A new study adds to the evidence that a class of diabetes drugs could help Parkinson’s patients, even if only a little. In the April 4 New England Journal of Medicine, researchers led by Olivier Rascol at Toulouse University Hospital, France, reported that PD patients taking the GLP-1 analogue lixisenatide maintained their motor abilities over the course of a year in a small Phase 2 trial, while patients on placebo declined. This follows reports that a similar GLP-1 analogue, exenatide, also halted decline in Phase 2. Together, the studies suggest this class of drugs is worth continuing to explore in larger Phase 3 studies.

  • Lixisenatide stabilized motor abilities in Parkinson’s patients over one year.
  • The small benefit versus placebo was maintained two months later.

Nigel Greig at the National Institutes of Health, Bethesda, Maryland, called the clinical effect small but meaningful, and said it supports prior findings with exenatide. He was a co-author on the exenatide study. “A valuable aspect of GLP-1 receptor agonists is that multiple potentially efficacious cascades are selectively triggered … to provide neuroprotective, neurotrophic, anti-neuroinflammatory, and reversal of brain insulin resistance actions,” he noted (comment below).

These beneficial brain effects were first shown in rodent models of PD two decades ago (Perry et al., 2002; Bertilsson et al., 2008; Harkavyi et al., 2008). The data led to clinical studies with exenatide. Like other glucagon-like peptide-1 receptor agonists, exenatide boosts insulin release, revving up glucose metabolism. In small studies, the drug stabilized motor abilities in people with moderate PD, but only in their “off-medication” state, i.e., when they had not yet taken their dopaminergic medications for the day (Jun 2013 news; Aug 2017 news).

In the new study, Rascol and colleagues tested lixisenatide, a GLP-1 mimic made by Sanofi. It was marketed under the brand name Adlyxin but has since been discontinued, for what the company said were business reasons. The Lixipark trial in France enrolled 156 participants with mild Parkinson’s disease. They were 60 years old on average and had been diagnosed about 1.5 years earlier. Participants injected themselves daily with 10 or 20 μg lixisenatide or placebo.

After 12 months, people on drug had notched a small numerical improvement of 0.04 points on the primary outcome measure, the Movement Disorders Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Part 3, which assesses motor abilities. This compared with a decline of 3.04 points for people on placebo, a statistically significant difference. Unlike in the exenatide trial, this difference was apparent while participants were taking dopaminergic drugs. The three-point difference between treatment and placebo groups was maintained after two months off lixisenatide and was seen in the off-medication state as well.

Lixisenatide did not demonstrate any benefit on secondary outcome measures. These included other parts of the MDS-UPDRS, which reflect non-motor symptoms and activities of daily living. Exenatide likewise had no effect on these measures.

The treatment group was twice as likely as the placebo group to experience side effects. These were mostly gastrointestinal, with almost half of people on lixisenatide having nausea, 13 percent vomiting, and 8 percent with acid reflux. A total of seven people dropped out of the study, four from the treatment group and three from placebo.

Greig noted that the lixisenatide study extends the benefits of GLP-1 analogues from moderate to mild PD. Recent mouse studies indicate that these medications may have greater benefits the earlier in disease they are started (Wang et al., 2021; Wang et al., 2024). In a similar vein, post hoc analysis from a trial of an exenatide variant, NLY01, found greater benefits in PD patients younger than the age of 60 (McGarry et al., 2024). In the lixisenatide trial, post hoc analysis likewise showed greater benefit for people under 60. They notched a five-point difference from the placebo group, compared with one point for those older than 60.

Exenatide is now in a Phase 3, 96-week trial of 200 mild-to-moderate PD patients in the U.K. (Vijiaratnam et al., 2021). A Phase 3 trial of lixisenatide is planned.

Also in Parkinson’s news, exploratory analyses from the Phase 2 Pasadena study of Roche’s anti-α-synuclein antibody prasinezumab are now published. In the April 15 Nature Medicine, researchers led by Gennaro Pagano at Roche in Basel, Switzerland, reported that a subgroup of participants with more rapidly progressing disease maintained their motor abilities better on prasinezumab (Apr 2021 conference news). Overall, the trial had been negative (Apr 2020 conference news). A new Phase 2 trial, Padova, is testing prasinezumab in patients with faster-progressing disease.—Madolyn Bowman Rogers

Comments

  1. It is wonderful to see a treatment strategy, proposed by my collaborators and me in 2002 in publications describing the neuroprotective/neurotrophic actions of GLP-1 receptor agonists, demonstrating efficacy in Parkinson’s disease (Perry et al., 2002; Perry et al., 2002). New effective treatment approaches remain a significant unmet need for PD. We first presented our work relating to the efficacy of GLP-1 receptor agonists in preclinical PD models in 2005 and this triggered a flurry of supportive publications in 2008/2009 (Bertilsson et al., 2008; Harkavyi et al., 2008; Li et al., 2009). 

    This lixisenatide PD study of Wassilios Meissner and collaborators is impressive, elegant, and provides a balanced evaluation of the primary and secondary measures of the trial, putting them into context with the current literature. The primary outcome measure (MDS-UPDRS Part III) relates to motor examination, and showed a small but statistically significant and meaningful separation from the placebo group after 12 months in this Phase 2, double-blind, randomized, placebo-controlled trial. Importantly, this difference remained following a two-month washout period when measured in the off-medication state. In this regard, this study nicely supports the exenatide PD trials of Foltynie and collaborators (Athauda et al., 2017; Aviles-Olmos et al., 2013) and, importantly, extended these beyond patients with moderate PD to those with milder disease—diagnosed less than three years earlier.

    Our recent collaborative studies with a sustained release form of exenatide (PT320) in the mitoPark mouse—which provides a valuable, slowly progressive model of PD—indicate that earlier treatment with a GLP-1 receptor agonist is preferential (Wang et al., 2021; Wang et al., 2024). A valuable aspect of GLP-1 receptor agonists is that multiple potentially efficacious cascades are selectively triggered by receptor activation, with the potential to positively impact a broad spectrum of PD patients to provide neuroprotective, neurotrophic, anti-neuroinflammatory and reversal of brain insulin resistance actions that have been described in recent reviews (Athauda and Foltynie, 2018; Glotfelty et al., 2020; Holscher, 2022; Kopp et al., 2022; Kalinderi et al., 2024).

    Meissner et al. provide thoughtful insight into potential future directions. Furthermore, the availability of clinically available, dual, and triple agonists from the diabetes/obesity field that can trigger GLP-1, GIP, and glucagon receptor stimulation may offer the PD field more than does a single GLP-1 receptor agonist. Other outcome measures of relevance to PD may, likewise, benefit from a GLP-1 receptor agonist approach—for example, our recent collaborative studies have demonstrated a mitigation of L-DOPA-induced dyskinesia across two different PD preclinical animal models using a clinically translatable dose of exenatide (PT320) (Yu et al., 2020; Kuo et al., 2023).

    Importantly, Meissner et al.’s trial and the exenatide studies by Foltynie and colleagues demonstrate that successful clinical translation can be achieved for neurodegenerative disorders—as it has for cancer and for cardiovascular disorders. This keeps our spirits alive and strong that, together, we can positively impact diseases such as Alzheimer’s, traumatic brain injury, tauopathies, multiple system atrophy, ALS, and others.

    References:

    . A novel neurotrophic property of glucagon-like peptide 1: a promoter of nerve growth factor-mediated differentiation in PC12 cells. J Pharmacol Exp Ther. 2002 Mar;300(3):958-66. PubMed.

    . Protection and reversal of excitotoxic neuronal damage by glucagon-like peptide-1 and exendin-4. J Pharmacol Exp Ther. 2002 Sep;302(3):881-8. PubMed.

    . Peptide hormone exendin-4 stimulates subventricular zone neurogenesis in the adult rodent brain and induces recovery in an animal model of Parkinson's disease. J Neurosci Res. 2008 Feb 1;86(2):326-38. PubMed.

    . Glucagon-like peptide 1 receptor stimulation reverses key deficits in distinct rodent models of Parkinson's disease. J Neuroinflammation. 2008;5:19. PubMed.

    . GLP-1 receptor stimulation preserves primary cortical and dopaminergic neurons in cellular and rodent models of stroke and Parkinsonism. Proc Natl Acad Sci U S A. 2009 Jan 27;106(4):1285-90. PubMed.

    . Exenatide once weekly versus placebo in Parkinson's disease: a randomised, double-blind, placebo-controlled trial. Lancet. 2017 Aug 3; PubMed.

    . Exenatide and the treatment of patients with Parkinson's disease. J Clin Invest. 2013 Jun 3;123(6):2730-6. PubMed.

    . Sustained Release GLP-1 Agonist PT320 Delays Disease Progression in a Mouse Model of Parkinson's Disease. ACS Pharmacol Transl Sci. 2021 Apr 9;4(2):858-869. Epub 2021 Mar 16 PubMed.

    . Attenuating mitochondrial dysfunction and morphological disruption with PT320 delays dopamine degeneration in MitoPark mice. J Biomed Sci. 2024 Apr 17;31(1):38. PubMed.

    . Protective effects of the GLP-1 mimetic exendin-4 in Parkinson's disease. Neuropharmacology. 2018 Jul 1;136(Pt B):260-270. Epub 2017 Sep 18 PubMed.

    . Glucagon-like peptide-1 (GLP-1)-based receptor agonists as a treatment for Parkinson's disease. Expert Opin Investig Drugs. 2020 Jun;29(6):595-602. Epub 2020 May 15 PubMed.

    . Glucagon-like peptide 1 and glucose-dependent insulinotropic peptide hormones and novel receptor agonists protect synapses in Alzheimer's and Parkinson's diseases. Front Synaptic Neurosci. 2022;14:955258. Epub 2022 Jul 27 PubMed.

    . Glucagon-like peptide-1 (GLP-1) receptor agonists and neuroinflammation: Implications for neurodegenerative disease treatment. Pharmacol Res. 2022 Dec;186:106550. Epub 2022 Nov 11 PubMed.

    . GLP-1 Receptor Agonists: A New Treatment in Parkinson's Disease. Int J Mol Sci. 2024 Mar 29;25(7) PubMed.

    . PT320, Sustained-Release Exendin-4, Mitigates L-DOPA-Induced Dyskinesia in a Rat 6-Hydroxydopamine Model of Parkinson's Disease. Front Neurosci. 2020;14:785. Epub 2020 Aug 11 PubMed.

    . PT320, a Sustained-Release GLP-1 Receptor Agonist, Ameliorates L-DOPA-Induced Dyskinesia in a Mouse Model of Parkinson's Disease. Int J Mol Sci. 2023 Feb 28;24(5) PubMed.

  2. This is an important publication, given it essentially replicates the findings of Athauda et al., who reported positive Phase 2 data of a very similar GLP-1 receptor agonist drug, exenatide, when given to patients with Parkinson’s disease (Athauda et al., 2017). 

    This cumulative clinical data, therefore, strongly supports the earlier laboratory and epidemiological data that GLP1 receptor stimulation in the brain has neuroprotective effects relevant to the neurodegenerative processes of Parkinson’s disease. Importantly, the beneficial effects seen are likely to be restricted to those GLP1 receptor agonists which can effectively access the brain, as has been demonstrated for exenatide (and are likely for the closely structurally related lixisenatide), but do not occur with liraglutide or semaglutide, while it remains unclear for the PEGylated formulation of exenatide, NLY01.

     

    The French lixisenatide trial was well-conducted and the results appear robust, although there remains a small risk of bias resulting from unblinding, given the same investigator was recording adverse events (weight loss and GI upset which occur in the lixisenatide patients) and rating the primary outcome. The authors are correct that further trial replication is necessary before any shift in clinical practice should be sought.

     

    While these findings are encouraging in the search for neuroprotective effects in Parkinson’s disease, there will remain speculation whether the mechanism of action of GLP-1 receptor drugs solely improves dopaminergic signaling (and therefore helps in the relief of symptoms), or whether they suppress the unfavorable neuroinflammatory state in PD, allowing cells to resume their normal neurotransmitter functions, and ultimately avoid premature cell death. Phase 3 trial data of the effects of two years’ exposure to exenatide in patients with Parkinson’s disease will hopefully address this question, and will be available in the second half of 2024.

    References:

    . Exenatide once weekly versus placebo in Parkinson's disease: a randomised, double-blind, placebo-controlled trial. Lancet. 2017 Aug 3; PubMed.

  3. The lixipark study is great news for PD patients as it shows halt of disease progression and confirms earlier clinical trials testing exenatide (Athauda et al., 2017; Aviles-Olmos et al., 2014) as well as a small Phase 2 trial testing the GLP-1 analogue liraglutide, which also showed some improvements (Hogg et al., 2023). We are at the verge of a new dawn where drugs of this type can make a real difference in the clinic (see Hölscher, 2024, for a review).

    We had tested lixisenatide in different preclinical models of AD and PD and found it to be very effective (Cai et al., 2014; Cai et al., 2017; Liu et al., 2015; McClean and Holscher, 2014). An important aspect is how well the drug can cross the blood-brain barrier. A recent study showed that there are large differences between the ability of GLP-1 class drugs and dual GLP-1/GIP receptor-agonist-type drugs to protect the brain (Rhea et al., 2023). Intriguingly, a recent Phase 2 trial testing a pegylated version of exenatide (NLY01) that does not enter the brain readily (Lv et al., 2021) did not show any improvements in primary and secondary readouts (McGarry et al., 2024). We therefore developed novel dual GLP-1/GIP receptor agonists that can enter the brain at an accelerated level (Hölscher, 2021; Rhea et al., 2023; Zhang et al., 2023). 

    This research area certainly deserves a lot more attention and support than it currently enjoys. Perhaps the positive results of the lixipark trial will shift opinions toward this promising direction.

    References:

    . Exenatide once weekly versus placebo in Parkinson's disease: a randomised, double-blind, placebo-controlled trial. Lancet. 2017 Aug 3; PubMed.

    . Motor and Cognitive Advantages Persist 12 Months After Exenatide Exposure in Parkinson's Disease. J Parkinsons Dis. 2014 Mar 24; PubMed.

    . Lixisenatide rescues spatial memory and synaptic plasticity from amyloid β protein-induced impairments in rats. Neuroscience. 2014 Feb 27;277C:6-13. PubMed.

    . Lixisenatide attenuates the detrimental effects of amyloid β protein on spatial working memory and hippocampal neurons in rats. Behav Brain Res. 2017 Feb 1;318:28-35. Epub 2016 Oct 21 PubMed.

    . Protective properties of GLP-1 and associated peptide hormones in neurodegenerative disorders. Br J Pharmacol. 2021 Apr 26; PubMed.

    . Glucagon-like peptide-1 class drugs show clear protective effects in Parkinson's and Alzheimer's disease clinical trials: A revolution in the making?. Neuropharmacology. 2024 Aug 1;253:109952. Epub 2024 Apr 25 PubMed.

    . Neuroprotective effects of lixisenatide and liraglutide in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease. Neuroscience. 2015 Sep 10;303:42-50. Epub 2015 Jul 2 PubMed.

    . The GLP-1/GIP dual-receptor agonist DA5-CH inhibits the NF-κB inflammatory pathway in the MPTP mouse model of Parkinson's disease more effectively than the GLP-1 single-receptor agonist NLY01. Brain Behav. 2021 Aug;11(8):e2231. Epub 2021 Jun 14 PubMed.

    . Lixisenatide, a drug developed to treat type 2 diabetes, shows neuroprotective effects in a mouse model of Alzheimer's disease. Neuropharmacology. 2014 Nov;86:241-58. Epub 2014 Aug 8 PubMed.

    . Safety, tolerability, and efficacy of NLY01 in early untreated Parkinson's disease: a randomised, double-blind, placebo-controlled trial. Lancet Neurol. 2024 Jan;23(1):37-45. PubMed.

    . Brain uptake pharmacokinetics of albiglutide, dulaglutide, tirzepatide, and DA5-CH in the search for new treatments of Alzheimer's and Parkinson's diseases. Tissue Barriers. 2023 Dec 14;:2292461. PubMed.

    . A Dual GLP-1/GIP Receptor Agonist Is More Effective than Liraglutide in the A53T Mouse Model of Parkinson's Disease. Parkinsons Dis. 2023;2023:7427136. Epub 2023 Sep 25 PubMed.

Make a Comment

To make a comment you must login or register.

References

Therapeutics Citations

  1. Exenatide
  2. Prasinezumab

News Citations

  1. Single-Blind Trial: Diabetes Drug Helps Parkinson’s, Maybe
  2. Diabetes Drug Improves Parkinson’s Motor Symptoms in Small Trial
  3. For α-Synuclein Immunotherapy, Is Going Later the Key?
  4. α-Synuclein Antibody Misses Primary, May Have Signal on Secondaries

Paper Citations

  1. . Protection and reversal of excitotoxic neuronal damage by glucagon-like peptide-1 and exendin-4. J Pharmacol Exp Ther. 2002 Sep;302(3):881-8. PubMed.
  2. . Peptide hormone exendin-4 stimulates subventricular zone neurogenesis in the adult rodent brain and induces recovery in an animal model of Parkinson's disease. J Neurosci Res. 2008 Feb 1;86(2):326-38. PubMed.
  3. . Glucagon-like peptide 1 receptor stimulation reverses key deficits in distinct rodent models of Parkinson's disease. J Neuroinflammation. 2008;5:19. PubMed.
  4. . Sustained Release GLP-1 Agonist PT320 Delays Disease Progression in a Mouse Model of Parkinson's Disease. ACS Pharmacol Transl Sci. 2021 Apr 9;4(2):858-869. Epub 2021 Mar 16 PubMed.
  5. . Attenuating mitochondrial dysfunction and morphological disruption with PT320 delays dopamine degeneration in MitoPark mice. J Biomed Sci. 2024 Apr 17;31(1):38. PubMed.
  6. . Safety, tolerability, and efficacy of NLY01 in early untreated Parkinson's disease: a randomised, double-blind, placebo-controlled trial. Lancet Neurol. 2024 Jan;23(1):37-45. PubMed.
  7. . Exenatide once weekly over 2 years as a potential disease-modifying treatment for Parkinson's disease: protocol for a multicentre, randomised, double blind, parallel group, placebo controlled, phase 3 trial: The 'Exenatide-PD3' study. BMJ Open. 2021 May 28;11(5):e047993. PubMed.

External Citations

  1. Padova

Further Reading

Primary Papers

  1. . Trial of Lixisenatide in Early Parkinson's Disease. N Engl J Med. 2024 Apr 4;390(13):1176-1185. PubMed.