Based on the preclinical results indicating that the dual inhibition of ATR and topoisomerase I was synergistically cytotoxic in SCLC, a proof-of-concept phase II trial of the ATR inhibitor berzosertib plus topotecan was conducted in the second or latter line of SCLC, which showed an ORR of 36% and a median PFS of 4.8 months [194]. The gene discussed is ATR; the disease is small cell lung carcinoma.