Combining Quizartinib with intensive chemotherapy in older patients with newly diagnosed AML: results of the UK NCRI AML18 Trial

We assessed the addition of the tyrosine kinase inhibitor Quizartinib, following intensive chemotherapy and as maintenance, in patients aged >60 years with AML or high-risk MDS, regardless of FLT3 mutation status. 463 patients (median age 68yrs) were randomised (1:1) to receive Quizartinib 40mg or not for 14 days immediately following chemotherapy courses 2 and 3, plus 28 additional days; those allocated Quizartinib were further randomised (1:1) to either 12 additional 28-day maintenance courses (long Quizartinib), or no further treatment (short Quizartinib). Median follow-up was 76 months. 314 patients were FLT3 wild type (WT); 116 had FLT3 mutations. The primary endpoint, overall survival (OS) unselected by FLT3 status, showed no significant difference (HR 0.99, 95% CI 0.79-1.24, p=0.937) and there was an increase in non-relapse mortality with Quizartinib (HR 1.64, 95% CI 1.04-2.59, p=0.032). In a pre-planned subgroup analysis, FLT3-mutated patients who received Quizartinib had significantly improved OS (HR 0.59, 95% CI 0.37-0.93, p=0.024) due to reduced relapse risk (HR 0.57, 95% CI 0.35-0.91, p=0.017) with greater benefit in the short Quizartinib group (HR 0.49, 95% CI 0.24-1.02, p=0.055). In FLT3-WT patients there was no survival benefit and no reduction in relapse risk. No significant differences were seen in time to hematologic count recovery or in the duration of hospitalisation. The most observed grade 3/4 adverse events were febrile neutropenia. In conclusion, the addition of Quizartinib to intensive chemotherapy, delayed until chemotherapy course 2, prolonged OS in older patients with FLT3-mutated AML but did not improve OS in non-FLT3 selected patients. ISRCTN-31682779, EudraCR-2013-002730-21