Abstract 2929: Modular peptide cargo delivery by targeting CD40 enables ligandome driven, precision immunotherapy via the Adaptable Drug Affinity Conjugate (ADAC™) technology

Abstract Agonistic anti-CD40 therapy has shown impressive efficacy in preclinical murine models, models inert to toxicity of high systemic drug exposure. Clinical data consist of pharmacodynamic responses reported as non-specific cytokine release, transient drop of CD40-expressing cells in blood and induction of co-stimulatory ligands/receptors on antigen-presenting cells, but so far clinically meaningful efficacy data on monotherapy use is lacking. Clinical data also indicate a bell-shaped dose-response curve, with excessive immune activation leading to immune exhaustion when combined with check-point inhibitors[1]. Intratumoral route of administration, bispecific antibodies for tumor drug localization or Antibody-Drug Conjugates (ADCs) carrying antigenic cargo are or have been assessed, but have associated clinical utility enigmas. Herein we present a novel solution ensuring modular peptide delivery along with an efficient T cell priming strategy; a bivalent anti-CD40 agonistic antibody equipped with a peptide-binding single chain variable fragment (scFv) that binds a short peptide tag (pTag) in the low nM range. The resulting drug strategy makes use of synthetic long peptide production of any tumor-associated antigen (TAA) of choice where the pTag itself ensures simple conjugate production to the protein, through affinity linkage, leading to a final rapid in-hospital mixing step. Data suggest that the novel candidate drug (STRIKE2001), now developed based on the ADAC concept[2], retains similar agonistic activity in its bispecific, IgG2 format and does not inhibit CD40L binding to the CD40 protein. Data further show impressive expansion of endogenous tumor-specific T cells (as measured by tetramer staining), along with effective anti-tumor responses in the TC1 model. In addition, by using the subcutaneous delivery strategy CD40 agonist exposure to liver and spleen is vastly reduced, limiting systemic immune toxicity/exhaustion risks[3]. [1] Padrón, L.J., et al. Sotigalimab and/or nivolumab with chemotherapy in first-line metastatic pancreatic cancer: clinical and immunologic analyses from the randomized phase 2 PRINCE trial. Nat Med 28, 1167-1177 (2022). https://doi.org/10.1038/s41591-022-01829-9 [2] Eltahir, M., et al. (2022), An Adaptable Antibody-Based Platform for Flexible Synthetic Peptide Delivery Built on Agonistic CD40 Antibodies. Adv. Therap., 5: 2200008. https://doi.org/10.1002/adtp.202200008 [3] Sandin, L., et al. Locally Delivered CD40 Agonist Antibody Accumulates in Secondary Lymphoid Organs and Eradicates Experimental Disseminated Bladder Cancer. Cancer Immunol Res 1 January 2014; 2 (1): 80-90. https://doi.org/10.1158/2326-6066.CIR-13-0067 Citation Format: Aman Mebrahtu, Ida Lauren, Rosanne Veerman, Alexandros Kostakis, Gözde Gucluler Akpinar, Oskar Andersson, Lindvi Gudmundsdotter, Tina Furebring, Helena Persson, Pierre Donnes, Johan Rockberg, Sara Mangsbo. Modular peptide cargo delivery by targeting CD40 enables ligandome driven, precision immunotherapy via the Adaptable Drug Affinity Conjugate (ADAC™) technology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2929.