Inhibrx's INBRX-106 Shows Promising Efficacy in HNSCC During Phase 2 Trials

Inhibrx Reports Encouraging Interim Results for INBRX-106 in Phase 2 Trials

Inhibrx Biosciences, a clinical-stage biopharmaceutical firm, presented new interim results from the randomized Phase 2 HexAgon study. This trial aimed to evaluate the safety and efficacy of INBRX-106, a hexavalent OX40 agonist, in combination with pembrolizumab compared to pembrolizumab monotherapy, particularly for patients with treatment-naïve, PD-L1 positive metastatic or unresectable recurrent Head and Neck Squamous Cell Carcinoma (HNSCC).

The interim analyses revealed a confirmed Objective Response Rate (cORR) of 44.0% in patients treated with the INBRX-106 and pembrolizumab combination, significantly higher than the 21.4% cORR from those receiving only pembrolizumab. This 22.6% absolute increase in response rates is noteworthy, highlighting the potential advantages of adding INBRX-106 in treatment strategies. Furthermore, among those responding to the combination treatment, the majority exhibited over 50% tumor shrinkage, with three patients achieving a complete radiographic response, an outcome that remains rare in HNSCC treatments.

The trial enrolled a total of 68 patients, with 33 assigned to the combination treatment and 35 to the control group. In the response-evaluable population—53 patients in total—11 out of 25 in the combination group achieved confirmed responses. These results are especially pertinent since PD-1 monotherapy has shown limited success in HNSCC, and the addition of INBRX-106 could provide a new avenue for improving outcomes.

A peripheral blood analysis showcased impressive T-cell activity among patients receiving the combination treatment. CD8+ and CD4+ T-cell counts revealed a mean expansion increase of up to 15-fold, supporting the mechanism behind the observed clinical outcomes and demonstrating the positive impact of OX40 agonism. While managing a generally well-tolerated safety profile, the most common side effects included rash, diarrhea, fatigue, and infusion-related reactions, mostly low-grade.

Mark Lappe, CEO of Inhibrx, expressed optimism about the findings, stating, “These early clinical results coupled with confirmed T-cell expansion support the potential for INBRX-106 to redefine immunotherapy efficacy.” The subsequent steps for the HexAgon study are crucial, with progression-free survival data anticipated in Q4 2026 and plans to commence a Phase 3 study by Q3 2026. The company aims to broaden its investigation of INBRX-106 to encompass other indications, including studies in non-small cell lung cancer (NSCLC).

With the potential to combine with various treatment strategies—such as vaccines and CAR-T therapies—INBRX-106 represents an innovative step forward in harnessing the immune system's capabilities in combating cancer. As Inhibrx advances this promising research, the implications for cancer immunotherapy could be transformative, expanding treatment opportunities and improving patient outcomes in challenging cases like HNSCC.

Conclusion

The encouraging interim data from Inhibrx regarding INBRX-106 may signal a fundamental shift in the treatment landscape for HNSCC and potentially other malignancies. Further research will be essential to validate these findings and determine the long-term impact of this novel therapeutic approach.