Key Highlights
- Shares of Inhibrx Biosciences climbed 17% Monday following encouraging Phase 2 clinical data for its head-and-neck cancer treatment INBRX-106.
- When paired with pembrolizumab, the therapy delivered a 44% objective response rate compared to just 21.4% for pembrolizumab monotherapy.
- In the evaluable patient population, 11 out of 25 patients responded to the combination versus 6 out of 28 receiving standard treatment; the combination arm recorded three complete responses while the control arm had none.
- Patients receiving the combination therapy 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 readout anticipated in Q4 2026.
Shares of Inhibrx Biosciences (INBX) surged 17% Monday following the release of encouraging interim Phase 2 data from the HexAgon clinical study evaluating INBRX-106 for treating head and neck cancer.
Inhibrx Biosciences, Inc., INBX
The biotech’s shares had already skyrocketed over 1,000% in the preceding 12 months, fueled by favorable data from INBRX-109, another oncology candidate, released last October.
The clinical trial evaluated INBRX-106 — characterized as a hexavalent OX40 agonist — combined with pembrolizumab versus pembrolizumab monotherapy. Study participants were treatment-naïve, first-line patients with PD-L1 positive, metastatic or unresectable recurrent head and neck squamous cell carcinoma.
The combination therapy arm achieved a confirmed objective response rate of 44%. By comparison, the control group receiving pembrolizumab monotherapy recorded a 21.4% response rate — representing a substantial 22.6 percentage point advantage.
The trial enrolled a total of 68 participants, with 33 assigned to combination therapy and 35 to the control group. Among the evaluable patient cohort of 53 individuals, analysis showed clear differentiation.
Specifically, 11 of 25 evaluable patients in the combination cohort demonstrated tumor response. Just 6 of 28 patients responded in the pembrolizumab-only group.
Notably, three patients achieved complete responses with the INBRX-106 combination regimen. Zero complete responses occurred in the control cohort.
Immune System Activation Data Reinforces Clinical Findings
Beyond tumor response metrics, immunological biomarker data proved particularly compelling. Patients treated with the combination demonstrated mean increases in CD8+ and CD4+ T-cell proliferation reaching up to 15-fold levels. Pembrolizumab monotherapy patients exhibited increases only up to 2.5-fold.
According to Inhibrx, these findings offer mechanistic validation for the observed clinical benefits — essentially confirming that the biological activity aligns with patient outcomes.
CEO Mark Lappe expressed that the organization was “greatly encouraged by these early clinical results,” emphasizing particularly the quality and depth of tumor responses already evident in treated patients.
Tolerability Profile Deemed Acceptable
The combination treatment demonstrated a tolerability profile that investigators characterized as manageable and aligned with expectations for dual immunotherapy approaches.
The most frequently observed treatment-emergent adverse events included rash, diarrhea, fatigue, and infusion-related reactions. The majority of these events were classified as low-grade in severity.
Importantly, no treatment-related fatalities occurred in either study arm.
Inhibrx indicated that progression-free survival analysis from the Phase 2 segment is projected for Q4 2026.
The Phase 3 segment of the HexAgon study is scheduled to commence patient enrollment in Q3 2026.
