Literature Review

No evidence for disease-modifying effect of levodopa in Parkinson’s disease

View on the News

LEAP supports today’s practice standards

This trial supports current clinical practice in two ways, according to Susan Bressman, MD, and Rachel Saunders‑Pullman, MD, MPH. On one hand, the study provides no evidence to suggest that levodopa slows Parkinson’s disease progression, Dr. Bressman and Dr. Saunders-Pullman wrote in an editorial accompanying the study. On the other hand, they added, it provides no evidence that clinicians should delay therapy when it is clinically indicated.

The LEAP trial (Levodopa in Early Parkinson’s Disease) was designed to resolve uncertainty over the potential effects of levodopa on disease progression, they noted. This was necessary because of the results of the placebo-controlled ELLDOPA trial, which was published about 14 years ago and suggested that patients randomized to 40 weeks of levodopa did not deteriorate clinically to the degree that was observed in patients randomized to placebo.

The primary end point of that trial was Unified Parkinson’s Disease Rating Scale (UPDRS) scores after a 2-week washout period.

While one interpretation of the UPDRS results from ELLDOPA was that levodopa slowed disease progression, another was that the 2-week washout period was too short, allowing for residual effects of levodopa on symptoms, suggested Dr. Bressman and Dr. Saunders-Pullman.

The randomized LEAP study now shows not only that there were no differences in UPDRS scores when using a delayed start trial design – which implies that there was no disease-modifying effect – but also that starting levodopa early did not have negative effects, the editorial authors wrote.

In particular, the researchers showed no differences in rates of dyskinesia or levodopa-related fluctuations in those started early versus those started later.

“The results of the current trial, taken together with those of other trials, support treatment that is guided by clinical need and that uses the lowest dose that provides a satisfactory clinical effect,” wrote the editorial’s authors.

Dr. Bressman and Dr. Saunders‑Pullman are with the Icahn School of Medicine at Mt. Sinai, New York. Their editorial appears in the New England Journal of Medicine (2019;380:389-90). Dr. Bressman reported disclosures related to Denali Therapeutics, the Michael J. Fox Foundation, and Prevail Therapeutics, while Dr. Saunders-Pullman reported disclosures with Denali Therapeutics, the National Institutes of Health, Genzyme Sanofi, and the Bigglesworth Family Foundation.



Levodopa did not significantly alter the course of Parkinson’s disease in a randomized, 80-week, delayed-start, clinical trial, investigators reported. The disease course was not significantly different for patients who had a full 80 weeks of levodopa/carbodopa therapy, compared with that seen with those who started treatment after a 40-week delay, according to the investigators.

Rob M.A. de Bie, MD, PhD, professor of movement disorders, university of amsterdam.

Dr. Rob de Bie

“These findings imply that levodopa had no disease-modifying effect on Parkinson’s disease over the period of the trial,” wrote investigator Rob M. A. de Bie, MD, PhD, professor of movement disorders at the University of Amsterdam, and his colleagues in the New England Journal of Medicine.

By contrast, results of an earlier randomized, placebo-controlled trial suggested that levodopa had disease-modifying effects, though the findings of that study were inconclusive, according to authors of an editorial (see Views on the News).

In the current multicenter trial, known as LEAP (Levodopa in Early Parkinson’s Disease) a total of 445 patients with early Parkinson’s disease were randomized to either 80 weeks of levodopa and carbodopa or to 40 weeks of placebo followed by 40 weeks of levodopa/carbodopa.

Levodopa was dosed at 100 mg three times per day, and carbodopa at 25 mg three times per day, according to the report.

There was no significant difference between the early and delayed treatment groups for primary outcome of the trial, which was change in the Unified Parkinson’s Disease Rating Scale (UPDRS) from baseline to week 80.

The mean change in UPDRS was –1.0 in the group of patients who had the full 80 weeks of levodopa/carbodopa and –2.0 for those who had delayed therapy, for a difference of 1 point (P = .44). Higher scores on the UPDRS signify worse disease.

At week 40, there was a change in UPDRS favoring the early-initiation strategy, which reflected the effects of levodopa on disease symptoms, investigators added.

Nausea was more common in the early-start group during the first 40 weeks of the trial. However, there were no differences between groups in other adverse events of particular interest, including dyskinesias and motor fluctuations related to levodopa, Dr. de Bie and his colleagues reported.

Taken together, these results suggest no beneficial or detrimental disease-modifying effect for an early treatment strategy, although further trials are warranted to evaluate other strategies, such as higher levodopa doses, longer administration, or starting the drug at later stages of disease, they wrote.

Dr. de Bie reported grants from ZonMw, Parkinson Vereniging, and Stichting Parkinsonfonds during the conduct of the study, as well as grants from GE Health and Medtronic outside the submitted work. Study authors provided disclosures related to Netherlands Organization for Scientific Research, Michael J. Fox Foundation, UCB, AbbVie, Boston Scientific, Biogen, Merck, and others.

SOURCE: Verschuur CVM et al. N Engl J Med. 2019;380:315-24.

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