RATIFY trial results available after almost 10 years in the making

Patient population

The investigators screened 3279 patients younger than 60 years with newly diagnosed AML and found 27% (n=887) to be FLT3-positive.

They randomized 717 patients—81% of the FLT3-positive patients—to either the midostaurin arm (n=360) or the placebo arm (n=357). These 717 patients were evaluable for the intent-to-treat analysis.

The median age was 47.1 (range, 19.0–59.8) in the midostaurin arm and 48.6 (range, 18.0–60.9) in the placebo arm. There were significantly more males in the midostaurin arm (48.1%) than in the placebo arm (40.6%, P=0.045).

And the arms were almost identical for FLT3 stratification. In the midostaurin group, 22.5% had FLT3 TKD (no ITD), 47.5% had an ITD allelic ratio (+/- FLT3 TKD) less than 0.7, and 30.0% had a ratio of 0.7 or more.

In the placebo arm, 22.7% had FLT3 TKD, and 47.6% and 29.7% had ITD allelic ratios less than and greater than 0.7, respectively.

Safety

Rash/desquamation was the only significant difference in grade 3-4 non-hematologic events between the arms, with 13% in the midostaurin arm and 8% in the placebo arm (P=0.02).

Other grade 3-4 non-hematologic events occurring in 10% of patients or more included, in the midostaurin and placebo arms, respectively: febrile neutropenia (81%, 82%), infection (40%, 38%), diarrhea (15%, 16%), hypokalemia (13%, 17%), pain (13%, 13%), other infection (12%, 12%), ALT/SGPT (12%, 9%), and fatigue (9%, 11%).

There were 18 deaths (5%) in the midostaurin arm and 19 (5.3%) in the placebo arm during induction and consolidation treatment.

Efficacy

OS was superior for patients randomized to midostaurin. The median survival was 74.7 months (range, 31.7-not estimable) in the midostaurin arm and 25.6 months (range,18.6-42.9) in the placebo arm (P=0.0076).

Overall, there were 357 deaths, 171 and 186 in the midostaurin and placebo arms, respectively.

The 5-year survival rate was 50.9% for midostaurin and 43.9% for placebo.

EFS was also superior for patients randomized to midostaurin (P=0.0032), at a median of 8.0 months for midostaurin and 3.6 months for placebo. The 5-year EFS was 27.5% for midostaurin and 19.3% for placebo.

The CR rates by day 60 were not significantly different between the arms, at 59% and 53% for midostaurin and placebo, respectively. And the median time to CR was the same in each group, at 35 days.

The survival benefit, both overall and event-free, was consistent regardless of whether the patients were FLT3-ITD high, low, or FLT3-TKD.

The OS and EFS benefits were also consistent in censored and uncensored analyses, despite the high stem cell transplant rate. Four hundred eight patients (57%) received a transplant, 212 in the midostaurin arm and 196 in the placebo arm.

“The trial was positive whether you censored the patients at transplant or you kept following them for the whole time,” Dr Stone said.

He concluded that this type of international collaborative AML study based on genotype at diagnosis is feasible to do. But it took “a lot of collaboration, a lot of cooperation, a lot of persistence, because the trial took a long time to conceive of, conduct, and analyze.”

*Data in the presentation differ from the abstract.