Abstract 2358: KHK2805, a novel ADCC- and CDC-enhanced anti-FOLR1 antibody with AccretaMab® technology, shows a potent anti-tumor activity in combination with pemetrexed

Abstract

Abstract Introduction: Folate receptor 1 (FOLR1, FR alpha) is a folate transporter which is expressed in many cancers including ovarian cancer (OvC) and non-small cell lung cancer (NSCLC), and which is an attractive target for cancer therapy, is currently the subject of ongoing studies. We established KHK2805, a novel anti-FOLR1 monoclonal antibody with AccretaMab® technology to enhance both the antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) activities. It was demonstrated that KHK2805 exhibits markedly high ADCC and CDC activity levels in clinical samples from ovarian cancer patients, while a tolerable safety profile has been observed in preclinical models using cynomolgus monkeys (100 mg/kg weekly for 4 weeks, intravenously). A greater understanding of the biology of FOLR1 is important for providing a novel therapeutic option for KHK2805 for patients with cancer. Pemetrexed (PEM), a second-generation anti-folate which inhibits thymidylate synthase, glycinamide ribonucleotide transformylase and dihydrofolate reductase, is used as a standard therapy for patients with cancers such as NSCLC. It is not fully understood how PEM treatment affects the expression of FOLR1 on cancer cells. We therefore examined the level of FOLR1 expression in cancer cells after PEM treatment, and the anti-tumor activity of KHK2805 in combination with PEM. Materials and Methods: The FOLR1 expression levels after PEM treatment were examined in OvC, NSCLC, and endometrial cancer cells by flow cytometry. The ADCC activity of KHK2805 against PEM-treated cells was evaluated. The anti-tumor activity of KHK2805 in combination with PEM was investigated in SCID mice. Results: Flow cytometry showed that PEM treatment increased the FOLR1 expression of various cancers such as OvC (IGROV1, SKOV3, MCAS), NSCLC (NCI-H1437, NCI-H2228), and endometrial cancer (MESSA, HEC1A, HEC1B) cells. In addition, PEM treatment enhanced the ADCC activity of KHK2805 against MCAS, NCI-H1437, and NCI-H2228, in comparison to cells that did not receive PEM treatment. Furthermore, the anti-tumor activity of KHK2805 in SCID mice bearing subcutaneous MCAS tumors was enhanced by PEM treatment. Conclusions: PEM induced further FOLR1 expression in OvC, NSCLC, and endometrial cancer, resulting in the enhancement of the ADCC activity of KHK2805. The use of KHK2805 with PEM might therefore be a potent therapeutic option. Citation Format: Munetoshi Ando, Keiko Nagata, Toshihiko Ishii, Ryuichiro Nakai, Takeshi Takahashi. KHK2805, a novel ADCC- and CDC-enhanced anti-FOLR1 antibody with AccretaMab® technology, shows a potent anti-tumor activity in combination with pemetrexed. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2358.