Background
Parkinson disease is a progressive neurological disorder that mainly affects movement. Common symptoms include slowness of movement, stiffness, tremor, and problems with balance and walking. Over time, these symptoms can interfere with daily activities such as dressing, writing, and getting up from a chair.
Standard treatments often aim to restore dopamine signaling in the brain, because Parkinson disease is associated with loss of dopamine-producing neurons. Levodopa remains the most effective symptomatic treatment, but in some people with early disease, clinicians may also use dopamine agonists. These medications can help improve motor function, though some are linked to side effects such as nausea, sleepiness, hallucinations, or impulse-control problems.
Tavapadon is a newer oral medicine taken once daily. It is designed as a selective D1/D5 receptor agonist, which means it targets a different part of the dopamine system than many older dopamine agonists. In theory, this selectivity may improve motor symptoms while reducing adverse effects related to D2/D3 receptor activation. The TEMPO-1 trial was conducted to test whether fixed doses of tavapadon could safely and effectively improve symptoms in adults with early Parkinson disease.
Study Design
TEMPO-1 was a phase 3, double-blind, placebo-controlled randomized clinical trial carried out at 102 sites in 12 countries between December 2019 and June 2024. Adults with early Parkinson disease were eligible if their disease duration was less than 3 years and they were either treatment-naive or had received less than 3 months of prior dopaminergic therapy.
A total of 751 adults were screened, and 529 were enrolled and randomized. Participants were assigned in a 1:1:1 ratio to receive tavapadon 5 mg once daily, tavapadon 15 mg once daily, or placebo for 27 weeks. This was followed by a 4-week safety follow-up period. The average age of participants was 63.7 years, and the average disease duration was 0.7 years. Women made up 35.3% of the study population.
The blinded design helped minimize bias, and the placebo group provided a direct comparison for assessing how much of the observed improvement was due to tavapadon rather than to expectation or natural variation in symptoms.
What the Researchers Measured
The main outcome was the change from baseline to week 26 in the combined score for parts II and III of the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale, or MDS-UPDRS. Part II reflects motor aspects of daily living, such as dressing, eating, and hygiene, while part III measures motor examination findings such as tremor, rigidity, and slowness. A lower score indicates fewer or less severe symptoms.
Key secondary outcomes included the change in MDS-UPDRS part II alone and the proportion of participants who reported feeling “much improved” or “very much improved” on the Patient Global Impression of Change, a patient-centered measure of overall perceived benefit.
Main Results
Both tavapadon doses led to meaningful improvement in motor symptoms compared with placebo. At week 26, participants taking tavapadon 5 mg had a 9.7-point decrease in the combined MDS-UPDRS parts II and III score, while those receiving placebo had a 1.8-point increase. The treatment difference was -11.5 points, with a 95% confidence interval from -13.8 to -9.2, and the result was highly statistically significant (P < .001). The standardized effect size was large, with d = 1.14.
Participants receiving tavapadon 15 mg also showed substantial benefit, with a 10.2-point decrease in the combined score versus a 1.8-point increase with placebo. The treatment difference was -12.1 points, with a 95% confidence interval from -14.4 to -9.8, again with P < .001. The effect size was similarly large, with d = 1.20.
These findings suggest that tavapadon improved both the everyday functional burden of Parkinson disease and the motor findings assessed during examination. Although the study used fixed doses rather than flexible dose titration, both doses were effective, and the magnitude of benefit was clinically meaningful.
Safety and Tolerability
Tavapadon had a favorable safety profile in this trial. Most adverse events were mild to moderate and were not serious. The most commonly reported side effects were nausea, headache, and dizziness.
Among the 354 participants who received tavapadon across both dose groups, nausea occurred in 90 participants (25.4%), headache in 59 (16.7%), and dizziness in 45 (12.7%). These are important side effects to consider because they can affect adherence, especially early in treatment. However, the overall safety findings were reassuring, and the trial authors reported that tavapadon was well tolerated.
For people with early Parkinson disease, tolerability matters as much as efficacy. A treatment that improves symptoms but is difficult to continue may not provide long-term benefit. The once-daily dosing schedule may also be attractive for people who prefer simpler regimens.
Clinical Meaning
The TEMPO-1 trial adds to growing evidence that selective dopamine receptor targeting may offer a useful treatment option in early Parkinson disease. Compared with placebo, both doses of tavapadon improved motor function over 27 weeks, and the medication was generally well tolerated.
If future studies confirm these results, tavapadon could become an additional option for symptom control in early disease, particularly for patients who are not yet using levodopa or who may benefit from a once-daily oral therapy. It may also be of interest to clinicians seeking treatments that balance efficacy with fewer dopamine-related adverse effects.
That said, this study does not answer every question. The trial followed participants for just over half a year, so longer-term effects, durability of benefit, and rare safety issues still need further study. It is also important to know how tavapadon compares directly with existing treatments in real-world practice, including levodopa and older dopamine agonists.
Limitations
As with any clinical trial, there are limits to what can be concluded. The study duration was relatively short for a chronic disease like Parkinson disease. The population consisted of adults with early disease, so the findings may not apply to people with more advanced symptoms. In addition, participants were closely monitored in a trial setting, which can sometimes produce different outcomes than everyday clinical care.
Another limitation is that the main reported outcomes focused on symptom improvement and short-term tolerability, rather than long-term quality of life, disease progression, or time to additional medication use. These are important considerations when selecting therapy for a neurodegenerative disorder.
Conclusion
In the TEMPO-1 randomized clinical trial, once-daily tavapadon at fixed doses of 5 mg and 15 mg improved motor symptoms in adults with early Parkinson disease compared with placebo. The treatment was generally well tolerated, with nausea, headache, and dizziness being the most common adverse events.
Overall, the study suggests that tavapadon may offer a promising new option for early Parkinson disease, combining meaningful symptom relief with a favorable short-term safety profile. Further research will be needed to determine its long-term role in Parkinson disease care.
Trial Registration
ClinicalTrials.gov Identifier: NCT04201093.
Citation
Pahwa R, Moro E, Espay AJ, Evans A, Saint-Hilaire M, Torres-Russotto D, Sanchez R, Leoni M, Duvvuri S, Combs C, Chang I, Tringali S, Boiser J, Zadikoff C, Antonini A. Fixed-Dose Tavapadon for Early Parkinson Disease: A Randomized Clinical Trial. JAMA Neurology. 2026;83(5):452-460. PMID: 41860533.
