minimal preclinical results demonstrated moderate clinical activity. All clinical DR5-targeting antibodies were well tolerated by patients even at high doses (with the exception of TAS266 due to its unique design). These findings underscore the predictive value of robust preclinical models on clinical outcomes. Notably, first-in-class BAT, Cancerlysin™ IMV-M, demonstrated potent efficacy in diverse xenograft cancer models and safety in non-human primates, marking a significant advancement in developing safe and effective anti-cancer drugs.

Releasing our model T - chimeric antigen receptor (CAR) T-cells for autoimmune indications.

This review provides an update on the rapidly growing field of engineered cellular therapies for autoimmune disorders, primarily focusing on clinical experience and correlative studies with chimeric antigen receptor (CAR) T-cells. To date, two case series describing treatment with CAR T-cell therapy for systemic lupus erythematosus (SLE) suggest that drug-free remission can be sustained in patients with previously treatment-refractory disease. The outcomes of these studies are similar, despite the use of different CAR constructs and lymphodepletion regimens. Although it is not yet clear whether the patients described have truly been cured, the majority of remissions have remained durable up to last follow-up at 1-2 years from treatment. Meanwhile, mechanistic studies are providing a window into how transient B-cell depletion mediates lasting benefit. With the encouraging data in SLE, CAR T-cells and other novel B-cell-depleting agents (e.g. bispecific T-cell engagers) are now being evaluated as treatment for other autoimmune conditions, with the goal of durable response. Recent reports highlight cellular therapies as a promising strategy for patients with treatment-refractory autoimmune conditions; however, there is still limited experience, and better insight into this therapeutic approach is expected to emerge rapidly.

Vδ2 T-cell engagers bivalent for Vδ2-TCR binding provide anti-tumor immunity and support robust Vγ9Vδ2 T-cell expansion.

Vγ9Vδ2 T-cells are antitumor immune effector cells that can detect metabolic dysregulation in cancer cells through phosphoantigen-induced conformational changes in the butyrophilin (BTN) 2A1/3A1 complex. In order to clinically exploit the anticancer properties of Vγ9Vδ2 T-cells, various approaches have been studied including phosphoantigen stimulation, agonistic BTN3A-specific antibodies, adoptive transfer of expanded Vγ9Vδ2 T-cells, and more recently bispecific antibodies. While Vγ9Vδ2 T-cells constitute a sizeable population, typically making up ~1-10% of the total T cell population, lower numbers have been observed with increasing age and in the context of disease. We evaluated whether bivalent single domain antibodies (VHHs) that link Vδ2-TCR specific VHHs with different affinities could support Vγ9Vδ2 T-cell expansion and could be incorporated in a bispecific engager format when additionally linked to a tumor antigen specific VHH. Bivalent VHHs that link a high and low affinity Vδ2-TCR specific VHH can support Vγ9Vδ2 T-cell expansion. The majority of Vγ9Vδ2 T-cells that expanded following exposure to these bivalent VHHs had an effector or central memory phenotype and expressed relatively low levels of PD-1. Bispecific engagers that incorporated the bivalent Vδ2-TCR specific VHH as well as a tumor antigen specific VHH triggered antitumor effector functions and supported expansion of Vγ9Vδ2 T-cells in vitro and in an in vivo model in NOG-hIL-15 mice. By enhancing the number of Vγ9Vδ2 T-cells available to exert antitumor effector functions, these novel Vδ2-bivalent bispecific T cell engagers may promote the overall efficacy of bispecific Vγ9Vδ2 T-cell engagement, particularly in patients with relatively low levels of Vγ9Vδ2 T-cells.

FDA Approval Summary: Teclistamab - A Bispecific CD3 T-cell Engager for Patients with Relapsed or Refractory Multiple Myeloma.

On October 25, 2022, the U.S. Food and Drug Administration (FDA) granted accelerated approval to teclistamab-cqyv (TECVAYLI; Janssen Biotech) for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least four prior lines of therapy, including a proteasome inhibitor, an immunomodulatory agent and an anti-CD38 monoclonal antibody. Substantial evidence of effectiveness was obtained from the MajesTEC-1 trial, a phase 1/2, single-arm, open-label, multi-center study. Patients received step-up doses of teclistamab at 0.06 mg/kg and 0.3 mg/kg followed by 1.5 mg/kg subcutaneously once weekly until disease progression or unacceptable toxicity. An overall response rate of 61.8% was observed, with a complete response or better rate of 28.2%. Cytokine release syndrome (CRS) occurred in 72% of patients and neurologic toxicity (NT) occurred in 57%, including immune effector cell-associated neurotoxicity syndrome (ICANS) in 6%. Due to the risk of CRS and NT, including ICANS, the U.S. prescribing information for teclistamab includes a boxed warning and teclistamab is available only through a restricted program under a risk evaluation and mitigation strategy. Here, we summarize the data and FDA review supporting the accelerated approval of teclistamab, a BCMA-directed bispecific antibody that was the first bispecific CD3 T-cell engager approved for treatment of multiple myeloma.

Rapid Systematic Screening of Bispecific Antibody Surrogate Geometries for T-Cell Engagement Using DNA Nanotechnology.

Bispecific antibodies (bsAbs) are emerging immune-therapeutics, and many formats exist that differ considerably in structure. However, little systematic data exist about how the spatial organization of their components influences activity, requiring innovative approaches combining empirical and quantitative frameworks. This study presents a modular DNA nanotechnology platform to generate numerous bsAbs with surrogate geometries that span the structural features of the BiTE, IgG-like, and IgG-conjugate platforms to screen for T-cell engagement. Results highlight interesting structure-activity relationships regarding bsAb potency and selectivity and raise questions regarding the molecular phenomena underlying activity. To elucidate some effects, the platform was paired with a simple mathematical model. This work is thus one of the first to systematically investigate and reveal the importance of the spatial organization of bsAb components on activity and equally provides an accessible and convenient tool for rapidly mapping out such trends for other combinations of target epitopes.

Tarlatamab-dlle: A New Hope for Patients with Extensive-Stage Small-Cell Lung Cancer.

Lung cancer is expected to contribute to about 0.234 million new cases and about 0.125 million mortalities in the United States in the year 2024. Small cell lung cancer (SCLC), a neuroendocrine carcinoma, has lesser prevalence but is more aggressive at an extensive stage where the tumor is not only confined to hemithorax, mediastinum, and supraclavicular region but spread beyond the supraclavicular region. The prognosis of SCLC, irrespective of the limited or extensive stage, is very poor. Only a 5-10% overall survival rate in five years is expected and with extensive-stage SCLC, long-term disease-free survival is rare. In May 2024, the USFDA approved Tarlatamab-dlle, a DLL3 targeted bi-specific T-cell engager, for treating extensive-stage SCLC in adult patients, on or after platinum-based chemotherapy or on progression. Before the approval of Tarlatamab-dlle, only a few drugs, such as Atezolizumab and Durvalumab, received FDA approval for treating extensive-stage SCLC. It might be possible that Tarlatamab-dlle received accelerated FDA approval for extensive-stage SCLC, leaving some questions unanswered at this stage. This manuscript is focused on clinical, pre-clinical, and other pharmacological aspects of Tarlatamab-dlle for extensive-stage SCLC.

Sustained Clinical Benefit and Intracranial Activity of Tarlatamab in Previously Treated Small Cell Lung Cancer: DeLLphi-300 Trial Update.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Tarlatamab, a bispecific T-cell engager immunotherapy targeting delta-like ligand 3, has shown durable anticancer activity and manageable safety in previously treated small cell lung cancer (SCLC) in DeLLphi-300 phase I and DeLLphi-301 phase II trials. Here, we report extended follow-up of DeLLphi-300 (median follow-up, 12.1 months [range, 0.2-34.3]) in fully enrolled cohorts treated with tarlatamab ≥10 mg dose administered once every two weeks, once every three weeks, or once on day 1 and once on day 8 of a 21-day cycle (N = 152). Overall, the objective response rate (ORR) was 25.0%; the median duration of response (mDOR) was 11.2 months (95% CI, 6.6 to 22.3), and the median overall survival (mOS) was 17.5 months (95% CI, 11.4 to not estimable [NE]). Among 17 patients receiving 10 mg tarlatamab once every two weeks, the ORR was 35.3%, the mDOR was 14.9 months (95% CI, 3.0 to NE), the mOS was 20.3 months (95% CI, 5.1 to NE), and 29.4% had sustained disease control with time on treatment ≥52 weeks. No new safety signals were identified. In modified Response Assessment in Neuro-Oncology Brain Metastases analyses, CNS tumor shrinkage of ≥30% was observed in 62.5% of patients (10 of 16) who had a baseline CNS lesion of ≥10 mm, including in a subset of patients with tumor shrinkage long after previous brain radiotherapy. In DeLLphi-300 extended follow-up, tarlatamab demonstrated unprecedented survival and potential findings of intracranial activity in previously treated SCLC.

Cutting-edge approaches to B-cell depletion in autoimmune diseases.

B-cell depletion therapy (BCDT) has been employed to treat autoimmune disease for ~20 years. Immunoglobulin G1 (IgG1) monoclonal antibodies targeting CD20 and utilizing effector function (eg, antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, antibody-dependent cellular phagocytosis) to eliminate B cells have historically been the predominant therapeutic approaches. More recently, diverse BCDT approaches targeting a variety of B-cell surface antigens have been developed for use in hematologic malignancies, including effector-function-enhanced monoclonal antibodies, chimeric antigen receptor T-cell (CAR-T) treatment, and bispecific T-cell engagers (TCEs). The latter category of antibodies employs CD3 engagement to augment the killing of target cells. Given the improvement in B-cell depletion observed with CAR-T and TCEs compared with conventional monospecific antibodies for treatment of hematologic malignancies and the recent case reports demonstrating therapeutic benefit of CAR-T in autoimmune disease, there is potential for these mechanisms to be effective for B-cell-mediated autoimmune disease. In this review, we discuss the various BCDTs that are being developed in autoimmune diseases, describing the molecule designs, depletion mechanisms, and potential advantages and disadvantages of each approach as they pertain to safety, efficacy, and patient experience. Additionally, recent advances and strategies with TCEs are presented to help broaden understanding of the potential for bispecific antibodies to safely and effectively engage T cells for deep B-cell depletion in autoimmune diseases.

T-cell engagers: model interrogation as a tool to quantify the interplay of relative affinity and target expression on trimer formation.

T-cell engagers (TCEs) represent a promising therapeutic strategy for various cancers and autoimmune disorders. These bispecific antibodies act as bridges, connecting T-cell receptors (TCRs) to target cells (either malignant or autoreactive) via interactions with specific tumour-associated antigens (TAAs) or autoantigens to form trimeric synapses, or trimers, that co-localise T-cells with target cells and stimulate their cytotoxic function. Bispecific TCEs are expected to exhibit a bell-shaped dose-response curve, with a defined optimal TCE exposure for maximizing trimer formation. The shape of the dose-response is determined by a non-trivial interplay of binding affinities, exposure and antigens expression levels. Furthermore, excessively low binding to the TCR may reduce efficacy, but mitigate risk of over-stimulating cytokine secretion or induce effector cell exhaustion. These inevitable trade-off highlights the importance of quantitatively understanding the relationship between TCE concentration, target expression, binding affinities, and trimer formation. We utilized a mechanistic target engagement model to show that, if the TCE design parameters are close to the recommended ranges found in the literature, relative affinities for TCR, TAA and target expression levels have qualitatively different, but predictable, effects on the resulting dose-response curve: higher expression levels shift the curve upwards, higher antigen affinity shifts the curve to the left, and higher TCR affinity shifts the curve upwards and to the left.

SAIL66, a next generation CLDN6-targeting T-cell engager, demonstrates potent antitumor efficacy through dual binding to CD3/CD137

BackgroundOvarian cancer remains a formidable challenge in oncology, necessitating innovative therapeutic approaches. Claudin-6 (CLDN6), a member of the tight junction molecule CLDN family, exhibits negligible expression in healthy tissues but...

Novel Bispecific T-Cell Engagers for the Treatment of Relapsed B Cell Non-Hodgkin Lymphomas: Current Knowledge and Treatment Considerations.

This article provides an overview of the novel treatments focusing on the class of bispecific T cell engagers (BiTEs) for the treatment of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL), the two most prevalent subtypes of B cell non-Hodgkin lymphomas (B-NHL). After a brief outline of these diseases, the difficulties in the management of relapsed or refractory (R/R) disease are highlighted. There are currently 4 main BiTEs showing promise in treating R/R B-NHL-glofitamab, epcoritamab, mosunetuzumab, and odronextamab. Although the rational of their mechanism of action is similar, there are significant differences in their respective clinical trial design, reported outcomes, and the final FDA approvals. Considerations for selecting a specific BiTE therapy, including treatment duration, cost, administration route, adverse effects, and impact on quality of life, are also discussed. Patient preferences and shared decision making should be acknowledged by healthcare providers. Finally, the importance of personalized treatment strategies and ongoing research to optimize outcomes in the evolving landscape of R/R B-NHL therapy cannot be overstated.

Blinatumomab infusion interruptions in pediatric patients rarely lead to readmission.

Blinatumomab is a bispecific T-cell engager administered as a 28-day continuous infusion. Infusions can be associated with interruptions requiring support from clinical staff, but the frequency of interventions with outpatient blinatumomab has not been characterized. This study is a single-center, retrospective review of patients who received blinatumomab between December 3, 2014 and October 31, 2021 to determine frequency and type of interventions. Forty patients received blinatumomab for 69 cycles. Clinical staff intervention was required in 31 (45%) cycles, only six (8.7%) cycles needed readmission. Management of outpatient blinatumomab infusions requires education and training of clinical staff and caregivers to quickly troubleshoot interruptions.

Identifying biomarkers for treatment of uveal melanoma by T cell engager using a QSP model.

Uveal melanoma (UM), the primary intraocular tumor in adults, arises from eye melanocytes and poses a significant threat to vision and health. Despite its rarity, UM is concerning due to its high potential for liver metastasis, resulting in a median survival of about a year after detection. Unlike cutaneous melanoma, UM responds poorly to immune checkpoint inhibition (ICI) due to its low tumor mutational burden and PD-1/PD-L1 expression. Tebentafusp, a bispecific T cell engager (TCE) approved for metastatic UM, showed potential in clinical trials, but the objective response rate remains modest. To enhance TCE efficacy, we explored quantitative systems pharmacology (QSP) modeling in this study. By integrating a TCE module into an existing QSP model and using clinical data on UM and tebentafusp, we aimed to identify and rank potential predictive biomarkers for patient selection. We selected 30 important predictive biomarkers, including model parameters and cell concentrations in tumor and blood compartments. We investigated biomarkers using different methods, including comparison of median levels in responders and non-responders, and a cutoff-based biomarker testing algorithm. CD8+ T cell density in the tumor and blood, CD8+ T cell to regulatory T cell ratio in the tumor, and naïve CD4+ density in the blood are examples of key biomarkers identified. Quantification of predictive power suggested a limited predictive power for single pre-treatment biomarkers, which was improved by early on-treatment biomarkers and combination of predictive biomarkers. Ultimately, this QSP model could facilitate biomarker-guided patient selection, improving clinical trial efficiency and UM treatment outcomes.

Impact of soluble BCMA and non–T-cell factors on refractoriness to BCMA targeting T-cell engagers in multiple myeloma

AbstractAdoptive T-cell therapy is a promising therapy for multiple myeloma (MM), but its efficacy hinges on understanding the relevant biologic and predictive markers of response. B-cell maturation antigen (BCMA) is a key target antigen in MM with active development of multiple anti-BCMA T-cell engagers (TCEs) and chimeric antigen receptor T-cell therapies. The regulation of surface BCMA expression by MM cells, which leads to shedding of soluble BCMA (sBCMA), has triggered debate about the significance of sBCMA as a predictive marker and its potential impact on treatment outcomes. To address this, we leveraged whole-genome sequencing and in vitro assays to demonstrate that sBCMA may independently predict primary refractoriness to anti-BCMA therapies. In addition to sBCMA, tumor burden and surface BCMA antigen density collectively influenced the anti-BCMA TCE cytotoxic efficacy. Correlative analyses of 163 patients treated with the anti-BCMA TCE teclistamab validated and further underscored the association between elevated baseline sBCMA (>400 ng/mL) and refractoriness. Importantly, increasing the TCE dose, using TCE against alternative targets (eg, GPRC5D), and gamma secretase inhibitors were able to overcome the high sBCMA levels. These findings highlight the importance of taking into account the baseline sBCMA levels, disease burden, and TCE dose intensity when administering anti-BCMA TCEs, thereby offering critical insights for optimizing therapeutic strategies to overcome specific high-risk features and primary anti-BCMA TCE refractoriness.

An Innovative Approach to Optimize First-In-Human Minimal Anticipated Biological Effect Level Based Starting Dose in Oncology Trials for Bispecific T-Cell Engagers: Experience from A Solid Tumor Bispecific T-Cell Engager.

Bispecific T-cell engagers (Bi-TCEs) have revolutionized the treatment and management of both hematological and solid tumor indications with opportunities to become best-in-class therapeutics for cancer. However, defining the dose and dosing regimen for the first-in-human (FIH) studies of Bi-TCEs can be challenging, as a high starting dose can expose subjects to serious toxicity while a low starting dose based on traditional minimal anticipated biological effect level (MABEL) approach could lead to lengthy dose escalations that exposes seriously ill patients to sub-therapeutic dosing. Leveraging our in-depth and broad clinical development experience across three generations of Bi-TCEs across both liquid and solid tumor indications, we developed an innovative modified MABEL approach for starting dose selection that integrates knowledge based on the target biology, indication, toxicology, in vitro, in vivo pharmacological evaluations, and translational pharmacokinetic/pharmacodynamic (PK/PD) modeling, together with anticipated safety profile. Compared to the traditional MABEL approach in which high effector to target (E:T) cell ratios are typically used, our innovative approach utilized an optimized E:T cell ratio that better reflects the tumor microenvironment. This modified MABEL approach was successfully applied to FIH dose selection for a half-life extended (HLE) Bi-TCE for gastric cancer. This modified MABEL approach enabled a 10-fold higher starting dose that was deemed safe and well tolerated and saved at least two dose-escalation cohorts before reaching the projected efficacious dose. This approach was successfully accepted by global regulatory agencies and can be applied for Bi-TCEs across both hematological and solid tumor indications for accelerating the clinical development for Bi-TCEs.

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.

Dosing Strategies and Quantitative Clinical Pharmacology for Bispecific T-Cell Engagers Development in Oncology.

Bispecific T-cell Engagers (TCEs) are promising anti-cancer treatments that bind to both the CD3 receptors on T cells and an antigen on the surface of tumor cells, creating an immune synapse, leading to killing of malignant tumor cells. These novel therapies have unique development challenges, with specific safety risks of cytokine release syndrome. These on-target adverse events fortunately can be mitigated and deconvoluted from efficacy via innovative dosing strategies, making clinical pharmacology key in the development of these therapies. This review assesses dose selection and the role of quantitative clinical pharmacology in the development of the first eight approved TCEs. Model informed drug development (MIDD) strategies can be used at every stage to guide TCE development. Mechanistic modeling approaches allow for (1) efficacious yet safe first-in-human dose selection as compared with in vitro minimum anticipated biological effect level (MABEL) approach; (2) rapid escalation and reducing number of patients with subtherapeutic doses through model-based adaptive design; (3) virtual testing of different step-up dosing regimens that may not be feasible to be evaluated in the clinic; and (4) selection and justification of the optimal clinical step-up and full treatment doses. As the knowledge base around TCEs continues to grow, the relevance and utilization of MIDD strategies for supporting the development and dose optimization of these molecules are expected to advance, optimizing the benefit-risk profile for cancer patients.