Annovis is attempting to lessen a-synuclein-induced pathogenesis by reducing the synthesis of the a-synuclein protein.

PNT article: First Patients Dosed in Clinical Trial Investigating ANVS401 as Treatment for Parkinson's and Alzheimer's
First Patients Dosed in ANVS41 Trial for Treating Parkinson's, Alzheimer's

Trial Record: Posiphen Dose-Finding, Biomarker Study in Early Alzheimer's and Parkinson's Patients
https://clinicaltrials.gov/ct2/show/NCT04524351

SoPD blog post (background info): Disney's "Attack of the synucleozid from Jupiter"
Disney’s “Attack of the synucleozid from Jupiter” – The Science of Parkinson's

Posiphen (ANVS401) mode of action:
Posiphen is an orally available small molecule drug that inhibits the translation of a-synuclein, by increasing the affinity of Iron Regulatory Protein-1 (IRP1) to the Iron-Response Element (IRE) of the SNCA gene's messenger RNA (mRNA). This represses translation by preventing the association of the mRNA with the ribosome.

Dosing has now been completed in Annovis Bio's Phase 2a Trial of Posiphen (ANVS401).

PNT article:
Dosing Finished in Phase 2a Trial of ANVS401 for Parkinson's, Alzheimer's

This Phase 2a trial is described in the study record as a trial in two parts. The first part has 14 early PD patients and 14 early AD patients, taking either 80 mg daily of ANVS401 or placebo. Patient involvement in part 1 has been completed, and some interim results have been announced. The second part has 40 early PD patients taking 5 mg, 10 mg, 20 mg or 40 mg (no placebo). Patient involvement in part 2 has now also been completed.

Some commentators regard the (early) release of interim data from part 1 as "drip feeding" results from an ongoing trial. For example, see this SoPD blog post comment from Simon:

Monthly Research Review – June 2021 – The Science of Parkinson's

Personally, I'm giving them the benefit of the doubt.