Feasibility of Targeting PIK3CA Mutations in Head and Neck Squamous Cell Carcinoma.

PIK3CA is the only frequently-mutated, directly druggable oncogene in head and neck squamous cell carcinoma (HNSCC). However, it is unclear if a molecularly-driven intervention trial can be launched successfully, particularly within a single-institution setting secondary to the infrastructure necessary for mutation detection, mutation prevalence, and patient willingness to participate. This study aimed to evaluate 1) local frequency of PIK3CA activating mutations in HNSCC, 2) timeliness of our mutation-profiling clinical pathway, and 3) patients' willingness to enroll in a novel neoadjuvant drug trial. Tissue biopsies of 25 consecutive cases of HNSCC were tested for activating PIK3CA mutations at three mutational hotspots by real-time polymerase chain reaction. Mutations prevalence and number of working days accrued in determining PIK3CA mutational status were calculated. In addition, 30 HNSCC patients were surveyed prospectively regarding their willingness to participate in a hypothetical drug trial. Survey data were summarized descriptively. 4 of 25 (16 %) tumors harbored a PIK3CA activating mutation, including one at codon E542K, two at codon E545K/D, and one at codon H1047R. On average, this result was obtained in approximately 15 working days (range, 9-24 working days). The majority of patients surveyed (70 %) indicated their willingness to participate in a targeted PIK3CA trial. This study provides evidence that within a single institution, PIK3CA activating mutations can be detected with expected frequency, with sufficient timeliness and sufficient patient interest to mount a targeted intervention trial that may lead to improved tumor response in selected HNSCC patients.