Dynamic PET/CT Evaluated the Response of Neoadjuvant Anti-PD1 Combination With Chemotherapy for Ⅱa-Ⅲb NSCLC

Inclusion Criteria: * Histologically or cytologically confirmed NSCLC, performed on a biopsy that occurred within the last 60 days * Computed tomography (CT) and Dynamic PET-CT within the last 30 days showing radiographic stage Ⅱa to Ⅲb lung cancer (mediastinal staging biopsy is allowed but not required) by the American Joint Committee on Cancer (AJCC) 8th edition * Potentially surgically resectable by a senior thoracic surgeon * No driver gene mutation. * Age≥18 years, and ≤75 years * Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 as assessed by the investigator * Adequate tissue specimens for correlative biomarker analysis. The patient should be willing to provide tissue from a newly obtained biopsy of a tumor lesion and surgical resected tumor lesion. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Resolution of all acute toxic effects of prior chemotherapy, radiotherapy or surgical procedures to NCI CTCAE version (v)5.0 grade 1 * Be willing and able to provide written informed consent for the trial * Absolute neutrophil count (ANC) \>= 1500 cells/ microlitre(uL) (within 10 days prior to the start of trial treatment). Platelets \>= 100 000 cells/uL (within 10 days prior to the start of trial treatment). Hemoglobin \>= 9.0 g/dL or \>= 5.6 mmol/L (criteria must be met without erythropoietin dependency and without packed red blood cell (pRBC) transfusion within last 2 weeks) (within 10 days prior to the start of trial treatment). Creatinine =\< 1.5 x upper limit of normal (ULN) OR measured or calculated creatinine clearance, glomerular filtration rate (GFR) can also be used in place of creatinine or creatinine clearance (CrCl) \>= 30 mL/min for patients with creatinine levels \> 1.5 x institutional ULN (within 10 days prior to the start of trial treatment) * Total bilirubin =\< 1.5 x ULN OR direct bilirubin =\< ULN for patients with total bilirubin levels \> 1.5 x ULN (within 10 days prior to the start of trial treatment) * Aspartate aminotransferase (AST) or serum glutamic-oxaloacetic transaminase (SGOT) and alanine aminotransferase (ALT) or serum glutamate pyruvate transaminase（SGPT) =\< 2.5 x ULN (=\< 5 x ULN for patients with liver metastases) (within 10 days prior to the start of trial treatment) * International normalized ratio (INR) OR prothrombin time (PT) =\< 1.5 x ULN unless patient is receiving anticoagulant therapy as long as PT or partial thromboplastin time (PTT) is within therapeutic range of intended use of anticoagulants (within 10 days prior to the start of trial treatment) * Activated partial thromboplastin time (aPTT)/PTT =\< 1.5 x ULN unless patient is receiving anticoagulant therapy as long as PT or partial thromboplastin time (PTT) is within therapeutic range of intended use of anticoagulants (within 10 days prior to the start of trial treatment) * Female patients of childbearing potential must have a negative urine or serum pregnancy test within 72 hours prior to receiving the first dose of trial medication. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required * Male and female patients of childbearing potential must be willing to use an adequate method of contraception as outlined, for the course of the trial through 120 days after the last dose of trial drug o Note: Abstinence is acceptable if this is the usual lifestyle and preferred contraception for the patient Exclusion Criteria: * Any approved anticancer therapy, including chemotherapy, hormonal therapy, or radiotherapy, within 5 years prior to initiation of study treatment; however, the following are allowed: * Hormone-replacement therapy or oral contraceptives * Herbal therapy \> 1 week prior to Cycle 1, Day 1 (herbal therapy intended as anticancer therapy must be discontinued at least 1 week prior to Cycle 1, Day 1) * Malignancies other than the disease under study within 5 years prior to Cycle 1, Day 1, with the exception of those with a negligible risk of metastasis or death and with expected curative outcome or undergoing active surveillance per standard-of-care management (e.g., chronic lymphocytic leukemia Rai Stage 0, prostate cancer with Gleason score ≤ 6, and prostate-specific antigen (PSA) ≤ 10 mg/mL, etc.) * Patients who are receiving any other investigational agents concurrently. * History of allergic reactions attributed to compounds of similar chemical or biologic composition to pembrolizumab, cisplatin, carboplatin, pemetrexed or gemcitabin. * Patients with active hepatitis B or C infections or a history of HIV infection. * Patients with past or resolved hepatitis B infection, defined as having a negative hepatitis B surface antigen (HBsAg) test and a positive for the antibody test to detect antibodies to hepatitis B core antigen (anti-HBc) are eligible. * Patients positive for hepatitis C virus (HCV) antibody are eligible only if polymerase chain reaction (PCR) is negative for HCV RNA. * Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection including tuberculosis (TB), symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements. * Known clinically significant liver disease, including active viral, alcoholic, or other hepatitis; cirrhosis; fatty liver; and inherited liver disease * Patients with controlled Type 1 diabetes mellitus on a stable insulin regimen may be eligible. * Severe infections within 4 weeks prior to Cycle 1, Day 1, including but not limited to hospitalization for complications of infection, bacteremia, or severe pneumonia * Signs or symptoms of infection within 2 weeks prior to Cycle 1, Day 1 Received oral or IV antibiotics within 2 weeks prior to Cycle 1, Day 1. Patients receiving prophylactic antibiotics (e.g., for prevention of a urinary tract infection or chronic obstructive pulmonary disease) are eligible * Major surgical procedure within 28 days prior to Cycle 1, Day 1 or anticipation of need for a major surgical procedure during the course of the study * Administration of a live, attenuated vaccine within 4 weeks before Cycle 1, Day 1 or anticipation that such a live, attenuated vaccine will be required during the study * Pregnant women * History of interstitial lung disease or pneumonitis of any cause * Is ineligible for an operation based on medical or oncologic contraindications to surgery * Is currently participating in or has participated in a trial of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of trial treatment o Note: Patients who have entered the follow-up phase of an investigational trial may participate as long as it has been 4 weeks after the last dose of the previous investigational agent