Methods employing and uses of a compound of formula (I) in inhibiting the growth of a tumor cell in a subject in need thereof. Methods employing and uses of a compound of formula (I) in treating pancreatic cancer in a subject in need of treatment for pancreatic cancer. Methods employing and uses of a compound of formula (I) in treating HER-2 positive breast cancer in a subject in need of treatment for HER-2 positive breast cancer. Methods employing and uses of a compound of formula (I) in treating drug resistant non-small cell lung cancer in a subject in need of treatment for drug resistant non-small cell lung cancer. Each of these methods can include administering to the subject an effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof.Method of manufacturing a medicament including a compound of formula (I) for treating a subject suffering from growth of a tumor cell; for treating a subject suffering from pancreatic cancer; for treating a subject suffering from HER-2 positive breast cancer; or for treating a subject suffering from drug resistant non-small cell lung cancer.