This is a phase 2 Study to investigate the safety, tolerability, and anti-tumor activity of golidocitinib in combination with sintilimab as the front-line treatment for patients with metastatic PD-L1 positive non-small cell lung cancer (NSCLC)

Inclusion Criteria:

1. Be able to provide a signed and dated, written informed consent.
2. Adults aged ≥18 to 75 years.
3. ECOG performance status 0-1.
4. Predicted life expectancy ≥ 12 weeks
5. Histologically or cytologically confirmed non-small-cell lung cancer (NSCLC) , Stage IIIB/IIIC (not suitable for concomitant chemoradiotherapy) or Stage IV according to AJCC 8th
6. Without EGFR or ALK mutations.
7. Adequate bone marrow reserve and organ system functions.
8. Patients with stable and symptomatic brain metastasis (BM) can be enrolled.

Part A Dose escalation:

Patients must have relapsed after or been refractory/intolerant to ≥ 1 prior systemic therapy(ies) for NSCLC

Part B dose expansion:

1. At least one measurable lesion according to RECIST 1.1.
2. Previously systemic untreated for advanced disease.
3. PD-L1 TPS ≥ 50% (cohort 1), PD-L1 TPS 1-49% (cohort 2)

Exclusion Criteria:

1. Histopathology confirmed a mixture of NSCLC and small-cell lung cancer
2. Known active central nervous system (CNS) metastases and/or carcinomatous meningitis.
3. Prior malignancy within 5 years
4. History of organ transplantation or hematopoietic stem cell transplantation
5. Sever lung function decline or interstitial lung disease that has required oral or IV steroids
6. Active autoimmune disease requiring systemic therapy within 2 years
7. Immunodeficiency, or being treated with immunosuppressive therapy (including systemic glucocorticoid) within 7 days prior to the first dose of study treatment.
8. Active infections
9. Significant cardiac disorder
10. Other serious or uncontrolled systemic diseases assessed by the investigator.

Part A Dose escalation:

1. Prior systemic therapy with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or stimulatory or synergistic T-cell receptor (CTLA-4、OX-40、CD137) within 4 weeks

Part B Dose Expansion:

1. Any prior systemic anti-tumor therapy
2. Prior systemic immunotherapy, including anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or stimulatory or synergistic T-cell receptor (CTLA-4、OX-40、CD137)