PROTAC ATR degrader-3 is a potent CRBN-based ATR PROTAC degrader with an DC50 of 127 nM. PROTAC ATR degrader-3 also degrades CHK1 with an DC50 of 135 nM. PROTAC ATR degrader-3 inhibits cancer cells proliferation, migration and invasion, triggers apoptosis and induces S phase arrest and DNA damage. PROTAC ATR degrader-3 achieves tumor growth inhibition in LoVo xenograft mouse model without apparent toxicity. PROTAC ATR degrader-3 can be used for the research of colorectal cancer[1].