Alectinib treatment of the ALK fusion-positive NSCLC and cabozantinib treatment of the MET mutated kidney cancer were accompanied by intolerable side effects, while in the case of the BRCA2 mutant pancreas cancer and the PIK3CA/KRAS-mutated breast cancer cases, deteriorating health conditions resulted in olaparib or alpelisib treatment cessation, respectively. This evidence concerns the gene PIK3CA and breast carcinoma.