Terns Pharma shelves obesity drug after mid-stage trial disappoints

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(Reuters) -Terns Pharmaceuticals said on Tuesday it will stop developing its experimental obesity drug after data from a mid-stage trial showed modest weight loss and raised safety concerns.

Shares of the company were down over 16% in extended trading.

The once-daily oral drug, TERN-601, which belongs to a class known as GLP-1 receptor agonists, helped patients lose up to 4.6% more weight than those on placebo over 12 weeks.

But the company said this was not enough to justify further investment.

“The threshold for a truly differentiated oral GLP-1RA therapy — one that delivers safety, tolerability and efficacy — is high,” said Chief Executive Officer Amy Burroughs, adding that the data “did not meet this threshold and likely preclude further development.”

About 11.9% of the 134 participants in the study stopped taking the drug due to side effects, mostly gastrointestinal issues like nausea and vomiting.

While these were generally mild or moderate, three patients experienced serious liver enzyme elevations after treatment ended. Two of those cases were linked to the drug, including one confirmed by a liver biopsy.

“We’re not surprised by the liver toxicity signal,” since TERN-601 shares a similar chemical structure — known as a pharmacophore — with Pfizer’s danuglipron and lotiglipron, both of which were discontinued due to liver safety concerns, said William Blair analyst Andy Hsieh.

Terns said the liver issues were unexpected, as earlier studies had not shown similar problems.

Burroughs said that Terns does not plan to invest further in metabolic disease.

With the obesity program now shelved, Terns will focus on its lead cancer drug TERN-701, which targets chronic myeloid leukemia, a type of blood cancer.

(Reporting by Kamal Choudhury in Bengaluru; Editing by Alan Barona)