To cite an example – pharmacodynamic tissue studies conducted on a phase I/II trial of erlotinib and cisplatin in patients with recurrent or metastatic HNSCC showed that high EGFR gene copy in tumor specimens may predict which patients are likely to respond to erlotinib, and decreased p-EGFR level in skin biopsies during therapy may represent a potential surrogate marker for improved clinical outcome. The gene discussed is EGFR; the disease is neoplasm.