Pharmaengine Inc., of Taipei, Taiwan, said the first patient was dosed in a phase Ib/II trial of PEP503 (NBTXR3), a nanoparticle formulation of hafnium oxide crystals, in head and neck squamous cell carcinoma (SCC) patients. The prospective, open-label, single-arm, nonrandomized study is designed to determine the optimal dose, safety and preliminary efficacy of PEP503 through intratumor injection in combination with the standard treatment of concurrent chemoradiotherapy in SCC of the oral cavity. A maximum of 42 patients may be enrolled.