Sosei sees $3bn sales potential for GSK's IBD discard

Sosei Heptares has lost GSK as a partner for an inflammatory bowel disease (IBD) drug candidate GSK4381406, but says it will take the programme forward as it has significant commercial potential.

The drug is billed as a first-in-class, oral GPR35 agonist that, according to Sosei Heptares, has generated promising preclinical data and is now ready to start clinical testing. The company has commissioned an independent commercial appraisal that suggests a peak sales potential of more than $3 billion.

GSK formed a partnership with Sosei Heptares to develop oral, small-molecule agonists of GPR35 in 2020, with initial payment and funding commitments of £34 million (around $43 million) and up to £336 million promised if the programme hit all its objectives.

GPR35 is an orphan G protein-coupled receptor (GPCR) that seems to be linked to IBD, and according to the Anglo-Japanese company GSK4381406 – which will soon be renamed – has already shown “mechanistic, preclinical and safety data” pointing to its potential as a treatment for conditions like ulcerative colitis and irritable bowel syndrome.

So why GSK’s change of heart? Sosei Heptares says it is because of “changes to both its immunology research strategy and immunology research leadership” and was not related to any of the data generated for the drug.

According to Sosei Heptares’ chief executive, Chris Cargill, GSK’s decision means it can take forward a project that has already benefited from significant investment and input arising from the collaboration.

“This represents a significant opportunity, and one we have capitalised on several times over recent years, to regain and re-partner promising programmes that have benefited from external collaboration and investment to validate their potential and advance them through development,” he said.

“The return of the GPR35 agonist program, with its first-in-class mechanism of action and potential to address major unmet needs in IBD worldwide, would be a welcome addition to our growing clinical pipeline,” he added.

The plan is to start a phase 1 trial that has already been approved by the UK’s Medicines and Healthcare products Regulatory Agency (MHRA), with a view to either taking the programme forward alone or with a partner.

Sosei Heptares said it can regain full rights to the drug, including all intellectual property licensed to GSK and preclinical data, with no upfront payment, although GSK would be in line for a modest royalty payment if it does reach the market. It also does not expect the handover to have an immediate impact on its 2023 financial results.