Phase II study of vorinostat (V) in combination with idarubicin and high-dose cytarabine (IA) as front-line therapy in patients (pts) with high-risk myelodyplsatic syndrome (MDS) or acute myeloid leukemia (AML)
7004 Background: Standard induction therapy for pts with AML has not changed over the last 2 decades nor has the outcome of these pts. We demonstrated in vitro and ex vivo that the combination of an histone deacetylase inhibitor with anthraycline is synergistic (Blood 2006;108:1174); an effect that could be mediated by activation of DNA damage/repair pathways, and found that such combination is safe in phase 1 trial (Blood 2007;110:1842). We designed a phase II study of V with IA as front-line therapy for MDS/AML. Methods: Pts with untreated int-2/high-risk MDS or AML ages 15–65 with adequate liver and renal functions and PS, and EF ≥ 50% were eligible. Pts with CBF were excluded. Initial dose of V was 500 mg orally TID for 3 days followed on day 4 by IA (I:12 mg/m2/dx3; A:1.5g/m2/dx4 over 24 hrs). After induction and if in CR, pt can receive 5 cycles of consolidation with V at the same dose and IA (I:8 mg/m2/dx2; A:0.75g/m2/dx3 over 24 hours) followed by 1 year of maintenance with V. The study was powered to demonstrate improvement in PFS at 7 months and acceptable toxicity. Prior to formal initiation of the phase II, the study had a “run-in” phase to confirm the safety of the triple combination. Correlative studies include analysis of DNA repair/damage pathways. Results: 22 pts have been registered. 3 pts with relapsed/refractory AML were treated in the run-in phase. No excess toxicity was observed; 2 achieved CR and 1 CRp. Following these, 19 pts were enrolled on the phase 2 portion. 17 pts were evaluable. Median age was 49 years. Median WBC at presentation was 12.75 x 109/L. Cytogenetic analysis were abnormal in 12 (71%), complex in 10 (59%). 8 (47%) had secondary disease. 4 (23%) were Flt-3 positive. No unexpected grade 3/4 toxicities have been observed. The CR rate was 82%. 1 pt acheived a marrow CR and 2 pts died during induction. CR were universally associated with CG response. All Flt-3+ pts achieved a CR. Only 2 pts (14%) have relapsed (4 and 5 months). The median PFS has not been reached. Conclusions: The combination of IA and V is safe and active in AML/MDS. No stopping rule has been met. Results will be compared with those of a parallel IA study at MDACC. Correlative analysis are ongoing. [Table: see text]