In a study on 100 resistant tumor samples from 44 patients [29], an alteration in the MAPK pathway was detected in 70% of the progressive tumors, while alterations of the PI3K –AKT pathway were detected in 22%; in 20% of patients, at least two mechanisms of resistance were detected in the same patient, and the alterations involved both pathways in all cases except for one; 13/16 patients, from whom multiple progressive biopsies were available, harbored multiple mechanisms of resistance. The gene discussed is PIK3CA; the disease is neoplasm.