DS-9606

DS-9606 is an investigational antibody-drug conjugate (ADC) developed by Daiichi Sankyo. It targets Claudin-6 (CLDN6), a tight junction protein aberrantly expressed in several cancers but largely absent from normal adult tissues. The ADC consists of a humanized monoclonal antibody directed against CLDN6, conjugated to a modified pyrrolobenzodiazepine (PBD) cytotoxic payload via a cleavable linker. This design enables targeted delivery of the potent PBD toxin to CLDN6-expressing tumor cells, inducing DNA crosslinking and cell death upon internalization. Early clinical data show promising activity in advanced solid tumors expressing CLDN6—including germ cell tumors, ovarian cancer, gastric/esophageal cancer, and non-small cell lung cancer—especially in heavily pretreated patients[1][2][5]. The drug is currently being evaluated in phase 1 trials for safety and efficacy.