Inclusion Criteria:
* 1\. Male or female, aged ≤ 80 years old
* 2\. ECOG performance status of 0-1
* 3\. Histologically or cytologically confirmed, unresectable Stage III (IIIA-N2, IIIB and IIIC) NSCLC according to 8th version of the International Association for the Study of Lung Cancer Staging Manual in Thoracic Oncology.
* 4\. Patients who have documentation of KRAS p.G12C prior to enrollment. This determination can be done either by solid or liquid biopsy.
* 5\. No prior treatment for unresectable Stage III (IIIA-N2, IIIB and IIIC) NSCLC.
* 6\. Having a life expectancy ≥ 12 weeks
* 7\. Patients must be ineligible for concurrent chemo-radiotherapy because of:
1. Tumor size ≥ 5 cm and lymph node N2 involvement
2. The target lesion has to be bulky disease and/or more than 35% of the total volume of the two lungs should receive more than 20 Gy (V20) or inadequate pulmonary function
3. Interstitial Lung diseases
4. Prior treatment with thoracic radiotherapy for any reason
5. Or under decision of a tumor committee as inappropriate due to local characteristics to perform treatment upfront
* 8\. PET-CT at baseline is mandatory to confirm the absence of distant disease and to confirm unresectable disease
* 9\. PET-CT positive mediastinic adenopathies must be histologically confirmed. Mediastinic involvement could be considered without histological test when no margin can be distinguished in the lymph node mass.
* 10\. Brain CT or MRI is mandatory
* 11\. Patients with at least 1 measurable lesion, as defined by RECIST v1.1.
* 12\. Adequate hematologic and organ function.
* 13\. All patients are notified of the investigational nature of this study and signed a written informed consent in accordance with institutional and national guidelines, including the Declaration of Helsinki prior to any trial-related intervention.
* 14\. Willingness and ability to comply with scheduled visits and study procedures
* 15\. For female patients of childbearing potential, a negative pregnancy test must have been documented prior to enrollment (within 14 days prior to enrollment).
* 16\. For female patients of childbearing potential, agreement (by patient and/or partner) to usea highly effective form(s) of contraception that results in a low failure rate (\< 1% per year)when used consistently and correctly, and to continue its use for 7 days after the last dose of AMG510 (Sotorasib). No hormonal methods and preferably barrier method always containing a spermicide, intrauterine device (IUD): intrauterine hormone-releasing system (IUS), bilateral tubal occlusion, vasectomized partner (on the understanding that this is the only one partner during the whole study duration), and sexual abstinence.
* 17\. For male patients with female partners of childbearing potential, agreement (by patient and/or partner) to use a highly effective form(s) of contraception that results in a low failure rate \[\< 1% per year\] when used consistently and correctly, and to continue its use for 7 days after the last dose of AMG510 (Sotorasib).
* 18\. Women who are not postmenopausal (≥ 12 months of non-therapy-induced amenorrhea) or surgically sterile must have a negative serum pregnancy test result within 14 days prior to enrollment.
* 19\. QTc interval must be ≤ 470 msec in females and ≤ 450 msec in males, based on the average obtained from three ECG.
Exclusion Criteria:
* 1\. Patients with a known sensitizing mutation in the epidermal growth factor receptor (EGFR) gene, ALK translocations or ROS1 mutations
* 2\. Weight loss \>10% within the previous 3 months
* 3\. Patients with uncontrolled neuropathy (sensory) grade 2 or greater regardless of cause according to CTCAE v5.0
* 4\. Major surgery within 28 days of study day 1
* 5\. Significant gastrointestinal disorder that results in significant malabsorption, requirement for intravenous alimentation, or inability to take oral medication
* 6\. Significant cardiovascular disease, such as New York Heart Association cardiac disease (ClassII or greater), myocardial infarction within 6 months prior to study day 1, unstable arrhythmias or unstable angina
* 7\. Ongoing cardiac dysrhythmias of CTCAE grade ≥2, uncontrolled atrial fibrillation of any grade or QTcF interval \> 470ms
* 8\. Severe infections within 4 weeks prior to randomization including, but not limited to hospitalization for complications of infection, bacteremia or severe pneumonia
* 9\. Therapeutic oral or intravenous antibiotics within 2 weeks prior to randomization
* 10\. Patients with any concomitant and uncontrolled medical disorder
* 11\. Patients with vena cava syndrome
* 12\. Malignant pleural or pericardial effusion: both will be considered as suggestive of metastaticdisease. Also, are excluded those with negative cytology but being exudates. Patients with non-visible by thoracic X-ray pleural effusion or too small to be safely punctured could be included.
* 13\. Prior treatment with anti-neoplasic drugs
* 14\. Malignancies other than NSCLC within 3 years prior to enrollment
* 15\. Women who are pregnant, lactating, or intending to become pregnant during the study.
* 16\. Positive test for HIV. All patients will be tested for HIV prior to inclusion into the study; patients who test positive for HIV will be excluded from the clinical study.
* 17\. Patients with active hepatitis B or hepatitis C.
* 18\. Active tuberculosis.
* 19\. Any other diseases, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or that may affect the interpretation of the results or renders the patient at high risk from treatment complications.
* 20\. Patients with illnesses or conditions that interfere with their capacity to understand follow and/or comply with study procedures.
* 21\. Known or suspected hypersensitivity to drugs with similar chemical structures to the study drug
* 22\. Evidence of any other disorder or significant laboratory finding that makes the patient undesirable to participate in the study
* 23\. Use of strong inducers of CYP3A4 within 14 days of half-lives (whichever is longer) prior to study day 1
* 24\. Use of proton pump inhibitors within 14 days to study day
