Dose-dependent antitumor efficacy was observed with ATG-018 in LoVo, OE21 and OCI-LY-19 CDX models. 10 mg/kg ATG-018 showed a statistically significant antitumor activity in all the three CDX models. In the OCI-LY-19 CDX model, 10 mg/kg ATG-018 showed 73.52 % TGI on day 14 after grouping (p value=0.0014), and 50mg/kg ATG-018 induced tumor regression. Single agent ATG-018 exhibited strong monotherapy efficacy in preclinical cancer models with certain homologous recombination deficiencies, suggesting a promising therapeutic strategy for such patient populations.