Inhibrx Shares Gain After Positive Phase 2 Head and Neck Cancer Drug Data

Shares of Inhibrx Biosciences, Inc. (NASDAQ: INBX) climbed 6% on Tuesday after the biotechnology firm released positive results from a Phase 2 trial of its cancer therapy, INBRX-106. The study evaluated the drug in combination with Merck's pembrolizumab (Keytruda) as a first-line treatment for a specific type of head and neck cancer.

Trial Meets Primary Endpoints

The HexAgon study assessed the combination therapy in patients with treatment-naïve, PD-L1 positive metastatic or unresectable recurrent head and neck squamous cell carcinoma. According to Inhibrx, the trial demonstrated a significant improvement over using pembrolizumab alone.

Key findings from the 63 evaluable patients include:

• A confirmed objective response rate (ORR) of 48.3% for the combination therapy, compared to 26.5% for the pembrolizumab-only control arm.
• Four patients in the combination group achieved a complete response, whereas no complete responses were observed in the control group.
• At the six-month mark, the progression-free survival rate was 72.4% for patients receiving the combination, versus 42.8% for those on pembrolizumab alone.

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Strong Results in HPV-Positive Patients

The data was particularly compelling in the subgroup of patients with HPV-positive cancer. In this cohort, the combination of INBRX-106 and pembrolizumab delivered an 80.0% confirmed objective response rate, substantially higher than the 33.3% rate in the control arm. Furthermore, 30% of these patients achieved a complete response, and their six-month progression-free survival rate was 90.0%, compared to 33.0% for the control.

Path Forward

Based on these encouraging results, Inhibrx announced plans to expand the Phase 2 portion of the trial by approximately 50 additional HPV-positive patients. The company stated this expansion is intended to support a potential accelerated regulatory pathway. Inhibrx also plans to consult with the U.S. Food and Drug Administration (FDA) on this framework before initiating a larger Phase 3 confirmatory study. The company noted the combination therapy was generally manageable, with common low-grade adverse events including rash, fatigue, and diarrhea.