The Efficacy and Safety of Fluzoparib Plus Irinotecan as Second-line Treatment in Patients With Homologous Recombination Deficiency (HRD) Metastatic Colorectal Cancer.

Inclusion Criteria: * 18-75 years； * Histological or cytological confirmed metastatic colorectal cancer; * HRD alterations（inclued BRCA1/2、ATM、CDK12、PALB2、Check2、RAD51C、RAD51D etc.）； * Intolerability toxicity occurs 8 weeks within first-line therapy; * ECOG PS 0-1; * Adequate hepatic, renal, heart, and hematologic functions; * Negative serum pregnancy test at screening for women of childbearing potential; * Informed consent was signed before the study began. Exclusion Criteria: * Prior treatment with PARPi drugs； * Symptomatic brain or meningeal metastases； * Patients have received local radiotherapy within 1 month prior to treatment; * Patients who had active bleeding or coagulopathy before enrollment, had a tendency to bleed, or were receiving thrombolytic therapy and were considered by the investigator to be ineligible for enrollment; * Women who are pregnant (with a positive pregnancy test before medication) or breastfeeding; * Expected survival \<3 months; * Received other investigational drugs within 4 weeks prior to treatment; * Patients who had active uncontrollable neurological, mental disease or mental disorder, poor compliance, unable to cooperate and describe the treatment response; * Allergy to the study drug or any of its excipients;