Combination of 5-azacytidine (5-AZA) and valproic acid (VPA) in advanced solid cancers: A phase I study

Abstract

3547 Background: 5-AZA is a DNA hypomethylating agent. VPA is a histone deacetylase inhibitor (HDACI). The combination of hypomethylating agents and HDACI has synergistic anticancer activity in vitro and in vivo. Based on this, we conducted a phase I study of the combination of 5-AZA and VPA in patients with advanced solid cancers. Methods: 5-AZA was administered SQ daily for 10 days. VPA was given orally daily titrated to 75–100 mcg/ml. Cycles were 28 days long. 5-AZA was started at 20 mg/m2 and escalated using an adaptive algorithm based on toxicity in the prior cohort. Each cohort included 6 patients (pts). Global DNA methylation was estimated with the LINE pyrosequencing assay in peripheral blood mononuclear cells on days 1 and 10 of each cycle. Histone H3 and H4 acetylation was assessed with western blots. Results: Forty seven patients were evaluable. Median age was 60 years (15–77). 5- AZA dose levels included 20, 25, 37.5, 47, 59, 75 and 94 mg/m2. One DLT occurred at 37.5 (Neutropenic fever (NF)). At 75 mg/m2, 1 grade 3 NF and at 94 mg/m2, 3 DLTs (2 NF and 1 thrombocytopenia) were observed. The MTD was 75 mg/m2 SQ daily for 10 days. Other toxicities included drowsiness (N=6), tremor (N=6), hypomagnesemia (N=1), anemia (N=2) and vomiting (N=1). Stable disease (SD) was observed in 16 pts (34%). One pt with rapidly progressive renal cell carcinoma had SD for 6 months (mos). Two pts with leiomyosarcoma of the uterus had SD for 8 and 6 mos. One pt with melanoma and two pts with uveal melanoma had SD for 4 mos. One pt with sinus adenoid cystic carcinoma and 1 with thymic carcinoma had SD for 4 mos. SD was also observed in pts with colon (N=3), sarcoma (N=2), papillary thyroid (N=2) and breast cancer (N=1). Global DNA hypomethylation was demonstrated in all of the doses of 5- AZA. Median LINE methylation pretreatment was 65% (59–70%), it declined to 61% (53–63%) by day 10 (p=0.001) and returned to baseline by day 0 of the next cycle. Histone acetylation was observed in 53% of the pts. Conclusions: The combination of 5-AZA and VPA in patients with advanced solid tumors is safe. The MTD of 5-AZA in combination with VPA was 75 mg/m2 SQ daily for 10 days. DLTs were neutropenic fever and thrombocytopenia. Clinical benefit (SD) was observed in 16 pts (34%). Transient global hypomethylation and histone acetylation were demonstrated. No significant financial relationships to disclose.