[Development of New Therapy for Malignant Mesothelioma Based on CD26 Molecule]

CD26 is a 110 kDa, type II transmembrane glycoprotein with dipeptidyl peptidase IV activity and is capable of cleaving Nterminal dipeptides with either L-proline or L-alanine at the penultimate position. Malignant mesothelioma(MM)is an aggressive malignancy arising from the mesothelial cells. It is generally associated with a history of asbestos exposure and has a very poor prognosis. Due to lack of efficacy of conventional treatments, novel therapeutic strategies are urgently needed to improve outcomes. Recently we showed that CD26 is preferentially expressed on epithelial type of MM cells but not on normal mesothelial cells. We have developed a highly biological active humanized anti-CD26 monoclonal antibody(mAb)and have published previously extensive in vivo data demonstrating the anti-tumor activity of humanized anti-CD26 mAb(YS110)in mouse xenograft models. The use of a humanized anti-CD26 mAb may therefore be a rational therapy for patients with MM. The first-in-human(FIH)phase I study performed in France demonstrates that humanized anti-CD26 therapy is generally well-tolerated with preliminary evidence of activity in patients with advanced/refractory CD26-expressing cancers, particularly refractory malignant mesothelioma. From the above results, the phase I clinical trial for malignant mesothelioma in Japan is to be started in the very near future.