808 Attacking carbonic anhydrase IX as a gateway to remodeling tumor hypoxia

Le résumé fourni par la source

Background Tumor hypoxia impedes T cell infiltration and effector function, rendering hypoxic solid tumors refractory to immune checkpoint blockade (ICB) and predicts poorer outcomes in patients.1 2 Previously, we have shown that the Hypoxia activated prodrug (HAP) TH-302 (evofosfamide) decreases tumor hypoxia and sensitizes murine prostate cancer to ICB.2 While TH-302 decreased tumor hypoxia in responding patients in a phase 1 clinical trial, non-responding patients remained immune to hypoxia reduction and attenuation of tumor proliferation.3 To overcome this limitation, we seek to target the hypoxic tumor microenvironment(TME) agnostic of its proliferation status using Carbonic anhydrase IX (CAIX) binding cytodepletive monoclonal antibodies(mAbs). CAIX is a cell surface enzyme strongly induced under hypoxia and has been correlated with poorer prognosis and ICB resistance.4 5 Lack of murine cross-reactivity amongst existing human CAIX antibodies like Girentuximab has significantly limited their evaluability in murine tumors. Therefore, murine CAIX (mCAIX) binding mAbs are necessary to study the ability of CAIX cytodepletion to remodel the hypoxic TME in murine tumors. In this study, we have developed and characterized novel mCAIX mAbs that bind to the hypoxic tumor stroma and serve as promising targets for future applications to reverse hypoxia associated ICB resistance. Methods Novel mCAIX binding mAbs were generated by hybridoma fusion of spleens from CAIX knockout mice vaccinated with CAIX recombinant proteins and CAIX+ DC2.4 dendritic cells. mCAIX binding antibodies were selected via Enzyme linked immunosorbent assay (ELISA) and flow cytometry screens. The ability of mCAIX mAbs to induce immune cell mediated depletion of CAIX+ cells was assessed in vitro. Further, the therapeutic efficacy of mCAIX mAbs against subcutaneous B16/BL6 melanoma overexpressing CAIX (B16-CAIX) progression was tested in vivo. The capacity of these antibodies to bind to hypoxic myeloid stroma extracted from in vivo growing B16/BL6 melanoma was determined by flow cytometry. Results We identified multiple mCAIX binding mAbs from fused hybridomas via flow cytometry and ELISA screens. We find that our novel mCAIX mAbs exhibit cytotoxic effector function in vitro, control B16-CAIX tumor progression and significantly extend survival in vivo. Additionally, our antibodies bind to B16 melanoma infiltrating monocytic myeloid derived suppressor cells and macrophages under tumor hypoxia. Conclusions Our novel mCAIX binding mAbs induce immune cell mediated cytodepletion in vitro and provide therapeutic benefit against melanoma expressing CAIX in vivo. Furthermore, our mCAIX mAbs bind to the hypoxic T cell suppressive stroma in B16/BL6 melanoma, warranting further studies to assess its therapeutic cooperativity with ICB. References Chouaib S, Noman MZ, Kosmatopoulos K, Curran MA. Hypoxic stress: obstacles and opportunities for innovative immunotherapy of cancer. Oncogene. 2017 Jan 26;36(4):439–445. Jayaprakash P, Ai M, Liu A, Budhani P, Bartkowiak T, Sheng J, Ager C, Nicholas C, Jaiswal AR, Sun Y, Shah K, Balasubramanyam S, Li N, Wang G, Ning J, Zal A, Zal T, Curran MA. Targeted hypoxia reduction restores T cell infiltration and sensitizes prostate cancer to immunotherapy. J Clin Invest. 2018 Nov 1;128(11):5137–5149. Hegde A, Jayaprakash P, Couillault CA, Piha-Paul S, Karp D, Rodon J, Pant S, Fu S, Dumbrava EE, Yap TA, Subbiah V, Bhosale P, Coarfa C, Higgins JP, Williams ET, Wilson TF, Lim J, Meric-Bernstam F, Sumner E, Zain H, Nguyen D, Nguyen LM, Rajapakshe K, Curran MA, Hong DS. A phase I dose-escalation study to evaluate the safety and tolerability of evofosfamide in combination with ipilimumab in advanced solid malignancies. Clin Cancer Res. 2021 Jun 1;27(11):3050–3060. Chafe SC, McDonald PC, Saberi S, Nemirovsky O, Venkateswaran G, Burugu S, Gao D, Delaidelli A, Kyle AH, Baker JHE, Gillespie JA, Bashashati A, Minchinton AI, Zhou Y, Shah SP, Dedhar S. Targeting hypoxia-induced carbonic anhydrase ix enhances immune-checkpoint blockade locally and systemically. Cancer Immunol Res. 2019 Jul;7(7):1064–1078. Zandberg DP, Menk AV, Velez M, Normolle D, DePeaux K, Liu A, Ferris RL, Delgoffe GM. Tumor hypoxia is associated with resistance to PD-1 blockade in squamous cell carcinoma of the head and neck. J Immunother Cancer. 2021 May;9(5):e002088.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.