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Therini Bio raises $36 million in series A

The start-up is all about targeting fibrins to treat neuroinflammatory conditions

by Shi En Kim
April 27, 2023 | A version of this story appeared in Volume 101, Issue 14


The top image is of a tissue cross section from the retina of a patient with diabetic macular edema. The bright red layer denotes fibrin proteins. The bottom image is a tissue cross section from a normal retina. Here, no fibrin, hence no bright red is present. Both tissue cross sections are about 0.75 mm long and 0.3 mm wide.
Credit: Therini Bio
(Top) Retina from a patient with diabetic macular edema. The bright red band denotes a layer of fibrin. (Bottom) Normal retina.

Therini Bio has closed a $36 million series A funding round. The company will use the proceeds to advance its pipeline of drugs that aim to treat neurodegenerative and retinal diseases.

Headshot of Therini Bio's CEO and president, Michael Quigley
Credit: Therini Bio
Therini Bio's CEO and president, Michael Quigley

The San Francisco-based company’s hallmark approach is targeting fibrins, which are fibrous proteins that are key components of blood clots. But fibrins also have a second, more deleterious role as a driver of chronic inflammation. Damage to the blood vessels in the blood-brain barrier may lead to a buildup of fibrins. These fibrins can activate the immune system and give rise to neurological disorders such as Alzheimer’s disease and multiple sclerosis. “We believe this chronic, smoldering inflammation is driving disease,” says Therini Bio president and CEO Michael Quigley.

Fibrin’s association with disease has been known for a century, he says, but efforts to target fibrin as a treatment strategy have been mostly unsuccessful. This is because suppressing fibrin’s role in inflammation also deactivates its critical clotting function, leading to a heightened risk of bleeding.

Therini Bio’s solution to decouple fibrin’s dual roles is to inhibit the protein only when it is in the conformational state that triggers inflammation. The company’s lead asset, THN391, is an antibody that selectively binds to inflammatory fibrins and spares those in the coagulation conformation. The fibrin-targeting immunotherapy is on the verge of entering early-stage clinical trials, with an expected readout by the end of 2024. The technology is based on the work of Katerina Akassoglou, a neurologist at the University of California San Francisco.


This story was updated on April 28, 2023, to correct the description of THN391's selectivity. THN391 spares fibrins that are in the coagulation-causing conformation, not those in an unmasked conformation.



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