Sorafenib Versus Placebo in Addition to Standard Therapy in Younger Patients with Newly Diagnosed Acute Myeloid Leukemia: Results from 267 Patients Treated in the Randomized Placebo-Controlled SAL-Soraml Trial

Background:

Sorafenib is a multi-kinase inhibitor with activity against several oncogenic kinases that may play a role in the pathogenesis of acute myeloid leukemia (AML). In-vitro data and results from non-randomized clinical trials suggest that sorafenib might be an effective drug for the treatment of AML. We present the results of the randomized placebo-controlled SORAML trial testing sorafenib versus placebo as add-on to standard induction and consolidation treatment in AML patients ≤60 years.

Patients and Methods:

Between March 2009 and October 2011, 276 patients from 25 centers were enrolled in the SORAML trial (NCT00893373). The main eligibility criteria were newly diagnosed AML, age from 18 to 60 years and suitability for intensive therapy. The treatment plan for all patients included two cycles of induction with DA (daunorubicin 60 mg/m² days 3-5 plus cytarabine 100 mg/m² cont. inf. days 1-7), followed by three cycles of high-dose cytarabine consolidation (3 g/m² b.i.d. days 1, 3, 5). Patients without response after DA I received second induction with HAM (cytarabine 3 g/m² b.i.d. days 1-3 plus mitoxantrone 10 mg/m² days 3-5). Allogeneic stem cell transplantation was scheduled for all intermediate-risk patients in first complete remission with a sibling donor and for all high-risk patients with a matched related or unrelated donor. At study inclusion, patients were randomized to receive either sorafenib (800 mg/day) or placebo as add-on to standard treatment in a double blinded fashion. Block randomization at a ratio of 1:1 was performed within cytogenetic and molecular risk strata, allocation was concealed and treatment was double blinded. Study medication was given on days 10-19 of DA I+II or HAM, from day 8 of each consolidation until 3 days before the start of the next consolidation and as maintenance for 12 months after the end of consolidation. The primary endpoint of the trial was event-free survival (EFS) with an event being defined as either failure to achieve a complete remission (CR) after induction, relapse or death. Secondary endpoints were relapse-free survival (RFS), overall survival (OS), CR rate and incidence of adverse events (AE). We present the results of the final analysis of the primary endpoint EFS (intent to treat) after the occurrence of 134 events.

Results:

Out of 276 enrolled patients, 267 received study treatment, 134 in the sorafenib arm and 133 in the placebo arm. Demographic and disease characteristics were equally distributed between the two arms; the incidence of FLT3-ITD was 17%. The median cumulative dose of administered study medication was similar in both arms. The CR rates were 59% versus 60% in the placebo versus sorafenib arm (p=0.764). After a median observation time of 36 months, the median EFS was 9.2 months in the placebo arm and 20.5 months in the sorafenib arm, corresponding to a 3-year EFS of 22% versus 40% (p=0.013). Median RFS after standard treatment plus placebo was 23 months and not yet reached after sorafenib treatment, corresponding to a 3-year RFS of 38% and 56%, respectively (p=0.017). The median OS had not been reached in either arm; the 3-year OS was 56% with placebo versus 63% with sorafenib (p=0.382). In 46 FLT3-ITD positive patients, no difference in EFS, but a trend for prolonged RFS and OS in favor of sorafenib was observed. The most common reported AEs Grade ≥3 were fever (40%), infections (22%) and bleeding events (2%). The risk for fever, bleeding events and hand-foot syndrome was significantly higher in the sorafenib arm while the incidence of all other AEs showed no significant differences.

Conclusions:

In younger AML patients, the addition of sorafenib to standard chemotherapy in a sequential manner is feasible and associated with antileukemic efficacy. We observed a higher incidence of infections and bleeding events under sorafenib. Whereas OS in both treatment arms was similar, sorafenib treatment resulted in a significantly prolonged EFS and RFS.

Figure 1:

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Event-free survival

Figure 1:

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Event-free survival

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