San Diego – September 11, 2026 -- Inhibrx Biosciences reported that its OX40 agonist INBRX-106, combined with pembrolizumab, produced a 48.3% confirmed objective response rate in first-line head and neck squamous cell carcinoma patients, nearly double the 26.5% seen with pembrolizumab alone.
Phase 2 data show the combination therapy nearly doubles response rates versus standard treatment
The randomized Phase 2 portion of the HexAgon study enrolled 68 patients across more than 80 sites in the United States, Europe and Asia, with 63 evaluable for the primary endpoint. Four patients (13.8%) on the combination arm achieved complete responses, compared with zero in the pembrolizumab-only control arm. Six-month progression-free survival reached 72.4% for the combination versus 42.8% for monotherapy, with median PFS of 9.6 months versus 4.9 months as of the August 19, 2026 data cutoff.
HPV-positive patients show the strongest signal, with 80% response rate and 30% complete remissions
In the HPV+ subgroup, INBRX-106 plus pembrolizumab delivered an 80.0% cORR versus 33.3% for pembrolizumab alone, with 30.0% of combination-arm patients achieving complete response compared with none in the control arm. Six-month PFS was 90.0% for the combination versus 33.0% for monotherapy, and median PFS in this subgroup had not yet been reached for the combination arm versus 4.6 months for pembrolizumab alone.
Company will expand trial by 50 HPV+ patients to pursue accelerated approval pathway
Inhibrx plans to add approximately 50 HPV-positive oropharyngeal squamous cell carcinoma patients (CPS ≥ 1) to the Phase 2 portion of HexAgon, aiming to align with the FDA on a framework for accelerated approval before initiating a confirmatory Phase 3 trial. The most common treatment-related adverse events—rash, fatigue and diarrhea—were predominantly low grade, according to the company.
Inhibrx targets lung cancer and vaccine combinations as next expansion frontiers
Beyond HNSCC, Inhibrx is running a Phase 1/2 study of INBRX-106 in the perioperative setting of non-small cell lung cancer, with initial results expected by mid-2027. The company also plans to explore combining INBRX-106 with therapeutic cancer vaccines, citing the drug's demonstrated ability to amplify antigen-driven T-cell responses in HPV-positive disease. Mark Lappe, Inhibrx co-founder and CEO, said the depth and durability of responses in HPV+ disease reinforce the company's rationale for expanding the OX40 agonism program into other highly immunogenic tumor types.