The primary hypothesis is that camrelizumab in combination with pemetrexed/ carboplatin will present a better efficacy for treatment of first line metastatic non-squamous non-small cell lung cancer and minimize the risk of toxicity

This is a prospective, open-label, phase Ⅱ studyto evaluate the efficacy and safetyof camrelizumab combined with pemetrexed/ carboplatin in participants with brain metastases ofnon-squamous non-small cell lung cancer.Paticipant was confirmed without EGFR activating mutation or ALK fusion, and received no prior systemic therapy.Patients would receive camrelizumab in combination with pemetrexed/ carboplatin for 4 cycles，followed by camrelizumab and pemetrexed as maitenance treatment until progression, camrelizumab will be administered no more than 24 months. PD-L1 expression assessed with 22C3 pharmDx assay will be used as a stratification factor.

Inclusion Criteria:

1. Histological or cytological diagnosis of non-squamous non-small cell lung cancer（NSCLC）
2. Patients with asymptomatic BM or intracranial hypertension symptoms can be controlled after dehydration therapy, who can continue medication to maintain stable symptoms at enrollment or during the study;
3. Patients with MRI confirmed parenchymal brain metastases with ≥ 3 brain lesions; or patients with 1-2 brain lesions who are not suitable for or refuse local therapy. At least one measurable lesion must be ≥ 5 mm in diameter in brain lesions; patients with local meningeal metastases are allowed to be included, but those with extensive meningeal metastases are not included;
4. No prior systemic therapy for metastatic NSCLC; chemotherapy and/or radiotherapy as part of neoadjuvant/adjuvant therapy are allowed, but the time interval from the end of surgery to diagnosis of advanced or metastatic disease should be no less than 6 months;
5. Study sites must be able to provide relevant documentation of EGFR mutation and ALK fusion status of subjects which must be negative. If tumor tissue samples at or after the diagnosis of advanced tumors are available, archived within 1 year prior to the first dose or freshly obtained, testing for PD-L1 levels can be performed prior to enrollment or during the study;
6. Age ≥ 18 years;
7. Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1;
8. Life expectancy of more than 3 months;
9. Adequate hematopoietic function, defined as absolute neutrophil count ≥ 1.5 × 109/L, platelet count ≥ 100 × 109 /L, hemoglobin ≥ 90 g/L [no blood transfusion within 7 days or no erythropoietin (EPO) dependence];
10. Adequate liver function, defined as total bilirubin level ≤ 1.5 times the upper limit of normal (ULN); for patients without liver metastases, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels ≤ 2.5 times ULN; for patients with documented liver metastases, AST and ALT levels ≤ 5 times ULN;
11. Adequate renal function, defined as serum creatinine ≤ 1.5 times ULN or calculated creatinine clearance ≥ 60 ml/min (Cockcroft-Gault formula); urine protein in urine routines less than 2+, if the patient has a urine protein ≥ 2+ at baseline, 24-hour urine should be collected and tested to ensure 24-hour urine protein quantification ≤ 1 g;
12. Adequate coagulation, defined as international normalized ratio (INR) or prothrombin time (PT) ≤ 1.5 times ULN; anticoagulant therapy is allowed, as long as the PT is within the intended range of the anticoagulant drugs;
13. Female subjects of childbearing potential should have a negative urine or serum pregnancy test within 7 days prior to receiving the first dose of the study drug (Cycle 1, Day 1). If a urine pregnancy test cannot be confirmed as negative, a blood pregnancy test is required; women and men of childbearing potential must agree to use appropriate methods of contraception or have been surgically sterilized during the study and within 90 days after the last dose of the study drugs;
14. Able to comply with the study and follow-up procedures;
15. Sign the written informed consent prior to the implementation of any study-related procedures.

Exclusion Criteria Subjects who meet any of the following criteria are not eligible for inclusion in this study:

1. Mixed non-small cell and small cell carcinoma, or adenosquamous cell lung cancer with an adenocarcinoma component < 50% (if the adenocarcinoma component is ≥ 50%, the inclusion criteria are met);

2. Currently participating in an interventional clinical trial, or receiving other study drugs or treatment with study devices within 4 weeks prior to the first dose;

3. Patients who have received prior systemic anti-tumor therapy;

4. Patients who have received solid organ or blood system transplantation;

5. Active autoimmune disease requiring systemic therapy (e.g., use of disease modifying drugs, corticosteroids, or immunosuppressants) within 2 years prior to the first dose. Substitution therapy (e.g., thyroxine, insulin, or physiologic corticosteroids for adrenal or pituitary insufficiency, etc.) is not considered systemic therapy;

6. Diagnosis of immunodeficiency or ongoing systemic glucocorticoid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of the study; physiologic doses of glucocorticoids (≤ 10 mg/day of prednisone or equivalent drugs) are allowed;

7. History of noninfectious pneumonitis requiring glucocorticoid therapy within 1 year prior to the first dose or current interstitial lung disease;

8. Known history of human immunodeficiency virus (HIV) infection (i.e., HIV 1/2 antibody positive);

9. Untreated active hepatitis B; Note: subjects with hepatitis B who meet the following criteria are also eligible for inclusion:

   1. HBV viral load must be < 500 IU/ml prior to the first dose, and anti-HBV therapy should be administered at the discretion of the investigator throughout the study to avoid viral reactivation;
   2. For subjects with anti-HBc (+), HBsAg (-), anti-HBs (-), and HBV viral load (-), prophylactic anti-HBV therapy is not required, but viral reactivation needs to be closely monitored;

10. Subjects with active HCV infection (HCV antibody positive and HCV-RNA level higher than the lower limit of detection);

11. Pregnant and lactating women;

12. Known allergy to Camrelizumab, Pemetrexed, Carboplatin, or any of their excipients;

13. Malignancies other than NSCLC within 5 years prior to enrollment, except adequately treated cervical carcinoma in situ, basal cell or squamous epithelial cell skin carcinoma, localized prostatic carcinoma after radical surgery, and ductal carcinoma in situ after radical surgery.

14. Subjects with active pulmonary tuberculosis (TB) are excluded. Suspected active TB need to be excluded by chest x-ray, sputum examination and clinical symptoms and signs.