isotretinoin and entinostat

Preclinical studies suggest that histone deacetylase (HDAC) inhibitors may restore tumour sensitivity to retinoids. The objective of this study was to determine the safety, tolerability, and the pharmacokinetic (PK)/pharmacodynamic (PD) profiles of the HDAC inhibitor entinostat in combination with 13-cis retinoic acid (CRA) in patients with solid tumours.. Patients with advanced solid tumours were treated with entinostat orally once weekly and with CRA orally twice daily × 3 weeks every 4 weeks. The starting dose for entinostat was 4 mg m(-2) with a fixed dose of CRA at 1 mg kg(-1) per day. Entinostat dose was escalated by 1 mg m(-2) increments. Pharmacokinetic concentrations of entinostat and CRA were determined by LC/MS/MS. Western blot analysis of peripheral blood mononuclear cells and tumour samples were performed to evaluate target inhibition.. A total of 19 patients were enroled. The maximum tolerated dose (MTD) was exceeded at the entinostat 5 mg m(-2) dose level (G3 hyponatremia, neutropenia, and anaemia). Fatigue (G1 or G2) was a common side effect. Entinostat exhibited substantial variability in clearance (147%) and exposure. CRA trough concentrations were consistent with prior reports. No objective responses were observed, however, prolonged stable disease occurred in patients with prostate, pancreatic, and kidney cancer. Data further showed increased tumour histone acetylation and decreased phosphorylated ERK protein expression.. The combination of entinostat with CRA was reasonably well tolerated. The recommended phase II doses are entinostat 4 mg m(-2) once weekly and CRA 1 mg kg(-1) per day. Although no tumour responses were seen, further evaluation of this combination is warranted.

Topics: Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Blotting, Western; Chromatography, Liquid; Female; Histone Deacetylase Inhibitors; Humans; Isotretinoin; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Pyridines; Tandem Mass Spectrometry; Treatment Outcome

In retinoid resistant epithelial tumors, the lack of retinoic acid receptor beta2 (RARbeta2) expression due to epigenetic silencing impairs the activation of retinoid target genes including RARbeta2, and has been associated with the development of cancer. In this study we developed a strategy to monitor the re-activation of RARbeta2 by chromatin remodeling agents combined with retinoids in real time, and to correlate the RARbeta2 re-activation with anti-tumor activity.. We selected the RARbeta2-negative retinoid resistant human prostate carcinoma cell line PC3 and stably transfected it with a luciferase expression vector under the control of a functional segment of RARbeta2 promoter (pGL2-RARbeta2-PC3). Then, we used the bioluminescence technology to monitor the reporter gene expression in real time both in vitro and in vivo following combination treatment with the histone deacetylase inhibitor MS-275 and 13-cis retinoic acid (CRA). Based on the effective dose for the RARbeta2 re-activation, we tested the anti-tumor activity of this drug combination.. Following combination treatment with MS-275 and CRA, we observed endogenous RARbeta2 re-expression, acetylation at the RARbeta2 promoter level, and synergistic activation of the luciferase reporter gene by real time imaging both in vitro and in vivo. Combination treatment with MS-275 and CRA restored retinoid sensitivity in human prostate carcinoma cell lines, and had a greater inhibitory effect on tumor cell growth than single agents in vitro and in vivo.. This study provides evidence that HDAC inhibitors restore retinoid sensitivity in prostate cancer cells, and in vivo real time imaging of RARbeta2 activation may represent a useful tool to study the pharmacodynamics of combination therapy with HDAC inhibitors and retinoids.

Topics: Animals; Benzamides; Cell Line, Tumor; Drug Therapy, Combination; Enzyme Inhibitors; Epigenesis, Genetic; Genes, Reporter; Histone Deacetylase Inhibitors; Humans; Isotretinoin; Luciferases; Male; Mice; Mice, Nude; Promoter Regions, Genetic; Prostatic Neoplasms; Pyridines; Receptors, Retinoic Acid; Transcriptional Activation; Xenograft Model Antitumor Assays

Histone deacetylase (HDAC) inhibitors have been shown to reverse epigenetic repression of certain genes, including retinoic acid receptor beta2 (RARbeta2). In this study, we examined whether RARbeta2 expression is repressed in human renal cell carcinoma (RCC) and whether the HDAC inhibitor MS-275 may revert its epigenetic repression.. Six human tumor RCC cell lines were analyzed for RARbeta2 gene expression and for methylation and acetylation status at the promoter level. Modulation of RARbeta2 expression and correlation with antitumor activity by combination of MS-275 with 13-cis-retinoic acid (CRA) was assessed in a RARbeta2-negative RCC cell line.. RARbeta2 expression was either strongly present, weakly expressed, or absent in the RCC cell lines analyzed. Methylation-specific PCR indicated that the RARbeta2 promoter was partially methylated in three of the cell lines. CRA treatment did not inhibit clonogenic growth in the RARbeta2-negative cell line RCC1.18, whereas MS-275 induced a dose-dependent inhibitory effect. A greater inhibitory effect was observed with combination treatment (MS-275 + CRA). Treatment with MS-275 was associated with histone acetylation at the promoter level and synergistic gene reexpression of RARbeta2 in combination with CRA. RARbeta2 reexpression was associated with synergistic induction of the retinoid-responsive gene HOXA5. In vivo, single-agent CRA treatment showed no significant effect, whereas MS-275 and the combination induced a regression of RCC1.18 tumor xenografts. Discontinuation of treatment produced tumor recurrence in MS-275-treated mice, whereas animals treated with the combination remained tumor free.. The HDAC inhibitor MS-275 seems to revert retinoid resistance due to epigenetic silencing of RARbeta2 in a human RCC model and has greater antitumor activity in combination with CRA compared with single agents. Thus, the combination of HDAC inhibitors and retinoids may represent a novel therapeutic approach in patients with RCC.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Blotting, Western; Carcinoma, Renal Cell; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Homeodomain Proteins; Humans; Isotretinoin; Kidney Neoplasms; Male; Mice; Mice, Nude; Mice, SCID; Phosphoproteins; Pyridines; Receptors, Retinoic Acid; Retinoic Acid Receptor alpha; Retinoic Acid Receptor gamma; Reverse Transcriptase Polymerase Chain Reaction; RNA, Neoplasm; Tretinoin; Xenograft Model Antitumor Assays