Pharmacokinetics of brain-penetrant, orally bioavailable ALK2 inhibitor

Diffuse Intrinsic Pontine Glioma (DIPG) is a rare and aggressive pediatric cancer located in the pons region of the brainstem, classified as a broader class of H3 K27M mutant Diffuse Midline Gliomas (DMG). Traditional drug development models struggle to address rare diseases like DIPG due to small patient populations and high risks. M4K Pharma focuses on developing an ALK2 enzyme inhibitor, the first therapeutic designed specifically for DIPG. We are leveraging highly potent, selective, and drug-like molecules targeting this protein to create a promising therapeutic option for children affected by this devastating disease. The following entries include the PK and DMPK evaluation of ALK2 inhibitor compounds, including M4K2009, M4K2281, and M4K2308, across a series of in vivo mouse studies. The datasets include oral (PO) and intraperitoneal (IP) exposure analyses, dose-escalation studies, formulation comparisons, BBB penetration assessments, tissue distribution measurements, and study protocols outlining dosing regimens, sample collection procedures, and bioanalytical methodologies. In addition, the studies characterize the metabolic conversion of M4K2281 to M4K2308 through N-demethylation and compare the brain exposure profiles of multiple ALK2 inhibitor candidates. Together, this data provides an integrated assessment of systemic exposure, tissue distribution, metabolic stability, and central nervous system penetration to support the selection and optimization of brain-penetrant ALK2 inhibitors for DIPG. The accompanying files also include key pharmacokinetic parameters, including Cmax, area under the curve (AUC), half-life (T½), mean residence time (MRT), dose proportionality analyses, and brain-to-plasma ratio measurements that inform compound progression into IND-enabling development. Table of key terms and definitions of the project. Key Term Definition Pharmacokinetics (PK) The study of how a drug is absorbed, distributed, metabolized, and eliminated over time within the body. Drug Metabolism and Pharmacokinetics (DMPK) The evaluation of a compound's absorption, distribution, metabolism, excretion, and overall exposure to support drug development. Blood-Brain Barrier (BBB) A highly selective barrier that regulates the movement of substances from the bloodstream into the brain and limits drug delivery to CNS tumors. Oral (PO) Administration Delivery of a drug by mouth to achieve systemic absorption and exposure. Intraperitoneal (IP) Administration Administration of a drug into the peritoneal cavity to achieve systemic exposure in animal studies. M4K2009 Lead orally bioavailable ALK2 inhibitor selected for development due to its favourable exposure and brain penetration properties. M4K2281 ALK2 inhibitor precursor compound that undergoes metabolic N-demethylation to form M4K2308. M4K2308 Brain-penetrant ALK2 inhibitor metabolite that demonstrates improved CNS exposure and favourable brain-to-plasma ratios. N-demethylation A metabolic process that removes a methyl group from a molecule, converting M4K2281 into M4K2308. Brain-to-Plasma Ratio A metric used to quantify CNS penetration by comparing drug concentrations in brain tissue relative to plasma concentrations. Dose Proportionality The relationship between dose and systemic exposure, where exposure increases proportionally as dose increases. Tissue Distribution The extent to which a compound is distributed into specific tissues, including brain and skeletal muscle. LC-MS/MS Liquid chromatography-tandem mass spectrometry; an analytical technique used to quantify drug concentrations in biological samples.