LONDON – – October 07, 2026 -- OncoBayes has completed preclinical work on OB-001, an oral drug candidate designed to overcome antibody-drug conjugate (ADC) resistance and boost brain penetration of tyrosine kinase inhibitors (TKIs), the privately held clinical-stage pharmaceutical company announced.
OB-001 raises osimertinib brain exposure by nearly 400% in mouse studies
In perfused-brain mouse models, pretreatment with OB-001 increased brain exposure of osimertinib by almost 400%, while plasma exposure remained broadly unchanged. The data, presented at AACR 2026, covered four gold-standard kinase inhibitors and showed systemic drug levels were largely unaffected by the efflux-pump inhibition.
Translational model projects improved CNS progression-free survival in EGFRm NSCLC
Based on a translational PK-PD-TGI model for osimertinib, OncoBayes projects the brain-exposure increase will deliver a step-change in CNS progression-free survival for patients with EGFR-mutated non-small cell lung cancer (NSCLC). Control of brain metastases remains a significant unmet need in both NSCLC and breast cancer treatment.
OB-001 targets the same efflux pumps driving ADC payload resistance
P-glycoprotein (P-gp) and BCRP, the two efflux pumps inhibited by OB-001, are present on both the blood-brain barrier and tumour cells, where their over-expression is a known resistance mechanism for ADCs by reducing payload concentration in tumours. Using a bidirectional transporter assay, OncoBayes demonstrated that OB-001 reduces efflux of three leading ADC payloads: SN-38 (used in sacituzumab govitecan, Trodelvy), DM4 (mirvetuximab soravtansine, Elahere), and DXd (trastuzumab deruxtecan, Enhertu).
Company moves toward parallel clinical trials combining OB-001 with osimertinib and T-DXd
OncoBayes is preparing a parallel clinical trial programme to generate proof-of-concept data for OB-001 in combination with osimertinib, alongside a separate evaluation of T-DXd re-sensitisation in resistant tumours. The once-daily oral tablet is intended as an adjunct therapy alongside existing oncology treatments rather than a standalone agent.
"This is a critical milestone for our team, and we are now well positioned to initiate our clinical plans with OB-001," said Jim Millen, Chief Executive Officer of OncoBayes. "OB-001 is on track to become a first-in-class drug with broad potential as a simple, oral adjunct to a range of blockbuster oncology therapies."