• 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:

‣ Tumor size ≥ 5 cm and lymph node N2 involvement

⁃ 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

⁃ Interstitial Lung diseases

⁃ Prior treatment with thoracic radiotherapy for any reason

⁃ 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.