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Inhibrx's INBRX-106 Nearly Doubles Response Rate and Achieves Interim Median PFS of 9.6 months in Phase 2 HNSCC Study

INBX
  • Inhibrx announced primary endpoint results from the Phase 2 HexAgon study showing INBRX-106 plus pembrolizumab achieved a 48.3% confirmed objective response rate (cORR) versus 26.5% for pembrolizumab alone in treatment-naïve metastatic or unresectable recurrent head and neck squamous cell carcinoma (HNSCC).
  • Six-month progression-free survival (PFS6) rates were 72.4% for the combination arm compared to 42.8% for pembrolizumab monotherapy, with median PFS of 9.6 months versus 4.9 months respectively.
  • Complete response rates reached 13.8% (4 patients) in the combination arm compared to 0% in the control arm.
  • Efficacy was most pronounced in HPV+ patients, with an 80.0% cORR, 30.0% complete response rate, and 90.0% PFS6 for the combination arm versus 33.3% cORR, 0% complete response, and 33.0% PFS6 for pembrolizumab alone.
  • The combination was generally manageable with the most common treatment-related adverse events being rash, fatigue, and diarrhea, which were predominantly low grade.
  • Inhibrx plans to expand the randomized Phase 2 study by approximately 50 additional HPV+ oropharyngeal squamous cell carcinoma patients to support a potential accelerated regulatory pathway.
  • The company intends to align with the FDA on the expanded Phase 2 framework before initiating a Phase 3 confirmatory trial.
  • Inhibrx is evaluating INBRX-106 in other highly immunogenic tumors, including a Phase 1/2 perioperative study in non-small cell lung cancer with results targeted for mid-2027.
  • The company plans to explore INBRX-106 in combination with therapeutic cancer vaccines based on observed T-cell responses in HPV+ disease.
  • The Phase 2 HexAgon study included 68 randomized patients across more than 80 sites in the United States, Europe, and Asia.