Phase II Study of Tipifarnib in Squamous Head and Neck Cancer With HRAS Mutations

This Phase II study will investigate the antitumor activity in terms of ORR of tipifarnib in subjects with locally advanced, unresectable or metastatic, relapsed and/or refractory tumors that carry HRAS mutations and for whom there is no curative therapy available. Subjects with information available on tumor HRAS status previously generated are eligible. All subjects must consent to provide at least 10 tumor slides from a prior diagnostic biopsy for a retrospective testing of HRAS gene status at a central facility. Subjects will be enrolled into three nonrandomized cohorts: * Cohort 1: Malignant thyroid tumors with HRAS mutations. * Cohort 2: Squamous Cell Carcinoma Head and Neck Cancer with HRAS mutations. * Cohort 3: Squamous Cell Carcinoma (SCC) with HRAS mutations other than HNSCC.