This study aims to explore the correlation of circulating tumor DNA(ctDNA) and the risk of progression in patients with advanced NSCLC who have long-term benefit from first-line immunotherapy (PFS 12 months)

Evidence suggests that circulating tumor DNA (ctDNA) analysis can noninvasively identify minimal residual disease (MRD) in clinical oncology. The researches will be sharply increased about ctDNA potential clinical application in the near future. In the early stage of NSCLC, ctDNA has been indicated to identify those at high risk of recurrence after radical surgery. And this study will focus on those patients with advanced NSCLC who have long-term benefit from first-line immunotherapy (PFS 12 months). 10ml plasma will be collected every three months until disease progression to interrogate ctDNA by high-depth panel sequencing, exploring its prediction value about the risk of progression. Meanwhile, the investigators would like to explore the lead time of detectable ctDNA before regular imaging finding.

Inclusion Criteria:

• Age ≥ 18 years old
• Advanced non-small cell lung cancer (stage IIIB-IV), pathological types limited to squamous cell carcinoma or non-squamous cell carcinoma, driver gene mutations (EGFR/ALK/ROS1) were negative
• General condition: ECOG score 0 or 1
• First-line monotherapy or combination immunotherapy
• The long-term benefit of immunotherapy was defined as PFS=12months
• Tumor tissue samples can be obtained at the time of enrollment, and at least 5 ~ 10 sections can be generated, and the pathological report indicates that the overall tumor content is not less than 10% or NGS testing with a fixed-panel is available; or no tumor tissue is available.
• At least one measurable lesion (except patients with CR after first-line treatment) can be evaluated according to RECIST1.1 standard.
• Have self-awareness, be able to understand the research scheme and voluntarily participate in the study, and can sign the informed consent form
• Have good compliance, be able to cooperate with the collection of specimens from each node and provide corresponding clinical information.

Exclusion Criteria:

• Serious primary diseases of the heart, liver and kidney
• Other malignant tumors within 3 years prior to diagnosis of NSCLC
• Women in pregnancy and lactation
• The active stage of human immunodeficiency virus (HIV) infection
• Patients with active systemic infection, pneumonia, tuberculosis, pericarditis
• Patients who cannot understand the content of the experiment and cannot cooperate and refuse to sign informed consent.

Clinically confirmed advanced NSCLC patients with long-term benefit after first-line immunotherapy