Population Pharmacokinetics of Oral Azacitidine, and Exposure-Response Analysis in Acute Myeloid Leukemia.

Oral azacitidine (oral-AZA) maintenance is approved for adults with acute myeloid leukemia (AML) in remission post-intensive chemotherapy, not proceeding to hematopoietic stem cell transplantation. This study aimed to develop a population pharmacokinetic (PopPK) model to characterize oral-AZA concentration-time profiles in patients with AML, myelodysplastic syndrome, or chronic myelomonocytic leukemia. PopPK-estimated exposure parameters were used to evaluate exposure-response relationships in the phase III QUAZAR AML-001 study. The PopPK dataset comprised 286 patients with 1,933 evaluable oral-AZA concentration records. The final PopPK model was a one-compartment model with first-order absorption incorporating an absorption lag time and first-order elimination. Regression analyses identified two oral-AZA exposure parameters (area under the plasma concentration-time curve at steady state (AUCss ); maximum plasma concentration (Cmax )) as statistically significant predictors for relapse-free survival (hazard ratio (HR) = 0.521, P < 0.001; HR = 0.630, P = 0.013; respectively), and AUCss as a significant predictor for overall survival (HR = 0.673, P = 0.042). The probability of grade ≥ 3 neutropenia was significantly increased with increases in AUCss (odds ratio (OR) = 5.71, 95% confidence interval (CI) = 2.73-12.62, P < 0.001), cumulative AUC through cycles 1 to 6 (OR = 2.71, 95% CI = 1.76-4.44, P < 0.001), and Cmax at steady-state (OR = 2.38, 95% CI = 1.23-4.76, P = 0.012). A decreasing trend was identified between AUCss and relapse-related schedule extensions, vs. an increasing trend between AUCss and event-related dose reductions. As the majority (56.8%) of patients required no dose modifications, and the proportions requiring schedule extension (19.4%) or dose reduction (22.9%) were almost equal, oral-AZA 300 mg once daily for 14 days is the optimal dosing schedule balancing survival benefit and safety risk.

Management of adverse events in patients with acute myeloid leukemia in remission receiving oral azacitidine: experience from the phase 3 randomized QUAZAR AML-001 trial.

BACKGROUND: Most older patients with acute myeloid leukemia (AML) who attain morphologic remission with intensive chemotherapy (IC) will eventually relapse and post-relapse prognosis is dismal. In the pivotal QUAZAR AML-001 trial, oral azacitidine maintenance therapy significantly prolonged overall survival by 9.9 months (P < 0.001) and relapse-free survival by 5.3 months (P < 0.001) compared with placebo in patients with AML in first remission after IC who were not candidates for transplant. Currently, the QUAZAR AML-001 trial provides the most comprehensive safety information associated with oral azacitidine maintenance therapy. Reviewed here are common adverse events (AEs) during oral azacitidine treatment in QUAZAR AML-001, and practical recommendations for AE management based on guidance from international cancer consortiums, regulatory authorities, and the authors' clinical experience treating patients in the trial. METHODS: QUAZAR AML-001 is an international, placebo-controlled randomized phase 3 study. Patients aged ≥ 55 years with AML and intermediate- or poor-risk cytogenetics at diagnosis, who had attained first complete remission (CR) or CR with incomplete blood count recovery (CRi) within 4 months before study entry, were randomized 1:1 to receive oral azacitidine 300 mg or placebo once-daily for 14 days in repeated 28-day cycles. Safety was assessed in all patients who received ≥ 1 dose of study drug. RESULTS: A total of 469 patients received oral azacitidine (n = 236) or placebo (n = 233). Median age was 68 years. Patients received a median of 12 (range 1-80) oral azacitidine treatment cycles or 6 (1-73) placebo cycles. Gastrointestinal AEs were common and typically low-grade. The most frequent grade 3-4 AEs during oral azacitidine therapy were hematologic events. AEs infrequently required permanent discontinuation of oral azacitidine (13%), suggesting they were effectively managed with use of concomitant medications and oral azacitidine dosing modifications. CONCLUSION: Oral azacitidine maintenance had a generally favorable safety profile. Prophylaxis with antiemetic agents, and blood count monitoring every other week, are recommended for at least the first 2 oral azacitidine treatment cycles, and as needed thereafter. Awareness of the type, onset, and duration of common AEs, and implementation of effective AE management, may maximize treatment adherence and optimize the survival benefits of oral azacitidine AML remission maintenance therapy. Trial registration This trial is registered on clinicaltrials.gov: NCT01757535 as of December 2012.