Tumor-targeted 4-1BB agonists for combination with T cell bispecific antibodies as off-the-shelf therapy.

Endogenous costimulatory molecules on T cells such as 4-1BB (CD137) can be leveraged for cancer immunotherapy. Systemic administration of agonistic anti-4-1BB antibodies, although effective preclinically, has not advanced to phase 3 trials because they have been hampered by both dependency on Fcγ receptor-mediated hyperclustering and hepatotoxicity. To overcome these issues, we engineered proteins simultaneously targeting 4-1BB and a tumor stroma or tumor antigen: FAP-4-1BBL (RG7826) and CD19-4-1BBL. In the presence of a T cell receptor signal, they provide potent T cell costimulation strictly dependent on tumor antigen-mediated hyperclustering without systemic activation by FcγR binding. We could show targeting of FAP-4-1BBL to FAP-expressing tumor stroma and lymph nodes in a colorectal cancer-bearing rhesus monkey. Combination of FAP-4-1BBL with tumor antigen-targeted T cell bispecific (TCB) molecules in human tumor samples led to increased IFN-γ and granzyme B secretion. Further, combination of FAP- or CD19-4-1BBL with CEA-TCB (RG7802) or CD20-TCB (RG6026), respectively, resulted in tumor remission in mouse models, accompanied by intratumoral accumulation of activated effector CD8+ T cells. FAP- and CD19-4-1BBL thus represent an off-the-shelf combination immunotherapy without requiring genetic modification of effector cells for the treatment of solid and hematological malignancies.

Biotherapeutics in non-clinical development: Strengthening the interface between safety, pharmacokinetics-pharmacodynamics and manufacturing.

Biological drugs comprise a wide field of different modalities with respect to structure, pharmacokinetics and pharmacological function. Considerable non-clinical experience in the development of proteins (e.g. insulin) and antibodies has been accumulated over the past thirty years. In order to improve the efficacy and the safety of these biotherapeutics, Fc modifications (e.g. Fc silent antibody versions), combinations (antibody-drug conjugates, protein-nanoparticle combinations), and new constructs (darpins, fynomers) have been introduced. In the last decade, advanced therapy medicinal products (ATMPs) in research and development have become a considerable and strongly growing part of the biotherapeutic portfolio. ATMPs consisting of gene and cell therapy modalities or even combinations of them, further expand the level of complexity, which already exists in non-clinical development strategies for biological drugs and has thereby led to a further diversification of expertise in safety and PKPD assessment of biological drugs. It is the fundamental rationale of the BioSafe meetings, held yearly in the EU and in the US, to convene experts on a regular basis and foster knowledge exchange and mutual understanding in this fast growing area. In order to reflect at least partially the variety of the biotherapeutics field, the 2016 EU BioSafe meeting addressed the following topics in six sessions: (i) In vitro Meets in vivo to Leverage Biologics Development (ii) New developments and regulatory considerations in the cell and gene therapy field (iii) CMC Challenges with Biologics development (iv) Minipigs in non-clinical safety assessment (v) Opportunities of PKPD Assessment in Less Common Administration Routes In the breakout sessions the following questions were discussed: (i) Cynomolgus monkey as a reprotoxicology Species: Impact of Immunomodulators on Early Pregnancy Maintenance (ii) Safety Risk of Inflammation and Autoimmunity Induced by Immunomodulators (iii) Experience with non-GMP Material in Pivotal Non-clinical Safety Studies to Support First in Man (FiM) Trials (iv) Safety Assessment of Combination Products for Non-oncology.

Cergutuzumab amunaleukin (CEA-IL2v), a CEA-targeted IL-2 variant-based immunocytokine for combination cancer immunotherapy: Overcoming limitations of aldesleukin and conventional IL-2-based immunocytokines.

We developed cergutuzumab amunaleukin (CEA-IL2v, RG7813), a novel monomeric CEA-targeted immunocytokine, that comprises a single IL-2 variant (IL2v) moiety with abolished CD25 binding, fused to the C-terminus of a high affinity, bivalent carcinoembryonic antigen (CEA)-specific antibody devoid of Fc-mediated effector functions. Its molecular design aims to (i) avoid preferential activation of regulatory T-cells vs. immune effector cells by removing CD25 binding; (ii) increase the therapeutic index of IL-2 therapy by (a) preferential retention at the tumor by having a lower dissociation rate from CEA-expressing cancer cells vs. IL-2R-expressing cells, (b) avoiding any FcγR-binding and Fc effector functions and (c) reduced binding to endothelial cells expressing CD25; and (iii) improve the pharmacokinetics, and thus convenience of administration, of IL-2. The crystal structure of the IL2v-IL-2Rßγ complex was determined and CEA-IL2v activity was assessed using human immune effector cells. Tumor targeting was investigated in tumor-bearing mice using 89Zr-labeled CEA-IL2v. Efficacy studies were performed in (a) syngeneic mouse models as monotherapy and combined with anti-PD-L1, and in (b) xenograft mouse models in combination with ADCC-mediating antibodies. CEA-IL2v binds to CEA with pM avidity but not to CD25, and consequently did not preferentially activate Tregs. In vivo, CEA-IL2v demonstrated superior pharmacokinetics and tumor targeting compared with a wild-type IL-2-based CEA immunocytokine (CEA-IL2wt). CEA-IL2v strongly expanded NK and CD8+ T cells, skewing the CD8+:CD4+ ratio toward CD8+ T cells both in the periphery and in the tumor, and mediated single agent efficacy in syngeneic MC38-CEA and PancO2-CEA models. Combination with trastuzumab, cetuximab and imgatuzumab, all of human IgG1 isotype, resulted in superior efficacy compared with the monotherapies alone. Combined with anti-PD-L1, CEA-IL2v mediated superior efficacy over the respective monotherapies, and over the combination with an untargeted control immunocytokine. These preclinical data support the ongoing clinical investigation of the cergutuzumab amunaleukin immunocytokine with abolished CD25 binding for the treatment of CEA-positive solid tumors in combination with PD-L1 checkpoint blockade and ADCC competent antibodies.

Non-clinical Safety Evaluation of Biotherapeutics - Challenges, Opportunities and new Insights.

New challenges and opportunities in nonclinical safety testing of biotherapeutics were presented and discussed at the 5th European BioSafe Annual General Membership meeting in November 2015 in Ludwigshafen. This article summarizes the presentations and discussions from both the main and the breakout sessions. The following topics were covered in six main sessions: The following questions were discussed across 4 breakout sessions (i-iv) and a case-study based general discussion (v).

Modulation of oral squamous cell carcinoma incidence in rats via diet and a novel calcium channel antagonist.

An unexpected dose related increase in oral squamous cell carcinomas was observed in a standard 2-year carcinogenicity study with a novel calcium channel blocker, in which Wistar rats received daily doses of 0, 1.5, 7, 20, or 40 mg/kg of the compound mixed with a standard diet containing fibers from barley. This finding was associated with an increased incidence of severe (destructive) periodontitis and the formation of oro-nasal fistulae at the 2 highest doses. Five assays of the compound for genotoxicity were negative indicating that a genotoxic effect was highly improbable. To investigate the underlying pathogenic mechanisms a second 2-year study in the same strain of rats was initiated and the influence of the diet and/or a possible local irritancy by the drug was assessed. In this second study the compound was administered by oral gavage at daily doses of 0, 7, or 40 mg/kg (later reduced to 20 mg/kg due to systemic intolerance) to rats maintained either on the standard diet or on a low fiber diet assumed to be less aggressive in terms of inducing periodontal lesions. Dose dependent gingival overgrowth (a class-related effect) was observed in the incisor and molar teeth area of all treated groups but was independent of the diet used. No oral tumors were found in the standard diet or low fiber diet controls and all treatment groups fed the low fiber diet, whereas in the high-dose group fed the standard diet a total of 8 oral squamous cell carcinomas were detected in association with an increased incidence of severe periodontitis. These results indicate that the increased incidence of squamous cell carcinomas observed upon chronic administration of the compound is not due to a direct tumorigenic effect of the drug. Tumor formation is attributable to severe periodontal disease favored by the diet and class related gingival overgrowth.

Modulation of gene and protein expression by carbon tetrachloride in the rat liver.

The gene and protein expression changes after exposure to a toxic compound might help elucidate its mechanism of action. In this paper we investigated the effect of carbon tetrachloride (CCl(4)) on the gene and protein expression in rat livers. Adult Wistar rats were administered CCl(4) and livers were harvested 6 or 24 h thereafter. The analysis of mitochondrial proteins on 2D gels showed the upregulation of two proteins involved in stress (catalase and uricase). Among the downregulated proteins, enzymes related to the metabolism of lipids and aminoacids were affected. Additionally, alpha-2-macroglobulin and senescence marker protein, two proteins whose decrease in expression has been connected to hepatocyte damage, were decreased. Several of the upregulated genes are involved in stress response, DNA and protein damage, and repair. Genes coding for several enzymes involved in different metabolic pathways, including some P450, were downregulated in the treated animals. In conclusion, a single dose of CCl(4) caused gene and protein expression changes that can be related to its mechanism of toxicity. Results from both technologies support previous publications and provide possible new toxicity markers. However, the correlation between gene and protein expression at a given time point is less apparent, partly as a result of different regulatory mechanisms between gene and protein expression.