Enhanced Therapeutic Activity of Non-Internalizing Small-Molecule-Drug Conjugates Targeting Carbonic Anhydrase IX in Combination with Targeted Interleukin-2

Abstract

Antibody-drug conjugates and small-molecule-drug conjugates have been proposed as alternatives to conventional anticancer cytotoxic agents, with the potential to deliver bioactive payloads to the site of disease, helping spare normal tissues. Here, we describe a novel small-molecule-drug conjugate, based on a high-affinity ligand specific to carbonic anhydrase IX. The product featured a peptidic linker, suitable for cleavage in the tumor extracellular environment, and monomethyl auristatin E as cytotoxic payload. A potent anticancer activity was observed in nude mice bearing SKRC-52 renal cell carcinoma xenografts, but no durable complete responses could be observed in this model. However, when the product was administered together with L19-IL2 (a clinical-stage fusion protein capable of delivering IL2 to the tumor neovasculature), all treated mice in the combination group could be rendered tumor free, in a process that favored the influx of natural killer cells into the tumor mass. The combination of L19-IL2 and the new small-molecule-drug conjugate also eradicated cancer in 100% of immunocompetent mice, bearing subcutaneously grafted CT26 colorectal cancer cells, which stably expressed carbonic anhydrase IX. These findings may be of clinical significance, because carbonic anhydrase IX is overexpressed in the majority of clear cell renal cell carcinomas and in approximately 30% of colorectal cancers. The targeted delivery of IL2 helps potentiate the action of targeted cytotoxics, leading to cancer eradication in models that cannot be cured by conventional chemotherapy. .

Innovative Linker Strategies for Tumor‐Targeted Drug Conjugates

“…Recent reports seem to indicate that the combination of cytotoxic agents and prodrugs with other treatments (e.g. immunotherapy or radiotherapy) is currently the leading strategy to induce tumor eradication and long‐lasting anticancer effects. It is conceivable that a deeper understanding of the effects of different payloads on the tumor biology (e.g.…”

“…Withint his frame, both pharmaceutical companies and academic laboratories are continuouslyi ntroducing new chemical linkers, either aiming at 100 %s elective drug release at the tumor site or to reduce toxicities in healthy organs.R ecent reports seem to indicate that the combination of cytotoxic agents and prodrugs with other treatments (e.g. immunotherapy or radiotherapy) [32,120] is currently the leading strategy to inducet umor eradication and long-lasting anticancer effects. It is conceivable that ad eeper understanding of the effects of different payloads on the tumor biology( e.g.…”

2nd PSL Chemical Biology Symposium (2019): At the Crossroads of Chemistry and Biology

“…They can furthermore potentiate the therapeutic effect of cytotoxic agentsinv ivo. [7] Jacqueline Cherfils:Regulation and inhibition of small GTPases on membranes…”

“…These antibody–cytokine fusions increase the therapeutic index of cytokines by targeting them to the tumor environment. They can furthermore potentiate the therapeutic effect of cytotoxic agents in vivo …”

A novel fully-human potency-matched dual cytokine-antibody fusion protein targets carbonic anhydrase IX in renal cell carcinomas

“…This antigen is virtually undetectable in most normal adult tissues, exception made for certain gastrointestinal structures (29). CAIX has been targeted in vivo using both antibody-and small molecule-based products, showing interesting results in imaging studies (30)(31)(32).…”