Landmark 321 · Trial in people
ASPro-PD: ambroxol Phase 3
Will tell us whether ambroxol slows Parkinson's over two years in 330 people, with and without a GBA gene change.
In short
The only Phase 3 test of whether a GCase-boosting drug slows Parkinson's: 330 people on ambroxol or placebo for two years, with a main readout expected around 2029.
- What it is
- Trial in people
- Outcome
- Result due Feb 2029
- When
- 2025–2029
- Size
- 330 people · Phase 3
- Approach
- Help cells clean up
- Research lane
- Lysosome & GBA
- Trial registry
- NCT05778617
- Last checked
- 19 Oct 2026
The research record
This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".
Who
Sponsor University College London; chief investigator Anthony Schapira, with Marco Toffoli, Tom Foltynie and others (protocol authors also include Karl Kieburtz, Olivier Rascol and Werner Poewe). Funded by Cure Parkinson's, the Van Andel Research Institute, the John Black Charitable Foundation and the Parkinson's Virtual Biotech. Registry NCT05778617; ISRCTN93097821.
What happened
- Design. Phase 3, UK only, randomised 1:1, double-blind, placebo-controlled; 330 participants; 104 weeks blinded, then a 26-week open-label extension where everyone gets ambroxol. A CSF sub-study aims for 106 people.
- Dose. 1,260 mg a day (three 420 mg tablets), reached by stepping up.
- Main measure. Change from baseline to week 104 in the sum of MDS-UPDRS parts I to III (a combined score for daily life, non-motor and motor signs), with part III scored off medication.
- Who joins. The aim is equal numbers with and without a GBA1 variant, and GBA1 status (none, severe variant, non-severe variant) is built into the analysis. Roughly 10 to 15% of people with Parkinson's carry a GBA1 variant.
- Status. Actual start 25 February 2025 (UCLH reported its first participant on 3 April 2025). Registry (record updated May 2025) shows recruiting, estimated primary completion February 2029, study completion September 2029. No results (checked 19 Oct 2026).
- Funder report (source sweep, Oct 2026). Cure Parkinson's says it funded the PD Frontline genetic screening platform in 2021 to build trial-ready GBA1 and LRRK2 cohorts, then funded ASPro-PD in 2022; its report expects results after the trial ends in 2029.
Why it moved us toward a cure
It tests the lysosome-recycling idea (landmark 16) at the size and length that can show slowing, after the small 2020 pilot (landmark 40). Including people without GBA1 variants tests whether ambroxol works beyond carriers. The null cognition result in carriers (landmark 320) makes the answer less certain.
Outcome
Pending. Expected readout around February 2029 (registry estimate).
Sources
- ClinicalTrials.gov NCT05778617 (API v2, read 19 Oct 2026)
- Toffoli et al., ASPro-PD protocol, J Neurol 2026;273:151, DOI 10.1007/s00415-026-13683-7
- UCLH, first participant, 3 Apr 2025 · Cure Parkinson's
- Cure Parkinson's Impact Report 2025 (1 Apr 2024 to 31 Mar 2025)
- Not yet verified: current recruitment numbers; any interim data; the protocol's own timeline (it gives no calendar dates).
How it connects
Built on
- tests Ambroxol: cough medicine to first Parkinson's trials · 2009
- builds on GBA mutations: commonest genetic risk factor · 2009
Led to
None recorded.