Construction Of Antibody-drug Conjugates Research Articles

A Novel Family of Acid-Cleavable Linker Based on Cyclic Acetal Motifs for the Production of Antibody-Drug Conjugates with High Potency and Selectivity.

Cleavable linkers have become the subject of intense study in the field of chemical biology, particularly because of their applications in the construction of antibody-drug conjugates (ADC), where they facilitate lysosomal cleavage and liberation of drugs from their carrier protein. Due to lysosomes' acidic nature, acid-labile motifs have attracted much attention, leading to the development of hydrazone and carbonate linkers among several other entities. Continuing our efforts in designing new moieties, we present here a family of cyclic acetals that exhibit excellent plasma stability and acid lability, notably in lysosomes. Incorporated in ADC, they led to potent constructs with picomolar potency in vitro and similar in vivo efficacy as the commercially available ADC Kadcyla in mouse xenograft models.

Abstract 3374: Development of novel and improved monoclonal antiMUC16 antibodies for the targeted therapy of ovarian cancer

Abstract There is a need for the development of better targeted therapies in the treatment of ovarian cancer. Monoclonal antibodies directed towards MUC16, a diagnostic and prognostic marker for ovarian cancer, with improved selectivity and specificity would be an instrumental component in the construction of novel methods of drug delivery and immunotherapies. C57BL/6 mice were immunized with various MUC16 peptides and truncated MUC16 constructs to extend the scope of MUC16 epitopes within the proximal COOH portion of the retained elements. Three rounds of hybridomas were made from harvested murine splenocytes, and subsequent rounds of peptide-based ELISA and cell-based flow cytometry were performed to select the most promising subclones from each of the fusions. Over 50 hybridomas producing antibodies against MUC16 have been identified and screened for reactivity with MUC16 peptide sequences and native, full-length MUC16 protein presented on the surface of ovarian cancer cell line cells. The antibodies were isotyped, and 10 have been selected for initial characterization. Non-overlapping epitopes were mapped via sequential and tandem peptide-based ELISA. With improved selectivity and specificity, these monoclonal antibodies will be used in the construction of antibody drug conjugates (ADCs) as potential targeted therapies in the treatment of ovarian cancer. Efficacy testing of the candidate antibodies in Matrigel invasion and direct growth inhibition assays is underway. Comparative effectiveness of the binding, internalization, and killing by ADCs in ovarian cancer cell lines will be presented. Antibodies against key MUC16 epitopes may have value in the development of antigen directed therapy. Citation Format: Ian Laster, Oladapo Yeku, David Spriggs. Development of novel and improved monoclonal antiMUC16 antibodies for the targeted therapy of ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3374.

Abstract 758: Head-to-head comparison of ADC and SMDC products, alone and in combination with antibody-IL2 fusion proteins

Abstract In an attempt to improve the therapeutic index of cancer chemotherapy, monoclonal antibodies and small organic ligands have been proposed as delivery vehicles, allowing the construction of antibody-drug conjugates (ADCs) and of small molecule-drug conjugates (SMDCs). Four ADC products have gained marketing authorization for cancer therapy, while SMDCs are still being investigated in clinical trials. SMDCs could in principle offer certain advantages compared to ADCs, such as a more rapid and uniform diffusion into the tumor mass, lower cost-of-goods and lack of immunogenicity, but a direct head-to-head comparison has not yet been reported. Here we describe a novel small molecule-drug conjugate, based on a high-affinity ligand specific to carbonic anhydrase IX. The product features a peptide linker, suitable for cleavage in the tumor extracellular environment, and monomethyl auristatin E as cytotoxic payload. We compared the therapeutic efficacy of the novel SMDC and of an anti-CAIX ADC, which were injected at equimolar doses in nude mice bearing SKRC-52 renal cell carcinoma xenografts. Both products showed a potent anti-cancer activity, although no complete tumor eradication was observed. Instead, when the SMDC was administered together with L19-IL2 (a clinical-stage fusion protein capable of delivering interleukin-2 to the tumor neo-vasculature), all treated mice in the combination group could be rendered tumor-free, in a process which 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, since carbonic anhydrase IX is over-expressed in the majority of clear-cell renal cell carcinomas and in approximately 30% of colorectal cancers. The targeted delivery of interleukin-2 helps potentiate the action of targeted cytotoxics leading to cancer eradication in models that cannot be cured by conventional chemotherapy. Citation Format: Samuele Cazzamalli, Alberto Dal Corso, Fontaine Widmayer, Dario Neri. Head-to-head comparison of ADC and SMDC products, alone and in combination with antibody-IL2 fusion proteins [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 758.

Challenges in Optimising the Successful Construction of Antibody Drug Conjugates in Cancer Therapy.

Although considerable progress has been made in the field of cancer chemotherapy, there remains a significant unmet medical need, with a requirement to move away from traditional cytotoxics and explore novel, smarter chemotherapeutic approaches. One such example of the smart chemotherapy approach is antibody-drug conjugates (ADCs), which consist of an antibody that binds selectively to a cancer antigen linked to a cytotoxic agent. When developing an ADC, it may be necessary to produce a variety of constructs to fully assess the optimal configuration for the molecule. By testing ADCs prepared using a range of cytotoxic agents, linkers, or different antibodies, it is possible to fully assess the optimal approach for this treatment modality before advancing to the clinic. Since the development and approval of first-generation ADCs, significant improvements in development technology have occurred. Here, we consider the advances made within the field of ADCs, focusing on the development of EDO-B278 and EDO-B776, both of which have demonstrated efficacy in preclinical testing. Although some limitations remain in this field of development, the potential reduction in toxicity offered by ADCs justifies the investment in research to find workable solutions that could ultimately provide patients with superior outcomes.