A Trail of CDK4 / 6 Inhibitor and MEK Inhibitor in the Treatment of Metastatic Digestive System Tumors

Inclusion Criteria: 1. Aged 18-75 years; 2. ECOG score ≤ 1; 3. Patients with advanced KRAS mutation or metastatic digestive system tumor confirmed by histology or cytology and imaging diagnosis; 4. According to Recist1.1, there was at least one measurable lesion; 5. The expected survival time was more than 12 weeks; Exclusion Criteria: 1. Patients who received any anti-tumor treatment within 4 weeks before enrollment, including radiotherapy, chemotherapy, molecular targeted therapy and immunotherapy, or participated in another intervention clinical trial; 2. Previous treatment with targeted BRAF, MEK, ERK or CDK family related inhibitors; 3. The third space effusion (such as massive pleural effusion or ascites) with clinical symptoms that cannot be controlled by drainage or other methods; 4. Allergy to any test drug and its excipients, or serious allergic history, or contraindication of the test drug; 5. Have a history of immunodeficiency, including HIV positive, or other acquired, congenital immunodeficiency diseases, or a history of organ transplantation;