Inhibrx Biosciences (INBX) Shares Soar 17% Following Promising Phase 2 Cancer Study Data

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Inhibrx Biosciences shares climbed 17% Monday following encouraging Phase 2 clinical trial data for INBRX-106 in head-and-neck cancer treatment.
The experimental drug paired with pembrolizumab delivered a 44% objective response rate compared to 21.4% for pembrolizumab monotherapy.
Among evaluable patients, 11 of 25 in the combination therapy group responded versus 6 of 28 receiving pembrolizumab alone; the combination arm recorded three complete responses while the control group had zero.
Patients receiving the combination treatment showed T-cell proliferation levels up to 15 times higher than those on pembrolizumab monotherapy.
The Phase 3 study portion is scheduled to launch in Q3 2026, with progression-free survival results anticipated in Q4 2026.

Inhibrx Biosciences (INBX) shares gained 17% Monday after the biotechnology company announced encouraging interim findings from its Phase 2 HexAgon clinical study evaluating INBRX-106, an investigational treatment for head and neck cancer.

Inhibrx Biosciences, Inc., INBX

The stock had previously surged over 1,000% in the preceding 12 months, propelled by encouraging data from INBRX-109, another oncology candidate, released in October.

The clinical trial evaluated INBRX-106 — a hexavalent OX40 agonist — combined with pembrolizumab versus pembrolizumab as a single agent. Study participants were first-line, treatment-naïve patients with PD-L1 positive metastatic or unresectable recurrent head and neck squamous cell carcinoma.

The combination therapy group achieved a 44% confirmed objective response rate. By contrast, the control group receiving only pembrolizumab registered a 21.4% response rate — representing a 22.6 percentage point advantage.

The clinical study recruited 68 patients in total, with 33 assigned to the combination therapy group and 35 to the control group. The evaluable patient population consisted of 53 individuals.

Within that cohort, 11 of 25 patients receiving the combination treatment demonstrated responses. In the pembrolizumab-only group, 6 of 28 patients responded.

The INBRX-106 combination arm produced three complete responses. The control arm recorded no complete responses.

Immune Cell Activity Reinforces Clinical Findings

Beyond the response rate metrics, the immunological data proved particularly noteworthy. Patients receiving the combination treatment exhibited up to a 15-fold mean elevation in CD8+ and CD4+ T-cell proliferation. Patients on pembrolizumab monotherapy demonstrated increases reaching only 2.5-fold.

Inhibrx indicated this biological evidence provides mechanistic validation for the clinical outcomes — essentially confirming the underlying biology aligns with patient responses.

CEO Mark Lappe expressed that the company was “greatly encouraged by these early clinical results,” highlighting particularly the quality and depth of responses currently being documented.

Tolerability Profile Deemed Acceptable

The combination regimen exhibited a safety profile the company characterized as manageable and aligned with expectations for an immunotherapy combination approach.

The most frequently observed treatment-related adverse events included rash, diarrhea, fatigue, and infusion-related reactions. The majority were classified as low-grade.

Neither trial arm reported any treatment-related fatalities.

Inhibrx stated that progression-free survival data from the Phase 2 segment is projected for Q4 2026.

The Phase 3 segment of the HexAgon study is planned to commence in Q3 2026.