T-cell Engager Research Articles

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.

1020P Highly potent and specific bivalent T cell engager (TCE) targeting PRAME on HLA-A*02:01

1020P Highly potent and specific bivalent T cell engager (TCE) targeting PRAME on HLA-A*02:01

657P Prospective validation of the T cell engager (TCE) score in patients treated with bispecific CD3 TCE antibodies in phase I clinical trials

657P Prospective validation of the T cell engager (TCE) score in patients treated with bispecific CD3 TCE antibodies in phase I clinical trials

656P Phase I/Ib open-label study of an HER2-targeted T cell engager (TCE)‒SAR443216 in patients (pts) with advanced solid tumors: Intravenous (IV) dose-escalation results

656P Phase I/Ib open-label study of an HER2-targeted T cell engager (TCE)‒SAR443216 in patients (pts) with advanced solid tumors: Intravenous (IV) dose-escalation results

Informing the Recommended Phase III Dose of Alnuctamab, a CD3 × BCMA T-Cell Engager, Using Population Pharmacokinetics and Exposure-Response Analysis.

Alnuctamab, a B-cell maturation antigen (BCMA)-targeting T-cell engager, has demonstrated encouraging antitumor activity in the phase I study CC-93269-MM-001 treating patients with relapsed or refractory multiple myeloma. Identification of a recommended Phase III dose (RP3D) was a key objective, as such population pharmacokinetic (PopPK) and exposure-response analysis was critical. Intravenous (IV) alnuctamab was administered in fixed doses (0.15-10 mg) or in step-up doses to a maximum 10-mg target dose. Subcutaneous (SC) step-up doses of 3 and 6 mg were followed by a target dose range of 10-60 mg. Concentration data from IV and SC alnuctamab administration was pooled and was well described by a two-compartment PopPK model with first-order absorption and elimination. Covariate analysis determined that the inclusion of baseline soluble BCMA (sBCMA) on clearance significantly improved model fitting. Individual exposure parameters were estimated from the final model to characterize exposure-response relationships. Switching from IV to SC administration improved the safety profile of alnuctamab by limiting the frequency of grade ≥2 CRS events. A significant exposure-CRS relationship was observed after the first SC dose, but not subsequent dose administrations. Exposure-safety analysis did not find a statistically significant relationship between increasing exposure and the probability of key safety events of interest. Logistic regression analysis for patients administered SC alnuctamab identified that increased exposure significantly increased the probability of response, although the additional benefit was minimal at exposures above 30 mg target dose. Considering the totality of exposure-response data, the clinical pharmacology assessment supported a SC RP3D of 3/6/30 mg.

Shifting the paradigm in personalized cancer care through next-generation therapeutics and computational pathology.

The incorporation of novel therapeutic agents such as antibody-drug conjugates, radio-conjugates, T-cell engagers, and chimeric antigen receptor cell therapies represents a paradigm shift in oncology. Cell-surface target quantification, quantitative assessment of receptor internalization, and changes in the tumor microenvironment (TME) are essential variables in the development of biomarkers for patient selection and therapeutic response. Assessing these parameters requires capabilities that transcend those of traditional biomarker approaches based on immunohistochemistry, in situ hybridization and/or sequencing assays. Computational pathology is emerging as a transformative solution in this new therapeutic landscape, enabling detailed assessment of not only target presence, expression levels, and intra-tumor distribution but also of additional phenotypic features of tumor cells and their surrounding TME. Here, we delineate the pivotal role of computational pathology in enhancing the efficacy and specificity of these advanced therapeutics, underscoring the integration of novel artificial intelligence models that promise to revolutionize biomarker discovery and drug development.

A novel bispecific T-cell engager using the ligand-target csGRP78 against acute myeloid leukemia

Current medical therapies for treating acute myeloid leukemia (AML) remain unmet, and AML patients may benefit from targeted immunotherapy approaches that focus on specific tumor antigens. GRP78, which is upregulated in various malignant tumors such as AML, is partially expressed as cell surface GRP78 (csGRP78) on the cell membrane, making it an ideal target for redirecting T cells, including T-cell engagers. However, considering the conventional approach of using two scFv segments to construct a bispecific T-cell engager (BiTE), we have undertaken the development of a novel BiTE that utilizes a cyclic peptide ligand to specifically target csGRP78, which we refer to as GRP78-CD3/BiTE. We studied the effects of GRP78-CD3/BiTE on treatments for AML in vitro and in vivo and assessed the pharmacokinetics of this engager. Our findings demonstrated that GRP78-CD3/BiTE could not only effectively mediate the cytotoxicity of T cells against csGRP78-expressing AML cells but also specifically eliminate primary AML tumor cells in vitro. Furthermore, GRP78-CD3/BiTE exhibited a longer half-life despite having a lower molecular weight than CD19-CD3/BiTE. In a xenograft mouse model of AML, treatment with GRP78-CD3/BiTE prolonged the survival time of the mice. Our findings demonstrate that GRP78-CD3/BiTE is effective and selective for eliminating csGRP78-expressing AML cells and suggest that this approach to targeted immunotherapy could lead to effective new treatments for AML.

Bispecific T-Cell Engagers: Sequencing, BCMA, GPRC5D, and Resistance

Bispecific T-Cell Engagers: Sequencing, BCMA, GPRC5D, and Resistance

CD64+ fibroblast-targeted vilanterol and a STING agonist augment CLDN18.2 BiTEs efficacy against pancreatic cancer by reducing desmoplasia and enriching stem-like CD8+ T cells

ObjectiveThe objective of this study is to improve the efficacy of CLDN18.2/CD3 bispecific T-cell engagers (BiTEs) as a promising immunotherapy against pancreatic ductal adenocarcinoma (PDAC).DesignHumanised hCD34+/hCD3e+, Trp53R172HKrasG12DPdx1-Cre (KPC), pancreas-specific Cldn18.2...

Complementary dual-virus strategy drives synthetic target and cognate T-cell engager expression for endogenous-antigen agnostic immunotherapy

Targeted antineoplastic immunotherapies have achieved remarkable clinical outcomes. However, resistance to these therapies due to target absence or antigen shedding limits their efficacy and excludes tumours from candidacy. To address this limitation, here we engineer an oncolytic rhabdovirus, vesicular stomatitis virus (VSVΔ51), to express a truncated targeted antigen, which allows for HER2-targeting with trastuzumab. The truncated HER2 (HER2T) lacks signaling capabilities and is efficiently expressed on infected cell surfaces. VSVΔ51-mediated HER2T expression simulates HER2-positive status in tumours, enabling effective treatment with the antibody-drug conjugate trastuzumab emtansine in vitro, ex vivo, and in vivo. Additionally, we combine VSVΔ51-HER2T with an oncolytic vaccinia virus expressing a HER2-targeted T-cell engager. This dual-virus therapeutic strategy demonstrates potent curative efficacy in vivo in female mice using CD3+ infiltrate for anti-tumour immunity. Our findings showcase the ability to tailor the tumour microenvironment using oncolytic viruses, thereby enhancing compatibility with “off-the-shelf” targeted therapies.

Cost-effectiveness of blinatumomab for the treatment of B‑precursor acute lymphoblastic leukemia pediatric patients with high‑risk first‑relapse in Mexico

BackgroundBlinatumomab is a CD3/CD19-directed bispecific T-cell engager molecule that engages T cells to lyse CD19-expressing B cells. Based on a multicenter, open-label, phase 3, randomized clinical trial (Clinical Trials ID: NCT02393859), we aimed to evaluate the cost-effectiveness (CE) of blinatumomab compared to standard consolidation chemotherapy (SC) for the treatment of pediatric patients with high-risk first-relapsed Philadelphia chromosome-negative B-cell precursor acute lymphoblastic leukemia (B-ALL) from a Mexico healthcare payer perspective. MethodsA decision-analytic model, a partitioned survival model, was used to estimate the life-years (LYs) and costs over a lifetime horizon. We assumed that patients who remained alive beyond a 5-year period were cured. To account for the lingering impacts of cancer treatment, an excess mortality rate was incorporated into the model. Event-free survival (EFS) and overall survival (OS) were estimated by fitting mixture-cure and standard parametric survival distributions to the time-to-event data from the phase 3 trial. The model accounted for treatment costs, adverse event costs, follow-up costs, subsequent allogeneic hematopoietic stem cell transplantation (alloHSCT) costs, and subsequent treatment costs. ResultsBlinatumomab was associated with a lifetime gained of 5.11 years at an incremental cost of $621,111 MXN, relative to SC. The ICER for blinatumomab vs Standard of care was estimated to be $121,526 MXN/LY gained in the base case. Cost-effectiveness was sensitive to varying the time horizon. Blinatumomab had a probability of 99 % of being cost-effective, relative to SC, at the willingness to pay threshold defined in Mexico. LimitationsHealth-related quality of life values were not included in the analysis and therefore we did not estimate the quality-adjusted life-years gained. ConclusionsBlinatumomab was associated with greater benefit in terms of OS and EFS relative to SC. Probabilistic, deterministic, and scenario analyses indicate that blinatumomab represents the best value for money. Therefore, blinatumomab administered as part of consolidation therapy in B-ALL pediatric patients with high-risk first relapse is a cost-effective option.

Novel immunotherapeutics against LGR5 to target multiple cancer types

We have developed and validated a highly specific, versatile antibody to the extracellular domain of human LGR5 (α-LGR5). α-LGR5 detects LGR5 overexpression in >90% of colorectal cancer (CRC), hepatocellular carcinoma (HCC) and pre-B-ALL tumour cells and was used to generate an Antibody-Drug Conjugate (α-LGR5-ADC), Bispecific T-cell Engager (α-LGR5-BiTE) and Chimeric Antigen Receptor (α-LGR5-CAR). α-LGR5-ADC was the most effective modality for targeting LGR5+ cancer cells in vitro and demonstrated potent anti-tumour efficacy in a murine model of human NALM6 pre-B-ALL driving tumour attrition to less than 1% of control treatment. α-LGR5-BiTE treatment was less effective in the pre-B-ALL cancer model yet promoted a twofold reduction in tumour burden. α-LGR5-CAR-T cells also showed specific and potent LGR5+ cancer cell killing in vitro and effective tumour targeting with a fourfold decrease in pre-B-ALL tumour burden relative to controls. Taken together, we show that α-LGR5 can not only be used as a research tool and a biomarker but also provides a versatile building block for a highly effective immune therapeutic portfolio targeting a range of LGR5-expressing cancer cells.

Living in LALA land? Forty years of attenuating Fc effector functions.

The Fc region of antibodies is vital for most of their physiological functions, many of which are engaged through binding to a range of Fc receptors. However, these same interactions are not always helpful or wanted when therapeutic antibodies are directed against self-antigens, and can sometimes cause catastrophic adverse reactions. Over the past 40 years, there have been intensive efforts to "silence" unwanted binding to Fc-gamma receptors, resulting in at least 45 different variants which have entered clinical trials. One of the best known is "LALA" (L234A/L235A). However, neither this, nor most of the other variants in clinical use are completely silenced, and in addition, the biophysical properties of many of them are compromised. I review the development of different variants to see what we can learn from their biological properties and use in the clinic. With the rise of powerful new uses of antibody therapy such as bispecific T-cell engagers, antibody-drug conjugates, and checkpoint inhibitors, it is increasingly important to optimize the Fc region as well as the antibody binding site in order to achieve the best combination of safety and efficacy.

IL1RAP-specific T cell engager depletes acute myeloid leukemia stem cells

BackgroundThe interleukin-1 receptor accessory protein (IL1RAP) is highly expressed on acute myeloid leukemia (AML) bulk blasts and leukemic stem cells (LSCs), but not on normal hematopoietic stem cells (HSCs), providing an opportunity to target and eliminate the disease, while sparing normal hematopoiesis. Herein, we report the activity of BIF002, a novel anti-IL1RAP/CD3 T cell engager (TCE) in AML.MethodsAntibodies to IL1RAP were isolated from CD138+ B cells collected from the immunized mice by optoelectric positioning and single cell sequencing. Individual mouse monoclonal antibodies (mAbs) were produced and characterized, from which we generated BIF002, an anti-human IL1RAP/CD3 TCE using Fab arm exchange. Mutations in human IgG1 Fc were introduced to reduce FcγR binding. The antileukemic activity of BIF002 was characterized in vitro and in vivo using multiple cell lines and patient derived AML samples.ResultsIL1RAP was found to be highly expressed on most human AML cell lines and primary blasts, including CD34+ LSC-enriched subpopulation from patients with both de novo and relapsed/refractory (R/R) leukemia, but not on normal HSCs. In co-culture of T cells from healthy donors and IL1RAPhigh AML cell lines and primary blasts, BIF002 induced dose- and effector-to-target (E:T) ratio-dependent T cell activation and leukemic cell lysis at subnanomolar concentrations. BIF002 administered intravenously along with human T cells led to depletion of leukemic cells, and significantly prolonged survival of IL1RAPhigh MOLM13 or AML patient-derived xenografts with no off-target side effects, compared to controls. Of note, BiF002 effectively redirects T cells to eliminate LSCs, as evidenced by the absence of disease initiation in secondary recipients of bone marrow (BM) from BIF002+T cells-treated donors (median survival not reached; all survived > 200 days) compared with recipients of BM from vehicle- (median survival: 26 days; p = 0.0004) or isotype control antibody+T cells-treated donors (26 days; p = 0.0002).ConclusionsThe novel anti-IL1RAP/CD3 TCE, BIF002, eradicates LSCs and significantly prolongs survival of AML xenografts, representing a promising, novel treatment for AML.

Differential expression in potential therapeutic target protein by treatment in small cell lung cancer with and without transformation.

202 Background: Small cell lung cancer (SCLC) is a disease with a poor prognosis. Besides combination strategy with immune checkpoint inhibitors (ICIs) and cytotoxic agents, antibody-drug conjugates (ADCs) and bispecific T-cell engagers (BiTE) are being developed. These drugs target tumor-associated surface protein. Whether prior treatment affect the transition of protein expression has not been fully investigated especially in the era of ICIs. The purpose of this study is to evaluate changes in protein expression in SCLC tissues before and after treatment. Methods: We included patients diagnosed with SCLC by surgery or biopsy and underwent re-biopsy after treatment (non-transformed group) at the National Cancer Center Hospital between 2014 and 2023. Patients who were initially diagnosed with non-small cell lung cancer and underwent transformation to SCLC (transformed group) were also included. Tissues were obtained by surgery, bronchoscopy, or CT-guided biopsy with an interval of at least 100 days. We investigated clinicopathological features in paired specimens focusing on DLL3, ASCL1, NEUROD1, POU2F3, and YAP1, which have been reported to be expressed in SCLC, as well as tumor-associated surface proteins potentially related to novel drug development. Results: Fourteen non-transformed group cases and 9 transformed group cases were included. Of these, pathology specimens were evaluable in a total of 15 cases: 9 for the non-transformed group and 6 for the transformed group. The median age was 68 years, 11 (73%) were male, 11 (73%) were smokers, 8 (53%) were in clinical stages I-IIIA, 1 (7%) in stages IIIB and 6 (40%) in stage IV. Among the transformed group, 4 of them were treated by Osimertinib before transformation. Progression free survival from first-line therapy was 298 days (255-446) vs. 314 days (245-NA) and overall survival was 1239 days (567-NA) vs. NA days (517-NA), respectively for non-transformed group and transformed group. For both these group of cases, we have evaluated several protein expressions as described above. The transition of these proteins within each group is presented in the conference. Conclusions: In this study, we focused not only on proteins already reported to be expressed in SCLC, but also on proteins that are potential new therapeutic targets and evaluated changes in protein expression. [Table: see text]

Engineered Protein-G variants for plug-and-play applications.

We have developed a portfolio of antibody-based modules that can be prefabricated as standalone units and snapped together in plug-and-play fashion to create uniquely powerful multifunctional assemblies. The basic building blocks are derived from multiple pairs of native and modified Fab scaffolds and protein G (PG) variants engineered by phage display to introduce high pair-wise specificity. The variety of possible Fab-PG pairings provides a highly orthogonal system that can be exploited to perform challenging cell biology operations in a straightforward manner. The simplest manifestation allows multiplexed antigen detection using PG variants fused to fluorescently labeled SNAP-tags. Moreover, Fabs can be readily attached to a PG-Fc dimer module which acts as the core unit to produce plug-and-play IgG-like assemblies, and the utility can be further expanded to produce bispecific analogs using the "knobs into holes" strategy. These core PG-Fc dimer modules can be made and stored in bulk to produce off-the-shelf customized IgG entities in minutes, not days or weeks by just adding a Fab with the desired antigen specificity. In another application, the bispecific modalities form the building block for fabricating potent Bispecific T-cell Engagers (BiTEs), demonstrating their efficacy in cancer cell-killing assays. Additionally, the system can be adapted to include commercial antibodies as building blocks, greatly increasing the target space. Crystal structure analysis reveals that a few strategically positioned interactions engender the specificity between the Fab-PG variant pairs, requiring minimal changes to match the scaffolds for different possible combinations. This plug-and-play platform offers a user-friendly and versatile approach to enhance the functionality of antibody-based reagents in cell biology research.

The expression of PD-L1 on tumor-derived exosomes enhances infiltration and anti-tumor activity of αCD3 × αPD-L1 bispecific antibody-armed T cells

Anti-cluster of differentiation (CD) 3 × α programmed death-ligand 1 (PD-L1) bispecific T-cell engager (BsTE)-bound T-cells (BsTE:T) are a promising new cancer treatment agent. However, the mechanisms of action of bispecific antibody-armed activated T-cells are poorly understood. Therefore, this study aimed to investigate the anti-tumor mechanism and efficacy of BsTE:T. The BsTE:T migration was assessed in vivo and in vitro using syngeneic and xenogeneic tumor models, flow cytometry, immunofluorescence staining, transwell migration assays, microfluidic chips, Exo View R100, western blotting, and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 technology. In murine B16 melanoma, MC38 colon cancer, and human multiple myeloma cells, BsTE:T exhibited superior tumor elimination relative to that of T-cells or BsTE alone. Moreover, BsTE:T migration into tumors was significantly enhanced owing to the presence of PD-L1 in tumor cells and secretion of PD-L1-containing exosomes. Furthermore, increased infiltration of CD44highCD62Llow effector memory CD8+ T-cells into tumors was closely associated with the anti-tumor effect of BsTE:T. Therefore, BsTE:T is an innovative potential anti-tumor therapy, and exosomal PD-L1 plays a crucial role both in vitro and in vivo in the anti-tumor activity of BsTE:T.Graphical abstract

Conversion of anti-tissue factor antibody sequences to chimeric antigen receptor and bi-specific T-cell engager format

BackgroundThe efficacy of antibody-targeted therapy of solid cancers is limited by the lack of consistent tumour-associated antigen expression. However, tumour-associated antigens shared with non-malignant cells may still be targeted using conditionally activated-antibodies, or by chimeric antigen receptor (CAR) T cells or CAR NK cells activated either by the tumour microenvironment or following 'unlocking' via multiple antigen-recognition. In this study, we have focused on tissue factor (TF; CD142), a type I membrane protein present on a range of solid tumours as a basis for future development of conditionally-activated BiTE or CAR T cells. TF is frequently upregulated on multiple solid tumours providing a selective advantage for growth, immune evasion and metastasis, as well as contributing to the pathology of thrombosis via the extrinsic coagulation pathway.MethodsTwo well-characterised anti-TF monoclonal antibodies (mAb) were cloned into expression or transposon vectors to produce single chain (scFv) BiTE for assessment as CAR and CD28-CD3-based CAR or CD3-based BiTE. The affinities of both scFv formats for TF were determined by surface plasmon resonance. Jurkat cell line-based assays were used to confirm the activity of the BiTE or CAR constructs.ResultsThe anti-TF mAb hATR-5 and TF8-5G9 mAb were shown to maintain their nanomolar affinities following conversion into a single chain (scFv) format and could be utilised as CD28-CD3-based CAR or CD3-based BiTE format.ConclusionBecause of the broad expression of TF on a range of solid cancers, anti-TF antibody formats provide a useful addition for the development of conditionally activated biologics for antibody and cellular-based therapy.