Inhibrx Biosciences (INBX) Stock Soars 17% Following Impressive Phase 2 Cancer Data

Key Highlights

• Shares of Inhibrx Biosciences climbed 17% Monday following encouraging Phase 2 clinical trial data for INBRX-106 in head-and-neck cancer treatment.
• The experimental therapy paired with pembrolizumab delivered a 44% objective response rate compared to just 21.4% for pembrolizumab monotherapy.
• Among evaluable patients, 11 of 25 responded in the combination therapy group versus 6 of 28 in the single-agent arm; the combination group also recorded three complete responses while the control arm had zero.
• Patients receiving combination treatment demonstrated T-cell proliferation levels up to 15 times greater than those treated with pembrolizumab alone.
• The company plans to initiate Phase 3 enrollment in Q3 2026, with progression-free survival outcomes anticipated by Q4 2026.

Shares of Inhibrx Biosciences (INBX) gained 17% Monday after the biotechnology company unveiled encouraging interim data from its Phase 2 HexAgon clinical study evaluating INBRX-106 for the treatment of head and neck cancer.

Inhibrx Biosciences, Inc., INBX

The equity had already experienced remarkable growth exceeding 1,000% during the previous year, fueled by favorable data from another oncology candidate, INBRX-109, announced in October.

The clinical study evaluated INBRX-106 — a hexavalent OX40 agonist compound — combined with pembrolizumab versus pembrolizumab administered as a single agent. The patient population consisted of first-line, treatment-naïve individuals with PD-L1 positive metastatic or unresectable recurrent head and neck squamous cell carcinoma.

The combination therapy arm achieved a 44% confirmed objective response rate. By comparison, the control arm receiving only pembrolizumab recorded a 21.4% response rate — representing a statistically meaningful 22.6 percentage point advantage.

The trial enrolled a total of 68 participants, with 33 assigned to the combination therapy arm and 35 to the control group. Of these, 53 patients comprised the evaluable population for efficacy analysis.

Within that evaluable cohort, 11 of 25 patients treated with the combination regimen demonstrated responses. In the pembrolizumab-only group, six of 28 patients responded.

Notably, three patients in the INBRX-106 combination arm achieved complete responses. The control arm recorded zero complete responses.

Immune Cell Activity Reinforces Clinical Findings

Beyond the headline response metrics, the immunological data proved particularly compelling. Patients treated with the combination therapy exhibited up to a 15-fold mean elevation in CD8+ and CD4+ T-cell proliferation compared to baseline. Patients receiving pembrolizumab monotherapy showed increases reaching only 2.5-fold.

According to Inhibrx, this biological evidence provides mechanistic validation for the clinical outcomes — demonstrating that the underlying immune system activation aligns with the patient benefit observed in the trial.

Toxicity Profile Deemed Acceptable

The combination regimen produced a safety profile that company officials characterized as manageable and aligned with expectations for dual immunotherapy approaches.

The most frequently observed treatment-related adverse events included rash, diarrhea, fatigue, and infusion-related reactions. The majority of these events were categorized as low-grade in severity.

Neither treatment arm reported any deaths attributed to the study medications.

Inhibrx indicated that progression-free survival outcomes from the Phase 2 segment are projected for release in Q4 2026.

The Phase 3 component of the HexAgon study is scheduled to commence patient enrollment during Q3 2026.

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