Inhibrx Biosciences Plans Head and Neck Cancer Trial Expansion Following High Response Rates

Inhibrx Biosciences Inc. (NASDAQ:INBX) announced primary endpoint results from the randomized Phase 2 portion of its HexAgon study.

• Inhibrx Biosciences stock is taking a hit today. What’s behind INBX decline?

The trial showed that its drug candidate INBRX-106 combined with Merck & Co Inc.’s (NYSE:MRK) Keytruda (pembrolizumab) outperformed pembrolizumab monotherapy in patients with head and neck squamous cell carcinoma.

Strong Primary Endpoint Results

The clinical trial evaluated 63 evaluable, treatment-naïve, PD-L1 positive patients across more than 80 international sites.

As of the Aug. 19, 2026 data cutoff, the combination arm achieved a confirmed objective response rate of 48.3% versus 26.5% for the control arm.

Four patients in the combination group reached a complete response, while no patients in the control group achieved a complete response.

The combination arm achieved a median progression-free survival of 9.6 months versus 4.9 months for monotherapy, with six-month progression-free survival rates reaching 72.4% and 42.8%, respectively.

Significant Response In HPV-Positive Cohort

The therapeutic benefit appeared particularly strong in HPV-positive patients. Within this group, the combination regimen produced an 80% confirmed objective response rate compared to 33.3% for pembrolizumab alone.

Complete responses occurred in 30% of HPV-positive combination patients, whereas 90% remained progression-free at six months.

Median progression-free survival for HPV-positive combination patients has not yet been reached.

The combination regimen showed a manageable safety profile.

Expansion Plans and Future Indications

Inhibrx plans to add approximately 50 HPV-positive patients to the Phase 2 trial to support a potential accelerated regulatory pathway.

The biopharmaceutical firm intends to align with the FDA to initiate a confirmatory Phase 3 study.

Furthermore, the company is conducting a Phase 1/2 trial evaluating INBRX-106 in perioperative non-small cell lung cancer, targeting initial results by mid-2027, and plans to evaluate combinations with cancer vaccines.

INBX Stock Price Activity: Inhibrx Biosciences shares were down 12.49% to $106.03 at the time of publication on Tuesday, according to Benzinga Pro data.

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