Abstract 5035: Preclinical development of a 89Zr-labeled human antibody as a novel immuno-PET agent for noninvasive cancer detection and monitoring response to treatment
Authors: Singh Abhay Kumar , Lewis Calvin D. , Boas Cristian AWV , Diebolder Philipp , Jethva Prashant N. , Rhee Aaron , Song Jong Hee , Goo Young Ah , Li Shunqiang , Liu Yongjian , Rogers Buck , Kapoor Vaishali , Hallahan Dennis E. 
Published: April 2023

Abstract
Lung cancer is the leading cause of cancer death worldwide. There is an unmet need for therapies to improve lung cancer outcomes without causing additional toxicities. Tax-interacting protein 1 (TIP1) is a radiation-inducible antigen that plays a role in lung cancer progression and resistance to therapy. TIP1 is a targetable cell surface protein. We developed human antibodies (Ab) that bind specifically to lung cancer. This study aimed to evaluate our lead anti-TIP1 human antibody targeting lung cancer in vitro and in vivo. Anti-TIP1 IgG1 Ab was developed by biopanning phage display human antibody library. The purified Ab was characterized by size-exclusion chromatography-HPLC (SEC-HPLC), mass spectrometry, ELISA, BIAcore and flow cytometry. Ab was labeled with 89Zr using desferrioxamine chelator. The surface binding of 89Zr-Ab was evaluated in the A549 and H460 lung cancer cells. Stability of the 89Zr-Ab was assessed in human serum. Mice bearing 3 patient-derived xenografts (PDX) lung tumors or A549 tumors were injected with 50 µCi of 89Zr-Ab. Small animal PET imaging and biodistribution were conducted over 7 days. Specific tumor uptake was evaluated in biodistribution studies on day 5 by injecting cold Ab before 89Zr-Ab. We obtained 95% pure anti-TIP1 Ab by SEC-HPLC. Mass spectrometry confirmed the intact mass and glycosylation pattern of the anti-TIP1 IgG1. The Ab is bound to recombinant TIP1 protein and cancer cell surface with high affinity. The radiochemical purity of the 89Zr-Ab was 99.9%, and the molar activity was 11.54 MBq/nmol with a radiolabeling yield of 91.4%. Both A549 and H460 cell lines demonstrated specific binding as &gt;70% inhibition was observed when the cold Ab was added. The ratio of SUV tumor to SUV muscle increased from 5.8 at 2 days to 6.3 at 7 days in PDX. In biodistribution studies, we found significantly higher (p&lt;0.05) tumor uptake of the anti-TIP1 Ab (9.15±3.13 %ID/gm) vs. isotype control (5.72±1.02 %ID/gm). Cold anti-TIP1 Ab significantly blocked (p&lt;0.0001) binding of the 89Zr-Ab in A549 tumors. The anti-TIP1 Ab targets lung cancer cells in vitro and in vivo. The Ab retained antigen-binding potential following labeling with 89Zr. This Ab can detect TIP1 positive tumors for therapy when conjugated with therapeutic radionuclides. IND enabling studies with the lead anti-TIP1 Ab are underway.
Citation Format: Abhay Kumar Singh, Calvin D. Lewis, Cristian AWV Boas, Philipp Diebolder, Prashant N. Jethva, Aaron Rhee, Jong Hee Song, Young Ah Goo, Shunqiang Li, Yongjian Liu, Buck Rogers, Vaishali Kapoor, Dennis E. Hallahan. Preclinical development of a 89Zr-labeled human antibody as a novel immuno-PET agent for noninvasive cancer detection and monitoring response to treatment. [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 5035.