This is a phase 1b, multicenter and open-label study of first-line chemotherapy (gemcitabine combined with nab-paclitaxel [gem/nab-P] or modified FOLFIRINOX [mFOLFIRINOX]) in combination with sotorasib for patients with locally advanced or metastatic pancreatic cancer harboring KRAS p.G12C mutation.The study will be conducted at approximately 25 sites distributed in two countries (Spain and France). The study will consist of a screening period, a treatment period, a safety follow-up (SFU) and long-term follow-up (LTFU) period. A minimum of 6 and a maximum of 15 patients will be enrolled to receive first-line chemotherapy (gem/nab-P or mFOLFIRINOX at investigator choice) in combination with sotorasib 960 mg daily (QD). An independent data monitoring committee (DMC) is planned for this study to review safety, PK, and, if applicable, efficacy data as per DMC charter. A minimum the two DMC is planned: one meeting after the first 3 evaluable patients have completed 1 month of treatment with sotorasib combined with mFOLFIRINOX, and the other meeting after the first 3 evaluable patients have completed 1 month of treatment with sotorasib combined with gem/nab-P. Patients may discontinue treatment because of disease progression, intolerance of treatment leading to treatment discontinuation, initiation of another anticancer therapy, or withdrawal of consent.