Experimental MS therapy safely reaches brain in first human trial
Phase 2 trial testing SUDO-550, a TYK2 inhibitor, planned for 2026
SUDO-550, an oral TYK2 inhibitor being developed by Sudo Biosciences, was found to be safe, well-tolerated, and to fully reach the brain in a first-in-human clinical trial involving healthy volunteers, according to clinical trial results.
The Phase 1 clinical trial, which began dosing late last year, also showed signs of near-complete inhibition of SUDO-550’s target in the blood and in the brain.
The company is now planning to launch a Phase 2 clinical trial to test its experimental therapy in multiple sclerosis (MS) in the first half of 2026.
“We believe SUDO-550 represents a new generation of selective TYK2 inhibitors engineered to safely reach the brain and modulate the inflammatory processes driving some of the most challenging autoimmune and neurologic diseases,” Scott Byrd, Sudo’s CEO, said in a company press release.
Experimental MS therapy reduces activity of key enzyme in unique way
In MS, the immune system mistakenly launches an inflammatory attack that damages nerve cells in the brain and spinal cord. TYK2, an enzyme that helps coordinate how cells respond to inflammatory signaling molecules and is overactive in MS and other autoimmune and neurologic diseases, has been explored as a treatment target in MS.
SUDO-550 is an allosteric inhibitor, meaning it reduces TYK2’s activity by changing its shape rather than directly blocking its active site. As SUDO-550 is more specific than other TYK2 inhibitors, it may cause fewer side effects while still easing inflammation.
The Phase 1 clinical trial evaluated the safety and tolerability of SUDO-550 in healthy volunteers, including those 65 years and older. Participants received single and multiple ascending doses of the medication.
The results showed that SUDO-550 stayed in the body for a long time and reached steady levels, making it suitable for once-daily use. Its effects were consistent across different dose levels.
SUDO-550 was also able to enter the brain and spinal cord, known as the central nervous system (CNS), and it reached equal levels in both the blood and the cerebrospinal fluid, which surrounds the brain and spinal cord.
These results support advancing SUDO-550 into Phase 2 and [bring] us a step closer to changing the treatment landscape for patients who currently have limited options.
Researchers also found that SUDO-550 achieved levels high enough to block more than 90% of the enzyme’s activity in both the blood and the CNS. This means it strongly inhibited the biological signals that drive inflammation, including those involving microglia and astrocytes, which are known to play a role in MS.
“The ability of SUDO-550 to access the CNS and achieve concentrations providing sustained inhibition of TYK2 pathways is highly encouraging,” said Ian Mills, Sudo’s chief medical officer. “This unique clinical profile differentiates SUDO-550 from other TYK2 inhibitors and highlights its potential to advance the standard of care for patients with MS.”
The results were similar for younger and older adults, suggesting SUDO-550 could be used in a wide range of patients.
“These results support advancing SUDO-550 into Phase 2 and [bring] us a step closer to changing the treatment landscape for patients who currently have limited options,” Byrd said.
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