Safety, Pharmacokinetics, and Clinical Activity of Adavosertib in Combination with Chemotherapy in Asian Patients with Advanced Solid Tumors: Phase Ib Study

BACKGROUND: The WEE1 inhibitor adavosertib (AZD1775) has been investigated in Western patients. OBJECTIVE: This open-label Phase Ib study (NCT02341456) investigated the safety, pharmacokinetics, and clinical activity of adavosertib in combination with carboplatin alone or paclitaxel plus carboplatin in Asian patients with advanced solid tumors and defined the recommended Phase II dose. PATIENTS AND METHODS: Nineteen patients received adavosertib 175 mg twice daily (bid) for 2.5 days (five doses) in combination with carboplatin (AUC 5) alone or paclitaxel (175 mg/m(2)) plus carboplatin, or adavosertib 225 mg bid for 2.5 days in combination with paclitaxel plus carboplatin in 21-day cycles. Preliminary safety and dose-limiting toxicity analyses were performed and dose escalation/de-escalation conducted as appropriate. RESULTS: Adavosertib 175 mg bid for 2.5 days with carboplatin alone or paclitaxel plus carboplatin was considered tolerable. Two patients receiving adavosertib 225 mg bid in combination with paclitaxel plus carboplatin experienced dose-limiting toxicities (grade 4 sepsis; grade 5 acute respiratory distress syndrome); this regimen was not considered tolerable. Grade ≥ 3 adverse events reported most commonly in any cohort included: anemia; decreased white blood cell count; decreased neutrophil count; neutropenia; decreased platelet count; thrombocytopenia; and febrile neutropenia. Exposure to adavosertib, as determined by pharmacokinetic analysis, in Asian patients was higher than that previously seen in Western patients. A partial response occurred in 2/12 evaluable patients (16.7%) at the recommended Phase II dose. CONCLUSIONS: Adavosertib 175 mg bid for 2.5 days was chosen as the recommended Phase II dose in combination with paclitaxel and carboplatin in Asian patients. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11523-020-00701-5) contains supplementary material, which is available to authorized users.