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The treatment paradigm in myeloma is constantly changing. Upfront use of monoclonal antibodies like daratumumab along with proteasome inhibitors (PI)s, and immune modulators (IMiD)s have significantly improved survival and outcomes, but also cause unique challenges at the time of relapse. Engaging immune T cells for tumour cell kill with chimeric antigenic T-cell (CAR T-cell) therapy and bispecific antibodies have become important therapeutic options in relapsed multiple myeloma. Bispecific antibodies are dual antigen targeting constructs that engage the T cells to plasma cells through various target antigens like B-cell membrane antigen (BCMA), G-protein-coupled receptor family C group 5 member D (GPRC5D), and Fc receptor-homolog 5 (FcRH5). These agents have proven to induce deep and durable responses in heavily pre-treated myeloma patients with a predictable safety profile and the ease of off-the-shelf availability. Significant research is ongoing to overcome resistance mechanisms like T cell exhaustion, target antigen mutation or loss and high disease burden. Various trials are also studying these agents as first line options in the newly diagnosed setting. These agents play an important role in the relapsed setting, and efforts are underway to optimize their sequencing in the myeloma treatment algorithm.

BACKGROUND: Bispecific T-cell engagers (BTEs) are novel agents used to treat hematological malignancies. Early trials were underpowered to define cardiovascular adverse events (CVAE) and no large-scale studies systematically examined the CVAEs associated with BTEs. METHODS: Leveraging the US Food and Drug Administrations Adverse Event Reporting System-(FAERS), we identified the relative frequency of CVAEs after initiation of five BTE products approved by the Food and Drug Administration between 2014 and 2023 for the treatment of hematological malignancies. Adjusted reporting ORs (aROR) were used to identify disproportionate reporting of CVAEs with BTEs compared with background rates in the database. Fatality rates and risk ratios (RRs) for each adverse event (AE) were calculated. RESULTS: From 3668 BTE-related cases reported to FAERS, 747 (20.4%) involved CVAEs. BTEs as a class were associated with fatal CVAEs (aROR 1.29 (95% CI 1.12 to 1.50)), an association mainly driven by teclistamab (aROR 2.44 (95% CI 1.65 to 3.60)). Teclistamab was also associated with a disproportionate risk of myocarditis (aROR 25.70 (95% CI 9.54 to 69.23)) and shock (aROR 3.63 (95% CI 2.30 to 5.74)), whereas blinatumomab was associated with a disproportionate risk of disseminated intravascular coagulation (aROR 3.02 (95% CI 1.98 to 4.60)) and hypotension (aROR 1.59 (95% CI 1.25 to 2.03)). CVAEs were more fatal compared with non-CVAEs (31.1% vs 17.4%; RR 1.76 (95% CI 1.54 to 2.03)). Most CVAEs (83.3%) did not overlap with cytokine release syndrome. CONCLUSION: In the first postmarketing surveillance study of BTEs, CVAEs were involved in approximately one in five AE reports and carried a significant mortality risk.

Multiple myeloma is a genetically complex and heterogenous malignancy with a 5-year survival rate of approximately 60%. Despite advances in therapy, patients experience cycles of remission and relapse, with each successive line of therapy associated with poorer outcomes; therefore, therapies with different mechanisms of action against new myeloma antigens are needed. G protein-coupled receptor class C group 5 member D (GPRC5D) has emerged as a novel therapeutic target for the treatment of multiple myeloma. We review the biology and target validation of GPRC5D, and clinical data from early phase trials of GPRC5D-targeting bispecific antibodies, talquetamab and forimtamig, and chimeric antigen receptor T cell (CAR-T) therapies, MCARH109, OriCAR-017, and BMS-986393. In addition to adverse events (AEs) associated with T-cell-redirection therapies irrespective of target, a consistent pattern of dermatologic and oral AEs has been reported across several trials of GPRC5D-targeting bispecific antibodies, as well as rare cerebellar events with CAR-T therapy. Additional studies are needed to understand the underlying mechanisms involved in the development of skin- and oral-related toxicities. We review the strategies that have been used to manage these GPRC5D-related toxicities. Preliminary efficacy data showed overall response rates for GPRC5D-targeting T-cell-redirecting therapies were ≥64%; most responders achieved a very good partial response or better. Pharmacokinetics/pharmacodynamics showed that these therapies led to cytokine release and T-cell activation. In conclusion, results from early phase trials of GPRC5D-targeting T-cell-redirecting agents have shown promising efficacy and manageable safety profiles, including lower infection rates compared with B-cell maturation antigen- and Fc receptor-like protein 5-targeting bispecific antibodies. Further clinical trials, including those investigating GPRC5D-targeting T-cell-redirecting agents in combination with other anti-myeloma therapies and with different treatment modalities, may help to elucidate the future optimal treatment regimen and sequence for patients with multiple myeloma and improve survival outcomes. Video Summary.

Treatment options for patients with biliary tract cancer are limited, and the prognosis is poor. CTX-009, a novel bispecific antibody targeting both DLL4 and VEGF-A, has demonstrated antitumor activity in patients with advanced cancers as both a monotherapy and in combination with chemotherapy. In a phase II study of patients with advanced biliary tract cancer who had received one or two prior therapies, CTX-009 with paclitaxel demonstrated a 37.5% overall response rate (ORR). Described here is the design of and rationale for COMPANION-002, a randomized phase II/III study, which will evaluate the safety and efficacy of CTX-009 in combination with paclitaxel versus paclitaxel alone as second-line treatment for patients with advanced biliary tract cancer. The primary end point is ORR, and crossover is allowed.Clinical Trial Registration: NCT05506943 (ClinicalTrials.gov).

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. [ABSTRACT FROM AUTHOR]

UNLABELLED: BCMA-targeted bispecific antibodies (BiAb) are efficacious in relapsed/refractory multiple myeloma; however, serious infections have emerged as important toxicities. In this retrospective study, we characterized all infections and their risk factors, and evaluated the impact of infection prophylaxis in patients treated with BCMA-targeted BiAbs. Among 37 patients, 15 (41%) experienced a grade 3-5 infection, with two infection-related deaths during deep remissions. Most (84%) infections occurred during disease remissions. The cumulative probability of grade 3-5 infection increased over time with no plateau. Among responders (n = 26), profound hypogammaglobulinemia occurred in 100% and continued throughout the entire duration of treatment. During periods when patients were receiving intravenous immunoglobulin (IVIg), the rate of grade 3-5 infections was 90% lower than during observation (incidence rate ratio, 0.10; 95% confidence interval, 0.01-0.80; P = 0.0307). No other risk factors for infection were identified. This study demonstrates that profound hypogammaglobulinemia is universal with BCMA-targeted BiAbs, with intravenous immunoglobulin potentially abrogating most of the infection risk. SIGNIFICANCE: To the best of our knowledge, this is the first study to comprehensively analyze risk factors and mitigation strategies to prevent infections in myeloma patients receiving anti-BCMA bispecific antibodies. Profound and prolonged hypogammaglobulinemia was universal among responders, while immunoglobulin replacement was associated with 90% lower rates of grade 3-5 infections. See related commentary by Garfall and Stadtmauer, p. 427 . This article is featured in Selected Articles from This Issue, p. 419.

MEDI5752 is a monovalent bispecific immunotherapy and is strategically unique as it combines both anti programmed cell death 1 and anti cytotoxic T-lymphocyte-associated protein 4 action. This is one of the first of this kind of molecule. The development of this molecule had been very interesting which is not usually described in regular clinical oncology journals thus losing an important piece of history of an upcoming subject. Only some phase I results in such development is published so far and no full report on this is available till now. This effort will try to record the facts and chain of events which actually occurred in inventing and bringing it in phase III trial. [ABSTRACT FROM AUTHOR]

Human cytomegalovirus is a ubiquitous herpesvirus that, while latent in most individuals, poses a great risk to immunocompromised patients. In contrast to directly acting traditional antiviral drugs, such as ganciclovir, we aim to emulate a physiological infection control using T cells. For this, we constructed several bispecific T-cell engager (BiTE) constructs targeting different viral glycoproteins of the murine cytomegalovirus and evaluated them in vitro for their efficacy. To isolate the target specific effect without viral immune evasion, we established stable reporter cell lines expressing the viral target glycoprotein B, and the glycoprotein complexes gN-gM and gH-gL, as well as nano-luciferase (nLuc). First, we evaluated binding capacities using flow cytometry and established killing assays, measuring nLuc-release upon cell lysis. All BiTE constructs proved to be functional mediators for T-cell recruitment and will allow a proof of concept for this treatment option. This might pave the way for strikingly safer immunosuppression in vulnerable patient groups. [ABSTRACT FROM AUTHOR]

Anticancer immunotherapies, such as immune checkpoint inhibitors, bispecific antibodies, and chimeric antigen receptor T cells, have improved outcomes for patients with a variety of malignancies. However, most patients either do not initially respond or do not exhibit durable responses due to primary or adaptive/acquired immune resistance mechanisms of the tumor microenvironment. These suppressive programs are myriad, different between patients with ostensibly the same cancer type, and can harness multiple cell types to reinforce their stability. Consequently, the overall benefit of monotherapies remains limited. Cutting-edge technologies now allow for extensive tumor profiling, which can be used to define tumor cell intrinsic and extrinsic pathways of primary and/or acquired immune resistance, herein referred to as features or feature sets of immune resistance to current therapies. We propose that cancers can be characterized by immune resistance archetypes, comprised of five feature sets encompassing known immune resistance mechanisms. Archetypes of resistance may inform new therapeutic strategies that concurrently address multiple cell axes and/or suppressive mechanisms, and clinicians may consequently be able to prioritize targeted therapy combinations for individual patients to improve overall efficacy and outcomes.

BackgroundHistorically, adults with relapsed-refractory acute lymphoblastic leukemia (ALL) experienced poor outcomes with intensive chemotherapy. This mature analysis explores the benefit of the addition of sequential blinatumomab to low-intensity mini-Hyper-CVD chemotherapy with inotuzumab ozogamicin in this setting.MethodsMini-Hyper-CVD (cyclophosphamide and dexamethasone at 50% dose reduction, no anthracycline, methotrexate at 75% dose reduction, cytarabine at 83% dose reduction) was combined with inotuzumab during the first 4 courses. From Patient #68 and onwards, inotuzumab was given in reduced and fractionated doses, and blinatumomab was added sequentially for 4 courses. Maintenance therapy with prednisone, vincristine, 6-mercaptopurine and methotrexate was given for 12 courses, and blinatumomab for 4 additional courses.ResultsAmong 110 patients (median age, 37 years) treated, 91 (83%) responded (complete response, 69 patients, 63%). Measurable residual disease negativity was documented in 75 patients (82% of responders). Fifty-three patients (48%) received allogeneic stem cell transplantation (SCT). Hepatic sinusoidal obstruction syndrome occurred in 9/67 patients (13%) on the original inotuzumab schedule and in 1/43 (2%) on the modified schedule. With a median follow-up of 48 months, the median overall survival (OS) was 17 months, and the 3 year OS was 40%. The 3 year OS was 34% with mini-Hyper-CVD plus inotuzumab and 52% with additional blinatumomab (P = 0.16). By landmark analysis at 4 months, the 3 year OS was 54%, similar between patients who did or did not receive allogeneic SCT.ConclusionLow-intensity mini-Hyper-CVD plus inotuzumab with or without blinatumomab showed efficacy in patients with relapsed-refractory ALL, with better survival after the addition of blinatumomab. Trial registration The trial was registered on clinicaltrials.gov with the identifier NCT01371630.

T cell engagers (TCEs) are becoming an integral class of biological therapeutic owing to their highly potent ability to eradicate cancer cells. Nevertheless, the widespread utility of classical CD3-targeted TCEs has been limited by narrow therapeutic index (TI) linked to systemic CD4+ T cell activation and aberrant cytokine release. One attractive approach to circumvent the systemic activation of pan CD3+ T cells and reduce the risk of cytokine release syndrome is to redirect specific subsets of T cells. A promising strategy is the use of peptide-major histocompatibility class I bispecific antibodies (pMHC-IgGs), which have emerged as an intriguing modality of TCE, based on their ability to selectively redirect highly reactive viral-specific effector memory cytotoxic CD8+ T cells to eliminate cancer cells. However, the relatively low frequency of these effector memory cells in human peripheral blood mononuclear cells (PBMCs) may hamper their redirection as effector cells for clinical applications. To mitigate this potential limitation, we report here the generation of a pMHC-IgG derivative known as guided-pMHC-staging (GPS) carrying a covalent fusion of a monovalent interleukin-2 (IL-2) mutein (H16A, F42A). Using an anti-epidermal growth factor receptor (EGFR) arm as a proof-of-concept, tumor-associated antigen paired with a single-chain HLA-A *02:01/CMVpp65 pMHC fusion moiety, we demonstrate in vitro that the IL-2-armored GPS modality robustly expands CMVpp65-specific CD8+ effector memory T cells and induces potent cytotoxic activity against target cancer cells. Similar to GPS, IL-2-armored GPS molecules induce modulated T cell activation and reduced cytokine release profile compared to an analogous CD3-targeted TCE. In vivo we show that IL-2-armored GPS, but not the corresponding GPS, effectively expands grafted CMVpp65 CD8+ T cells from unstimulated human PBMCs in an NSG mouse model. Lastly, we demonstrate that the IL-2-armored GPS modality exhibits a favorable developability profile and monoclonal antibody-like pharmacokinetic properties in human neonatal Fc receptor transgenic mice. Overall, IL-2-armored GPS represents an attractive approach for treating cancer with the potential for inducing vaccine-like antiviral T cell expansion, immune cell redirection as a TCE, and significantly widened TI due to reduced cytokine release.

Bispecific antibodies (bsAb) and multispecific antibodies (msAb) encompass a diverse variety of formats that can concurrently bind multiple epitopes, unlocking mechanisms to address previously difficult-to-treat or incurable diseases. Early assessment of candidate developability enables demotion of antibodies with low potential and promotion of the most promising candidates for further development. Protein-based therapies have a stringent set of developability requirements in order to be competitive (e.g. high-concentration formulation, and long half-life) and their assessment requires a robust toolkit of methods, few of which are validated for interrogating bsAbs/msAbs. Important considerations when assessing the developability of bsAbs/msAbs include their molecular format, likelihood for immunogenicity, specificity, stability, and potential for high-volume production. Here, we summarize the critical aspects of developability assessment, and provide guidance on how to develop a comprehensive plan tailored to a given bsAb/msAb.

In contrast to natural antibodies that rely mainly on the heavy chain to establish contacts with their cognate antigen, we have developed a bispecific antibody format in which the light chain (LC) drives antigen binding and specificity. To better understand epitope-paratope interactions in this context, we determined the X-ray crystallographic structures of an antigen binding fragment (Fab) in complex with human CD47 and another Fab in complex with human PD-L1. These Fabs contain a κ-LC and a λ-LC, respectively, which are paired with an identical heavy chain (HC). The structural analysis of these complexes revealed the dominant contribution of the LCs to antigen binding, but also that the common HC provides some contacts in both CD47 and PD-L1 Fab complexes. The anti-CD47 Fab was affinity optimized by diversifying complementary-determining regions of the LC followed by phage display selections. Using homology modeling, the contributions of the amino acid modification to the affinity increase were analyzed. Our results demonstrate that, despite a less prominent role in natural antibodies, the LC can mediate high affinity binding to different antigens and neutralize their biological function. Importantly, Fabs containing a common variable heavy (VH) domain enable the generation of bispecific antibodies retaining a truly native structure, maximizing their therapeutic potential.

ABSTRACTThe development of bispecific antibodies that bind at least two different targets relies on bringing together multiple binding domains with different binding properties and biophysical characteristics to produce a drug-like therapeutic. These building blocks play an important role in the overall quality of the molecule and can influence many important aspects from potency and specificity to stability and half-life. Single-domain antibodies, particularly camelid-derived variable heavy domain of heavy chain (VHH) antibodies, are becoming an increasingly popular choice for bispecific construction due to their single-domain modularity, favorable biophysical properties, and potential to work in multiple antibody formats. Here, we review the use of VHH domains as building blocks in the construction of multispecific antibodies and the challenges in creating optimized molecules. In addition to exploring traditional approaches to VHH development, we review the integration of machine learning techniques at various stages of the process. Specifically, the utilization of machine learning for structural prediction, lead identification, lead optimization, and humanization of VHH antibodies.

Bispecific antibodies (BsAbs) represent an emerging class of immunotherapy, but inefficiency in the current discovery has limited their broad clinical availability. Here we report a high throughput, agnostic, single-cell-based functional screening pipeline, comprising molecular and cell engineering for efficient generation of BsAb library cells, followed by functional interrogation at the single-cell level to identify and sort positive clones and downstream sequence identification and functionality characterization. Using a CD19xCD3 bispecific T cell engager (BiTE) as a model, we demonstrate that our single-cell platform possesses a high throughput screening efficiency of up to one and a half million variant library cells per run and can isolate rare functional clones at a low abundance of 0.008%. Using a complex CD19xCD3 BiTE-expressing cell library with approximately 22,300 unique variants comprising combinatorially varied scFvs, connecting linkers and VL/VH orientations, we have identified 98 unique clones, including extremely rare ones (~ 0.001% abundance). We also discovered BiTEs that exhibit novel properties and insights to design variable preferences for functionality. We expect our single-cell platform to not only increase the discovery efficiency of new immunotherapeutics, but also enable identifying generalizable design principles based on an in-depth understanding of the inter-relationships between sequence, structure, and function.

Introduction: The therapeutic potential of bispecific antibodies is becoming widely recognised, with over a hundred formats already described. For many applications, enhanced tissue penetration is sought, so bispecifics with low molecular weight may offer a route to enhanced potency. Here we report the design of bi- and tri-specific antibody-based constructs with molecular weights as low as 14.5 and 22 kDa respectively. Methods: Autonomous bovine ultra-long CDR H3 (knob domain peptide) modules have been engineered with artificial coiled-coil stalks derived from Sin Nombre orthohantavirus nucleocapsid protein and human Beclin-1, and joined in series to produce bi- and tri-specific antibody-based constructs with exceptionally low molecular weights. Results: Knob domain peptides with coiled-coil stalks retain high, independent antigen binding affinity, exhibit exceptional levels of thermal stability, and can be readily joined head-to-tail yielding the smallest described multi-specific antibody format. The resulting constructs are able to bind simultaneously to all their targets with no interference. Discussion: Compared to existing bispecific formats, the reduced molecular weight of the knob domain fusions may enable enhanced tissue penetration and facilitate binding to cryptic epitopes that are inaccessible to conventional antibodies. Furthermore, they can be easily produced at high yield as recombinant products and are free from the heavy-light chain mispairing issue. Taken together, our approach offers an efficient route to modular construction of minimalistic bi- and multi-specifics, thereby further broadening the therapeutic scope for knob domain peptides. [ABSTRACT FROM AUTHOR]

Introduction: Although checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy. Methods: TYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352). Results: Twenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1-2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro. Discussion: This study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed. [ABSTRACT FROM AUTHOR]

Anaplastic thyroid cancer represents a rare, highly aggressive form of thyroid cancer with a poor prognosis and an overall survival ranging from 5 to 12 months. Unfortunately, treatment options remain limited, even for patients with a targetable driver mutation. Here, we present a case of a patient with a BRAF V600E-mutated, PD-L1 positive (tumor proportion score of 95%) anaplastic thyroid cancer refractory to standard therapies, including debulking surgery, followed by chemoradiation, who had further progressed on PD-1 monotherapy, and was unable to tolerate BRAF/MEK inhibition. Ongoing treatment with FS118, a bispecific LAG-3/PD-L1 antagonist, has afforded 3 years of disease control, including a late confirmed partial response, with excellent tolerability. Given this response, further investigation is required to delineate the mechanism by which dual PD-L1/LAG-3 blockade by FS118 overcomes initial PD-1 pathway resistance, and therefore, identify which patients are most likely to benefit. Simultaneously, expanded use should be considered for those with refractory disease, especially if PD-L1 positive. Insights Dual PD-L1/LAG-3 blockade may be an effective treatment strategy for refractory metastatic tumors, including anaplastic thyroid cancer.

BackgroundTeclistamab is a T-cell-redirecting bispecific antibody that targets both CD3 expressed on the surface of T cells and B-cell maturation antigen expressed on the surface of myeloma cells. In the phase 1 dose-defining portion of the study, teclistamab showed promising efficacy in patients with relapsed or refractory multiple myeloma.MethodsIn this phase 1-2 study, we enrolled patients who had relapsed or refractory myeloma after at least three therapy lines, including triple-class exposure to an immunomodulatory drug, a proteasome inhibitor, and an anti-CD38 antibody. Patients received a weekly subcutaneous injection of teclistamab (at a dose of 1.5 mg per kilogram of body weight) after receiving step-up doses of 0.06 mg and 0.3 mg per kilogram. The primary end point was the overall response (partial response or better).ResultsAmong 165 patients who received teclistamab, 77.6% had triple-class refractory disease (median, five previous therapy lines). With a median follow-up of 14.1 months, the overall response rate was 63.0%, with 65 patients (39.4%) having a complete response or better. A total of 44 patients (26.7%) were found to have no minimal residual disease (MRD); the MRD-negativity rate among the patients with a complete response or better was 46%. The median duration of response was 18.4 months (95% confidence interval [CI], 14.9 to not estimable). The median duration of progression-free survival was 11.3 months (95% CI, 8.8 to 17.1). Common adverse events included cytokine release syndrome (in 72.1% of the patients; grade 3, 0.6%; no grade 4), neutropenia (in 70.9%; grade 3 or 4, 64.2%), anemia (in 52.1%; grade 3 or 4, 37.0%), and thrombocytopenia (in 40.0%; grade 3 or 4, 21.2%). Infections were frequent (in 76.4%; grade 3 or 4, 44.8%). Neurotoxic events occurred in 24 patients (14.5%), including immune effector cell-associated neurotoxicity syndrome in 5 patients (3.0%; all grade 1 or 2).ConclusionsTeclistamab resulted in a high rate of deep and durable response in patients with triple-class-exposed relapsed or refractory multiple myeloma. Cytopenias and infections were common; toxic effects that were consistent with T-cell redirection were mostly grade 1 or 2. (Funded by Janssen Research and Development; MajesTEC-1 ClinicalTrials.gov numbers, NCT03145181 and NCT04557098.).

PURPOSE: Subset analyses from phase III evaluation of epidermal growth factor receptor inhibition (EGFRi) suggest improved outcomes in patients with EGFR-amplified gastroesophageal adenocarcinoma (GEA), but large-scale analyses are lacking. This multi-institutional analysis sought to determine the role of EGFRi in the largest cohort of patients with EGFR-amplified GEA to date. PATIENTS AND METHODS: A total of 60 patients from 15 tertiary cancer centers in six countries met the inclusion criteria. These criteria required histologically confirmed GEA in the metastatic or unresectable setting with EGFR amplification identified by using a Clinical Laboratory Improvement Amendments-approved assay, and who received on- or off-protocol EGFRi. Testing could be by tissue next-generation sequencing, plasma circulating tumor DNA next-generation sequencing, and/or fluorescence in situ hybridization performed by a Clinical Laboratory Improvement Amendments approved laboratory. Treatment patterns and outcomes analysis was also performed using a deidentified clinicogenomic database (CGDB). RESULTS: Sixty patients with EGFR-amplified GEA received EGFRi, including 31 of 60 patients (52%) with concurrent chemotherapy. Across treatment lines, patients achieved a 43% objective response rate with a median progression-free survival of 4.6 months (95% CI, 3.5 to 6.4). Patients receiving EGFRi in first-, second-, and third-line therapy achieved a median overall survival of 20.6 months (95% CI, 13.5 to not reached [NR]), 9 months (95% CI, 7.9 to NR), and 8.4 months (7.6 to NR), respectively. This survival far exceeded the 11.2-month (95% CI, 8.7 to 14.2) median overall survival from first-line initiation of non-EGFRi therapy in patients with EGFR-amplified GEA in the CGDB. Despite this benefit, analysis of the CGDB (January 2011-December 2020) suggests that only 5% of patients with EGFR-amplified GEA received EGFRi. CONCLUSION: Patients with EGFR-amplified GEA derive significant benefit from EGFRi. Further prospective investigation of EGFRi in a well-selected patient population is ongoing in an upcoming trial of amivantamab in EGFR and/or MET amplified GEA.

INTRODUCTION: There are more than two dozen bispecific antibodies (BsAbs) in development with a variety of designs which are relevant to breast cancer. The field of BsAbs for breast cancer includes agents that co-direct immune recognition of the cancer cell, target unique cancer antigens, and target the microenvironment. BsAbs are being developed for use as antibody-drug conjugates and as homing signals for engineered T-cells. AREAS COVERED: This review covers potential targets for bispecific antibodies, agents in pre-clinical development, agents in clinical trials, combinatorial therapies, and future directions. EXPERT OPINION: There is no BsAb approval expected for breast cancer in the near term, but late-stage trials are underway. Future BsAb roles in breast cancer are possible given unmet needs in estrogen receptor+ disease, residual disease, and de-escalating chemotherapy use. The HER2+ space shows hints of success for BsAbs, but is already crowded. Areas of unmet need still exist.

Epidermal growth factor receptor exon 20 insertion mutations (EGFRexon20ins) are detected in approximately 2% of patients with non-small cell lung cancer (NSCLC). Due to a lack of effective therapy, the prognosis of these patients is typically poor. Sunvozertinib (DZD9008) was designed as an oral, potent, irreversible, and selective EGFR tyrosine kinase inhibitor, showing activity against EGFRexon20ins and other mutations. In both cell lines and xenograft models, sunvozertinib shows potent antitumor activity. In the two ongoing phase I clinical studies, sunvozertinib was tolerated up to 400 mg once daily. The most common drug-related adverse events included diarrhea and skin rash. Antitumor efficacy was observed at the doses of 100 mg and above in patients with EGFRexon20ins NSCLC across different subtypes, with prior amivantamab treatment as well as with baseline brain metastasis. The median duration of response has not been reached.SignificanceWe report the discovery and early clinical development of sunvozertinib, a potential treatment option for the unmet medical need of EGFRexon20ins NSCLC. This article is highlighted in the In This Issue feature, p. 1599.

Bispecific T-cell engager (BiTE) molecules are biologic T cell-directing immunotherapies. Blinatumomab is approved for treatment of B-cell malignancies, but BiTE molecule development in solid tumors has been more challenging. Here, we employed intravital imaging to characterize exposure and pharmacodynamic response of an anti-muCD3/anti-huEGFRvIII mouse surrogate BiTE molecule in EGFR variant III (EGFRvIII)-positive breast tumors implanted within immunocompetent mice. Our study revealed heterogeneous temporal and spatial dynamics of BiTE molecule extravasation into solid tumors, highlighting physical barriers to BiTE molecule function. We also discovered that high, homogeneous EGFRvIII expression on cancer cells was necessary for a BiTE molecule to efficiently clear tumors. In addition, we found that resident tumor-infiltrating lymphocytes (TIL) were sufficient for optimal tumor killing only at high BiTE molecule dosage, whereas inclusion of peripheral T-cell recruitment was synergistic at moderate to low dosages. We report that deletion of stimulatory conventional type I DCs (cDC1) diminished BiTE molecule-induced T-cell activation and tumor clearance, suggesting that in situ antigen-presenting cell (APC) engagements modulate the extent of BiTE molecule efficacy. In summary, our work identified multiple requirements for optimal BiTE molecule efficacy in solid tumors, providing insights that could be harnessed for solid cancer immunotherapy development.

Background: PD-1/PD-L1 blockade plays a crucial role in cancer immunotherapy. Exploration of new technologies to further enhance the efficacy of PD-1/PD-L1 blockade is therefore of potential medical importance. Nanotherapeutics can accumulate in tumor tissues due to enhanced permeability and retention (EPR) effects. In this study, a novel nanotherapeutic for cancer immunotherapy was implemented with albumin nanoparticles functionalized by both PD-1 and PD-L1 aptamers. Results: Albumin nanoparticles (NP) were functionalized with either PD-1 aptamers (PD1-NP), PD-L1 aptamers (PDL1-NP), or both types of aptamers (PD1-NP-PDL1). Average sizes of PD1-NP, PDL1-NP, and PD1-NP-PDL1 were 141.8 nm, 141.8 nm, and 164.2 nm, respectively. PD1-NP had good affinity for activated T cells that expresses PD-1. Similarly, PDL1-NP could bind with MDA-MB-231 or CT26 tumor cells that express PD-L1. Moreover, the bispecific PD1-NP-PDL1 could bind with both the activated T cells and the PD-L1-expressing tumor cells, and tether the two type of cells together. Functionally, aptamer-modified nanoparticles exhibited stronger immune-stimulating effects vs. free aptamers. Specifically, PD1-NP or PDL1-NP induced stronger lymphocyte-mediated cytotoxicity against PD-L1-expressing tumor cells in vitro vs. free PD-1 or PD-L1 aptamers. Animal studies also showed that PD1-NP or PDL1-NP significantly improved antitumor efficacy against CT26 colon cancer in vivo vs. free PD-1 or PD-L1 aptamers. Importantly, the bispecific PD1-NP-PDL1 further boosted the in vivo antitumor efficacy compared with PD1-NP or PDL1-NP, without raising systemic toxicity. Conclusion: The results suggest that the bispecific PD1-NP-PDL1 is a promising nanotherapeutic to improve the efficacy of PD-1/PD-L1 blockade, and may have application potential in colon cancer treatment. [ABSTRACT FROM AUTHOR]

IntroductionThe therapeutic potential of bispecific antibodies is becoming widely recognised, with over a hundred formats already described. For many applications, enhanced tissue penetration is sought, so bispecifics with low molecular weight may offer a route to enhanced potency. Here we report the design of bi- and tri-specific antibody-based constructs with molecular weights as low as 14.5 and 22 kDa respectively.MethodsAutonomous bovine ultra-long CDR H3 (knob domain peptide) modules have been engineered with artificial coiled-coil stalks derived from Sin Nombre orthohantavirus nucleocapsid protein and human Beclin-1, and joined in series to produce bi- and tri-specific antibody-based constructs with exceptionally low molecular weights.ResultsKnob domain peptides with coiled-coil stalks retain high, independent antigen binding affinity, exhibit exceptional levels of thermal stability, and can be readily joined head-to-tail yielding the smallest described multi-specific antibody format. The resulting constructs are able to bind simultaneously to all their targets with no interference.DiscussionCompared to existing bispecific formats, the reduced molecular weight of the knob domain fusions may enable enhanced tissue penetration and facilitate binding to cryptic epitopes that are inaccessible to conventional antibodies. Furthermore, they can be easily produced at high yield as recombinant products and are free from the heavy-light chain mispairing issue. Taken together, our approach offers an efficient route to modular construction of minimalistic bi- and multi-specifics, thereby further broadening the therapeutic scope for knob domain peptides.

IntroductionAlthough checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy.MethodsTYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352).ResultsTwenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1–2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro.DiscussionThis study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed.

BackgroundOdronextamab is a hinge-stabilised, fully human IgG4-based CD20 × CD3 bispecific antibody that binds CD3 on T cells and CD20 on B cells. We aimed to evaluate the safety and antitumour activity of odronextamab in patients with relapsed or refractory B-cell non-Hodgkin lymphoma.MethodsThis single-arm, multicentre, phase 1, dose-escalation and dose-expansion (ELM-1) trial was conducted at ten academic sites across the USA and Germany. Patients aged 18 years or older with CD20-positive relapsed or refractory B-cell malignancies who previously received CD20-directed antibody therapy and who had at least one measurable lesion, and an ECOG performance status of 0 or 1 were included. Patients received intravenous odronextamab, according to a step-up dosing schedule in cycle 1, followed by treatment once per week at target doses ranging from 0·1 mg to 320 mg during cycles 2-4 (each cycle was 21 days). After cycle 4, maintenance treatment occurred every 2 weeks until disease progression or unacceptable toxicity. The primary endpoint of safety was assessed by the incidence of adverse events and dose-limiting toxicities to determine the maximum tolerated dose or phase 2 dose of odronextamab, or both. Preliminary antitumour activity, as measured by objective response rate, was a secondary endpoint. This study is registered with ClinicalTrials.gov, NCT02290951.FindingsFrom Feb 4, 2015, to Sept 25, 2021, 145 heavily pretreated patients (median of 3 (IQR 2-5] previous therapies) were enrolled (94 to the dose-escalation and 51 to the dose-expansion part of the study). The median age of patients was 67·0 years (IQR 57·0-73·0); 101 (70%) were male and 44 (30%) were female; most participants were White (119 [82%]) and not Hispanic or Latino (132 [91%]). 42 (29%) patients received previous CAR T therapy and 119 (82%) were refractory to the last line of therapy. Median duration of follow-up was 4·2 months (IQR 1·5-11·5). During dose escalation, odronextamab was administered up to the maximum dose of 320 mg once per week and no dose-limiting toxicities were observed. The recommended dose for expansion in patients with follicular lymphoma grade 1-3a was 80 mg and was 160 mg for patients with diffuse large B-cell lymphoma. Cytokine release syndrome and neurological treatment-emergent adverse events were predominantly low grade and did not result in treatment discontinuation. The most common grade 3 or worse treatment-emergent adverse events were anaemia (36 [25%]), lymphopenia (28 [19%]), hypophosphataemia (27 [19%]), neutropenia (27 [19%]), and thrombocytopenia (20 [14%]). Serious treatment-emergent adverse events occurred in 89 (61%) of 145 patients; the most frequent were cytokine release syndrome (41 [28%]), pyrexia (11 [8%]), pneumonia (nine [6%]), and infusion-related reaction (six [4%]). Four deaths were considered related to treatment (gastric perforation in a patient with gastric involvement by lymphoma, lung infection, pneumonia, and tumour-lysis syndrome). Objective response rate was 51% (95% CI 42-59; 72 of 142). In patients with follicular lymphoma who received odronextamab doses of 5 mg or higher, the objective response rate was 91% (95% CI 75-98; 29 of 32) and the complete response rate was 72% (95% CI 53-86; 23 of 32). In patients with diffuse large B-cell lymphoma without previous CAR T-cell therapy who received doses of 80 mg or higher, the objective response rate was 53% (eight of 15) and all responses were complete responses. In patients with diffuse large B-cell lymphoma who had previous CAR T-cell therapy and received doses of 80 mg or higher, the objective response rate was 33% (ten of 30) and complete response rate was 27% (eight of 30).InterpretationOdronextamab monotherapy showed a manageable safety profile and encouraging preliminary activity, including durable responses in heavily pretreated patients with B-cell non-Hodgkin lymphoma, supporting further clinical investigation in phase 2 and 3 trials.FundingRegeneron Pharmaceuticals.

Increased tumor infiltrating lymphocytes (TIL) are associated with improved patient responses to immunotherapy. As a result, there is interest in enhancing lymphocyte trafficking particularly to colon cancers since the majority are checkpoint blockade-resistant and microsatellite stable. Here, we demonstrate that activated T-cells (ATC) armed with anti-CD3 x anti-EGFR bispecific antibody increases TIL and mediate anti-tumor cytotoxicity while decreasing tumor cell viability. Furthermore, treatment induces endogenous anti-tumor immunity that resisted tumor rechallenge and increased memory T-cell subsets in the tumor. When combined with targeted tumor expression of the tumor necrosis factor superfamily member LIGHT, activated T-cell proliferation and infiltration were further enhanced, and human colorectal tumor regressions were observed. Our data indicate that tumor-targeted armed bispecific antibody increases TIL trafficking and is a potentially potent strategy that can be paired with combination immunotherapy to battle microsatellite stable colon cancer. SIGNIFICANCE: Enhancing trafficking of tumor infiltrating lymphocytes (TILs) to solid tumors has been shown to improve outcomes. Unfortunately, few strategies have been successful in the clinical setting for solid tumors, particularly for "cold" microsatellite stable colon cancers. In order to address this gap in knowledge, this study combined TNFSF14/LIGHT immunomodulation with a bispecific antibody armed with activated T-cells targeted to the tumor. This unique T-cell trafficking strategy successfully generated anti-tumor immunity in a microsatellite stable colon cancer model, stimulated T-cell infiltration, and holds promise as a combination immunotherapy for treating advanced and metastatic colorectal cancer.

Dilpacimab (formerly ABT-165), a novel dual-variable domain immunoglobulin, targets both delta-like ligand 4 (DLL4) and VEGF pathways. Here, we present safety, pharmacokinetic (PK), pharmacodynamic (PD), and preliminary efficacy data from a phase I study (trial registration ID: NCT01946074) of dilpacimab in patients with advanced solid tumors. Eligible patients (≥18 years) received dilpacimab intravenously on days 1 and 15 in 28-day cycles at escalating dose levels (range, 1.25-7.5 mg/kg) until progressive disease or unacceptable toxicity. As of August 2018, 55 patients with solid tumors were enrolled in the dilpacimab monotherapy dose-escalation and dose-expansion cohorts. The most common treatment-related adverse events (TRAE) included hypertension (60.0%), headache (30.9%), and fatigue (21.8%). A TRAE of special interest was gastrointestinal perforation, occurring in 2 patients (3.6%; 1 with ovarian and 1 with prostate cancer) and resulting in 1 death. The PK of dilpacimab showed a half-life ranging from 4.9 to 9.5 days, and biomarker analysis demonstrated that the drug bound to both VEGF and DLL4 targets. The recommended phase II dose for dilpacimab monotherapy was established as 3.75 mg/kg, primarily on the basis of tolerability through multiple cycles. A partial response was achieved in 10.9% of patients (including 4 of 16 patients with ovarian cancer). The remaining patients had either stable disease (52.7%), progressive disease (23.6%), or were deemed unevaluable (12.7%). These results demonstrate that dilpacimab monotherapy has an acceptable safety profile, with clinical activity observed in patients with advanced solid tumors.

UNLABELLED: Despite many recent advances in therapy, there is still no plateau in overall survival curves in multiple myeloma. Bispecific antibodies are a novel immunotherapeutic approach designed to bind antigens on malignant plasma cells and cytotoxic immune effector cells. Early-phase clinical trials targeting B-cell maturation antigen (BCMA), GPRC5D, and FcRH5 have demonstrated a favorable safety profile, with mainly low-grade cytokine release syndrome, cytopenias, and infections. Although dose escalation is ongoing in several studies, early efficacy data show response rates in the most active dose cohorts between 61% and 83% with many deep responses; however, durability remains to be established. Further clinical trial data are eagerly anticipated. SIGNIFICANCE: Overall survival of triple-class refractory multiple myeloma remains poor. Bispecific antibodies are a novel immunotherapeutic modality with a favorable safety profile and impressive preliminary efficacy in heavily treated patients. Although more data are needed, bispecifics will likely become an integral part of the multiple myeloma treatment paradigm in the near future. Studies in earlier lines of therapy and in combination with other active anti-multiple myeloma agents will help further define the role of bispecifics in multiple myeloma.

Bispecific antibodies (bsAbs) have attracted significant attention due to their dual binding activity, which permits simultaneous targeting of antigens and synergistic binding effects beyond what can be obtained even with combinations of conventional monospecific antibodies. Despite the tremendous therapeutic potential, the design and construction of bsAbs are often hampered by practical issues arising from the increased structural complexity as compared to conventional monospecific antibodies. The issues are diverse in nature, spanning from decreased biophysical stability from fusion of exogenous antigen-binding domains to antibody chain mispairing leading to formation of antibody-related impurities that are very difficult to remove. The added complexity requires judicious design considerations as well as extensive molecular engineering to ensure formation of high quality bsAbs with the intended mode of action and favorable drug-like qualities. In this review, we highlight and summarize some of the key considerations in design of bsAbs as well as state-of-the-art engineering principles that can be applied in efficient construction of bsAbs with diverse molecular formats.

ABSTRACTBispecific antibodies represent an increasingly large fraction of biologics in therapeutic development due to their expanded scope in functional capabilities. Asymmetric monovalent bispecific IgGs (bsIgGs) have the additional advantage of maintaining a native antibody-like structure, which can provide favorable pharmacology and pharmacokinetic profiles. The production of correctly assembled asymmetric monovalent bsIgGs, however, is a complex engineering endeavor due to the propensity for non-cognate heavy and light chains to mis-pair. Previously, we introduced the DuetMab platform as a general solution for the production of bsIgGs, which utilizes an engineered interchain disulfide bond in one of the CH1-CL domains to promote orthogonal chain pairing between heavy and light chains. While highly effective in promoting cognate heavy and light chain pairing, residual chain mispairing could be detected for specific combinations of Fv pairs. Here, we present enhancements to the DuetMab design that improve chain pairing and production through the introduction of novel electrostatic steering mutations at the CH1-CL interface with lambda light chains (CH1-Cλ). These mutations work together with previously established charge-pair mutations at the CH1-CL interface with kappa light chains (CH1-Cκ) and Fab disulfide engineering to promote cognate heavy and light chain pairing and enable the reliable production of bsIgGs. Importantly, these enhanced DuetMabs do not require engineering of the variable domains and are robust when applied to a panel of bsIgGs with diverse Fv sequences. We present a comprehensive biochemical, biophysical, and functional characterization of the resulting DuetMabs to demonstrate compatibility with industrial production benchmarks. Overall, this enhanced DuetMab platform substantially streamlines process development of these disruptive biotherapeutics.

ABSTRACTA challenge when developing therapeutic antibodies is the identification of candidates with favorable pharmacokinetics (PK) early in development. A key determinant of immunoglobulin (IgG) serum half‑life in vivo is the efficiency of pH-dependent binding to the neonatal Fc receptor (FcRn). Numerous studies have proposed techniques to assess FcRn binding of IgG-based therapeutics in vitro, enabling prediction of serum half-life prior to clinical assessment. FcRn high-performance liquid chromatography (HPLC) assays FcRn binding of therapeutic IgGs across a pH gradient, allowing the correlation of IgG column retention time to the half‑life of a therapeutic IgG in vivo. However, as FcRn retention time cannot be directly compared to an in vivo parameter, modifications to FcRn-HPLC are required to enable interpretation of the data within a physiological context, to provide more accurate estimations of serum half-life. This study presents an important modification to this method, FcRn-pH-HPLC, which reproducibly measures FcRn dissociation pH, allowing correlation with previously established half-lives of therapeutic antibodies. Furthermore, the influence of incorporating various antibody modifications, binding modules, and their orientations within IgGs and bispecifics on FcRn dissociation pH was evaluated using antibodies from the redirected optimized cell killing (ROCK®) platform. Target and effector antigen-binding domain sequences, their presentation format and orientation within a bispecific antibody alter FcRn retention; tested Fc domain modifications and incorporating stabilizing disulfide bonds had minimal effect. This study may inform the generation of mono-, bi- and multi-specific antibodies with tailored half-lives based on FcRn binding properties in vitro, to differentiate antibody-based therapeutic candidates with optimal developability.

ABSTRACTBispecific antibodies (bsAbs) enable dual binding of different antigens with potential synergistic targeting effects and innovative therapeutic possibilities. The formation of bsAbs is, however, often dependent on complex engineering strategies with a high risk of antibody chain mispairing leading to contamination of the final product with incorrectly assembled antibody species. This study demonstrates formation of bsAbs in a generic and conceptually easy manner through fusion of single-domain antibodies (sdAbs) onto IgG scaffolds through flexible 10 amino acid linkers to form high-quality bsAbs with both binding functionalities intact and minimal product-related impurities. SdAbs are attractive fusion partners due to their small and monomeric nature combined with antigen-binding capabilities comparable to conventional human antibodies. By systematically comparing a comprehensive panel of symmetric αPD-L1×αHER2 antibodies, including reversely mirrored antigen specificities, we investigate how the molecular geometry affects production, stability, antigen binding and CD16a binding. SdAb fusion of the heavy chain was generally preferred over light chain fusion for promoting good expression and high biophysical stability as well as maintaining efficient binding to both antigens. We find that N-terminal sdAb fusion might sterically hinder antigen-binding to the Fv region of the IgG scaffold, whereas C-terminal fusion might disturb antigen-binding to the fused sdAb. Our work demonstrates a toolbox of complementary methods for in-depth analysis of key features, such as in-solution dual antigen binding, thermal stability, and aggregation propensity, to ensure high bsAb quality. These techniques can be executed at high-throughput and/or with very low material consumption and thus represent valuable tools for bsAb screening and development.

ABSTRACTThe binding properties of bispecific antibodies (bsAb) are crucial for their function, especially when two antigens are targeted on the same cell surface. Dynamic interactions between each of the antibody’s arms and its cognate target cause the formation and decay of a biologically functional ternary complex. How association and dissociation processes work cooperatively, and how they influence the avidity of the ternary complex, is still poorly understood. Here, we present a biosensor assay for the simultaneous measurement of the binding kinetics of the therapeutic bsAb emicizumab (Hemlibra®) and its two targets, the blood coagulation factors IX and X (FIX, FX). We describe an automated workflow to characterize binary and ternary-binding modes, utilizing a Y-shaped DNA nanostructure to immobilize the antigens on a sensor and to emulate conditions on a cell or platelet surface by presenting the antigens with optimal accessibility for the bsAb flown over the sensor as analyte. We find that emicizumab binds FX much stronger than FIX (Kd = 0.05 µM vs. 5 µM, t1/2 = 20 s vs. 1 s) with profound consequences on the avidity of the ternary complex, which is dominated by FX’s binding properties and a hand-off mechanism from FX to FIX. Moreover, formation and decay of the ternary complex depend on the bsAb concentration during the association phase. Emicizumab’s in-vivo mode of action and the catalytic activation of FX can be rationalized from the analyzed binding kinetics. The assay and workflow are well suited for the screening of bispecific binders in drug discovery and provide valuable new kinetic information.Abbreviations: bsAb: bispecific antibody; FVIII/FIX/FX: coagulation factors VIII/IX/X; SPR: surface plasmon resonance; kon: association rate constant; koff: dissociation rate constant; KD: equilibrium dissociation constant; t1/2: dissociation half-life

T cell engagers, a category of T cell-retargeting immunotherapy, are rapidly transforming clinical cancer care. However, the lack of tumor-specific targets poses a significant roadblock for broad adaptation of this therapeutic modality in many indications, often resulting in systemic on-target off-tumor toxicity. Though various tumor-derived intracellular mutations provide a massive pool of potential tumor-specific antigens, targeting them is extremely challenging, partly due to the low copy number of tumor associated antigen (TAA)-derived pMHC on tumor cell surface. Further, the interplay of binding geometry and format valency in relation to the capacity of a T cell engager to efficiently target low density cell-surface pMHC is not well understood. Using the Wilms' tumor 1 (WT1) oncoprotein as a proof-of-principle TAA, combined with an array of IgG-like T cell engager modalities that differ in their anti-TAA valency and binding geometry, we show that the ability to induce an immunological synapse formation, resulting in potent killing of WT1 positive cancer cell lines is primarily dependent on the distinct geometrical conformations between the Fab arms of anti-WT1-HLA-A*02:01 and anti-CD3. The augmented avidity conferred by the binding of two anti-WT1-HLA-A*02:01 Fab arms has only minimal influence on cell killing potency. These findings demonstrate the need for careful examination of key design parameters for the development of nextgeneration T cell engagers targeting low density TAA-pMHCs on tumor cells. [ABSTRACT FROM AUTHOR]

Bispecific antibodies have emerged as a promising class of therapeutics in the field of oncology, offering an innovative approach to target cancer cells while sparing healthy tissues. These antibodies are designed to bind two different antigens, enabling them to bridge immune cells with cancer cells, resulting in enhanced tumor cell killing and improved treatment responses. This review article summarizes the current landscape of bispecific antibodies in lung cancer, including their mechanisms of action, clinical development, and potential applications in other solid tumor malignancies. Additionally, the challenges and opportunities associated with their use in the clinic are discussed, along with future directions for research and development in this exciting area of cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Despite the development of next-generation antiandrogens, metastatic castration-resistant prostate cancer (mCRPC) remains incurable. Here, we describe a unique semisynthetic bispecific antibody that uses site-specific unnatural amino acid conjugation to combine the potency of a T cell-recruiting anti-CD3 antibody with the specificity of an imaging ligand (DUPA) for prostate-specific membrane antigen. This format enabled optimization of structure and function to produce a candidate (CCW702) with specific, potent in vitro cytotoxicity and improved stability compared with a bispecific single-chain variable fragment format. In vivo, CCW702 eliminated C4-2 xenografts with as few as three weekly subcutaneous doses and prevented growth of PCSD1 patient-derived xenograft tumors in mice. In cynomolgus monkeys, CCW702 was well tolerated up to 34.1 mg/kg per dose, with near-complete subcutaneous bioavailability and a PK profile supporting testing of a weekly dosing regimen in patients. CCW702 is being evaluated in a first in-human clinical trial for men with mCRPC who had progressed on prior therapies (NCT04077021).

Immune-based therapies have revolutionized cancer treatments. Cardiovascular sequelae from these treatments, however, have emerged as critical complications, representing new challenges in cardio-oncology. Immune therapies include a broad range of novel drugs, from antibodies and other biologics, including immune checkpoint inhibitors and bispecific T-cell engagers, to cell-based therapies, such as chimeric-antigen receptor T-cell therapies. The recognition of immunotherapy-associated cardiovascular side effects has also catapulted new research questions revolving around the interactions between the immune and cardiovascular systems, and the signaling cascades affected by T cell activation, cytokine release, and immune system dysregulation. Here, we review the specific mechanisms of immune activation from immunotherapies and the resulting cardiovascular toxicities associated with immune activation and excess cytokine production.

Abstract Background Immune checkpoint blockade (ICB) is a promising strategy for cancer treatment and has achieved remarkable clinical results. Further improvement of ICB efficacy may advance cancer immunotherapy and has evident medical importance. Here in this study, a PD-1 aptamer was functionalized with a tumor-homing nucleolin aptamer (AS1411) to build a novel bispecific agent (BiApt) for boosting the efficacy of ICB therapy. Results The two aptamers were coupled together via sticky ends to form BiApt, which had an average size of 11.70 nm. Flow cytometry revealed that BiApt could bind with both the activated T cells and the nucleolin-expressing tumor cells. In addition, BiApt could recruit more T cells to the vicinity of nucleolin-positive tumor cells. Functionally, BiApt enhanced the PBMC-mediated anticancer cytotoxicity in vitro compared with free PD-1 aptamer. Moreover, in an animal model of CT26 colon cancer, BiApt significantly boosted the antitumor efficacy vs. free PD-1 aptamer. Conclusion The results suggest that bispecific agent combining ICB and tumor-homing functions has potential to improve the efficacy of ICB immunotherapy.

MYC is a powerful transcription factor overexpressed in many human cancers including B cell and prostate cancers. Antibody therapeutics are exciting opportunities to attack cancers but require knowledge of surface proteins that change due to oncogene expression. To identify how MYC overexpression remodels the cell surface proteome in a cell autologous fashion and in different cell types, we investigated the impact of MYC overexpression on 800 surface proteins in three isogenic model cell lines either of B cell or prostate cell origin engineered to have high or low MYC levels. We found that MYC overexpression resulted in dramatic remodeling (both up- and down-regulation) of the cell surfaceome in a cell type-dependent fashion. We found systematic and large increases in distinct sets of >80 transporters including nucleoside transporters and nutrient transporters making cells more sensitive to toxic nucleoside analogs like cytarabine, commonly used for treating hematological cancers. Paradoxically, MYC overexpression also increased expression of surface proteins driving cell turnover such as TNFRSF10B, also known as death receptor 5, and immune cell attacking signals such as the natural killer cell activating ligand NCR3LG1, also known as B7-H6. We generated recombinant antibodies to these two targets and verified their up-regulation in MYC overexpression cell lines and showed they were sensitive to bispecific T cell engagers (BiTEs). Our studies demonstrate how MYC overexpression leads to dramatic bidirectional remodeling of the surfaceome in a cell type-dependent but functionally convergent fashion and identify surface targets or combinations thereof as possible candidates for cytotoxic metabolite or immunotherapy.

BackgroundThe treatment paradigm for patients with relapsed/refractory B-cell acute lymphoblastic leukemia (rrALL) has been revolutionized given recent clinical trials demonstrating remarkable success of immunotherapies and leading to drug approvals by United States and European agencies. We report experience with commercial blinatumomab and inotuzumab use at two North American pediatric oncology centers in children and adolescents/young adults with B-ALL.ProcedurePatients 0-25 years old treated with the CD19 × CD3 bispecific T cell-engaging antibody blinatumomab and/or the CD22 antibody-drug conjugate inotuzumab from January 1, 2010, to June 1, 2018, were eligible. Disease status included relapsed B-ALL in second or greater relapse, primary chemotherapy-refractory B-ALL, or B-ALL complicated by severe infection precluding delivery of conventional chemotherapy.ResultsWe identified 27 patients who received blinatumomab and/or inotuzumab outside of clinical trials during the study period. Four of the 13 patients (31%) with relapsed disease achieved minimal residual disease (MRD)-negative remission, and five patients (39%) underwent hematopoietic stem cell transplant (HSCT). In the 12 patients with primary chemorefractory B-ALL treated with immunotherapy, 11 (92%) achieved MRD-negative remission as assessed by flow cytometry; 10 patients (83%) underwent subsequent HSCT. Two patients with B-ALL in MRD-negative remission received blinatumomab due to severe infection and remained in remission after chemotherapy continuation.ConclusionsBlinatumomab and inotuzumab can induce deep remissions in patients with rrALL and facilitate subsequent HSCT or other cellular therapies. Blinatumomab can also serve as an effective bridging therapy during severe infection. The optimal timing, choice of immunotherapeutic agent(s), and duration of responses require further investigation via larger-scale clinical trials.

Numerous neutralizing antibodies that target SARS-CoV-2 have been reported, and most directly block binding of the viral Spike receptor-binding domain (RBD) to angiotensin-converting enzyme II (ACE2). Here, we deliberately exploit non-neutralizing RBD antibodies, showing they can dramatically assist in neutralization when linked to neutralizing binders. We identified antigen-binding fragments (Fabs) by phage display that bind RBD, but do not block ACE2 or neutralize virus as IgGs. When these non-neutralizing Fabs were assembled into bispecific VH/Fab IgGs with a neutralizing VH domain, we observed a ~ 25-fold potency improvement in neutralizing SARS-CoV-2 compared to the mono-specific bi-valent VH-Fc alone or the cocktail of the VH-Fc and IgG. This effect was epitope-dependent, reflecting the unique geometry of the bispecific antibody toward Spike. Our results show that a bispecific antibody that combines both neutralizing and non-neutralizing epitopes on Spike-RBD is a promising and rapid engineering strategy to improve the potency of SARS-CoV-2 antibodies.

Despite recent advances in treatment, relapses in multiple myeloma (MM) are inevitable. Off-the-shelf immunotherapeutics represent a promising avenue for research, with various classes of agents under development and several demonstrating deep and durable responses in patients who have exhausted all available therapies. Antibody-drug conjugates (ADCs) seek to improve on naked monoclonal antibodies by delivering a cytotoxic payload directly to tumor cells while largely limiting systemic effects. Belantamab mafodotin, a B-cell maturation antigen (BCMA)-targeted ADC, has shown response rates >30% in a phase 2 trial of highly refractory patients and is being investigated in a variety of settings and combinations. Several other ADCs are in earlier stages of development that target cell surface antigens that are internalized, including BCMA, CD38, CD46, CD56, CD74, and CD138. Bispecifics are designed to bring cytotoxic immune effector cells into proximity with tumor cells, and several agents have shown high response rates in early trials. Current targets include BCMA, CD38, GPRC5d, and FCRH5, and all of these seek to engage T cells through CD3. Bispecifics targeting natural killer (NK) cells through CD16 are still in preclinical development. Trispecific antibodies may represent an advance over bispecifics by providing a T-cell costimulatory signal such as CD28, or alternatively, dual MM antigens to increase specificity of NK or T-cell targeting. This is an area of active preclinical research at this time. Lastly, designed ankyrin repeat proteins, which are small antibody-mimetic proteins with high target-binding affinity, have the potential to block multiple pathways at once and provide stimulatory signals to the immune system.

T cell engagers, a category of T cell-retargeting immunotherapy, are rapidly transforming clinical cancer care. However, the lack of tumor-specific targets poses a significant roadblock for broad adaptation of this therapeutic modality in many indications, often resulting in systemic on-target off-tumor toxicity. Though various tumor-derived intracellular mutations provide a massive pool of potential tumor-specific antigens, targeting them is extremely challenging, partly due to the low copy number of tumor associated antigen (TAA)-derived pMHC on tumor cell surface. Further, the interplay of binding geometry and format valency in relation to the capacity of a T cell engager to efficiently target low density cell-surface pMHC is not well understood. Using the Wilms’ tumor 1 (WT1) oncoprotein as a proof-of-principle TAA, combined with an array of IgG-like T cell engager modalities that differ in their anti-TAA valency and binding geometry, we show that the ability to induce an immunological synapse formation, resulting in potent killing of WT1 positive cancer cell lines is primarily dependent on the distinct geometrical conformations between the Fab arms of anti-WT1-HLA-A*02:01 and anti-CD3. The augmented avidity conferred by the binding of two anti-WT1-HLA-A*02:01 Fab arms has only minimal influence on cell killing potency. These findings demonstrate the need for careful examination of key design parameters for the development of next-generation T cell engagers targeting low density TAA-pMHCs on tumor cells.

Several key advances in the treatment of B-cell non-Hodgkin lymphoma (B-NHL) over the past two decades have strategically exploited B-cell lineage markers suitable for targeting by immunotherapies. First, the addition of the anti-CD20 monoclonal antibody (mAb) rituximab to a range of standard therapies conferred remarkable outcomes improvements in diverse settings, perhaps most prominently an overall survival advantage in newly diagnosed diffuse large B-cell lymphoma (DLBCL). Subsequently, multiple chimeric antigen receptor (CAR) T-cell therapies targeting CD19 have revolutionized the treatment of relapsed/refractory (rel/ref) DLBCL and are active in other B-NHL subtypes as well. Most recently, the longstanding aspiration to exploit patients' endogenous T-cells to combat lymphoma has been achieved via T-cell redirecting therapies such as bispecific antibodies (BsAbs) that incorporate dual targeting of a T-cell antigen such as CD3 plus a B-cell antigen such as CD19 or CD20 expressed by the tumor. These novel agents have demonstrated impressive activity as monotherapies in patients with heavily pre-treated, rel/ref B-NHL of a variety of subtypes. Now, myriad clinical trials are exploring combinations of T-cell redirectors with targeted therapies, antibody-drug conjugates, conventional chemotherapy, and even new immunotherapies. Here, we highlight key landmarks in the development of T-cell redirecting therapies for the treatment of B-NHL, emerging evidence and lessons from recent clinical trials, and exciting new directions in this arena. [ABSTRACT FROM AUTHOR]

Bispecific antibodies are a promising type of therapy for the treatment of cancer due to their ability to simultaneously inhibit different proteins playing a role in cancer progression. The development in lung cancer has been singularly intense because of the increasingly vast knowledge of the underlying molecular routes, in particular, in oncogene-driven tumors. In this review, we present the current landscape of bispecific antibodies for the treatment of lung cancer and discuss potential scenarios where the role of these therapeutics might expand in the near future. [ABSTRACT FROM AUTHOR]

CD19-directed immunotherapies are clinically effective for treating B cell malignancies but also cause a high incidence of neurotoxicity. A subset of patients treated with chimeric antigen receptor (CAR) T cells or bispecific T cell engager (BiTE) antibodies display severe neurotoxicity, including fatal cerebral edema associated with T cell infiltration into the brain. Here, we report that mural cells, which surround the endothelium and are critical for blood-brain-barrier integrity, express CD19. We identify CD19 expression in brain mural cells using single-cell RNA sequencing data and confirm perivascular staining at the protein level. CD19 expression in the brain begins early in development alongside the emergence of mural cell lineages and persists throughout adulthood across brain regions. Mouse mural cells demonstrate lower levels of Cd19 expression, suggesting limitations in preclinical animal models of neurotoxicity. These data suggest an on-target mechanism for neurotoxicity in CD19-directed therapies and highlight the utility of human single-cell atlases for designing immunotherapies.

Despite considerable advances in the treatment of multiple myeloma (MM) in the last decade, a substantial proportion of patients do not respond to current therapies or have a short duration of response. Furthermore, these treatments can have notable morbidity and are not uniformly tolerated in all patients. As there is no cure for MM, patients eventually become resistant to therapies, leading to development of relapsed/refractory MM. Therefore, an unmet need exists for MM treatments with novel mechanisms of action that can provide durable responses, evade resistance to prior therapies, and/or are better tolerated. B-cell maturation antigen (BCMA) is preferentially expressed by mature B lymphocytes, and its overexpression and activation are associated with MM in preclinical models and humans, supporting its potential utility as a therapeutic target for MM. Moreover, the use of BCMA as a biomarker for MM is supported by its prognostic value, correlation with clinical status, and its ability to be used in traditionally difficult-to-monitor patient populations. Here, we review three common treatment modalities used to target BCMA in the treatment of MM: bispecific antibody constructs, antibody-drug conjugates, and chimeric antigen receptor (CAR)-modified T-cell therapy. We provide an overview of preliminary clinical data from trials using these therapies, including the BiTE® (bispecific T-cell engager) immuno-oncology therapy AMG 420, the antibody-drug conjugate GSK2857916, and several CAR T-cell therapeutic agents including bb2121, NIH CAR-BCMA, and LCAR-B38M. Notable antimyeloma activity and high minimal residual disease negativity rates have been observed with several of these treatments. These clinical data outline the potential for BCMA-targeted therapies to improve the treatment landscape for MM. Importantly, clinical results to date suggest that these therapies may hold promise for deep and durable responses and support further investigation in earlier lines of treatment, including newly diagnosed MM.