From target discovery to clinical trials with armed antibody products

An Engineered IFNγ-Antibody Fusion Protein with Improved Tumor-Homing Properties

Interferon-gamma (IFNγ) is one of the central cytokines produced by the innate and adaptive immune systems. IFNγ directly favors tumor growth control by enhancing the immunogenicity of tumor cells, induces IP-10 secretion facilitating (CXCR3+) immune cell infiltration, and can prime macrophages to an M1-like phenotype inducing proinflammatory cytokine release. We had previously reported that the targeted delivery of IFNγ to neoplastic lesions may be limited by the trapping of IFNγ-based products by cognate receptors found in different organs. Here we describe a novel fusion protein consisting of the L19 antibody, specific to the alternatively spliced extra-domain B of fibronectin (EDB), fused to a variant of IFNγ with reduced affinity to its cognate receptor. The product (named L19-IFNγ KRG) selectively localized to tumors in mice, showed favorable pharmacokinetic profiles in monkeys and regained biological activity upon antigen binding. The fusion protein was investigated in two murine models of cancer, both as monotherapy and in combination with therapeutic modalities which are frequently used for cancer therapy. L19-IFNγ KRG induced tumor growth retardation and increased the intratumoral concentration of T cells and NK cells in combination with anti-PD-1.

VHH characterization.Recombinant VHHs: Production, characterization and affinity

Among the biological approaches to therapeutics, are the cells, such as CAR-T cells engineered or not, the antibodies armed or not, and the smaller protein scaffolds that can be modified to render them specific of other proteins, à la façon of antibodies. For several years, we explored ways to substitute antibodies by nanobodies (also known as VHHs), the smallest recognizing part of camelids' heavy-chain antibodies: production of those small proteins in host microorganisms, minute analyses, characterization, and qualification of their affinity towards designed targets. Here, we present three standard VHHs described in the literature: anti-albumin, anti-EGF receptor and anti-HER2, a typical cancer cell surface -associated protein. Because they differ slightly in global structure, they are good models to assess our body of analytical methodologies. The VHHs were expressed in several bacteria strains in order to identify and overcome the bottlenecks to obtain homogeneous preparations of this protein. A large panel of biophysical tools, ranging from spectroscopy to mass spectrometry, was here combined to assess VHH structural features and the impact of the disulfide bond. The routes are now ready to move to more complex VHHs raised against specific targets in numerous areas including oncology.

Identification and Validation of Novel Subtype-Specific Protein Biomarkers in Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Pancreatic ductal adenocarcinoma (PDAC) has been subclassified into 3 molecular subtypes: classical, quasi-mesenchymal, and exocrine-like. These subtypes exhibit differences in patient survival and drug resistance to conventional therapies. The aim of the current study is to identify novel subtype-specific protein biomarkers facilitating subtype stratification of patients with PDAC and novel therapy development.

METHODS

A set of 12 human patient-derived primary cell lines was used as a starting material for an advanced label-free proteomics approach leading to the identification of novel cell surface and secreted biomarkers. Cell surface protein identification was achieved by in vitro biotinylation, followed by mass spectrometric analysis of purified biotin-tagged proteins. Proteins secreted into a chemically defined serum-free cell culture medium were analyzed by shotgun proteomics.

RESULTS

Of 3288 identified proteins, 2 pan-PDAC (protocadherin-1 and lipocalin-2) and 2 exocrine-like-specific (cadherin-17 and galectin-4) biomarker candidates have been validated. Proximity ligation assay analysis of the 2 exocrine-like biomarkers revealed their co-localization on the surface of exocrine-like cells.

CONCLUSIONS

The study reports the identification and validation of novel PDAC biomarkers relevant for the development of patient stratification tools. In addition, cadherin-17 and galectin-4 may serve as targets for bispecific antibodies as novel therapeutics in PDAC.

Structural insights and biomedical potential of IgNAR scaffolds from sharks

In addition to antibodies with the classical composition of heavy and light chains, the adaptive immune repertoire of sharks also includes a heavy-chain only isotype, where antigen binding is mediated exclusively by a small and highly stable domain, referred to as vNAR. In recent years, due to their high affinity and specificity combined with their small size, high physicochemical stability and low-cost of production, vNAR fragments have evolved as promising target-binding scaffolds that can be tailor-made for applications in medicine and biotechnology. This review highlights the structural features of vNAR molecules, addresses aspects of their generation using immunization or in vitro high throughput screening methods and provides examples of therapeutic, diagnostic and other biotechnological applications.