Vaccine to Treat Multiple Sclerosis Showing Promise and Soon to Enter Phase 3 Clinical Testing

A therapeutic vaccine for patients with multiple sclerosis (MS), called Xemys, is showing positive results in pre-clinical and clinical trials, and is soon to enter Phase 3 clinical testing. Xemys was developed by researchers at the Institute of Bioorganic Chemistry of the Russian Academy of Sciences and their colleagues.

While traditional vaccines are designed to prevent disease, the scientists are working on something new: a therapeutic vaccine, or a vaccination that treats an existing illness.

Results from a Phase 1 dose-escalating trial in patients with relapsing-remitting MS (RRMS) or secondary progressive MS (SPMS), who failed to achieve sustained responses with standard of care disease-modifying drugs like β-interferons and glatiramer acetate, have now been published in the Neurotherapeutics journal, in a study titled “CD206-Targeted Liposomal Myelin Basic Protein Peptides in patients with Multiple Sclerosis Resistant to First-Line Disease-Modifying Therapies: A First-in-Human, Proof-of-Concept Dose-Escalation Study.”

“Many laboratories around the world are working on finding effective solutions for the treatment and therapy of multiple sclerosis,” said Alexey Belogurov, PhD, senior research associate at the Laboratory of Biocatalysis of the Institute of Bioorganic Chemistry of the Russian Academy of Sciences, and the study’s first author, in a press release.

Dr. Belogurov adds that, in Russia, the majority of drugs are purchased abroad with at a high cost. “It is obvious that, in order to solve social and economic problems, it is necessary to create high-quality domestic medications, and this is what we are now doing.” he said.

The research team developed a vaccine that delivers three fragments of myelin basic protein (MBP) inside liposomes (a lipid vesicle used as a vehicle) to cells from the immune system, resulting in immune tolerance toward myelin proteins. (MBP is a structural part of the myelin membrane that is thought to be a primary target of the immune system.)

Preclinical tests were performed in rats with experimental autoimmune encephalomyelitis, the animal model for MS in humans, where the positive effects of the three MBP fragments on immune cells were established. Among the selected fragments, one was seen to have a therapeutic effect in the early stages of the disease, whereas the other two prevent the development of pathologies in the remission phase. Combining all three fragments in a vaccine was found to be the most effective approach.

A Phase 2a proof-of-concept trial, reported in Multiple Sclerosis News Today, also showed Xemys as effective in slowing or preventing disease progression and relapses. Specifically, at 20 weeks after study enrollment, seven of the 20 patients (37%) treated had no evidence of disease activity as measured by NEDA (No Evidence of Disease Activity) scores, and 16 (85%) were free of relapse.

“The vaccines developed were tested in a series of clinical trials on healthy volunteers and patients suffering from multiple sclerosis. These trials were conducted at five national centers in Russia. We discovered that the drug is well tolerated, and has a very low probability of developing adverse events,” Dr. Belogurov concluded.

MS is a chronic neurodegenerative disease, caused by an abnormal immune-mediated response that results in the loss of the myelin sheaths that surround the nerve cells. Although a number of treatment strategies have been found to be successful in reducing disease progression, they are often associated with adverse events, and some patients remain refractory to these agents.