BackgroundS110 is a novel dinucleoside analog that could have advantages over existing DNA methyltransferase (DNMT) inhibitors such as decitabine. A potential therapeutic role for S110 is to increase fetal hemoglobin (HbF) levels to treat β-hemoglobinopathies. In these experiments the effect of S110 on HbF levels in baboons and its ability to reduce DNA methylation of the γ-globin gene promoter in vivo were evaluated.MethodsThe effect of S110 on HbF and γ-globin promoter DNA methylation was examined in cultured human erythroid progenitors and in vivo in the baboon pre-clinical model. S110 pharmacokinetics was also examined in the baboon model.ResultsS110 increased HbF and reduced DNA methylation of the γ-globin promoter in human erythroid progenitors and in baboons when administered subcutaneously. Pharmacokinetic analysis was consistent with rapid conversion of S110 into the deoxycytosine analog decitabine that binds and depletes DNA.ConclusionS110 is rapidly converted into decitabine, hypomethylates DNA, and induces HbF in cultured human erythroid progenitors and the baboon pre-clinical model.

Although CSF penetration is minimal, MP470 has demonstrated potent activity against cancer cell lines in vitro and in vivo, and further clinical investigation is warranted.

Background: MP-470 is an orally bioavailable multi-targeted tyrosine kinase inhibitor specifically designed to be a potent inhibitor of mutant c-Kit and PDGFR. MP-470 is also active as an inhibitor of DNA repair following chemotherapy. MP-470 has shown significant synergistic activity with DNA damaging chemotherapy in several xenograft models and in a phase I combination study. Oral bioavailability of this agent is limited by its solubility but not permeability. An in vitro/in vivo iterative approach was utilized preclinically for formulation selection. In the Beagle dog model, the oral bioavailability of MP-470 is enhanced to a maximum of 4–5-fold by formulating it in tocopherols and lipidic surfactants with self-emulsification ability (5%, dry powder vs. 20%, lipid suspension). Results presented herein are from a randomized two-way crossover pharmacokinetic (PK) study evaluating two formulations in healthy human subjects. Methods: Twelve healthy male subjects 18–45 years with a body mass index of 18–35 kg/m2 were randomized in a 1:1 ratio to receive either a 100 mg dry powder capsule or 90 mg (3 × 30 mg) lipid suspension capsules in a fasted condition with 240 mL of water. Subjects receiving MP-470 90 mg lipid suspension capsules ingested all three capsules within one minute. The alternate formulation was administered after a 14 day washout. Plasma for PK assessments was collected and evaluated at pre-dose through hour 48 post MP-470 administration. Results: Comparative PK results from twelve subjects are summarized below. Additional information will be summarized in the final presentation. Conclusions: Solubility of the drug in the formulation vehicle alone plays a limited role in bioavailability enhancement; rather the ability of the formulation to keep the drug in solution after dilution in the GI tract seems critical. It is also possible that physiological mechanisms such as active transport or metabolism contribute to the enhanced absorption of MP-470 in the tocopherol-based vehicles. Consistent with preclinical Beagle dog data, the lipid suspension formulation offers an enhanced oral bioavailability over the dry powder formulation in healthy human subjects. The lipid suspension formulation will be utilized in future MP-470 clinical studies. Pharmacokinetic summary - Dry Powder vs. Lipid Suspension Capsules Parameters 100 mg MP-470 Dry Powder Average (CV, n=12) 90 mg MP-470 Lipid Suspension Average (CV, n=12) Average % Increase* (95% CI) Cmax (ng/mL) 23.2 (71%) 132.6 (55%) 635% (420%, 851%) Tmax (h) 4.1 (44%) 1.7 (54%) - AUClast (ng·h/mL) 253 (54%) 488 (40%) 131% (85%, 177%) Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B209.

1872 SGI-110, is a novel second generation DNA methylation inhibitor that is currently in Phase I/II clinical study for treatment of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). SGI-110 is a dinucleotide of decitabine and guanosine developed to be more biologically stable than decitabine by making it less prone to deamination by cytidine deaminase, thus offering a promising alternative to current hypomethylating agents approved in MDS. SGI-110 demonstrated potent activity in vivo using different routes of administration (Chuang JC, et al, Mol Cancer Ther, 2010; 9:1443-50). We report here the results of a novel SGI-110 non-aqueous formulation intended for clinical use. The clinical formulation can be administered in small volumes subcutaneously (SC) up to a concentration of 100 mg/mL. We evaluated 2 regimens: daily SC × 5 days (in rats, and rabbits); and weekly SC (once weekly in rabbits, and cynomolgus monkeys; and twice weekly in rats). Both regimens are intended for 28-day cycles. The 5-day regimen was well tolerated up to a dose of 1.5 mg/kg/day × 5 in the most sensitive species (rabbit) which is equivalent to 18 mg/m2/day × 5 in humans. The weekly regimen was also well tolerated up to 1.5 mg/kg weekly × 3 in rabbits, and up to 3 mg/kg weekly × 3 in monkeys (equivalent to 36 mg/m2 weekly × 3 in humans). Rats tolerated much higher doses (30 mg/kg/day × 5; and 20 mg/kg twice weekly × 4 weeks). The main toxicity was myelosuppression in all species. The relative bioavailability of SGI-110 dosed SC is close to 100%. In vivo, SGI-110 rapidly converts to decitabine in rats, and rabbits, with much slower conversion in monkeys compared to other species, possibly sustaining efficacy for longer duration. Dose proportional pharmacokinetics and no significant accumulation of both SGI-110 and decitabine levels were evident after SC treatment in both the 5-day and the weekly regimens. We studied changes in LINE-1 DNA methylation in rats and monkeys after SGI-110 SC administration. Changes in LINE-1 DNA methylation after SGI-110 SC weekly × 4 in rats at tolerated doses of 12.5, 25 and 30 mg/kg/week were evident during the first recovery week (Day 31) and were dose-dependent. Maximum methylation reduction was observed with 30 mg/kg/week of SGI-110. These data in rats suggest a delayed pharmacodynamic effect. In monkeys, SGI-110 was administered at 3 mg/kg/week SC for 3 weeks (Days 1, 8 and 15). Reduction in LINE-1 DNA methylation became evident by Day 8, reached a maximum reduction of 10–15% by Day 15–22, and was maintained until Day 29. LINE-1 methylation levels were significantly reduced from baseline levels (p< 0.05) from Days 8–29. On Day 1, an average Cmax of 33.4 ng/mL at a Tmax of 1 hr and AUC of 120 ng*hr/mL were achieved for decitabine compared to Cmax of 184 ng/mL at a Tmax of 1 hr and AUC of 381 ng*hr/mL for SGI-110. On Day 15, an increase in the average SGI-110 AUC to 592 ng*hr/mL was observed suggesting some accumulation. All other pharmacokinetic parameters for decitabine and SGI-110 were similar to those on Day 1. Compared to other animal species tested, levels of SGI-110 were consistently and substantially higher in monkey plasma across studies. SGI-110 was well tolerated in monkeys at this dose with only mild reversible myelosuppresion and no deaths. In conclusion, based on the non-human primate monkey data, this uniquely developed low volume non-aqueous SC formulation of SGI-110 may allow sustained efficacy with less frequent weekly dosing offering a new alternative to MDS and AML patients. SGI-110 is being studied in a first-in-human study. This study is a randomized Phase I/II, dose escalation, multicenter study of two subcutaneous regimens (daily on Days 1–5, and weekly × 3 on Days 1, 8, 15, both given in a 28-day cycle) in relapsed or refractory MDS, and relapsed, refractory, or elderly AML patients. Disclosures: Scholl: SuperGen: Employment. Joshi-Hangal:SuperGen: Employment. Inloes:SuperGen: Employment. Shi:SuperGen: Employment. Taverna:SuperGen, Inc.: Employment. Choy:SuperGen, Inc.: Employment. Redkar:SuperGen: Employment. Azab:SuperGen: Employment.

Increased fetal hemoglobin (HbF) levels can ameliorate the symptoms of patients with sickle cell disease and increase their life span. The DNA methyltransferase (DNMT) inhibitor decitabine increases HbF in non-human primates (baboons) and sickle cell patients and offers great promise as an effective therapeutic agent for the treatment of this disease. The goal of this investigation was to develop and test new compounds that inhibit DNMT, increase HbF, and offer significant advantages compared to decitabine such as increased stablity, reduced cytotoxicity, and a lower potential for mutagenicity. S110 is decitabine-guanine dinucleotide developed by Supergen, Inc., that is cytosine deaminase resistant and more stable in plasma than decitabine. Experiments were performed to compare the effect of S110 and decitabine on γ-globin expression in human erythroid progenitor cell cultures derived from CD34+ peripheral blood cells. Cultures were treated with decitabine (1 X 10−6 M) or S110 (1 and 5 X 10−6 M) on day 8. Forty eight hours later, RNA was purified for real time PCR analysis of ε- and γ-globin gene expression by the ΔΔCT method using α-globin as a control. Effects on globin polypeptide chain expression was determined by HPLC analysis of freeze-thaw lysates prepared 72 hours following drug addition. Both S110 and decitabine increased expression of ε-globin and γ-globin mRNA and the γ/γ + β polypeptide chain ratio (see Table). Effect of S110 on ε-and γ-globin mRNA and the γ / γ + β chain ratio in Human Erythroid Progenitor Cultures (n=4) DRUG CONCENTRATION ε-globin mRNA (Fold increase) γ-globin mRNA (Fold increase) Globin chain ratio (γ/γ + β) Untreated 3 +/− 3.3 Decitabine 1 X 10-6 M 3 +/− 24.8 2 +/− 2.8 8 +/− 3.2 S110 1 x 10-6 M 5 +/− 4.2 4 +/− 1.1 8 +/− 1.9 S110 5 X 10−6 9 +/− 34.5 35 +/− 1.5 2 +/− 2.9 The effect of S110 on HbF levels in vivo was then tested in non-human primates. Two baboons (PA 7256; PA 7470, P. anubis) were phlebotomized for eight days to achieve a HCT of 20 followed by treatment with S110 (1mg/kg/d; sc) for ten days. Pretreatment HbF levels were 3.1% (PA 7256) and 3.5% (PA 7470). Following S110 treatment, peak HbF levels of 46.1% (PA 7256) and 75.5% (PA 7470) were attained that were similar to levels observed in animals treated with equivalent molar doses of decitabine. Bisulfite sequence analysis showed that the level of DNA methylation of 5 CpG sites within the γ-globin promoter in purified BM erythroblasts following S110 administration was significantly lower (41.5%, PA 7256; 16.3%, PA 7470) compared to erythroblasts from bled, untreated baboons (70.8%; n=4). Pharmacokinetics was also evaluated in parallel to assess systemic exposure. These data demonstrate that S110, a newly developed decitabine-guanine dinucleotide, effectively increased HbF and reduced DNA methylation in cultured human erythroid progenitor cells and in experimental non-human primates.