9291 is the code name of the experimental drug, the full name is called AZD9291, different people, drug resistance occurs at different times, need to be specifically analyzed, the initial treatment of patients about 18 months drug resistance, second-line treatment patients about one year drug resistance. The drug now on the market is called ositinib, is used to treat non-small cell lung adenocarcinoma 3rd generation targeted drugs, following erlotinib, gefitinib resistance can be selected after the 3rd generation of TKI class small molecule drugs. As a patient, there is no need to worry too much about the emergence of drug resistance time. As long as in accordance with the prescribed usage, take it every day, the emergence of adverse reactions, if it is a mild case can be tolerated, if the symptoms are slightly heavier, appropriate to the hospital consultation, the use of relevant treatments to alleviate the adverse reactions, try to prolong the duration of the medication, there is a certain benefit. Patients with medication is one aspect, psychological treatment is also one aspect, do not due to too much worry about drug resistance things affect their mood of treatment. As long as under the guidance of the doctor to receive standardized treatment, while paying attention to regular review.