What’s Hot in PD? Choosing Between Subcutaneous Apomorphine Infusions, Intestinal Pumps (Duopa) and Deep Brain Stimulation: Implications of the TOLEDO Trial

Over time, surgical therapies have improved treatment options for a generation of people with Parkinson’s disease (PD) who experience worsening motor fluctuations and dyskinesia. Lesion therapies, such as deep brain stimulation (DBS), are powerful options for people with these troublesome symptoms. Levodopa/carbidopa intestinal pump therapy (Duopa) provide an option for symptom relief without brain surgery. In this month’s edition of What’s Hot in Parkinson’s disease, we examine the results of the recently completed apomorphine TOLEDO pump trial, a new study examining subcutaneous apomorphine infusion (a pump therapy that delivers PD medication similar to insulin pumps for diabetes). These results may influence an individual’s decision to pursue levodopa/carbidopa intestinal gel pumps (Duopa) or deep brain stimulation.

About subcutaneous apomorphine treatment

Recently, there has been hope among the PD community that subcutaneous apomorphine treatment may  provide a less invasive option to directly address troublesome motor fluctuations. A person with Parkinson’s or a caregiver can administer the setup and procedure of a pump. A small delivery tube is placed under the skin and connected to an external pumping device filled with apomorphine. Duopa pump therapy a similar option, however is more prone to complications associated with the gastroduodenal levodopa/carbidopa gel delivery tube.

Prior to the recently published TOLEDO trial, subcutaneous apomorphine infusion had only been tested in open-label studies, which lacked control groups or the use of a placebo to more accurately test the treatment. Regina Katzenschlager, MD, and colleagues conducted a randomized placebo controlled multicenter double-blind study — the gold standard of research studies — utilizing 23 clinical trial centers across Europe and published their findings in the July issue of Lancet Neurology. 

How does the TOLEDO trial help people with Parkinson’s?

Though there were 107 people with Parkinson’s enrolled in the study, 36 did not complete the full double blind observational period. Participants had to be diagnosed at least three years prior to enrollment. Researchers were most interested in studying people with PD who have persistent motor fluctuations, despite medication. Over the course of the 12-week study, participants were randomized, some receiving three to eight milligrams per hour of apomorphine subcutaneous injections, while others received a placebo saline infusion. The infusions were only administered during waking hours — approximately 16 hours a day. The flow rates for the devices and the PD medications could be adjusted during the first four weeks of therapy. 

Apomorphine infusion improved off time by more than two hours a day; however, it surprisingly did not influence quality of life. The primary outcome variable for the study was the change in daily dopaminergic off medication time. The apomorphine infusion reduced off time compared with placebo. Data from 106 participants was analyzed. Six subjects in the apomorphine group withdrew and 44 percent had nodules (growth of tissue) where the pump was infused. The most common side effects were erythema (reddening of skin) at the infusion site, nausea and dyskinesia.

The dyskinesia scores among participants were so mild that it would be hard to judge how the apomorphine therapy would have performed if administered to moderate to severe dyskinesia cases. However, one could speculate that the apomorphine infusion would likely worsen dyskinesia as it did in 15 percent of subjects who were randomly chosen to receive the apomorphine. Finally, the four-week period where medications and apomorphine could both be simultaneously adjusted in the study, made the results difficult to evaluate. Regardless, since the study design was double blind, there was a clear benefit in improving on dopaminergic time in the apomorphine, but not in the placebo group.

What is the bottom line for the PD community? 

If you are experiencing mild to moderate Parkinson’s motor fluctuations, apomorphine infusion treatment may be beneficial — even though it is not FDA-approved in the U.S. It would make sense to try a subcutaneous apomorphine before trying the more invasive levodopa/carbidopa intestinal gel pumps or deep brain stimulation.

Unlike apomorphine infusions, both the Duopa levodopa/carbidopa intestinal gel pump and DBS have been associated with improvements in quality of life. Collectively, research suggests that both the Duopa pump and DBS approaches would have greater benefits than apomorphine infusions but have increased risks. 

Deep brain stimulation remains the most powerful treatment for severe dyskinesia. In some cases, apomorphine infusions may worsen dyskinesia. The implications of forming nodules and erythema where the pump is inserted, for short and long term apomorphine infusion treatment, remains unknown. Future and hopefully larger comparative studies can help guide people with Parkinson’s and doctors in therapy choices. 

Selected References:

Regina Katzenschlager, Werner Poewe, Olivier Rascol, Claudia Trenkwalder, Günther Deuschl, K Ray Chaudhuri, Tove Henriksen, Teus van Laar, Kevin Spivey, Senthil Vel, Harry Staines, Andrew Lees. Apomorphine subcutaneous infusion in patients with Parkinson’s disease with persistent motor fluctuations (TOLEDO): a multicentre, double-blind, randomised, placebo-controlled trial. Lancet Neurology. Published online July 2018.

Okun MS. Subcutaneous Apomorphine Treatment: Results of the TOLEDO Trial. NEJM Journal Watch Neurology, 2018.