Antitumor Activities by a Humanized Cancer‐Specific Anti‐Podoplanin Monoclonal Antibody <scp>humPMab</scp>‐117 Against Human Tumors

Podoplanin (PDPN), also referred to as T1α/Aggrus, is a type I transmembrane sialoglycoprotein that plays a crucial role in invasiveness, stemness, and epithelial-to-mesenchymal transition, all of which contribute to the malignant progression of tumors. Therefore, a monoclonal antibody (mAb) against PDPN has been evaluated in preclinical models as a promising tumor therapy strategy. However, PDPN plays an essential role in normal development, such as in the development of the lungs. On-target toxicity by anti-PDPN mAbs to normal cells should be avoided to minimize adverse effects. A cancer-specific mAb against PDPN, PMab-117 (rat IgM, kappa), was previously established. This study engineered the humanized IgG₁ version (humPMab-117) to investigate antitumor activity. Flow cytometry analysis confirmed that humPMab-117 recognized PDPN-overexpressed glioma LN229 (LN229/PDPN) cells as well as PDPN-positive PC-10 (human lung squamous cell carcinoma) and LN319 (human glioblastoma) cells. In contrast, humPMab-117 did not react with normal epithelial cells from the lung bronchus, gingiva, mammary gland, corneal, and normal kidney podocytes, suggesting that humPMab-117 retains cancer-specific reactivity. Furthermore, humPMab-117 effectively induced antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity against LN229/PDPN, PC-10, and LN319 cells. In the xenograft tumor models, humPMab-117 demonstrated strong antitumor efficacy. These results suggest the potential of humPMab-117 as a therapeutic antibody for treating PDPN-positive malignant tumors.