Inhibrx Biosciences' (INBX) experimental cancer drug, INBRX-106, nearly doubled the response rate when combined with pembrolizumab in a phase 2 trial for head and neck cancer, the drugmaker said Tuesday.

The combination produced a confirmed objective response rate of 48.3%, compared with 26.5% for pembrolizumab alone, Inhibrx said.

Complete responses occurred in 13.8% of patients receiving the combination, while none were reported in the control group, with median progression-free survival of 9.6 months versus 4.9 months, respectively, the company said.

The benefit was stronger in patients with HPV-positive disease, with an 80% confirmed objective response rate for the combination versus 33.3% for pembrolizumab alone, the company said.

Inhibrx said it plans to add about 50 HPV-positive oropharyngeal cancer patients to the phase 2 trial and then discuss a potential phase 3 confirmatory study with the US Food and Drug Administration.