The primary objective of this study is to evaluate the efficacy and safety of Ensartinib in advanced ALK-positive non-small cell lung cancer, and the mechanisms of population pharmacokinetics and resistance to Ensartinib.

Participants will receive Ensartinib at 225 mg orally once a day (QD). Treatments will continue until disease progression, meeting one of treatment discontinuation criteria (eg, patient decision, adverse event, pregnancy). At the time of disease progression, participants will enter a survival follow-up until death, withdrawal of consent or study closure, whichever occurs earlier. Collection of venous blood sample from participants included 3 times: before treatment, 8 weeks of treatment, and disease progression. Blood specimens of 8 ml were collected each time for ctDNA NGS testing, and evaluation of Ensartinib population pharmacokinetics with blood sampling after 8 weeks.

Inclusion Criteria:

1. Histologically or cytologically confirmed stage III b or IV NSCLC, according to the International Association for the Study of Lung Cancer staging manual in Thoracic Oncology, 8th edition.
2. Documented ALK-positive disease according to FISH , Ventana IHC ,RT-PCR or NGS;
3. Patients must have demonstrated progression during or after ALK-TKI treatment;
4. Eastern cooperative oncology group performance status (ECOG PS) of 0-2, overall survival>3 months;
5. Patients need radiotherapy or can receive radiotherapy, such as bone metastatic lesions, intrapulmonary lesions, adrenal lesions, etc.
6. Initially general blood tests including complete blood count, biochemistry, electrolytes, and urine biochemistry were performed as a routine screening in order to identify any abnormalities.
7. Male and female patients must agree to abstain or to use two highly effective forms of contraception during the treatment period and for 90 days after the last dose of study medication.

Exclusion Criteria:

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Histologically or cytologically confirmed stage III b or IV NSCLC with ALK -rearrangement