Abstract 313: Novel bioengineered monoclonal antibodies targeting oxidized macrophage migration inhibitory factor as anti-cancer therapeutics and companion diagnostics
Authors: Schinagl Alexander , Thiele Michael , Mirkina Irina , Rossmueller Gregor , Tarazona Alejandro A. Puchol , Kerschbaumer Randolf J. 
Published: June 2022

Abstract
Background: Macrophage Migration Inhibitory Factor (MIF) has been described as a pleiotropic cytokine known to exacerbate tumor growth (Chesney and Mitchell, 2015). Due to its ubiquitous nature, MIF can be considered as an inappropriate target for therapeutic intervention. However, we discovered oxidized MIF (oxMIF) as the disease-related isoform of MIF, which is specifically present in tumor tissue (Schinagl A et al., 2016). A 1st generation anti-oxMIF monoclonal antibody (mAb) demonstrated an acceptable safety profile and efficacy signal in a phase 1 clinical trial (Mahalingam D et al., 2020). Two bioengineered 2nd generation anti-oxMIF mAbs with highly improved biophysicochemical and biological properties were generated and compared to the 1st generation anti-oxMIF mAb. Both bioengineered mAbs share identical variable domains, but distinct heavy-chain constant regions, to increase effector functions and efficacy of the therapeutic mAb ON203 and to reduce interactions with FcγRs for the radio diagnostic mAb ON102.
Methods: Hydrophobicity and stability were determined by HIC and SEC. ADCC and ADCP activity were investigated by reporter and PBMC-mediated cell killing assays. Tumor penetration was assessed using IRDye 800CW or Zr89-labeled mAb in tumor-bearing Balb/c or Balb/c nude mice. PK and bioavailability were assessed in Balb/c nude mice. Efficacy was determined in PC3 xenograft models in NMRI nude mice.
Results: Bioengineering significantly reduced hydrophobicity of ON203 and ON102, leading to improved stability and strongly reduced aggregation but retaining the low nM affinity for oxMIF. This further resulted in a two-fold improved bioavailability and tumor accumulation after 24-48h and a three-fold enhanced retention on day 7 in mice harboring solid tumors of the colon, when compared to the 1st generation anti-oxMIF mAb. In contrast to previously described anti-oxMIF reference, ON203 and ON102 did not mediate any unspecific release of MCP-1, IL-6, or TNF-α from PBMCs. Reporter and PBMC-mediated cell killing assays proved ADCC activity of ON203 with EC50 values of 0.1-0.8 nM and ADCP activity with EC50 values of 2.3 nM, whereas the 1st generation anti-oxMIF mAb was at least 10-fold less potent. Our findings for ON203 translated into abolishment of tumor growth in NMRI nude mice harboring human PC3 prostate cancer cells, showing superior efficacy compared to the 1st generation anti-oxMIF mAb.
Conclusion: ON203 has a high potential to significantly improve efficacy compared to the 1st generation anti-oxMIF mAb, with Zr89-ON102 as companion diagnostic for patient stratification. We aim to develop these anti-oxMIF mAbs together for clinical use to create new treatment options for patients with solid tumors, with a clear rationale to combine ON203 with other immunotherapies or checkpoint inhibitors (Noe and Mitchell, 2020).
Citation Format: Alexander Schinagl, Michael Thiele, Irina Mirkina, Gregor Rossmueller, Alejandro A. Puchol Tarazona, Randolf J. Kerschbaumer. Novel bioengineered monoclonal antibodies targeting oxidized macrophage migration inhibitory factor as anti-cancer therapeutics and companion diagnostics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 313.