biostudies-literatureUnknown43(6)Kuboki Y<h4>Background</h4>Ceralasertib is an oral, selective, and potent inhibitor of ATR serine/threonine kinase, a key protein involved in cell cycle checkpoint regulation and DNA damage response. We report preliminary safety, tolerability, and pharmacokinetic data of ceralasertib monotherapy in Japanese patients with advanced solid tumors.<h4>Methods</h4>In this phase 1, open-label study, patients orally received ceralasertib twice daily 240 mg on days 1-7 (Cohort 1) or 160 mg on days 1-14 (Cohort 2) of a 28-day cycle, respectively; both cohorts also received a single ceralasertib dose 4 days before Cycle 1. Patients were aged ≥ 18 years with solid malignancies refractory to standard therapies or for which no standard therapy exists. The primary objective was to determine ceralasertib safety; Investigational new drugs1235-1246https://www.ebi.ac.uk/biostudies/studies/S-EPMC12753540biostudies-literatureCeralasertib, an ATR kinase inhibitor, as monotherapy in Japanese patients with advanced solid malignancies: Results from a phase 1 study.PMC12753540Nakajima HYamamoto NKoyama TNii MFujisawa TIwata KTakahashi YKmieciak AKawata TKuboki YKatsuya YMatsubara NMurayama KSlade DSato JKawasumi HfalseCeralasertib, an ATR kinase inhibitor, as monotherapy in Japanese patients with advanced solid malignancies: Results from a phase 1 study.<h4>Background</h4>Ceralasertib is an oral, selective, and potent inhibitor of ATR serine/threonine kinase, a key protein involved in cell cycle checkpoint regulation and DNA damage response. We report preliminary safety, tolerability, and pharmacokinetic data of ceralasertib monotherapy in Japanese patients with advanced solid tumors.<h4>Methods</h4>In this phase 1, open-label study, patients orally received ceralasertib twice daily 240 mg on days 1-7 (Cohort 1) or 160 mg on days 1-14 (Cohort 2) of a 28-day cycle, respectively; both cohorts also received a single ceralasertib dose 4 days before Cycle 1. Patients were aged ≥ 18 years with solid malignancies refractory to standard therapies or for which no standard therapy exists. The primary objective was to determine ceralasertib safety; 2025-01-01T00:00:00Z2025 Dec2026-06-06T09:01:21.798Z2026-05-28T03:11:25.583ZS-EPMC127535404135173010.1007/s10637-025-01592-x