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With increasing numbers of bispecific antibodies (BsAbs) and multispecific products entering the clinic, recent data highlight immunogenicity as an emerging challenge in the development of such novel biologics. This review focuses on the immunogenicity risk assessment (IgRA) of BsAb-based immunotherapies for cancer, highlighting several risk factors that need to be considered. These include the novel scaffolds consisting of bioengineered sequences, the potentially synergistic immunomodulating mechanisms of action (MOAs) from different domains of the BsAb, as well as several other product-related and patient-related factors. In addition, the clinical relevance of anti-drug antibodies (ADAs) against selected BsAbs developed as anticancer agents is reviewed and the advances in our knowledge of tools and strategies for immunogenicity prediction, monitoring, and mitigation are discussed. It is critical to implement a drug-specific IgRA during the early development stage to guide ADA monitoring and risk management strategies. This IgRA may include a combination of several assessment tools to identify drug-specific risks as well as a proactive risk mitigation approach for candidate or format selection during the preclinical stage. The IgRA is an on-going process throughout clinical development. IgRA during the clinical stage may bridge the gap between preclinical immunogenicity prediction and clinical immunogenicity, and retrospectively guide optimization efforts for next-generation BsAbs. This iterative process throughout development may improve the reliability of the IgRA and enable the implementation of effective risk mitigation strategies, laying the foundation for improved clinical success.

Bringing safe and effective drugs to patients is of utmost importance for the pharmaceutical industry, with immunogenicity (IG) being a critical factor that influences both aspects. Biotherapeutics can elicit unwanted immune responses, potentially leading to (severe) safety implications, reduced patient benefits, and may result in termination of development. Therefore, understanding IG risks throughout drug development is essential for both drug developers and health agencies (HAs). The Immunogenicity Risk Assessment (IRA) facilitates the identification of IG risk factors and allows the establishment of effective mitigation and monitoring strategies. In this publication, the European Immunogenicity Platform (EIP) presents a comprehensive IRA framework aligned across pharmaceutical industry, emphasizing its significance in product development - from early de-risking to bioanalytical monitoring and mitigation measures during clinical trials. The EIP also provides an updated list of IG risks, offers distinct recommendations for assigning overall IG risk levels prior to the start of clinical development and highlights business considerations within this assessment.

IntroductionIn oncology, anti-drug antibody (ADA) development that significantly curtails response durability has not historically risen to a level of concern. The relevance and attention ascribed to ADAs in oncology clinical studies have therefore been limited, and the extant literature on this subject scarce. In recent years, T cell engagers have gained preeminence within the prolific field of cancer immunotherapy. These drugs whose mode of action is expected to potently stimulate anti-tumor immunity, may potentially induce ADAs as an unintended corollary due to an overall augmentation of the immune response. ADA formation is therefore emerging as an important determinant in the successful clinical development of such biologics.MethodsHere we describe the immunogenicity and its impact observed to pasotuxizumab (AMG 212), a prostate-specific membrane antigen (PSMA)-targeting bispecific T cell engager (BiTE®) molecule in NCT01723475, a first-in-human (FIH), multicenter, dose-escalation study in patients with metastatic castration-resistant prostate cancer (mCRPC). To explain the disparity in ADA incidence observed between the SC and CIV arms of the study, we interrogated other patient and product-specific factors that may have explained the difference beyond the route of administration.ResultsTreatment-emergent ADAs (TE-ADA) developed in all subjects treated with at least 1 cycle of AMG 212 in the subcutaneous (SC) arm. These ADAs were neutralizing and resulted in profound exposure loss that was associated with contemporaneous reversal of initial Prostate Surface Antigen (PSA) responses, curtailing durability of PSA response in patients. Pivoting from SC to a continuous intravenous (CIV) administration route remarkably yielded no subjects developing ADA to AMG 212. Through a series of stepwise functional assays, our investigation revealed that alongside a more historically immunogenic route of administration, non-tolerant T cell epitopes within the AMG 212 amino acid sequence were likely driving the high-titer, sustained ADA response observed in the SC arm.DiscussionThese mechanistic insights into the AMG 212 ADA response underscore the importance of performing preclinical immunogenicity risk evaluation as well as advocate for continuous iteration to better our biologics.

AMG 256 is a bi-specific, heteroimmunoglobulin molecule with an anti-PD-1 antibody domain and a single IL-21 mutein domain on the C-terminus. Nonclinical studies in cynomolgus monkeys revealed that AMG 256 administration led to the development of immunogenicity-mediated responses and indicated that the IL-21 mutein domain of AMG 256 could enhance the anti-drug antibody response directed toward the monoclonal antibody domain. Anti-AMG 256 IgE were also observed in cynomolgus monkeys. A first-in-human (FIH) study in patients with advanced solid tumors was designed with these risks in mind. AMG 256 elicited ADA in 28 of 33 subjects (84.8%). However, ADA responses were only robust and exposure-impacting at the 2 lowest doses. At mid to high doses, ADA responses remained low magnitude and all subjects maintained exposure, despite most subjects developing ADA. Limited drug-specific IgE were also observed during the FIH study. ADA responses were not associated with any type of adverse event. The AMG 256 program represents a unique case where nonclinical studies informed on the risk of immunogenicity in humans, due to the IL-21-driven nature of the response.

ABP 501, a monoclonal anti‐tumor necrosis factor antibody, was the first adalimumab biosimilar approved in the US and EU as a 50 mg/mL formulation. An ABP 501 100 mg/mL high‐concentration formulation is also now approved. This study compares pharmacokinetics (PK), safety, and immunogenicity of the low‐ (ABP 501‐LCF) and high‐concentration (ABP 501‐HCF) formulations in healthy adults. This was a randomized, single‐blind, single‐dose, parallel‐group study in healthy adults. Participants were randomized to receive 40 mg of ABP 501 as HCF or LCF. Primary PK endpoints were area under the concentration‐time curve from time 0 extrapolated to infinity (AUCinf) and maximum observed concentration (Cmax) with a 90% confidence interval (CI) for the ratio of least square (LS) geometric means (GM) with a similarity margin of 0.80–1.25. Secondary endpoints included other PK parameters, safety, and immunogenicity. Baseline demographic and other characteristics were comparable between groups. Following study injection, ratios of LS GM (90% CIs) for AUCinf and Cmax between ABP 501‐HCF and ABP 501‐LCF were 1.04 (0.9634, 1.1297) and 1.06 (0.9960, 1.138), falling within the similarity margin. Both formulations were well tolerated with comparable adverse events. The occurrence of anti‐drug antibodies and neutralizing antibodies was comparable between groups. This study demonstrates PK similarity between ABP 501‐HCF and ABP 501‐LCF following a single subcutaneous injection in healthy adults. Immunogenicity and safety profiles were also similar. Given the totality of evidence of similarity of ABP 501 with adalimumab reference product (RP), it is anticipated that ABP 501‐HCF will perform similarly to the RP. Trial Registration: NCT04270747. Consistent with previously demonstrated similarity of biosimilar ABP 501 (adalimumab‐atto) with adalimumab reference product, this study in healthy adults demonstrates the pharmacokinetic, safety, and immunogenicity similarity of a high‐concentration formulation (100 mg/mL) of ABP 501 with the original 50mg/mL formulation.

AMG 966 is a bi-specific, heteroimmunoglobulin molecule that binds both tumor necrosis factor alpha (TNFα) and TNF-like ligand 1A (TL1A). In a first-in-human clinical study in healthy volunteers, AMG 966 elicited anti-drug antibodies (ADA) in 53 of 54 subjects (98.1%), despite a paucity of T cell epitopes observed in T cell assays. ADA were neutralizing and bound to all domains of AMG 966. Development of ADA correlated with loss of exposure. In vitro studies demonstrated that at certain drug-to-target ratios, AMG 966 forms large immune complexes with TNFα and TL1A, partially restoring the ability of the aglycosylated Fc domain to bind FcγRIa and FcγRIIa, leading to the formation of ADA. In addition to ADA against AMG 966, antibodies to endogenous TNFα were also detected in the sera of subjects dosed with AMG 966. This suggests that the formation of immune complexes between a therapeutic and target can cause loss of tolerance and elicit an antibody response against the target.

[This corrects the article DOI: 10.3389/fimmu.2024.1345473.].

With more than 100 therapeutic proteins (TP) approved since the first EMA guidance on immunogenicity in 2007, a vast amount of clinical experience with a variety of therapeutic proteins has been gained. This has provided data on anti-drug antibodies (ADA) and their observed clinical impact, or lack thereof. It has become evident that not all ADA responses are clinically relevant. The current “standard practice” is to test for ADA in all patients on every study. It is essential that we acknowledge the immunogenicity data gained from marketed TPs and that options for immunogenicity testing reflect this information. Improvements in bioanalytical support throughout the drug development process will eliminate extraneous, non-impactful practices. We propose that low-risk therapeutic proteins could be supported with an event-driven (“collect-and-hold”) immunogenicity testing strategy throughout early phases of the clinical program. In the absence of an event, only pivotal studies (where ADA incidence and impact can be decisively assessed) would include default ADA testing. In keeping with the “standard practice,” immunogenicity risk assessment must be an on-going and real-time evaluation. This approach has the potential to deliver meaningful, clinically relevant immunogenicity results while maintaining an emphasis on patient safety.

Introduction Nerve growth factor plays a key role in the pathology of osteoarthritis (OA) related chronic pain. The aim of these studies was to evaluate the safety, tolerability, pharmacokinetics, and clinical response of AMG 403, a human anti-nerve growth factor monoclonal antibody, in healthy volunteers and subjects with knee OA. Methods Two phase I, randomized, placebo-controlled, double-blind studies were conducted. The single-ascending dose study randomized healthy volunteers ( n  = 48) 3:1 to receive AMG 403 (1, 3, 10, or 30 mg intravenously; or 10 or 30 mg subcutaneously; n  = 8 per group) or placebo. The multiple-ascending dose study randomized knee OA subjects ( n  = 18) 3:1 to receive AMG 403 (3, 10, or 20 mg subcutaneously once monthly for four doses) or placebo. Safety, tolerability, and pharmacokinetics (PK) were assessed for both studies. Patient’s and physician’s disease assessments and total WOMAC score were determined in knee OA subjects. Results AMG 403 appeared to be well-tolerated after single and multiple doses, except for subject-reported hyperesthesia, pain, and paresthesia (mild to moderate severity). These treatment-emergent neurosensory events showed evidence of reversibility and a possible dose-dependence. Three serious adverse events were reported in AMG 403 treated subjects, but were not considered treatment related. AMG 403 PK was linear with an estimated half-life of 19.6 to 25.8 days. After multiple doses, AMG 403 PK showed modest accumulation (≤2.4-fold increase) in systemic exposure. Knee OA diagnosis, body weight, and anti-drug antibody development did not appear to affect AMG 403 PK. Patient’s and physician’s disease assessments and total WOMAC score showed improvement in AMG 403 treated knee OA subjects compared with placebo. Conclusions AMG 403 was generally safe and well-tolerated in both healthy volunteers and knee OA patients, and exhibited linear pharmacokinetics. Preliminary clinical efficacy was observed in knee OA subjects. Trial registration ClinicalTrials.gov NCT02348879 . Registered 23 December 2014. Clintrials.gov NCT02318407 . Registered 2 December 2014.