Background Hypomethylating agents (HMAs) such as decitabine and azacitidine have been successfully used in the clinic to treat hematological malignancies by parenteral administration (IV or SC). Due to low oral bioavailability of these agents, relatively high doses are required to achieve therapeutic systemic exposures by the oral route. Higher oral doses can be associated with significant GI toxicities due to intestinal enterocytes being exposed to high concentrations of these agents in the lumen. One of the main factors contributing to low oral bioavailability of HMAs is the high first-pass effect due to cytidine deaminase in GI and liver. Methods In this study, E7727, a novel CDA inhibitor (CDAi) was combined with decitabine (3 mg/kg) for oral administration in cynomolgus (cyn) monkeys at E7727 doses of 0.1-10 mg/kg. Results Systemic AUC exposures for decitabine increased from 21.7 ng*hr/mL (without E7727) to as high as 1,494 ng*hr/mL at 10mg/kg E7727. At a dose combination of 1 mg/kg CDAi and 3 mg/kg decitabine (corresponding to a human equivalent dose of 36 mg/m2), AUC exposures were 301±94 ng*hr/mL, which are slightly higher than the published clinical therapeutic range after decitabine IV infusion of 20 mg/m2 (115-220 ng*hr/mL), suggesting that a combination approach for oral CDAi+decitabine is feasible to achieve required clinical exposures at a range of relatively low-dose(s). In addition, the concentration-time profile of decitabine when combined with CDAi resembled that achieved with IV decitabine over 1 hour infusion. The effect of drug-drug interaction between CDAi and decitabine was modeled based on a relationship between CDAi Ki (∼ 0.14 µM based on IC50) and Cmaxlevels and appeared to predict the observed fold-increases in decitabine AUC with high concordance. In addition, low dose oral decitabine+CDAi achieved decitabine exposures that produce potent hypomethylation as observed by LINE-1 assay. Conclusion Pronounced increase in oral decitabine exposures was achieved when combined with the novel CDA inhibitor E7727. Cyn monkeys appear to be a relevant model for human PK based on similar background of circulating serum cytidine levels reflective of similar CDA status between humans and cyn monkeys. These data support the initiation of clinical First in Human (FIH) study of ASTX727, a novel oral HMA combining oral decitabine with the CDAi E7727. Disclosures: Oganesian: Astex Pharmaceuticals: Employment. Redkar:Astex Pharmaceuticals: Employment. Taverna:Astex Pharmaceuticals Inc.: Employment. Joshi-Hangal:Astex Pharmaceuticals, Inc.: Employment. Azab:Astex Pharmaceuticals Inc.: Employment.

Amuvatinib LSC, 300 mg every 8 h, is being studied in cancer patients based on the improved exposure and similar safety profile to amuvatinib DPC. A lipid-based formulation approach may be a useful tool for other low aqueous soluble compounds.

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.

SGI-110 is a second generation hypomethylating agent being developed for treatment in myelodysplastic syndrome (MDS) and solid tumor malignancies. In previous work, SGI-110 has demonstrated potent in vivo activity in a number of tumor types, including non-hematological cell lines. Current efforts are underway to optimize formulation and delivery of SGI-110 for first-in-human (FIH) studies. In animals, SGI-110 is well-tolerated across multiple species utilizing multiple routes of drug delivery. Tolerability studies have been performed in mouse, rat, and rabbit models with multiple dose routes and schedules. Myelosuppression is an observed toxicity endpoint for hypomethylating agents. Hence, myelotoxic effects were investigated by comparing RBCs and bone marrow cellularity of mice treated with and without SGI-110. Mice dosed with SGI-110 for five consecutive days showed a significant decrease in RBCs at the end of the dosing period and a continued decrease one week after dosing. Bone marrow cellularity also showed a decrease at the end of dosing, but recovered to near normal levels one week later. Interestingly, RBCs from SGI-110 treated mice were elevated in the bone marrow after the dosing period. Pyrosequencing methylation analysis of colon samples was also evaluated in this study. A significant decrease in B1 methylation was observed in colon samples of treated mice, indicating global DNA methylation is being inhibited. Decreased levels in several hematology parameters and decreases in bone marrow cellularity were also observed in rat and rabbit studies after five consecutive days of SGI-110 dosing. Increased dosing frequency, while maintaining the same total dose per week, appears to result in increased toxicity. Previous pharmacokinetic studies have shown that SGI-110 rapidly metabolizes to decitabine, an FDA-approved drug for MDS. Multiple formulations and different routes of delivery were examined to determine the optimal dose form to be used in FIH studies. Subcutaneous dosing results in bioavailability that is similar to that of intravenous dosing. Subcutaneous dosing appears to reduce the Cmax while maintaining similar AUC values when compared to intravenous dosing. Similar results in pharmacokinetic parameters are observed when the delivery vehicle is changed from an aqueous to non-aqueous formulation. SGI-110 is a novel hypomethylating agent that is well-tolerated in rodent models, provides excellent PK exposure, and demonstrates inhibition of DNA methylation in a mouse model. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A190.