Inhibrx’s INBRX-106 shows potential benefit in HNSCC

Inhibrx (INBX) Biosciences announced positive interim results from the randomized, first-line Phase 2 portion of the HexAgon study. The trial evaluated the safety and efficacy of INBRX-106, a hexavalent OX40 agonist, in combination with pembrolizumab – the combination arm – versus pembrolizumab monotherapy – the control arm – in first-line patients with treatment-naive, PD-L1 positive metastatic or unresectable recurrent Head and Neck Squamous Cell Carcinoma, or HNSCC. 11 out of 25 patients in the INBRX-106 combination arm achieved a confirmed objective response, compared with 6 out of 28 patients in the control arm. This represents a 22.6% absolute increase in confirmed responses. Three complete responses were observed in the INBRX-106 combination arm. 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 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 progression-free survival data from the Phase 2 portion of the HexAgon study are expected to become available in Q4. The company plans to begin the Phase 3 portion of the HexAgon study during Q3. In addition, the company is beginning to plan for expansion into the front-line metastatic NSCLC setting, with studies expected to begin in 2027.