TMS-007

BIIB131, a small molecule, is currently in Phase 2 for the treatment of acute ischemic stroke. Safety and metabolism of BIIB131 were evaluated following intravenous administration to rats and monkeys. Exposure increased dose-proportionally in rats up to 60 mg/kg and more than dose-proportionally in monkeys at greater than 10 mg/kg accompanied by prolonged half-life and safety findings. The BIIB131 was poorly metabolized in microsomes with no inhibition of CYPs. BIIB131-glucuronide, formed by UGT1A1, accounted for 21.5% metabolism in human hepatocytes and 28-40% in rat bile. In rats, excretion was primarily via the bile. BIIB131 inhibited the hERG and Nav1.5 cardiac channels by 39% but showed no effect on cardiovascular parameters in monkeys. Toxicology findings were limited to reversable hematuria, changes in urinary parameters and local effects. A MTD of 30 mg/kg was established in monkeys, the most sensitive species, at total plasma C_max and AUC of 6- and 14-fold, respectively, greater than the NOAEL. The Phase 1 study started with intravenous 0.05 mg/kg and ascended to 6.0 mg/kg which corresponded to safety margins of 147- to 0.9-fold (for C_max) within the linear drug exposure. Thus, the preclinical profile of BIIB131 has been appropriately characterized and supports its further clinical development.

Capillary microsampling (CMS) is a technique that can significantly reduce the blood collection volume compared to conventional sampling methods, and thus is much preferred for studies in rats and mice. BIIB131 (SMTP-7) is a novel thrombolytic drug candidate currently under Phase 2 clinical development for the treatment of acute ischemic stroke. To support the safety studies in rats, an accurate and reliable CMS LC-MS/MS assay for the quantification of BIIB131 in rat plasma was developed and validated. This method utilized stable-isotope labeled [¹³C₅¹⁵N₂]-BIIB131 as the internal standard. The samples were extracted using acid-assisted liquid-liquid extraction with methyl tert-butyl ether (MTBE) and formic acid. The chromatographic separation was achieved on an ACE Excel 3 Super C18 analytical column (2.1 mm × 50 mm, 3.0 µm) using a gradient elution. The mass spectrometric detection of BIIB131 and its internal standard was achieved using positive ion electrospray multiple reaction monitoring (MRM). The standard curve ranged from 0.50 to 300 ng/mL for BIIB131 and was fitted to a 1/x² weighted linear regression model. For regular QCs, the intra-assay precision was 1.7-6.1 % CV, the inter-assay precision was 2.7-11.0 % CV, and the intra-assay and inter-assay accuracy (%Bias) were -20.0-10.6 % and -7.8-6.3 %, respectively. For CMS QCs, the intra-assay and inter-assay precision were 2.2-13.6 % and 6.7-12.9 % CV, and the intra-assay and inter-assay accuracy (%Bias) were -13.2-15.0 % and -7.8-4.2 %, respectively. The validated CMS LC-MS/MS method has been successfully applied to a safety study in rats.