Experimental vaccine shows early signs of benefit in Parkinson’s
Interim Phase 2 results show strong immune response, stable biomarkers
- Experimental vaccine ACI-7104 shows early signals of benefit in a Phase 2 trial for early Parkinson's disease.
- The vaccine targets toxic alpha-synuclein and triggered strong immune responses in all treated patients.
- IInterim data show stable biomarkers and motor scores, hinting at possible benefit.
ACI-7104, an experimental vaccine being tested in people with early-stage Parkinson’s disease, has been generally well tolerated and is showing early signals that it may slow disease progression, according to interim Phase 2 data from its developer, AC Immune.
“The interim Phase 2 data shows the potential of our [ACI-7104] active immunotherapy to slow the progression of Parkinson’s disease and hold the promise of a tremendous step forward for millions of patients. The consistent signs of efficacy, combined with the continuing strong safety record, underline [ACI-7104]’s potential to transform [Parkinson’s] treatment and are a strong basis for accelerating development,” Andrea Pfeifer, AC Immune’s CEO, said in a company press release.
Pfeifer said that AC Immune plans to meet with regulators to review these data and discuss the next steps in developing ACI-7104.
Parkinson’s is a neurological disorder marked by toxic clumps of the protein alpha-synuclein in brain cells. ACI-7104 (also known as ACI-7104.056) is designed to stimulate the immune system to produce antibodies that target this protein, with the goal of preventing these toxic clumps from forming and potentially slowing disease progression.
Phase 2 trial tests whether ACI-7104 can slow Parkinson’s progression
AC Immune is conducting a Phase 2 trial called VacSYn (NCT06015841) to evaluate ACI-7104 in people with early-stage Parkinson’s disease. In Part 1 of the study, 34 patients were randomized 3:1 to receive the vaccine or a placebo. The interim analysis included participants who had been treated for at least 12 months (48 weeks), with some followed for up to 18 months (74 weeks).
Results showed that all patients treated with ACI-7104 developed robust antibody responses against the alpha-synuclein protein as intended. At week 76, after six doses, antibody levels in the blood were more than 500-times higher than in the placebo group. Antibody levels in cerebrospinal fluid (CSF) were also detectable at levels far above those seen in the placebo group, and changes in CSF antibodies tracked closely with changes in blood levels — indicating that the immune response reached the central nervous system.
Analyses of CSF also showed that, among placebo-treated patients, alpha-synuclein levels declined over time, which is typical in Parkinson’s disease as more of the protein accumulates inside brain cells. In contrast to the natural progression, protein levels in CSF remained stable in patients receiving ACI-7104, AC Immune said. The company also reported stabilization of other biomarkers, including neurofilament light chain (NfL), a marker of nerve fiber damage.
Among participants followed for up to 18 months (74 weeks), those in the placebo group showed the expected worsening of motor function over time. In contrast, motor function in patients treated with ACI-7104 “did not show meaningful progression” during the same period, according to AC Immune.
“The remarkable consistency of the trends observed across multiple disease-related biomarkers and on clinical assessments in the treatment arm are very promising. Importantly, clinical and biomarker outcomes provide signals that the immunological response elicited by ACI-7104 may be associated with beneficial effects on [Parkinson’s] progression,” said Werner Poewe, MD, a Parkinson’s expert at Innsbruck Medical University in Austria.
AC Immune also reported that the investigational vaccine was generally well tolerated, with “no clinically relevant safety issues reported.”
“Overall, these findings are highly encouraging and fully support further development of the program. If further substantiated the current data would have major implications for future [Parkinson’s] therapy,” Poewe said. “For the first time, we are seeing signals that targeting the underlying pathology of Parkinson’s with active immunotherapy could slow disease progression.”
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