Daiichi Sankyo has halted a late-stage trial of its HER3 inhibitor patritumab after seeing no evidence of efficacy at an interim analysis.
The two-stage trial of patritumab (U3-1287/AMG 888) in combination with Roche’s EGFR inhibitor Tarceva (erlotinib) patients with non-small cell lung cancer (NSCLC) was stopped on the advice of the independent data monitoring committee, said the company in a statement.
HER3 (also known as ErbB3) is another member of the HER (human epidermal growth factor receptor) family targeted by established drugs such as Roche’s Herceptin (trastuzumab), which binds to HER2. It has been proposed as a potential drug target in cancer since the 1990s but to date no HER3-targeting drugs have been approved for use.
Researchers have hypothesised that inhibiting EGFR and HER3 in tandem could lead to greater efficiency and also overcome resistance to currently available EGFR-directed drugs.
“We are disappointed that this study did not confirm the hypothesis that effective HER3 inhibition in combination with erlotinib would provide clinically relevant tumour growth control in subjects with advanced NSCLC,” said Daiichi Sankyo’s head of oncology R&D Antoine Yver.
He stressed however that the results do not necessarily undermine the potential role of HER3 as a cancer drug target.
Other companies working on HER3 inhibitors include Merrimack Pharma, whose seribantumab (MM-121) candidate is in phase III, as well as GlaxoSmithKline with GKS2849330 (phase I) and Roche’s Genentech unit which has a dual HER3/EGFR inhibitor called MEHD7945A in mid-stage trials.
“This particular result does not directly affect the science of patritumab in other settings,” said Yver.
Daiichi Sankyo is also testing patritumab in a phase II trial in head and neck cancer, in combination with Eli Lilly’s EGFR inhibitor Erbitux (cetuximab) and platinum-based chemotherapy.
The antibody was developed by Daiichi Sankyo’s German subsidiary U3 Pharma, which is being shut down alongside a major reduction in headcount the Japanese drugmaker announced last year. Patritumab is the only drug from U3 that remains in clinical development.