Autobahn Therapeutics’ journey through the clinic has been anything but speedy.
The ARCH-backed startup launched out of stealth more than four years ago in June 2020, armed with $76 million to try to reverse the effects of multiple sclerosis. But several years later, it decided to shift gears to psychiatric disorders, bringing in a $32.7 million raise in September 2022 to back its work in treatment-resistant depression.
Now with the company finally ready to put its lead program into Phase 2, Autobahn has closed a $100 million Series C, it announced Wednesday. The cash will help researchers launch two Phase 2 studies for its lead program ABX-002, including a placebo-controlled proof-of-concept trial looking at major depressive disorder and bipolar disorder depression.
Autobahn CEO Kevin Finney told Endpoints News that the company could have continued to develop ABX-002 for MS, but it changed its focus after realizing that a backup program, ABX-101, could potentially treat MS more effectively.
The FDA’s neuro group, headed by then-chief Billy Dunn, also demonstrated enthusiasm for ABX-002’s biology as an adjunctive treatment for depression, Finney said.
“If you think about what we’re aiming to do — advance drugs to help patients — we were just convinced that there’s a really, really solid data package” in psychiatry, he said. “We felt like that is the fastest way for us, with the highest statistical chance, of developing a drug and getting it to the finish line.”
ABX-002 is a thyroid hormone receptor beta (TRβ) agonist, and synthetic thyroid hormones are already used off-label to supplement the effects of antidepressants like SSRIs and SNRIs. While ABX-002 isn’t entirely the same, it’s similar enough that the FDA was interested in seeing a drug developed in the space, Finney said.
The challenge was avoiding some of the side effects that patients face when taking synthetic thyroid hormones, which affect both the alpha and beta receptors and can lead to increased heart rates of an extra 15 beats per minute, Finney said. By only targeting the beta receptor, ABX-002 can still get into the brain while minimizing peripheral CNS toxicity.
The FDA “would never approve a drug where you’re increasing heart rate, but psychiatrists still learned how to manage it,” Finney said. “Our drug is very different. It’s designed to have high central concentrations, and it’s beta-selective versus alpha, and those alpha receptors are the ones in the heart that are associated with heart rate increases.”
Autobahn’s placebo-controlled Phase 2 study will start enrolling patients next month, with the goal of reading out topline data in October 2025, Finney said. Patients will be allowed to continue taking their existing treatment regimens, and researchers expect to recruit about 230 people.
The company will also conduct a smaller trial that it’s calling an “exploratory pharmacodynamics” study with about 30 to 40 patients with bipolar depression. It should start by the end of 2024 and also read out in the fourth quarter of next year. “We may or may not have a placebo control group,” Finney said.
Newpath Partners led Wednesday’s Series C. New investors included Canaan Partners, Monograph Capital and Insight Partners. All previous investors, a group that includes Biogen, Bristol Myers Squibb and Pfizer Ventures, also participated.