Abstract 6294: CXCR5 is a very promising drug target for the development of antibody-drug conjugates to treat patients with lymphoma

Abstract

Abstract Introduction: The chemokine receptor CXCR5 is highly expressed in tumor cells from different lymphoma types and represents a viable drug target for the development of antibody-drug conjugates (ADC) to treat patients with lymphoma.   Methods: Immunohistochemistry of human tissues of different lymphoma types were stained using antibodies against human CXCR5, CD20, CD70 and CD79b. Slides were examined by a pathologist and scored for expression. CXCR5 expression on tumor cell lines was analyzed by flow cytometry. Cell surface receptor density was analyzed by Quantibrite ™ PE-beads. Evaluation of antibody internalization was performed using the Operetta High Content Imaging System. NOD/SCID mice were transplanted subcutaneously with lymphoma patient-derived (PDX) tumor specimens and treated with 2mg/kg or 10mg/kg VIP924 CXCR5-ADC or isotype control. Results: CXCR5 reveals very low to no expression in most tissues except for lymph nodes. Expression of CXCR5 and other B-cell targets like CD19, CD20, CD70 and CD79b was analyzed on patient-derived tumor samples. High expression of CXCR5 was found on naïve and previously treated diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and chronic lymphocytic leukemia (CLL) samples. Based on these results, we developed a CXCR5 targeted ADC with a novel, highly potent kinesin spindle protein inhibitor (KSPi) payload linked via a legumain-cleavable linker (VIP924). To compare the performance of KSPi ADCs, the same effector chemistry was attached to antibodies against other B-cell targets and tested in cytotoxicity assays in various cell lines. CXCR5-targeted ADC demonstrates significantly higher activity compared to the other ADCs tested except for the CD79b ADC with equal potency. VIP924 was then tested in vivo in different PDX tumor mouse models with different levels of CXCR5 expression. In the LY2264 and HBL-1 DLBCL models, we obtained a tumor growth inhibition of 68% and 100% respectively compared to isotype control. The median survival time for the isotype control group was 29 days and median survival time for the mice treated with 10mg/kg VIP924 could not be determined as all mice survived until the end of the study (Day 37). No effect on body weight or any adverse effects in the VIP924 treated mice were observed. Conclusions: CXCR5 is a highly attractive target in hematological malignancies such as DLBCL, MCL, and FL due to high protein expression and almost no expression in healthy tissues. CXCR5-targeting ADC with KSPi payload showed high potency and superiority to other B-cell-targeted ADCs in vitro on a broad range of lymphoma cell lines. VIP924 with a novel legumain-cleavable linker showed activity in in vivo PDX models from lymphoma patients. Due to the high CXCR5 expression found in relapsed DLBCL patients, VIP924 may bring promising new treatment options for previously treated patients with lymphoma. Citation Format: Tibor Schomber, Beatrix Stelte-Ludwig, Amy J. Johnson, Oliver von Ahsen, Christoph Schatz, Raquel Izumi, Ahmed Hamdy, Hans-Georg Lerchen. CXCR5 is a very promising drug target for the development of antibody-drug conjugates to treat patients with lymphoma [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 6294.