# OncoBayes progressing OB-001 to tackle ADC resistance and TKI brain penetration

- Link: https://www.thailand-business-news.com/pr-news/oncobayes-progressing-ob-001-to-tackle-adc-resistance-and-tki-brain-penetration
- Published: 2026-10-07T13:00:00+07:00
- Author: PR Newswire

LONDON, Oct. 7, 2026 /PRNewswire/ — OncoBayes, a privately held clinical-stage pharmaceutical
company, today announced the successful completion of preclinical work with OB-001,
demonstrating the product’s potential to tackle two major unmet needs in oncology:
ADC resistance and the brain penetration of tyrosine kinase inhibitors (TKIs).

OB-001 is a highly selective and effective inhibitor of two key efflux pumps (P-
gp and BCRP), which are present both on the blood-brain barrier and on tumour cells.
The product is being developed as a once-daily oral tablet, which will be used in
combination with a number of gold standard oncology treatments in order to optimise
their efficacy.

In perfused-brain mouse studies, OB-001 pretreatment significantly raised brain 
exposure of four gold standard kinase inhibitors – whilst systemic (plasma) exposure
remained broadly unchanged. Data presented at AACR 2026 demonstrated that OB-001
could increase the brain exposure of osimertinib by almost 400% with minimal systemic
changes^([1],[2]). Based on a translational PK-PD-TGI model for osimertinib, this
increase is projected to deliver a step-change in CNS progression-free survival 
for EGFRm NSCLC patients. The improved control of brain metastases is still a major
area of unmet need in NSCLC and breast cancer.

The same efflux pumps have also been identified as a key resistance mechanism impacting
ADCs – with the over-expression of these pumps leading to reduced payload concentrations
in the tumour. Preclinical work using a bidirectional transporter assay demonstrated
that OB-001 reduces efflux for several leading payloads, including SN-38 (e.g. sacituzumab
govitecan, Trodelvy®), DM4 (e.g. mirvetuximab soravtansine, Elahere®) and DXd (e.
g. trastuzumab deruxtecan, Enhertu®).

Plans are currently underway to move into a parallel clinical trial programme to
generate POC data in combination with osimertinib, and also evaluate T-DXd re-sensitisation.

"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 for 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. This is truly a pipeline
in a product opportunity."

References: 
^(1. )AACR2026 Abstract 5873. 1 April 2026; 86 (7_Supplement): 5873.
[https://doi.org/10.1158/1538-7445.AM2026-5873](https://doi.org/10.1158/1538-7445.AM2026-5873).
^(2. )Cancer Research Communications 1 May 2026; 6 (5): 1213–1219. [https://doi.org/10.1158/2767-9764.CRC-25-0553](https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1158_2767-2D9764.CRC-2D25-2D0553&d=DwMFAg&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=kuYbvllu4QLn4DTnlHmV7LPO6uFRrVFzjIUm1ucUmpU&m=pc04esVDLwonDxcvKP7Yod3kH1bwhz8Y8UuMh5bdixgcOHZCL_1w9gkRNzV2-OLl&s=epbphPmRmDa55jpgqGmKR882SHrmoDHrHVGJY3fjQ8I&e=).

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