Design and Characterization of Novel Antibody-Cytokine Fusion Proteins Based on Interleukin-21

Nanobodies in cytokine‑mediated immunotherapy and immunoimaging (Review)

Cytokines are the main regulators of innate and adaptive immunity, mediating communications between the cells of the immune system and regulating biological functions, including cell motility, differentiation, growth and apoptosis. Cytokines and cytokine receptors have been used in the treatment of tumors and autoimmune diseases, and to intervene in cytokine storms. Indeed, the use of monoclonal antibodies to block cytokine‑receptor interactions, as well as antibody‑cytokine fusion proteins has exhibited immense potential for the treatment of tumors and autoimmune diseases. Compared with these traditional types of antibodies, nanobodies not only maintain a high affinity and specificity, but also have the advantages of high thermal stability, a high capacity for chemical manipulation, low immunogenicity, good tissue permeability, rapid clearance and economic production. Thus, nanobodies have extensive potential for use in the diagnosis and treatment of cytokine‑related diseases. The present review summarizes the application of nanobodies in cytokine‑mediated immunotherapy and immunoimaging.

Anti-Claudin18.2-IL-21 fusion protein bifunctional molecule has more powerful anti-tumor effect and better safety

Antibody or antibody-like protein drugs related to tumor immunotherapy are now widely used. Here, we describe an antibody-fusion protein drug IMAB362-mIL-21 with mouse IL-21 (mIL-21) fused into the C-terminal domain of IMAB362 (a clinical antibody drug against Claudin18.2), that we expect can achieve tumor targeting and activate local anti-tumor immune response more effectively, while reducing the systemic side effects of individual cytokines. In vitro assays comparing the fusion protein IMAB362-mIL-21 to IMAB362 and mIL-21, IMAB362-mIL-21 was able to recognize its cognate antigen Claudin18.2 and natural receptor mIL-21R with similar binding affinities, mediate equivalent ADCC activity and activate IL-21R-mediated downstream signal pathway. In in vivo assays, IMAB362-mIL-21 produced stronger anti-tumor effects compared with IMAB362 or mIL-21 or their combination at equimolar concentrations. Moreover, according to routine blood indicators, mIL-21-Fc and the combined treatment group had significant decreases (P < 0.01) in red blood cells (RBC), hemoglobin (HGB) and hematocrit (HCT), while the IMAB362-mIL-21 group did not. The above results have shown that IMAB362-mIL-21 can produce better anti-tumor effects without obvious hematological toxicity, which is sufficient to show that this kind of antibody-cytokine protein has better application value than IMAB362 or IL-21 as single drugs or in combination. Therefore, this bifunctional molecule combined tumor-targeting and immune activation effectively and has good application prospects.

Immunopathogenesis of Atopic Dermatitis: Focus on Interleukins as Disease Drivers and Therapeutic Targets for Novel Treatments

Atopic dermatitis is a chronic, recurrent inflammatory skin disorder manifesting by eczematous lesions and intense pruritus. Atopic dermatitis develops primarily as a result of an epidermal barrier defect and immunological imbalance. Advances in understanding these pathogenetic hallmarks, and particularly the complex role of interleukins as atopic dermatitis drivers, resulted in achieving significant therapeutic breakthroughs. Novel medications involve monoclonal antibodies specifically blocking the function of selected interleukins and small molecules such as Janus kinase inhibitors limiting downstream signaling to reduce the expression of a wider array of proinflammatory factors. Nevertheless, a subset of patients remains refractory to those treatments, highlighting the complexity of atopic dermatitis immunopathogenesis in different populations. In this review, we address the immunological heterogeneity of atopic dermatitis endotypes and phenotypes and present novel interleukin-oriented therapies for this disease.

Targeted chain-exchange-mediated reconstitution of a split type-I cytokine for conditional immunotherapy

Antibody-cytokine fusions targeted against tumor-associated antigens (TAAs) are promising cancer immunotherapy agents, with many such molecules currently undergoing clinical trials. However, due to the limited number of tumor-specific targets, on-target off-tumor effects can lead to systemic toxicity. Additionally, targeted cytokines can be scavenged by cytokine receptors on peripheral cells, decreasing tumor penetration. This study aims at overcoming these issues by engineering a platform for targeted conditionally active type I cytokines. Building on our previously reported PACE (Prodrug-Activating Chain Exchange) platform, we split the type I cytokine interleukin-4 (IL-4) to create two inactive IL-4 prodrugs, and fused these split IL-4 counterparts to the C-termini of antibody-like molecules that undergo proximity-induced chain exchange. In doing so, we developed IL-4 prodrugs that preferentially reconstitute into active IL-4 on target cells. We demonstrate that pre-assembled split IL-4 (without additional inactivation) retains activity and present two different strategies of splitting and inactivating IL-4. Using an IL-4 responsive cell-line, we show that IL-4 prodrugs are targeted to TAAs on target cells and regain activity upon chain exchange, primarily in a cis-activation setting. Furthermore, we demonstrate that split IL-4 complementation is also possible in a trans-activation setting, which opens up the possibility for activation of immune cells in the tumor vicinity. We demonstrate that targeted on-cell prodrug conversion is more efficient than nonspecific activation in-solution. Due to the structural similarity between IL-4 and other type I cytokines relevant in cancer immunotherapy such as IL-2, IL-15, and IL-21, cytokine-PACE may be expanded to develop a variety of targeted conditionally active cytokines for cancer immunotherapy.