AMSTERDAM – For patients with FLT3-mutated, relapsed or refractory acute myeloid leukemia (AML), gilteritinib (Xospata) offers better median overall survival than salvage chemotherapy, according to results from the phase 3 ADMIRAL trial.
Patients treated with gilteritinib also more often responded to therapy and entered remission, reported lead author, of the University of Pennsylvania, Philadelphia.
To overcome resistance mechanisms to existing FLT3 inhibitors, drug developers have been seeking agents with activity against both FLT3-ITD and FLT3-TKD mutations, Dr. Perl explained during his presentation at the annual congress of the European Hematology Association. “Gilteritinib is one of these agents,” he said, noting a unique mechanism of action that also may limit toxicity concerns associated with existing FLT3 inhibitors.
The internationalinvolved 371 patients with FLT3-mutated AML who had not responded to induction therapy or were untreated after first relapse.
The population was randomized in a 2:1 ratio to receive either gilteritinib 120 mg/day or one of four salvage chemotherapy regimens: azacitidine (AZA), low-dose cytarabine (LoDAC), mitoxantrone/etoposide/cytarabine (MEC), or fludarabine/cytarabine/granulocyte colony-stimulating factor/idarubicin (FLAG-IDA).
Coprimary endpoints were overall survival and the combined rate of complete remission and complete remission with partial hematologic recovery (CR/CRh). Secondary endpoints were complete remission rate and event-free survival.
Demographic data showed that the median patient age was 62 years with a broad range (19-85 years). Most patients were positive for FLT3-ITD (88.4%), while fewer tested positive for FLT3-TKD (8.4%) or both mutations (1.9%). Relapsed AML was more common than refractory disease (60.6% vs. 39.4%).
The efficacy analysis revealed that patients treated with gilteritinib had a median overall survival of 9.3 months, significantly longer than the 5.6 months among those treated with salvage chemotherapy (hazard ratio for death = 0.637; P = .0007). The 1-year survival rate was 37.1% for the gilteritinib group, compared with 16.7% among those who received chemotherapy.
The superiority of gilteritinib was further supported by twofold higher rates of CR/CRh (34.0% vs. 15.3%) and complete remission (21.1% vs. 10.5%). Similarly, median event-free survival was significantly longer in the gilteritinib group (2.8 vs. 0.7 months). Most subgroups, such as age and sex, showed consistent benefit.
Overall, gilteritinib demonstrated a favorable safety profile. After adjusting for exposure duration, serious treatment related adverse events were more common in the chemotherapy group than the gilteritinib group (9.2% vs. 7.1%). Common grade 3 or higher adverse events related to gilteritinib were anemia (19.5%), febrile neutropenia (15.4%), thrombocytopenia (12.2%), and decreased platelet count (12.2%).
“We were able to give [gilteritinib] in an outpatient setting,” Dr. Perl said.
Although comparisons between responses based on mutation type were not possible, owing to small sample sizes, Dr. Perl highlighted that gilteritinib showed activity against both FLT3 mutation subtypes.
“This drug has been approved on the results of this study,” Dr. Perl said. “Because of this, we have a new standard of care for this population.”
The study was funded by Astellas. The investigators reported financial relationships with AbbVie, Bayer, Takeda, and other companies.
SOURCE: Perl A et al. EHA Congress, .