Key Highlights
- Shares of Inhibrx Biosciences climbed 17% Monday following encouraging Phase 2 clinical data for INBRX-106 in head-and-neck cancer patients.
- The experimental therapy paired with pembrolizumab delivered a 44% objective response rate compared to 21.4% with pembrolizumab monotherapy.
- Among evaluable patients, 11 of 25 responded in the combination cohort versus 6 of 28 in the monotherapy group; the combination arm recorded three complete responses while the control arm had none.
- 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 and anticipates progression-free survival results in Q4 2026.
Shares of Inhibrx Biosciences (INBX) climbed 17% during Monday trading following the biotechnology company’s announcement of encouraging preliminary Phase 2 data from its HexAgon clinical study evaluating INBRX-106 for head and neck cancer.
Inhibrx Biosciences, Inc., INBX
The biotech’s shares had already soared more than 1,000% during the previous 12 months, largely propelled by encouraging data from a separate oncology candidate, INBRX-109, reported in October.
The clinical study evaluated INBRX-106 — a hexavalent OX40 agonist — administered alongside pembrolizumab versus pembrolizumab administered as a single agent. The patient population consisted of treatment-naïve, first-line, PD-L1 positive individuals with metastatic or unresectable recurrent head and neck squamous cell carcinoma.
Patients receiving the combination regimen achieved a confirmed objective response rate of 44%. Meanwhile, the control cohort treated with pembrolizumab monotherapy registered a 21.4% response rate — representing a 22.6 percentage point advantage for the combination approach.
The trial recruited 68 participants in total, with 33 assigned to the combination cohort and 35 to the control group. The evaluable patient population numbered 53 individuals.
Within this evaluable group, 11 of 25 combination-treated patients demonstrated responses. In contrast, 6 of 28 patients receiving pembrolizumab alone showed responses.
The INBRX-106 combination cohort recorded three complete responses. The control arm documented zero complete responses.
Immune Cell Activity Reinforces Clinical Findings
Beyond objective response metrics, the immunological data proved particularly noteworthy. Participants treated with the combination demonstrated mean increases in CD8+ and CD4+ T-cell proliferation of up to 15-fold. Patients receiving pembrolizumab monotherapy exhibited increases reaching only 2.5-fold.
According to Inhibrx, these findings offer mechanistic validation for the clinical outcomes — essentially demonstrating that the underlying biological activity aligns with the patient responses observed in the trial.
CEO Mark Lappe expressed that the company was “greatly encouraged by these early clinical results,” emphasizing particularly the quality and depth of responses already evident in treated patients.
Tolerability Profile Deemed Acceptable
The combination regimen exhibited a safety profile characterized by the company as manageable and aligned with expectations for a dual immunotherapy approach.
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.
Neither study arm reported any treatment-related fatalities.
Inhibrx indicated that progression-free survival data from the Phase 2 component should become available in Q4 2026.
The Phase 3 segment of the HexAgon study is scheduled to commence in Q3 2026.
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