Abstract 1862: Synergistic and long-lasing anti-tumor efficacy of CBA-1205, a novel glycoengineered humanized antibody targeting DLK-1, in combination with lenvatinib in human HCC xenograft models
Authors: Nakamura Koji , Sakaguchi Izumi , Takahashi Kota 
Published: June 2023

Abstract
Delta-like 1 homolog (DLK-1), a non-canonical notch ligand, is a membrane protein with 6 tandem EGF-like motifs in extracellular region. While the expression of DLK-1 is restricted in some neuroendocrine tissues such as adrenal gland and hypophysis in normal adult tissues, its over-expression in cancers have been reported in a variety of cancer types, such as hepatocellular carcinoma (HCC), small cell lung carcinoma, ovarian carcinoma, adrenal cortical carcinoma, pancreatic carcinoma, gastrointestinal stromal tumor, etc. Interestingly, it has been suggested that DLK-1 is a marker of cancer stem cells in HCC. CBA-1205 is a humanized antibody (IgG1/κ) targeting DLK-1, which is glycoengineered by GlymaxX® to potentiate antibody-dependent cellular cytotoxicity (ADCC) activity. CBA-1205 showed no toxicology issues in cynomolgus monkey GLP studies and the Phase 1 clinical trial in patients with solid tumors is under way (JapicCTI-205384). Previously, we demonstrated potent anti-tumor efficacy of CBA-1205 as a monotherapy in multiple human DLK-1 positive cancer xenograft mouse models including HCC (AACR 2019 annual meeting). Lenvatinib is an oral multi-kinase inhibitor which has been used for 1st line therapy of unresectable advanced HCC globally. The purpose of present study is to evaluate the combinatorial efficacy of CBA-1205 with lenvatinib in two HCC xenograft models (Hep3B and HepG2). Hep3B model was sensitive to lenvatinib monotherapy; oral daily dosing of lenvatinib at 3 mg/kg treatment showed 50% tumor growth inhibition (TGI) and at 10 mg/kg treatment showed more than 80% TGI. In contrast HepG2 model was less sensitive to Lenvatinib; TGI at 3 mg/kg treatment group was 20 % and that for 10 mg/kg treatment group was 50 %. When CBA-1205 (1 mg/kg, twice a week, total 4 times) was intraperitoneally administered in combination with 3 mg/kg of lenvatinib (daily, total 10 times) in Hep3B xenograft mice, synergistic and long-lasting anti-tumor efficacy was observed compared either with CBA-1205 treatment alone or lenvatinib treatment alone. Tumor growth of all mice (N=8) treated with CBA-1205 and lenvatinib showed almost complete inhibition even 2 weeks after the last dosing. More importantly, 4 out of 8 mice in CBA-1205 and lenvatinib treatment group showed tumor regression. Similar results were obtained with CBA-1205 at 1 mg/kg dosage in combination with lenvatinib at 10 mg/kg dosage in HepG2 xenograft model. In conclusion, we demonstrated synergistic and long-lasting anti-tumor efficacy of CBA-1205 in combination with lenvatinib in two different HCC pre-clinical models suggesting that the combination could be a new treatment option for unresectable advanced HCC.
Citation Format: Koji Nakamura, Izumi Sakaguchi, Kota Takahashi. Synergistic and long-lasing anti-tumor efficacy of CBA-1205, a novel glycoengineered humanized antibody targeting DLK-1, in combination with lenvatinib in human HCC xenograft models [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 1862.