Inhibrx's INBRX-106 and Keytruda Combination Therapy Demonstrates Doubled Objective Response Rate in Phase 2 Trial
Positive interim data from the HexAgon Phase 2 trial evaluating INBRX-106, a hexavalent OX40 agonist developed by Inhibrx Biosciences, Inc. (INBX), in combination with Keytruda (pembrolizumab), from Merck & Co., Inc. (MRK), has been announced. The trial, conducted in 68 patients with previously treated, unresectable, or metastatic head and neck squamous cell carcinoma (HNSCC), showed that the combination therapy achieved an objective response rate (ORR) of 44%, more than doubling the 21.4% observed in the Keytruda monotherapy arm. Notably, the combination therapy arm included three patients who achieved complete response (CR), a result not seen in the monotherapy arm, demonstrating a potent anti-cancer effect. This data is attracting significant attention from the academic and industry communities as it represents a potential breakthrough in the OX40-targeted immuno-oncology field, where many global pharmaceutical companies have previously failed.
The success can be attributed to the innovative hexavalent structure design, which overcame the limitations of previous bivalent structures that failed to adequately activate immune T cells. Inhibrx designed INBRX-106 with a hexavalent structure that can simultaneously stimulate OX40 receptors on T cells, effectively overcoming immune suppression in the tumor microenvironment. The clinical results demonstrate that the innovative molecular structure design of the drug can translate into meaningful clinical responses in patients.
The positive clinical results have further fueled interest in Inhibrx Biosciences as a potential M&A target for global pharmaceutical companies. According to reports, Merck, facing the upcoming patent expiration of Keytruda and in need of portfolio diversification, as well as Merck KGaA and Ono Pharmaceutical, are showing significant interest in acquiring Inhibrx to gain access to INBRX-106. While Inhibrx's current market capitalization is less than $2 billion, market analysts suggest that the company's acquisition value could reach up to $9 billion (USD) following the successful Phase 2 trial. Previously, Inhibrx spun out its oncology pipeline through an independent listing after selling its rare disease division to Sanofi for $1.7 billion, further demonstrating the success of this strategy.
Inhibrx plans to initiate the Phase 3 part of the HexAgon trial within the third quarter of this year, based on the interim data. Additionally, the company plans to release additional progression-free survival (PFS) data in the fourth quarter, which will further solidify the drug's credibility by demonstrating long-term survival benefits in patients. Furthermore, Inhibrx plans to initiate a perioperative Phase 2 trial in non-small cell lung cancer (NSCLC) and expand the indication to first-line metastatic NSCLC next year. The company is also exploring the potential for combination therapies with various immunotherapeutic platforms, including cancer vaccines, T-cell engagers, and CAR-T cell therapies, suggesting that INBRX-106's role in the oncology field will continue to expand.
Inhibrx Biosciences (INBX) achieved an objective response rate (ORR) of 44% in its Phase 2 trial, more than double that of the Keytruda monotherapy arm, which is considered a breakthrough in the OX40 field, where companies like AstraZeneca have previously failed. With the HNSCC market expected to grow from $2.53 billion in 2025 to $6 billion in 2033, the Phase 3 trial, scheduled to begin in the third quarter of 2026, has the potential to change the standard of care. In the short term, the progression-free survival (PFS) data, to be released in the fourth quarter of this year, will be a key milestone in demonstrating Inhibrx's short-term pipeline value. In the medium to long term, the company's pipeline value could be valued at up to $9 billion as M&A competition among major pharmaceutical companies, including Merck, intensifies ahead of the Keytruda patent expiration. Industry experts are paying attention to the potential for the hexavalent structure-based immune activation platform to expand to other indications, such as non-small cell lung cancer (NSCLC), and become the standard of care.