Extended dosing with CC-486 (oral azacitidine) in patients with myeloid malignancies

CC-486 (oral azacitidine) is an epigenetic modifier in clinical development for treatment of hematological cancers. This study of extended CC-486 dosing included patients with myelodysplastic syndromes (MDSs), chronic myelomonocytic leukemia (CMML), or acute myeloid leukemia (AML). After a pharmacokinetic assessment period, 31 patients (MDS n = 18, CMML n = 4, and AML n = 9) entered a clinical phase in which they received CC-486 300 mg once-daily for 21 days of repeated 28-day cycles. Median age was 71 years (range: 53-93); 42% of patients were aged ≥75 years. A total of 5 patients with AML (63%) had prior MDS. Median number of CC-486 treatment cycles was 4 (range: 1-32). The most common treatment-emergent adverse events (TEAEs) were gastrointestinal (84% of patients) and hematologic (81%). Most common grade 3-4 TEAEs were neutropenia (n = 13, 42%) and anemia (n = 9, 29%). Ten patients experienced grade 4 neutropenia. Infrequently, CC-486 dose was interrupted or reduced due to gastrointestinal (n = 5, 16%) or hematologic (n = 6, 19%) TEAEs. Overall response rate (complete remission [CR], CR with incomplete hematological recovery [CRi], partial remission [PR], marrow CR) in the MDS/CMML subgroups was 32% and in the AML subgroup (CR/CRi/PR) was 22%. Red blood cell transfusion independence rates in the MDS/CMML and AML subgroups were 33% and 25%, respectively, and 2 MDS/CMML patients attained hematologic improvement as a best response on-study. No baseline gene mutation was predictive of response/nonresponse. CC-486 allows flexible dosing and schedules to improve tolerability or response. Neutropenia in early treatment cycles deserves scrutiny and may warrant initiation of prophylactic antibiotics. KEY POINTS: The safety profile of oral CC-486 was comparable to that of injectable azacitidine; most adverse events were hematological and gastrointestinal. Extended (21-day/cycle) CC-486 dosing induced responses in patients with hematological malignancies, many of whom had prior DNMTi failure.