The oral small molecule IRAK4 inhibitor emavusertib (CA-4948) has demonstrated promising efficacy in patients with relapsed/refractory acute myeloid leukemia (AML), particularly those harboring FLT3 mutations who had previously failed other targeted therapies.
In the ongoing phase 1/2 TakeAim Leukemia trial (NCT04278768), researchers evaluated emavusertib at a recommended phase 2 dose of 300 mg twice daily. Among 19 evaluable patients with FLT3-mutated AML who had received two or fewer prior lines of therapy, the response rates were particularly encouraging.
Strong Response Rates in FLT3-Mutated Population
The trial data revealed that six patients achieved complete remission (CR), while two additional patients reached CR with either incomplete hematological recovery (CRi) or partial hematological recovery. Two more patients attained morphologic leukemia-free state. Notably, two patients who achieved CR and CRi subsequently proceeded to allogeneic stem cell transplantation.
"Emavusertib may be able to not just hit the bypass mechanisms for the previous diseases, but may have higher efficacy compared with the other FLT3 inhibitors that patients were already refractory to," explained Dr. Eric S. Winer, clinical director of Adult Leukemia at Dana-Farber Cancer Institute and assistant professor of medicine at Harvard Medical School.
Overcoming Resistance to Prior FLT3 Inhibitors
A significant finding from the study was the drug's effectiveness in patients previously treated with FLT3 inhibitors such as midostaurin (Rydapt) or gilteritinib (Xospata). The positive responses in this population suggest emavusertib's potential to overcome resistance mechanisms associated with earlier FLT3 inhibitor therapy.
Activity in Spliceosome Factor Mutations
While the response rates were most pronounced in FLT3-mutated patients, the trial also demonstrated clinical activity in patients with spliceosome factor mutations. This cohort included heavily pretreated patients who had previously received hypomethylating agents combined with venetoclax, indicating emavusertib's potential utility across multiple resistant disease settings.
Clinical Implications
These findings suggest a potentially important therapeutic advance for AML patients who have exhausted other treatment options. The ability to achieve responses in patients previously treated with FLT3 inhibitors represents a particularly significant development in addressing the persistent challenge of treatment resistance in AML.
