PIK3CA and metastatic neoplasm: Additionally for HPV+ OPSCC patients with recurrent or metastatic disease, rigosertib (a PI3K (phosphatidylinositol-3 kinase) and PLK (Polo-like kinase) signalling pathway inhibitor) is being investigated in a phase II trial (ClinicalTrials.gov, NCT01807546), and in a phase I trial used as initial treatment before platinum based RT-C (ClinicalTrials.gov, NCT02107235).