Abstract

Background Decitabine (DAC), a hypomethylating agent, has shown activity in MDS. DAC 150 mg/m2 by continuous infusion has been associated with CR rates of 10% to 20%. We investigated optimizing the dose schedule of DAC in MDS.

Study Group and Methods Patients (pts) with IPSS intermediate 1–2 & high risk MDS were randomized to one of 3 schedules of DAC: 1) 20 mg/m2 IV over 1 hour daily x 5; 2) 10 mg/m2 IV over 1 hour daily x 10; or 3)10 mg/m2 subcutaneously (SQ) BID x 5. A total of 95 pts are to be treated; Bayesian randomization is implemented based on CR rates. Courses were given every 28 days. Delays to allow counts recovery were permitted every 3 courses, or if myelosuppression without disease, or severe myelosuppression complications. Pts were allowed to receive erythropoietin 40,000 units weekly for anemia, or GCSF if needed. Response criteria for CR & PR were as for AML (PR requiring also ↓ blasts by >50%). Clinical benefit (CB) referred to one or more of: platelets î by ≥ 50% and >30 x 109/L, or granulocytes increase by ≥ 100% and to >109/L, or hemoglobin î by ≥ 2 g/dl or transfusion independence, or splenomegaly ↓ by 50% or more, or monocytes ↓ by 50% or more (pretreatment >5 x 109/L).

Results 92 pts have been treated; median age 65 (31–90) yrs; 66% >60 yrs old. IPSS: intermediate-1 25%; intermediate-2 38%; high 19%; CMML 17% Cytogenetic abnormalities 57%; secondary MDS 17%; marrow blasts > 10% in 31%. 27 pts had prior erythropoietin; 17 had prior GCSF; 22 had other prior therapies. Presently, 89 pts have received 1 course. Results: 32 CR (36%); 7 PR (8%); 13 marrow CR + CB (15%); 16 CB (18%); overall response 68/89=76%. Median courses to CR 3 (range 1 to 6). Median follow-up of 9 months; 48 pts continue on DAC. Compared with a 114 pts with MDS who received intensive chemotherapy (2000–2004), CR rate was lower with DAC (36% vs. 45%), overall response rate was favorable; 6-week mortality was lower with DAC (1% vs. 21%); and estimated survival favorable (p = 0.00007). CR rates by schedule: 5 days IV 24/58 (41%); 5 days SQ 4/14 (28%); 10 day IV 4/17 (24%). There was more myelosuppression with 10 day IV. After 55 patients were randomized, the 5 day IV arm was determined statistically superior, therefore, remaining patients were not randomized, but were treated with 5 days IV therapy.

Conclusions DAC has significant anti-MDS activity; 2) optimal schedule: 20 mg/m2 IV over 1 hour daily x 5; 3) timely repeated courses needed for optimal response.