This study is an open-label, phase I clinical study to evaluate the efficacy, tolerability and safety of recombinant fully human anti-TIGIT antibody (IBI939) in combination with recombinant fully human anti-programmed cell death receptor 1 (PD-1) antibody (sintilimab) in subjects with advanced lung cancer.

Inclusion Criteria:

1. Signed the Informed Consent Form;
2. Male or female ≥ 18 and≤75 years of age;
3. Life expectancy ≥ 12 weeks;
4. Eastern Cooperative Oncology Group Performance Status (ECOG PS) score is 0 or 1
5. Have at least 1 lesion (not previously irradiated) with an accurately measured longest diameter ≥ 10 mm by computed tomography (CT) or magnetic resonance imaging (MRI) (intravenous contrast agent is preferred) at baseline (except lymph nodes which must have short axis ≥ 15 mm) according to RECIST V1.1 and lesions amenable to repeated accurate measurements.
6. Histologically or cytologicallyconfirmed non-small cell lung or small cell lung cancer

Exclusion Criteria:

1. Previous exposure to immune-mediated therapy; previous use of antitumor vaccine;
2. Received the last anti-tumor therapy within 4 weeks prior to the first dose of study drug;
3. Received any investigational agent within 4 weeks prior to the first dose of study drug;
4. Received systemic treatment with Chinese herbal medicine indicated for cancer or drugs used for immunoregulation (including thymosin, interferon, interleukin, except for local use for pleural effusion) within 2 weeks before the first dose;
5. Are participating in another interventional clinical study, or observational (non-interventional) clinical study or in the follow-up phase of an interventional study;