Inhibrx Biosciences Inc. (NASDAQ: INBX) announced primary endpoint results from the randomized Phase 2 portion of its HexAgon study. The trial evaluated the combination of the company's drug candidate INBRX-106 and Merck & Co Inc.'s (NYSE: MRK) Keytruda (pembrolizumab) against pembrolizumab monotherapy in patients with head and neck squamous cell carcinoma.
As of the Aug. 19, 2026 data cutoff, the combination arm achieved a confirmed objective response rate of 48.3% compared to 26.5% for the control arm. The trial included 63 evaluable, treatment-naïve, PD-L1 positive patients across more than 80 international sites. Specifically, four patients in the combination group reached a complete response, while the control group saw none.
Progression-free survival data showed a median of 9.6 months for the combination versus 4.9 months for monotherapy. Six-month progression-free survival rates were 72.4% and 42.8%, respectively. The therapeutic benefit appeared particularly strong in the HPV-positive cohort, where the combination regimen produced an 80% confirmed objective response rate compared to 33.3% for pembrolizumab alone.
In response to these results, Inhibrx plans to add approximately 50 HPV-positive patients to the Phase 2 trial to support a potential accelerated regulatory pathway. The company intends to align with the FDA to initiate a confirmatory Phase 3 study. Additionally, Inhibrx is conducting a Phase 1/2 trial evaluating INBRX-106 in perioperative non-small cell lung cancer, with initial results expected by mid-2027.
