This is a prospective, open, phase I clinical study to evaluate the safety and tolerability of a CDK4 / 6 inhibitor and a 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;