This is a prospective, single arm, phase II study to evaluate the efficacy and safety of Envafolimab in subjects with locally advanced/unresectable (Stage III) non-small cell lung cancer that has not progressed after prior concurrent/sequential chemoradiotherapy.

Trial design: This is a single-arm, open-label trial in patients with locally advanced/unresectable (stage III) NSCLC who did not have disease progression after concurrent/sequential chemoradiotherapy to evaluate the efficacy of Envafolimab as a consolidation treatment of the efficacy and safety.

Background:The PACIFIC and GEMSTONE-301 studies have shown the efficacy of immunization as consolidation therapy in stage III NSCLC.

Patients with stage III NSCLC who did not have disease progression after at least two cycles of concurrent/sequential chemoradiotherapy (including platinum) will receive Envafolimab (300mg, Q3W, subcutaneous injection) within 1-42 days after the end of chemoradiotherapy. The maximum duration of Envafolimab treatment is 2 years.

Inclusion Criteria:

1. Age at least 18 years.
2. Have histologically confirmed locally advanced/unresectable stage III non-small cell lung cancer.
3. The first dose of Envafolimab will be administered within 1-42 days (including 42 days) after concurrent/sequential chemoradiotherapy is completed.
4. ECOG performance status 0-2.
5. Life expectancy ≥ 12 weeks.
6. Adequate organ function.
7. For female subjects of childbearing age, urine or serum pregnancy test shall be conducted before receiving the first study drug administration, and the result is negative.
8. The subject and the subject's sexual partner need to use a medically approved contraceptive measure during the study treatment period and within 6 months after the end of the study treatment period.
9. Willing to participate in this trial; fully understand and informed of this trial, and able to provide written informed consent form (ICF).

Exclusion Criteria:

1. Disease progression after concurrent/sequential chemoradiotherapy.
2. Has received a live vaccine within 28 days prior to the first dose of investigational product.
3. Major surgical procedure (as determined by investigators) within 28 days prior to the first dose of investigational product.
4. Known positive driver gene mutation, such as EGFR sensitive mutation, ALK gene translocation or ROS1 rearrangement.
5. Received any antibody/drug targeting T-cell coregulatory proteins (immune checkpoints), with a washout period of less than 28 days.
6. Known history of human immunodeficiency virus (HIV) infection and/or acquired immune deficiency syndrome.
7. Subjects at active phase of chronic hepatitis B or with active hepatitis C.
8. History of organ transplantation.
9. History of inflammatory bowel disease or active inflammatory bowel disease (for example Crohn's disease or ulcerative colitis).
10. Severe allergic reaction to other monoclonal antibodies.
11. Subjects with other conditions that in the investigator's opinion may influence subject's compliance or make subjects not suitable for participating in this trial.