Envafolimab Plus Docetaxel In Combination With or Without Trilaciclib Versus Docetaxel in Advanced NSCLC

Inclusion Criteria: * Male or female subjects aged≥ 18 years old * Metastatic or advanced (stage IV) NSCLC confirmed by tissue or pathology * Patients with advanced NSCLC who had previously failed treatment with platinum-containing chemotherapy combined with PD-1 inhibitor * Disease must be measurable by Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1).,and has at least one measurable lesion * Patients with asymptomatic brain metastasis or whose symptoms are stable after treatment * Patients who responded to initial therapy or whose disease was stable for at least 3 months * Laboratory tests met the following criteria: 1. Hemoglobin (Hb)≥100 g/L(female), ≥110g/L(male) 2. Neutrophils (ANC)≥1.5×109/L 3. platelet count (PLT)≥100×109/L 4. Cr≤ 15mg/L or CrCl≥ 60 mL/min 5. TBIL≤ 1.5×ULN 6. ALT and AST ≤ 3 × ULN or ≤5× ULN(patients with liver metastases) 7. Albumin ≥ 30 g/L * Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 1 * Estimated life expectancy of more than 12 weeks * Women: All women with potential fertility must have negative serum pregnancy tests during the screening period and must have reliable contraception after signing the informed consent form until 3 months after the last dose * Already signed an informed consent form Exclusion Criteria: * Diagnosis of other malignancies than NSCLC within 5 years prior to the first dose administration (excluding radically treated cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma, and/or radically resected carcinoma in situ) * Toxicity not recovered to ≤ Grade 1 from prior anticancer therapy * Previous treatment with PD-L1 inhibitors * ≥grade 3 immune-related adverse reactions have occurred during previous PD-1 inhibitors treatment * Patients with known or suspected interstitial pneumonia * Patients with known positive driving genes(EGFR,ALK,ROS1) * Have used or requirement of treatment with prednisone \> 10 mg/day or equivalent systemic corticosteroids within 14 days prior to the first dose of study drug * Administration of live attenuated vaccines within 28 days prior to the first study drug treatment or planned administration during the study * Uncontrolled ischemic heart disease or clinically significant congestive heart failure (NYHA grade III or IV) * Have stroke or cardiovascular events within 6 months prior to enrollment * QTcF\>480 msec or QTcF\>500 msec(patients with ventricular pacemakers) * Patients who have received hematopoietic stem cell or bone marrow transplants * Allergic to the study drug or its ingredients * Any other circumstances in which the researcher believes that the patient is not suitable to participate in this study