Abstract 5747: Assessment of neuro-pharmacokinetic behavior of BDTX-1535 in brain tumor patients by a validated LC-MS/MS method

Abstract BDTX-1535 is an orally available, highly potent, irreversible inhibitor of epidermal growth factor receptor (EGFR), targeting a range of EGFR mutations, including extracellular variants and amplifications commonly expressed in glioblastoma. To assess CNS penetration of BDTX-1535 in glioblastoma patients, a novel bioanalytical method was developed to measure total and unbound BDTX-1535 levels in human brain tumor tissue, plasma, whole blood and cerebrospinal fluid (CSF). The method was validated using plasma as a surrogate matrix over the concentration range of 0.2-500 nM on an LC-MS/MS system. The MS/MS detection was conducted in positive electrospray ionization mode, while chromatography was performed using a Kinetex™ F5 column (50 × 2.1 mm, 1.7 µm) with a total 3.8-minute gradient elution time. The maximum coefficient of variation for both intra- and inter-day precision was 16.3%, with accuracy ranging from 91.5% – 107.2% across all matrices. BDTX-1535 was stable in human whole blood, plasma and brain homogenate for at least 4 hours at room temperature (RT) and 105 days at -20°C, as well as in stock and working solutions for at least 9 hours (RT) and 52 days (4°C). Equilibrium dialysis experiments revealed the unbound fractions of 0.01 and 0.08 for BDTX-1535 in human brain and plasma, respectively. The validated method is currently employed to assess BDTX-1535 levels in human brain tumor tissue, CSF, blood and plasma in an ongoing trial on recurrent high-grade glioma patients (NCT06072586). Initial results of measured total and unbound drug levels in the gadolinium-enhancing and non-enhancing brain tumor regions indicate significant brain penetration ability of BDTX-1535 in high-grade glioma patients. Citation Format: Vahuni Karapetyan, Tigran Margaryan, Nader Sanai, Artak Tovmasyan. Assessment of neuro-pharmacokinetic behavior of BDTX-1535 in brain tumor patients by a validated LC-MS/MS method [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5747.