Background

This dopamine receptor agonist is approved to treat Parkinson’s disease and restless legs syndrome in Europe and the U.S. It is formulated as a once-daily transdermal patch, in doses from 1 to 8 mg. Side effects include dyskinesia, constipation, nausea, dizziness, fatigue, insomnia, sleepiness, confusion, and hallucinations. Psychosis and impulse control disorders like pathological gambling are rare but serious side effects (Rotigotine, 2017).

In Alzheimer’s disease, deficits in dopamine signaling may contribute to cognitive decline. Decrements in executive function associated with diminished frontal cortical activity further diminish daily function, separate from memory loss. A group in Rome has investigated rotigotine’s effect on cortical function and plasticity in people with Alzheimer’s by using repetitive transcranial magnetic stimulation (rTMS). The drug reportedly upped cortical excitability and cholinergic transmission, reversing impairments in LTP-like cortical plasticity in these patients. In a small study of 30 people, rotigotine treatment for 24 weeks was reported to improve scores on the MMSE and the Frontal Assessment Battery (FAB), which tests cognitive functions related to prefrontal cortical activity (Martorana et al., 2013; Koch et al., 2014). Rotigotine was evaluated in a small number of taupathy patients (Moretti et al., 2014; Moretti et al., 2014).

Findings

From June 2016 to December 2018, the investigators conducted a single-center, double-blind Phase 2 trial of rotigotine added onto acetylcholinesterase inhibitor therapy in mild to moderate Alzheimer’s. The trial enrolled 94 people with probable AD, CDR of 0.5 or 1, and MMSE scores between 18 and 24. Treatment consisted of a 2 mg rotigotine transdermal patch daily for one week, followed by 4 mg daily for 23 weeks, or a placebo patch for 24 weeks. All took a stable dose of donepezil, galantamine, or rivastigmine. The primary outcome was change in ADAS-Cog over 24 weeks; secondary outcomes included change in the FAB, the ADCS-Activities of Daily Living, the Neuropsychiatric Inventory, and cortical activity measured by transcranial magnetic stimulation combined with encephalography (TMS-EEG). 

The trial was negative on the primary endpoint, with no difference between groups on the ADAS-Cog. The treated group appeared to benefit on two secondary outcomes. Scores on the FAB rose by 0.48 points with rotigotine versus a 0.66-point decrease on placebo. The ADCS-ADL worsened by 3.32 points with rotigotine versus 7.24 for placebo. The NPI stayed unchanged in either group. EEG measures indicated increased prefrontal cortical activity in the rotigotine but not placebo groups. More people on rotigotine had adverse events; 11 dropped out compared with five on placebo. Side effects on rotigotine included nausea and dizziness in three people, allergic reactions to the patch in two, and visual hallucinations, pneumonia, sleep disorders, and anxiety in one person each (Koch et al., 2020). 

In June 2021, the same investigators launched a Phase 2 trial testing rotigotine in frontotemporal dementia patients. Seventy-five participants newly diagnosed with behavioral variant FTD are to be randomized to six months of 4 or 6 mg per day, or placebo, delivered via transdermal patch. The sole primary outcome is the Frontal Assessment Battery to evaluate executive function. Fifteen secondary outcomes span functional, neuropsychiatric, and cognitive domains, DEG-PET, transcranial stimulation and EEG, and safety. Funded by the Fondazione Santa Lucia and the Alzheimer's Drug Discovery Foundation, the trial is running at three centers in Italy through April 2024.

For more on these trials, see clinicaltrials.gov. For all rotigotine trials, see clinicaltrials.gov.