Glypican‐3‐Specific Antibody Drug Conjugates Targeting Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second most common cause of cancer‐related death in the world. Therapeutic outcomes of HCC remain unsatisfactory, and novel treatments are urgently needed. GPC3 (glypican‐3) is an emerging target for HCC, given the findings that 1) GPC3 is highly expressed in more than 70% of HCC; (2) elevated GPC3 expression is linked with poor HCC prognosis; and (3) GPC3‐specific therapeutics, including immunotoxin, bispecific antibody and chimeric antigen receptor T cells. have shown promising results. Here, we postulate that GPC3 is a potential target of antibody‐drug conjugates (ADCs) for treating liver cancer. To determine the payload for ADCs against liver cancer, we screened three large drug libraries (> 9,000 compounds) against HCC cell lines and found that the most potent drugs are DNA‐damaging agents. Duocarmycin SA and pyrrolobenzodiazepine dimer were chosen as the payloads to construct two GPC3‐specific ADCs: hYP7‐DC and hYP7‐PC. Both ADCs showed potency at picomolar concentrations against a panel of GPC3‐positive cancer cell lines, but not GPC3 negative cell lines. To improve potency, we investigated the synergetic effect of hYP7‐DC with approved drugs. Gemcitabine showed a synergetic effect with hYP7‐DC in vitro and in vivo . Furthermore, single treatment of hYP7‐PC induced tumor regression in multiple mouse models. Conclusion : We provide an example of an ADC targeting GPC3, suggesting a strategy for liver cancer therapy.