Background

Podoplanin (PDPN) is a specific ligand of C-type lectin-like recepotor-2 (CLEC-2), and is involved in cancer metastasis. The physiological PDPN function has been discussed in many normal tissues, including lymphatic endothelial cells, pulmonary type I alveolar cells, and renal podocytes. Herein, we aimed to produce cancer-specific anti-PDPN monoclonal antibodies (mAbs). Furthermore, we investigated whether the reactivity of cancer-specific anti-PDPN mAbs might be a prognostic marker of oral cancer.

Materials and methods

We immunized mice with LN229/PDPN cells, and screened mAbs, which react with PDPN-expressing cancer cell lines, such as glioblastoma cell lines and lung squamous cell carcinoma cell lines and do not react with PDPN-expressing normal cells, including primary lymphatic endothelial cells and renal epithelial cell lines in flow cytometry. Furthermore, we investigated the reactivity of anti-PDPN mAbs by immunohistochemistry against oral cancers. Anti-tumor activities by mouse-human chimeric LpMab-23 (chLpMab-23) were examined using mouse xenograft models of oral cancer cells. Finally, we analyzed the association between the reactivity of anti-PDPN mAbs and clinical/pathological features of oral cancers.

Results

We established LpMab-23, a cancer-specific anti-PDPN mAb. LpMab-23 reacted with PDPN-expressing cancer cell lines in flow cytometry. In contrast, LpMab-23 recognized PDPN-expressing normal cells very weakly. LpMab-23 reacted only with PDPN-expressing cancer cells, not with lymphatic endothelial cells in oral cancer tissues by immunohistochemistry. The epitope mapping of anti-PDPN mAbs revealed that LpMab-23 recognized a cancer-specific glycopeptide including Thr55/Ser56. chLpMab-23 revealed high ADCC and anti-tumor activities against oral cancers. The Kaplan-Meier curves of the five-year new metastasis-free survival rate (nMFS) were significantly lower in LpMab-23-positive patients than in the patients with LpMab-23-negative ones.

Conclusions

A cancer-specific anti-PDPN mAb (LpMab-23) and its mouse-human chimeric mAb (chLpMab-23) were successfully established. LpMab-23 is advantageous in anti-tumor activities. LpMab-23-positive cases could be a useful predictor of poor prognosis for oral cancer.

Citation Format: Takashi Miwa, Shinji Yamada, Mika K. Kaneko, Yoshikazu Furusawa, Masato Fukui, Yukinari Kato. LpMab-23: an anti-podoplanin cancer-specific antibody for a prognostic marker of oral cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2983.