
Vik Bajaj's startup incubator at Foresite uncloaks an immunology player with a lead TYK2 inhibitor in tow
Looking at a healthcare system made more unequal by Covid-19, Foresite Capital managing director Vik Bajaj recently kickstarted an expansive plan to launch five innovative startups to address unmet need. Just weeks after the first of those biotechs emerged from stealth, a second has now uncloaked, and it’s got immunology in its sights.
Esker Therapeutics launched Wednesday with a $70 million Series A to pursue precision immunology targets backed by Bajaj’s team at Foresite, the biotech said. Foresite footed the entire round for Esker as it continues to develop its pipeline and advance its lead compound.
Under the leadership of founder and CEO June Lee, Esker is putting ESK-001, a TYK2 inhibitor first focused on psoriasis, through its paces in a Phase I safety and tolerability study in healthy patients with a readout expected by year’s end. Those results will help provide proof of concept for Esker’s discovery platform, which the biotech hopes to leverage to identify genetic targets for patients who have been left behind in the “come-one-come-all” immunology market, Lee told Endpoints News.
“I really am excited by that vision that we started out with,” Lee said. “That we could do better in immunology than we have been doing. We’ve got to do what oncology has been doing. There are a lot of patients that haven’t been doing great, and I think that’s because we fail to recognize the heterogeneity in these autoimmune conditions.”

Platform plays are nothing new in biotech, but Lee has reason to believe in this one, primarily because of Bajaj’s leadership and mission, she said. Lee also touted her team’s program for TYK2, a signaling pathway in the pan-JAK class, which is in the same chemical class, she said, as Bristol Myers Squibb’s deucravacitinib. That drug recently won a head-to-head Phase III test against Amgen’s Otezla in psoriasis.
Preclinical data have shown the Esker molecule’s promise as a truly selective molecule for TYK2, Lee said, a key assertion given the ongoing safety concerns about other JAK inhibitors, primarily Pfizer’s Xeljanz. Lee knows there are a lot of players out there touting their own “truly selective” TYK2 compounds, but she thinks Esker’s molecule will eventually pull away from the pack.
“There’s a lot of people out there claiming to have the best compound, and it guess it depends on what you define as best,” she said. “What I will say is we have a highly selective TYK2 compound that is also highly derisked.”
Lee, the former chief development officer at MyoKardia who joined the team in February, was one of a group of biotech leaders tapped as part of Bajaj’s expansive plan to launch five startups utilizing his team’s engine to address unmet needs across the healthcare spectrum.
Esker joins Sestina Bio, a synthetic biology player aiming to create sustainable sources for chemicals and materials, as the only two of Foresite Labs’ startups revealed to the public so far, but Bajaj told Endpoints last month that the other companies will focus on precision medicine in cardiometabolic disorders, mapping the “protein interactome,” and collating real-time, real-world data.
“What we continue to look for are entrepreneurs in residence who want to change this part of the world, change the healthcare system and have the ambition to be on a platform like that,” Bajaj said. “That’s what’s really going to gate the number of companies that we create — it’s in finding those good relationships and people who really want to adopt something as their mission or come to us with ideas that they think we can help with.”
Esker is currently working with a full-time staff of four with plans to expand as part of an “aggressive growth strategy” once the company locks in a lease in South San Francisco that is currently in the works, Lee said. Meanwhile, Lee’s team is working with about a dozen consultants at the startup.