Patritumab (U3-1287) is an anti-HER3 monoclonal antibody with potential antitumor activity and inhibits phosphorylation of EGFR, HER2, HER3, ERK, and AKT.Patritumab promotes apoptosis and inhibits proliferation in non-small cell lung cancer.

Patritumab targets the extracellular domain (ECD) of HER3 and induces apoptosis in DiFi-HRG4 cells (10 μg/mL; 5 days)[1]. Patritumab (10 μg/mL; 6 h) markedly inhibits the phosphorylation of HER3 and AKT in DiFi-HRG4 cells without affecting that of ERK[1]. Additionally, Patritumab (10 μg/mL; 48 h) induces the cleavage of PARP, accompanied by both up-regulation of BIM and down-regulation of survivin expression[1].

In a DiFi-HRG tumor xenografts model in mice, Patritumab (1 mg/mouse; intraperitoneal; twice a week for 4 weeks) combines with 1 mg Cetuximab and restores Cetuximab sensitivity[1]. Heregulin produced by colorectal cancer tumors harboring wild-type KRAS induces Cetuximab resistance, and combination therapy with cetuximab and patritumab overcomes such resistance in vivo[1].