LRRK2 inhibitor hits target, appears safe for Parkinson’s disease

Mutations in leucine-rich recurrent kinase 2 increase a person’s risk of developing Parkinson’s disease. In the June 8 issue of Science Translational Medicine, Dana Jennings and colleagues at Denali Therapeutics, south of San Francisco, published the first preclinical clinical trial data and the first clinical trial data on DNL201, an LRRK2 inhibitor.

  • DNL201 inactivates LRRK2 kinase in blood cells.
  • It crosses the blood-brain barrier and does not cause any serious side effects.
  • The trial of the second phase of the modified version began in April.

In cell culture, the small molecule inhibited LRRK2 activity and restored lysosomal function. In macaques, DNL201 reduced LRRK2 activity in peripheral blood monocytes without apparent toxicity.

In a Phase 1 study in healthy adults and Phase 1B in people with PD, DNL201 reduced the amount of phosphorylated LRRK2 in the blood, and normal levels of the lysosomal marker in urine, reaching the same drug concentration in the cerebrospinal fluid as in the blood. Over the course of both 28-day trials, the drug caused mild to moderate side effects.

“[This] The study represents a major step forward for LRRK2 kinase inhibition as a therapeutic strategy in humans, demonstrating targeted engagement and, importantly, safety and tolerability, writes Patrick Lewis, University College London, in an accompanying editorial.

Others were cautiously optimistic. Warren Olano, of Clintrex Research Corp., Sarasota, Florida, said, “As with many other drugs under investigation, DNL201 has promising results in preclinical models and appears relatively safe in short-term human studies, but it still has a long way to go. Let’s cut it off.” Exhale. Dario Alessi, of the University of Dundee, Scotland, agreed. “Although this is an impressive preclinical clinical work, we don’t yet know whether this drug will slow disease progression and whether it will benefit patients without the LRRK2 mutation,” he told Al-Zafour.

In PD, overactivation of LRRK2 results in particle disruption, which promotes the proliferation of faulty α-synuclein, the main component of Lewy bodies (News September 2018). In mouse models of disease, genetically deregulating this kinase, or quelling it with the inhibitor PF-06447475, results in reduced alpha-synuclein accumulation and loss of dopaminergic neurons (Daher et al, 2014; Daher et al, 2015).

Now, Jennings and co-authors Sarah Huntürk-Rodrigues and Anastasia Henry of Denali report that DNL201 attenuated LRRK2 activity and normalized lysosomal autophagy in mice and human cell cultures. Treated cortical neurons from LRRK2 mutant mice had less phosphorylated LRRK2 and less phosphorylated Rab10, an LRRK2 substrate. A decrease in both indicates decreased kinase activity. In astrocytes from the hits, the inhibitor restored normal lysosomal protein degradation. In human neuroblastoma cells overexpressing mutant LRRK2, DNL201 shrinks the amplified particles to their normal shape and size.

Scientists have seen similar effects on non-human primates. Macaques were injected intravenously with 16 mg/kg of DNL201 daily for 28 days and it was 80 percent lower than p-LRRK2 and p-Rab12, another LRRK2 substrate, in blood cells and brain tissue. The drug reached a similar concentration in cerebrospinal fluid as in blood, indicating that DNL201 readily entered the brain.

In a 39-week toxicological study, monkeys given up to 32 mg/kg daily maintained normal vital signs and kidney function. However, some cells in the lungs and kidneys swollen. These cells returned to normal after the researchers stopped giving the drug to the animals. This cellular side effect has been reported in monkeys following systemic LRRK2 inhibition, and does not appear to affect respiration (April News 2020). “Blocking 50-80 percent of LRRK2 activity, rather than all of that, may prevent some effects of lung cells by allowing the kinase to maintain housekeeping,” Alessi suggested.

How does DNL201 fare in people? It was tested in two trials: Phase 1 in 122 healthy adults, ages 18 to 70, and Phase 1b in 28 people with mild to moderate Parkinson’s. Of these, eight carried the common G2019S variant LRRK2, which increases the risk of disease, although it is not 100 percent penetrant.

Healthy volunteers took 25, 50, 80 or 100 mg of DNL201 twice daily for 10 days. They gave samples of blood, CSF and urine. The drug easily crossed the BBB, as indicated by the ratio of CSF drug to the blood of about one. In people who took the highest dose, plasma levels of p-LRRK2 and p-Rab10 decreased by 80 percent and urinary levels of phosphate (monoglycerol) decreased by about 75 percent. This lipid membrane is a marker of lysosomal distress, and urine BMP is elevated in LRRK2 mutation carriers (Alcalay et al., 2020).

The authors believe that the decrease in BMP indicates improved lysosome function. Alissi agreed. “BMP may be a very useful, non-invasive marker,” he said, and noted that Olanow was more cautious. “While peripheral biomarkers show targeted involvement, this does not guarantee that you will see the same effect in the brain.”

As for side effects, the volunteers appeared to tolerate the drug well, with the most common adverse events being headache, dizziness, and nausea. Five volunteers withdrew. Four took the medication, and three of them discontinued due to side effects.

In the Phase 1B trial, 12 participants with PD took 50 mg, nine took 30 mg DNL201, and seven took a placebo three times daily for 28 days. Serum p-LRRK2 levels decreased by 55 and 85 percent after low or high doses, respectively, while p-Rab10 levels decreased by 80 and 87 percent (see image below). Since carriers of the LRRK2 mutation and people with sporadic PD have twice the amount of p-Rab10 in blood cells as those in controls, the authors believe that LRRK2 activity must be at least halved to achieve a therapeutic effect. Urinary BMP decreased by about 60 percent after the high dose of DNL201, but the smaller decrease after the low dose was not statistically significant.

LRRK2 dynamics. In subjects with PD, baseline (BL) levels of p-Rab10 decreased on the first day of dosing with 30 mg (yellow) or 50 mg (orange) DNL201, and remained low on day 28. In subjects taking placebo (lane grey), p-Rab10 levels increased over the course of the experiment. [Courtesy of Jennings et al., Science Translational Medicine, 2022.]

Most adverse events were mild or moderate. As with the other experience, headache was the most common. One PD volunteer withdrew due to a moderate headache and hypotension. Lung and kidney function remained normal. As expected during this short trial, motor symptoms or cognition did not change, as judged by the Unified Parkinson’s Disease Rating Scale (UPDRS), the Non-Motor Symptoms Scale, or the Montreal Cognitive Assessment.

Since then, Denali has dropped the DNL201 for the DNL151, which the company says has better pharmacokinetics. The two Phase 1 trials, one in 186 healthy adults and one in 36 people with cerebral palsy, ended in February 2021 and December 2020 respectively, although no data has been released yet.

DNL151 Phase 2 trial began in April. About 640 people with early-stage Parkinson’s disease will take 225 mg of the drug or placebo daily for 48 to 144 weeks. As an initial outcome, the trial will measure the time until symptoms worsen in UPDRS. Secondary endpoints include adverse events, change from baseline UPDRS score and time to deterioration in daily activities. The trial is due to end in 2025.

Blocking LRRK2 kinase activity may also correct autosomal dysfunction caused by mutations other than those of the kinase. Jennings and colleagues report that DNL201 partially restored lysosomal protein turnover in fibroblasts from a person with Gaucher disease, a lysosomal storage disorder. Gaucher can be caused by variants in the enzyme lysosomal glucocerebrosidase (GBA). People with GBA mutations are also at increased risk of developing PD, and there is some evidence that LRRK2 inhibition enhances glucocerebrosidase activity, although it is not clear whether this is what DNL201 did in this case (Sanyal et al., 2020; Ysselstein et al. al., 2019). Chelsea Widman Burke

Therapeutic quotes

  1. DNL201

  2. No. DNL151

news quotes

  1. Does LRRK2 clear α-Synuclein from the cell?

  2. Feeling relieved? Pulmonary effects of LRRK2 inhibitors are mild.

search forms

  1. LRRK2 G2019S KI Mouse

paper quotes

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    Abrogation of alpha-synuclein-mediated dopaminergic neurodegeneration in LRRK2 .-deficient mice.
    Brock Nettle Acad Science USA. 2014 Jun 24; 111 (25): 9289-94. Epub 2014 Jun 9
    PubMed.
  2. .
    Leucine-rich repeat kinase 2 (LRRK2) pharmacological inhibition slows down the neurodegeneration induced by the α-Synuclein gene..
    J Byul Kim. 2015 Aug 7; 290 (32): 19433-44. Epub 2015 Jun 15
    PubMed.
  3. .
    Elevated urinary bis-phosphate levels (monoglycerol) in LRRK2 G2019S mutant carriers: implications for therapeutic development..
    Move Discord. 2020 January; 35 (1): 134-141. Epub 2019 Sep 10
    PubMed.
  4. .
    Inflammatory and somatic defects in GBA1 mutant astrocytes are normalized by LRRK2 . inhibition.
    Move Discord. 2020 May; 35 (5): 760-773. Epub 2020 Feb 8
    PubMed.
  5. .
    LRRK2 regulates lysosomal glucocerebrosidase kinase activity in neurons derived from Parkinson’s disease patients..
    nat common. 2019 Dec 5; 10 (1): 5570.
    PubMed.

External citations

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  2. Stage 1 B

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  5. The second phase

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