Padlock banks $23M with a fresh approach to autoimmune disease

Padlock Therapeutics CEO Michael Gilman

The majority of treatments for autoimmune diseases have a simple hypothesis: If the immune system is flaring up, attack its defenses and tamp it down. But startup Padlock Therapeutics has a novel approach it believes could cut in on the inflammatory process before things get so dire, and the biotech has $23 million in fresh cash to explore the idea.

Founded earlier this year by Atlas Venture, Padlock is at work on treatments that promise to stem the production of agents that set off the immune system's alarms in the first place, blocking enzymes called protein-arginine deiminases, or PADs. The enzymes play an active role in transforming the amino acid arginine into citrulline, which triggers the body's natural defenses in diseases like rheumatoid arthritis (RA). By interrupting the activity of PADs, Padlock hopes to cut out the offending proteins without suppressing the immune system, CEO Michael Gilman explains.

"The idea is, if you had a drug that inhibited the activity of these PADs, you could essentially shut off the supply line of antigens," Gilman said, thereby relieving symptoms of autoimmune disease.

With its $23 million Series A, Padlock is getting to work on PAD-blocking approaches to RA, lupus and multiple sclerosis, hoping to craft new treatments that could complement or exceed what's already on the market. Atlas led the biotech's funding round, joined by Index Ventures, Johnson & Johnson ($JNJ) Development and MS Ventures, the biotech investment arm of Merck KGaA.

Padlock's next step is to take the new funds and forge proper drug candidates out of its promising hits and leads, Gilman said. The cash should be enough to get Padlock's first molecule through preclinical studies, he said, but the company's not yet sure which of its three target diseases will get the first go. Each ailment has a different relationship with PADs, Gilman said, and there are 5 known PAD enzymes, making for "a ton of biology left to figure out."

For Gilman, Padlock represents the latest stop on "this strange round trip that very few people do." After 5 years at the helm of Biogen Idec's ($BIIB) R&D operation, Gilman decamped for the startup world in 2007, founding the Atlas-seeded Stromedix to focus on treatments for fibrosis. Five years later, his old employer came calling with a $562.5 million offer for Stromedix, bringing him back into the fold as head of early-stage research.

That back and forth "helped me realize that I am much happier in kind of a scrappy, unstructured, depoliticized type of environment," Gilman said. And so he ended his second stint at Biogen last year, gravitating back to Atlas and co-founding Padlock shortly thereafter. Now Gilman is settling into life outside of Big Biotech, which, as he often points out on Twitter, sometimes requires one to take pleasure in austerity.

"I like to do stuff, and at a little company, everybody has to do everything," he said. "You have to sort of get off on unjamming the printer and rebooting the router."

For Atlas, where Gilman is a partner, Padlock's A round caps a busy year of launches and first-time financings. The biotech joins Quartet Medicine, Unum Therapeutics, Raze Therapeutics, Navitor Pharmaceuticals, Spero Therapeutics and others among Atlas' freshman class of upstarts, 12 of which began life in the firm's seed program.

"Atlas Venture is proud to see yet another seed company achieve successful validation of its innovative hypothesis with support from a strong syndicate of investors," Bruce Booth, Atlas partner and Padlock chairman, said in a statement. "With the outstanding scientific and business leadership of the founding team and their considerable financial resources, Padlock is well positioned to be the industry leader in development of therapies targeting PAD enzymes and in turn making a significant difference to patients suffering with autoimmune disease."

- read the announcement

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