Inhibrx Reports Interim Phase 2 Data for INBRX-106 in First-Line HNSCC; Initial Results Demonstrate Potential Costimulatory Benefit Over PD-1 Monotherapy
Rhea-AI Summary
Inhibrx (Nasdaq: INBX) reported interim Phase 2 HexAgon data for INBRX-106 plus pembrolizumab in first-line PD-L1–high HNSCC. In 53 response-evaluable patients, the combination showed a 44.0% confirmed objective response rate versus 21.4% with pembrolizumab alone, including three complete responses versus none in control.
Combination treatment produced up to a 15-fold increase in peripheral CD8+ and CD4+ T-cell proliferation and a manageable safety profile without treatment-related deaths. Progression-free survival data are expected in Q4 2026, with a Phase 3 start planned for Q3 2026 and expansion into NSCLC studies.
AI-generated analysis. Not financial advice.
Positive
- Confirmed objective response rate 44.0% vs 21.4% with pembrolizumab alone in evaluable patients
- Three complete responses with INBRX-106 combination vs zero with pembrolizumab monotherapy
- Up to 15-fold increase in CD8+ and CD4+ T-cell proliferation in combination arm
- Safety profile described as manageable with no treatment-related deaths reported
- Phase 3 HexAgon study planned to begin in Q3 2026
- Planned expansion into perioperative and metastatic NSCLC settings from 2026–2027
Negative
- Interim analysis based on 53 of 68 enrolled patients; 15 not yet evaluable
- Key efficacy endpoint progression-free survival not available until expected Q4 2026
- Most common treatment-related adverse events include rash, diarrhea, fatigue, infusion reactions
- Current data limited to PD-L1 CPS ≥ 20, metastatic or unresectable recurrent HNSCC population
News Market Reaction – INBX
On the day this news was published, INBX declined 5.04%, reflecting a notable negative market reaction. Argus tracked a peak move of +11.9% during that session. Argus tracked a trough of -30.6% from its starting point during tracking. Our momentum scanner triggered 44 alerts that day, indicating elevated trading interest and price volatility. This price movement removed approximately $104M from the company's valuation, bringing the market cap to $1.96B at that time.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Market Reality Check
Peers on Argus
INBX is up 7.89% on positive Phase 2 HNSCC data. Only one peer in the momentum scanner (PRTA, up 5.69%) and broader peers show mixed moves (e.g., LXRX +18.34%, DMAC -3.08%, PRTA -2.45%), indicating a stock-specific reaction rather than a sector-wide move.
Previous Clinical trial Reports
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| Oct 23 | Registrational trial win | Positive | +102.0% | Positive topline ozekibart chondrosarcoma data with strong PFS benefit. |
| Jan 21 | Early colorectal data | Positive | -4.2% | Preliminary Phase 1 ozekibart colorectal combo data with durable disease control. |
Clinical trial readouts have often produced large moves, including a triple‑digit gain on strong registrational data, but direction has not been uniformly positive.
Over the last year, Inhibrx has repeatedly moved on clinical data. A Jan 21, 2025 Phase 1 colorectal update caused a modest decline despite promising responses, while a Oct 23, 2025 registrational chondrosarcoma win drove a 102.01% jump. Today’s INBRX‑106 Phase 2 HNSCC results add another positive clinical catalyst alongside ozekibart’s late‑stage progress, reinforcing a narrative of pipeline‑driven value but with volatile event‑driven reactions.
Historical Comparison
Past clinical trial headlines for INBX moved the stock by an average of 48.93%. Today’s 7.89% move on INBRX‑106 HNSCC data is smaller but directionally consistent with prior positive readouts.
Clinical news flow shows advancement from early ozekibart colorectal data to registrational success in chondrosarcoma, while INBRX‑106 now contributes randomized Phase 2 proof‑of‑concept in first‑line HNSCC.
Market Pulse Summary
The stock moved -5.0% in the session following this news. A negative reaction despite positive interim efficacy would fit the stock’s occasionally contrarian responses to clinical updates. While the combo shows a 22.6% absolute cORR advantage and three complete responses, investors may focus on interim nature, sample size of 68 patients, or future trial costs. Given past volatility around clinical and regulatory milestones, sentiment could diverge from the apparent strength of early data as new information arrives.
Key Terms
objective response rate medical
cORR medical
pd-1 medical
pd-l1 medical
progression-free survival medical
non-small cell lung cancer medical
checkpoint inhibitors medical
car-ts medical
AI-generated analysis. Not financial advice.
- Interim analyses show INBRX-106 + pembrolizumab achieved a
44.0% confirmed Objective Response Rate (cORR): In the preliminary confirmed response-evaluable population, the INBRX-106 + pembrolizumab combination achieved a cORR of44.0% versus21.4% with pembrolizumab alone, representing a22.6% absolute increase in cORR. - Superior depth of response: Responding patients in the combination arm demonstrated deeper tumor reductions overall, with the majority achieving target lesion shrinkage exceeding
50% ; notably, three patients achieved a complete radiographic response. - Up to 15-fold mean increase in systemic T-Cell expansion: Peripheral blood analysis showed robust CD8+ and CD4+ T-cell proliferation in combination-treated patients, providing mechanistic support for the observed clinical activity.
- Manageable safety profile: The combination demonstrated a manageable preliminary safety profile consistent with that expected from an immunotherapy combination.
HNSCC was selected as a proof-of-concept indication, as PD-1 monotherapy is active in this tumor type but leaves significant room for improvement. The trial design was modeled after KEYNOTE-048, focusing on patients with high PD-L1 expression (CPS ≥ 20) in order to further sharpen the ability to detect a treatment effect above checkpoint inhibition alone. A clear signal of added benefit in this study design would support INBRX-106's potential to enhance checkpoint inhibitor efficacy across checkpoint inhibitor-sensitive indications.
The Phase 2 portion of the HexAgon study enrolled 68 patients: 33 randomized to the combination arm and 35 to the control arm. Baseline prognostic factors are largely balanced between both arms and the study is being conducted at over 80 sites in
In the evaluable population, 11 out of 25 patients (
These clinical findings were supported by pharmacodynamic data, which showed up to a 15-fold increase in peripheral CD8+ and CD4+ T-cell proliferation and up to a four-fold increase in activation in INBRX-106 combination-treated patients compared with up to 2.5-fold and 1.5-fold increases, respectively, in those receiving pembrolizumab alone. The observation of robust systemic T-cell expansion and activation in combination-treated patients, alongside the clinical activity observed in this arm, is consistent with the expected mechanism of action of INBRX-106 as a potent T-cell costimulator.
The combination of INBRX-106 and pembrolizumab was generally manageable, with a safety profile consistent with the addition of an active immunostimulatory agent to checkpoint blockade. The most common treatment-related adverse events were rash, diarrhea, fatigue, and infusion-related reactions, which were predominantly low-grade. No treatment-related deaths were reported in either arm.
"We are greatly encouraged by these early clinical results," said Mark Lappe, Chief Executive Officer of Inhibrx. "These data, coupled with the clear evidence of T-cell expansion and superior depth of response, give us confidence that INBRX-106 could be the first costimulatory agent to fundamentally shift the efficacy ceiling of immunotherapy, and open the door to combinations with new modalities that could be enhanced by OX40 agonism."
Next Steps
The progression-free survival data from the Phase 2 portion of the HexAgon study are expected to become available in the fourth quarter of 2026. The Company plans to begin the Phase 3 portion of the HexAgon study during the third quarter of 2026.
Based on these promising early results, the Company also aims to evaluate INBRX-106 across broader indications to potentially improve the efficacy of checkpoint inhibitors. This strategy includes initiating a study in the perioperative setting in non-small cell lung cancer (NSCLC) later this quarter. The Company believes OX40 agonism has the greatest potential to drive cure in earlier-stage disease settings, where patients typically retain a more active and responsive immune system. In addition, the Company is beginning to plan for expansion into the front-line metastatic NSCLC setting, with studies expected to begin in 2027. Outside of combination with checkpoint inhibitors, the Company plans to explore combinations with agents that could benefit from T-cell costimulation, such as vaccines, T-cell engagers, and CAR-Ts.
About INBRX-106
INBRX-106 is a hexavalent agonist targeting OX40 (CD134), a costimulatory receptor on T-cells. Utilizing Inhibrx's proprietary single-domain antibody (sdAb) platform, INBRX-106 is designed to achieve the high-order receptor clustering necessary for robust T-cell activation and survival, a feat that has eluded traditional bivalent antibody approaches. To date, over 175 patients have been treated with INBRX-106.
About Inhibrx Biosciences, Inc.
Inhibrx Biosciences is a clinical-stage biopharmaceutical company focused on developing a broad pipeline of novel biologic therapeutic candidates. Inhibrx Biosciences utilizes diverse methods of protein engineering to address the specific requirements of complex target and disease biology, including its proprietary protein engineering platforms. Inhibrx Biosciences was incorporated in January 2024 as a direct, wholly-owned subsidiary of Inhibrx, Inc. Prior to the sale of Inhibrx, Inc. and the INBRX-101 program to Sanofi S.A., Inhibrx Biosciences acquired certain corporate infrastructure and other assets and liabilities through a series of internal restructuring transactions effected by Inhibrx, Inc. Inhibrx, Inc. also completed a distribution to holders of its shares of common stock of
Forward-Looking Statements
Inhibrx cautions you that statements contained in this press release regarding matters that are not historical facts are forward-looking statements. These statements are based on Inhibrx's current beliefs and expectations. These forward-looking statements include, but are not limited to, statements regarding: Inhibrx's judgments and beliefs regarding the strength of Inhibrx's pipeline; statements regarding the safety and efficacy of its therapeutic candidate, INBRX-106, based on topline and interim results; the potential for INBRX-106 to be used for the treatment of HNSCC; the clinical development of INBRX-106, including expected enrollment in the expansion cohort, data readouts, regulatory submissions and interactions, and the timing thereof; any presumption that topline, interim or preliminary data will be representative of final data or data in later clinical trials, including data from the remaining 15 patients in the overall population for the Phase 2 trial for INBRX-106 in first-line HNSCC; Inhibrx's plans to evaluate INBRX-106 across broader indications and to explore combinations with other therapies; Inhibrx's plans to expand into the front-line metastatic NSCLC setting, with studies expected to begin in 2027; and Inhibrx's plans to begin the Phase 3 portion of the HexAgon study during the third quarter of 2026. Actual results may differ from those set forth in this press release due to the risks and uncertainties inherent in Inhibrx's business, including, without limitation, risks and uncertainties regarding: topline data may not accurately reflect the complete results of a particular study or trial and remain subject to audit, and final data may differ materially from topline data; the initiation, timing, progress and results of its preclinical studies and clinical trials, and its research and development programs; its ability to advance therapeutic candidates into, and successfully complete, clinical trials; its interpretation of topline, interim or preliminary data from its clinical trials, including interpretations regarding disease control and disease response; results from preclinical studies or early clinical trials not necessarily being predictive of future results; unexpected adverse side effects or inadequate efficacy of its therapeutic candidates that may limit their development, regulatory approval and/or commercialization; the potential for its programs and prospects to be negatively impacted by developments relating to its competitors, including the results of studies or regulatory determinations relating to its competitors; the timing or likelihood of regulatory filings and approvals and regulatory developments in the
Investor and Media Contact:
Kelly Deck, CFO
ir@inhibrx.com
858-795-4260
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SOURCE Inhibrx Biosciences, Inc.