Azacitidine-Containing Induction Regimens Followed by Azacitidine Maintenance Therapy in High Risk Acute Myeloid Leukemia: First Results of the Randomized Phase-II AMLSG 12-09 Study (ClinicalTrials.gov No. NCT01180322)

A large proportion of patients are currently not eligible for genotype-adapted strategies in acute myeloid leukemia (AML), in particular those lacking specific genetic aberrations such as PML-RARA, CBFB-MYH11, RUNX1-RUNX1T1, NPM1 or activating FLT3 mutations. This subgroup of patients accounts for about one-third of all AML patients and mainly includes the large group of AML with myelodysplasia-related changes, AML with recurrent cytogenetic abnormalities [inv(3) or t(3;3), t(9;11), t(v;11q23)] and cytogenetically normal AML (CN-AML) with wild-type NPM1 and FLT3. Prognosis in this subgroup of patients is generally poor. Azacitidine has been shown to be active in AML with low blast counts frequently observed in AML with myelodysplasia-related changes and in CN-AML in the absence of specific gene mutations.

To evaluate clinical efficacy of azacitidine in combination with intensive induction chemotherapy and in maintenance for two years as single agent in patients with AML who are not candidates for genotype-adapted treatment approaches.

Patients with AML in the absence of specific genetic aberrations (PML-RARA, CBFB-MYH11, RUNX1-RUNX1T1, NPM1 mutation, activating FLT3 mutations) who are fit for intensive chemotherapy were eligible. Patients were up-front randomized for induction therapy into one standard arm and three experimental arms; i) ICE (standard arm), idarubicin (12 mg/m²/day, iv, days 1,3,5), cytarabine (100 mg/m²/day, cont. infusion, days 1–7), etoposide (100 mg/m²/day, iv, days 1,2,3); ii) AZA-prior, azacitidine (100 mg/m²/day, sc, days 1–5), idarubicin (12 mg/m²/day, iv, days 6, 8, 10), etoposide 100 mg/m²/day, iv, days 6,7,8); iii) AZA-concurrent, azacitidine (100 mg/m²/day, sc, days 1–5), idarubicin (12 mg/m²/day, iv, days 1,3,5), etoposide 100 mg/m²/day, iv, days 1,2,3); iv) AZA-after, idarubicin (12 mg/m²/day, iv, days 1,3,5), etoposide 100 mg/m²/day, iv, days 1,2,3), azacitidine (100 mg/m²/day, sc, days 4–8). After two induction cycles for patients achieving complete remission (CR), consolidation therapy was prioritized; first priority) allogeneic hematopoietic blood stem cell transplantation (HSCT) from matched related as well as unrelated donors, second priority) 3 courses of high-dose cytarabine followed by two-year maintenance therapy with azacitidine as single agent (50 mg/m²/day, sc, days 1–5, every 4 weeks) in patients initially randomized to experimental treatment. The primary endpoint was achievement of CR. The statistical design of the study was based on the Simon's optimal two-stage design applied for each arm separately. The null hypothesis was CR-rate equal or below 0.40 whereas the alternative hypothesis was a CR rate of at least 0.55 with a power of 80% and a level of significance of 5%. Thus, in each arm at least 12 of 26 patients with response to induction therapy were necessary after the first to proceed to the second stage.

During the first stage of the study 104 patients were randomized; median age was 62.5 years (range 18–82), 46% were female. Data on cytogenetics showed intermediate risk karyotype in 67% (n=50) including CN-AML (n=31) and high-risk karyotype in 33% (n=25). The most frequent serious adverse events were grade 3/4 infection with an overall incidence of 25% and ranging from 20 to 34% in the different treatment arms. The number of responding patients in the treatment arms AZA-prior and AZA-concurrent after the first stage of the study were 11 of 26 (42%) and 10 of 26 (38%)Both arms, AZA-prior and were terminated accordingly. In contrast, the treatment arms ICE and AZA-after were carried forward to the second stage of patient recruitment since responding patients at that time were 14 of 26 (54%) in both arms. In total, 100 patients each have been enrolled in both treatment arms, ICE and AZA-after, with CR-rates of 59% and 52%, respectively (p=0.39). To date, 60 patients received an allogeneic HSCT (n=36 matched unrelated donors, n=23 matched related donors, n=1 haploidentical family donor). Maintenance treatment was started in 12 patients.

Induction therapy with ICE or idarubicin, etoposide followed by azacitidine (AZA-after) appears equally effective in producing CR in patients with AML who are not candidates for genotype-adapted treatment approaches. An amendment perpetuating the treatment arms ICE and AZA-after within a phase-III concept is planned.

Schlenk:Celgene: Research Funding. Off Label Use: Azacitidine combined with intensive chemotherapy.