Inhibrx Shares Rise After Positive Phase 2 Head and Neck Cancer Data

Inhibrx Biosciences (NASDAQ:INBX) shares gained 6% on Tuesday after the biotechnology company reported encouraging Phase 2 results for INBRX-106 in combination with pembrolizumab in patients with head and neck cancer.

Data from the HexAgon study showed a confirmed objective response rate of 48.3% among patients receiving the combination, compared with 26.5% for those treated with pembrolizumab alone.

The trial is evaluating first-line treatment in patients with treatment-naïve, PD-L1-positive metastatic or unresectable recurrent head and neck squamous cell carcinoma.

Combination Shows Higher Response Rate

The reported analysis included 63 evaluable patients, comprising 29 in the INBRX-106 plus pembrolizumab arm and 34 in the pembrolizumab control group.

Four patients receiving the combination achieved a complete response, while there were no complete responses among patients receiving pembrolizumab alone.

At six months, the progression-free survival rate was 72.4% for the combination group, compared with 42.8% for the control arm.

The results represent an early clinical signal from a relatively small Phase 2 population, and further study will be required to establish the treatment’s efficacy and safety profile.

HPV-Positive Patients Show Stronger Results

The response was particularly pronounced among HPV-positive patients.

In this subgroup, the confirmed objective response rate reached 80.0% with INBRX-106 plus pembrolizumab, compared with 33.3% for pembrolizumab alone.

A complete response was recorded in 30.0% of HPV-positive patients receiving the combination, versus none in the control group.

Six-month progression-free survival was 90.0% for the combination arm and 33.0% for pembrolizumab alone.

The combination’s safety profile was described as generally manageable. The most common treatment-related adverse events were rash, fatigue and diarrhoea, with most reported at a low grade.

Inhibrx Plans HexAgon Trial Expansion

Following the results, Inhibrx plans to expand the Phase 2 portion of HexAgon by approximately 50 additional HPV-positive patients.

The company intends to use the additional data to support discussions around a potential accelerated regulatory pathway.

Inhibrx also plans to align with the U.S. Food and Drug Administration on the proposed regulatory framework before beginning a Phase 3 confirmatory study.

The planned expansion will provide additional evidence on whether the response rates observed in the current Phase 2 population can be reproduced in a larger group of HPV-positive patients.

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