Pharmacotherapeutic group: Antineoplastic agents, pyrimidine analogues; ATC code: L01BC07
Mechanism of action
Azacitidine is believed to exert its antineoplastic effects by multiple mechanisms including cytotoxicity on abnormal haematopoietic cells in the bone marrow and hypomethylation of DNA. The cytotoxic effects of azacitidine may result from multiple mechanisms, including inhibition of DNA, RNA and protein synthesis, incorporation into RNA and DNA, and activation of DNA damage pathways. Non-proliferating cells are relatively insensitive to azacitidine. Incorporation of azacitidine into DNA results in the inactivation of DNA methyltransferases, leading to hypomethylation of DNA. DNA hypomethylation of aberrantly methylated genes involved in normal cell cycle regulation, differentiation and death pathways may result in gene re-expression and restoration of cancer-suppressing functions to cancer cells. The relative importance of DNA hypomethylation versus cytotoxicity or other activities of azacitidine to clinical outcomes has not been established.
Clinical efficacy and safety
Adult population (MDS, CMML and AML [20-30% marrow blasts])
The efficacy and safety of Vidaza were studied in an international, multicentre, controlled, open-label, randomised, parallel-group, Phase 3 comparative study (AZA PH GL 2003 CL 001) in adult patients with: intermediate-2 and high-risk MDS according to the International Prognostic Scoring System (IPSS), refractory anaemia with excess blasts (RAEB), refractory anaemia with excess blasts in transformation (RAEB-T) and modified chronic myelomonocytic leukaemia (mCMML) according to the French American British (FAB) classification system. RAEB-T patients (21-30% blasts) are now considered to be AML patients under the current WHO classification system. Azacitidine plus best supportive care (BSC) (n = 179) was compared to conventional care regimens (CCR). CCR consisted of BSC alone (n = 105), low-dose cytarabine plus BSC (n = 49) or standard induction chemotherapy plus BSC (n = 25). Patients were pre-selected by their physician to 1 of the 3 CCR prior to randomisation. Patients received this pre-selected regimen if not randomised to Vidaza. As part of the inclusion criteria, patients were required to have an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. Patients with secondary MDS were excluded from the study. The primary endpoint of the study was overall survival. Vidaza was administered at a subcutaneous dose of 75 mg/m2 daily for 7 days, followed by a rest period of 21 days (28-day treatment cycle) for a median of 9 cycles (range = 1-39) and a mean of 10.2 cycles. Within the Intent to Treat population (ITT), the median age was 69 years (range 38 to 88 years).
In the ITT analysis of 358 patients (179 azacitidine and 179 CCR), Vidaza treatment was associated with a median survival of 24.46 months versus 15.02 months for those receiving CCR treatment, a difference of 9.4 months, with a stratified log-rank p-value of 0.0001. The hazard ratio (HR) for the treatment effect was 0.58 (95% CI: 0.43, 0.77). The two-year survival rates were 50.8% in patients receiving azacitidine versus 26.2% in patients receiving CCR (p < 0.0001).

KEY: AZA = azacitidine; CCR = conventional care regimens; CI = confidence interval; HR = hazard ratio
The survival benefits of Vidaza were consistent regardless of the CCR treatment option (BSC alone, low-dose cytarabine plus BSC or standard induction chemotherapy plus BSC) utilised in the control arm.
When IPSS cytogenetic subgroups were analysed, similar findings in terms of median overall survival were observed in all groups (good, intermediate, poor cytogenetics, including monosomy 7).
On analyses of age subgroups, an increase in median overall survival was observed for all groups (< 65 years, ≥ 65 years and ≥ 75 years).
Vidaza treatment was associated with a median time to death or transformation to AML of 13.0 months versus 7.6 months for those receiving CCR treatment, an improvement of 5.4 months with a stratified log-rank p-value of 0.0025.
Vidaza treatment was also associated with a reduction in cytopenias, and their related symptoms. Vidaza treatment led to a reduced need for red blood cell (RBC) and platelet transfusions. Of the patients in the azacitidine group who were RBC transfusion dependent at baseline, 45.0% of these patients became RBC transfusion independent during the treatment period, compared with 11.4% of the patients in the combined CCR groups (a statistically significant (p < 0.0001) difference of 33.6% (95% CI: 22.4, 44.6). In patients who were RBC transfusion dependent at baseline and became independent, the median duration of RBC transfusion independence was 13 months in the azacitidine group.
Response was assessed by the investigator or by the Independent Review Committee (IRC). Overall response (complete remission [CR] + partial remission [PR]) as determined by the investigator was 29% in the azacitidine group and 12% in the combined CCR group (p = 0.0001). Overall response (CR + PR) as determined by the IRC in AZA PH GL 2003 CL 001 was 7% (12/179) in the azacitidine group compared with 1% (2/179) in the combined CCR group (p = 0.0113). The differences between the IRC and investigator assessments of response were a consequence of the International Working Group (IWG) criteria requiring improvement in peripheral blood counts and maintenance of these improvements for a minimum of 56 days. A survival benefit was also demonstrated in patients that had not achieved a complete/partial response following azacitidine treatment. Haematological improvement (major or minor) as determined by the IRC was achieved in 49% of patients receiving azacitidine compared with 29% of patients treated with combined CCR (p < 0.0001).
In patients with one or more cytogenetic abnormalities at baseline, the percentage of patients with a major cytogenetic response was similar in the azacitidine and combined CCR groups. Minor cytogenetic response was statistically significantly (p = 0.0015) higher in the azacitidine group (34%) compared with the combined CCR group (10%).
Adult population aged 65 years or older with AML with > 30% marrow blasts
The results presented below represent the intent-to-treat population studied in AZA-AML-001 (see section 4.1 for the approved indication).
The efficacy and safety of Vidaza was studied in an international, multicentre, controlled, open-label, parallel group Phase 3 study in patients 65 years and older with newly diagnosed de novo or secondary AML with > 30% bone marrow blasts according to the WHO classification, who were not eligible for HSCT. Vidaza plus BSC (n = 241) was compared to CCR. CCR consisted of BSC alone (n = 45), low-dose cytarabine plus BSC (n = 158), or standard intensive chemotherapy with cytarabine and anthracycline plus BSC (n = 44). Patients were pre-selected by their physician to 1 of the 3 CCRs prior to randomization. Patients received the pre-selected regimen if not randomised to Vidaza. As part of the inclusion criteria, patients were required to have an ECOG performance status of 0-2 and intermediate- or poor-risk cytogenetic abnormalities. The primary endpoint of the study was overall survival.
Vidaza was administered at a SC dose of 75mg/m2/day for 7 days, followed by a rest period of 21 days (28 day treatment cycle), for a median of 6 cycles (range: 1 to 28), BSC-only patients for a median of 3 cycles (range: 1 to 20), low-dose cytarabine patients for a median of 4 cycles (range 1 to 25) and standard intensive chemotherapy patients for a median of 2 cycles (range: 1 to 3, induction cycle plus 1 or 2 consolidation cycles).
The individual baseline parameters were comparable between the Vidaza and CCR groups. The median age of the subjects was 75.0 years (range: 64 to 91 years), 75.2% were Caucasian and 59.0% were male. At baseline 60.7% were classified as AML not otherwise specified, 32.4% AML with myelodysplasia-related changes, 4.1% therapy-related myeloid neoplasms and 2.9% AML with recurrent genetic abnormalities according to the WHO classification.
In the ITT analysis of 488 patients (241 Vidaza and 247 CCR), Vidaza treatment was associated with a median survival of 10.4 months versus 6.5 months for those receiving CCR treatment, a difference of 3.8 months, with a stratified log-rank p-value of 0.1009 (two-sided). The hazard ratio for the treatment effect was 0.85 (95% CI = 0.69, 1.03). The one-year survival rates were 46.5% in patients receiving Vidaza versus 34.3% in patients receiving CCR.

The Cox PH model adjusted for pre-specified baseline prognostic factors defined a HR for Vidaza versus CCR of 0.80 (95% CI = 0.66, 0.99; p = 0.0355).
In addition, although the study was not powered to demonstrate a statistically significant difference when comparing azacitidine to the preselection CCR treatment groups, the survival of Vidaza treated patients was longer when compared to CCR treatment options BSC alone, low-dose cytarabine plus BSC and were similar when compared to standard intensive chemotherapy plus BSC.
In all pre-specified subgroups (age [< 75 years and ≥ 75 years], gender, race, ECOG performance status [0 or 1 and 2] , baseline cytogenetic risk [intermediate and poor], geographic region, WHO classification of AML [including AML with myelodysplasia-related changes], baseline WBC count [≤ 5 x109/L and > 5 x 109/L], baseline bone marrow blasts [≤ 50% and > 50%] and prior history of MDS), there was a trend in OS benefit in favour of Vidaza. In a few pre-specified subgroups, the OS HR reached statistical significance including patients with poor cytogenetic risk, patients with AML with myelodysplasia-related changes, patients < 75 years, female patients and white patients.
Haematologic and cytogenetic responses were assessed by the investigator and by the IRC with similar results. Overall response rate (complete remission [CR] + complete remission with incomplete blood count recovery [CRi]) as determined by the IRC was 27.8% in the Vidaza group and 25.1% in the combined CCR group (p = 0.5384). In patients who achieved CR or CRi, the median duration of remission was 10.4 months (95% CI = 7.2, 15.2) for the Vidaza subjects and 12.3 months (95% CI = 9.0, 17.0) for the CCR subjects. A survival benefit was also demonstrated in patients that had not achieved a complete response for Vidaza compared to CCR.
Vidaza treatment improved peripheral blood counts and led to a reduced need for RBC and platelet transfusions. A patient was considered RBC or platelet transfusion dependent at baseline if the subject had one or more RBC or platelet transfusions during the 56 days (8 weeks) on or prior to randomization, respectively. A patient was considered RBC or platelet transfusion independent during the treatment period if the subject had no RBC or platelet transfusions during any consecutive 56 days during the reporting period, respectively.
Of the patients in the Vidaza group who were RBC transfusion dependent at baseline, 38.5% (95% CI = 31.1, 46.2) of these patients became RBC transfusion independent during the treatment period, compared with 27.6% of (95% CI = 20.9, 35.1) patients in the combined CCR groups. In patients who were RBC transfusion dependent at baseline and achieved transfusion independence on treatment, the median duration of RBC transfusion independence was 13.9 months in the Vidaza group and was not reached in the CCR group.
Of the patients in the Vidaza group who were platelet transfusion dependent at baseline, 40.6% (95% CI = 30.9, 50.8) of these patients became platelet transfusion independent during the treatment period, compared with 29.3% of (95% CI = 19.7, 40.4) patients in the combined CCR groups. In patients who were platelet transfusion dependent at baseline and achieved transfusion independence on treatment, the median duration of platelet transfusion independence was 10.8 months in the Vidaza group and 19.2 months in the CCR group.
Health- Related Quality of Life (HRQoL) was assessed using the European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC QLQ-C30). HRQoL data could be analysed for a subset of the full study population. While there are limitations in the analysis, the available data suggest that patients do not experience meaningful deterioration in quality of life during treatment with Vidaza.
Paediatric population
Study AZA-JMML-001 was a Phase 2, international, multicentre, open-label study to evaluate the pharmacokinetics, pharmacodynamics, safety and activity of Vidaza prior to HSCT in paediatric patients with newly diagnosed advanced MDS or JMML. The primary objective of the clinical study was to evaluate the effect of Vidaza on response rate at Cycle 3, Day 28.
Patients (MDS, n = 10; JMML, n = 18, 3 months to 15 years; 71% male) were treated with intravenous Vidaza 75 mg/m2, daily on Days 1 to 7 of a 28-day cycle for a minimum of 3 cycles and a maximum of 6 cycles.
Enrolment in the MDS study arm was stopped after 10 MDS patients due to a lack of efficacy: no confirmed responses were recorded in these 10 patients.
In the JMML study arm, 18 patients (13 PTPN11, 3 NRAS, 1 KRAS somatic mutations and 1 clinical diagnosis of neurofibromatosis type 1 [NF-1]) were enrolled. Sixteen patients completed 3 cycles of therapy and 5 of them completed 6 cycles. A total of 11 JMML patients had a clinical response at Cycle 3, Day 28, of these 11 subjects, 9 (50%) subjects had a confirmed clinical response (3 subjects with cCR and 6 subjects with cPR). Among the cohort of JMML patients treated with Vidaza, 7 (43.8%) patients had a sustained platelet response (counts ≥ 100 × 109/L) and 7 (43.8%) patients required transfusions at HSCT. 17 of 18 patients proceeded to HSCT.
Because of the study design (small patient numbers and various confounding factors), it cannot be concluded from this clinical study whether Vidaza prior to HSCT improves survival outcome in JMML patients.
Study AZA-AML-004 was a Phase 2, multicentre, open-label study to evaluate the safety, pharmacodynamics and efficacy of Vidaza compared to no anti-cancer treatment in children and young adults with AML in molecular relapse after CR1.
Seven patients (median age 6.7 years [range 2 to 12 years]; 71.4% male) were treated with intravenous Vidaza 100 mg/m2, daily on Days 1 to 7 of each 28-day cycle for a maximum of 3 cycles.
Five patients had minimal residual disease (MRD) assessment at Day 84 with 4 patients achieving either molecular stabilization (n = 3) or molecular improvement (n = 1) and 1 patient had clinical relapse. Six of 7 patients (90% [95% CI = 0.4, 1.0]) treated with azacitidine underwent HSCT.
Due to the small sample size, the efficacy of Vidaza in paediatric AML cannot be established.
See section 4.8 for safety information.