Risvodetinib shows potential to slow disease progression in clinical trial

Early findings in Phase 2 study also support treatment safety, tolerability

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by Andrea Lobo |

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Risvodetinib, an oral therapy being developed by Inhibikase Therapeutics for Parkinson’s disease, appears to stabilize disease status and severity, according to data covering 25 patients who finished 12 weeks of dosing in an ongoing Phase 2 clinical trial.

Over those trial weeks, clinician and patient impressions of disease status “is not changing,” Inhibikase reported in a company press release.

Patients’ experience also appears to be positive, with all of these 25 adults indicating their interest in continuing or starting with the treatment in a one-year extension study, it added.

Top-line results from the Phase 2 201 trial (NCT05424276) may be available in the second half of the year, depending on patient enrollment. The placebo-controlled trial still may be recruiting eligible adults, ages 30 to 80, diagnosed with Parkinson’s and not using any anti-parkinsonian treatment, at sites across the U.S.

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Early trial findings were presented at the AD/PD 2024 International Conference on Alzheimer’s and Parkinson’s Diseases, held this month in Lisbon, Portugal, and virtually, in the oral presentation “The 201 Trial in Untreated Parkinson’s Disease.

“The 201 Trial evaluating three doses of risvodetinib in untreated Parkinson’s patients is beginning to yield information about the experience of participants on risvodetinib,” said Milton Werner, Inhibikase’s president and CEO.

Risvodetinib, also known as IkT-148009, is an oral small molecule designed to block the activation of Abelson tyrosine kinase, a signaling molecule involved in multiple cell processes and a known target for Parkinson’s treatment. This inhibition helps to restore protective mechanisms in the brain and gastrointestinal tract, preventing the loss of dopaminergic neurons (dopamine-secreting nerve cells) to the disease. As such, it could help to slow or stop Parkinson’s progression.

Eligible patients are those who have never used, and are not planning to start, a treatment to control Parkinson’s, but they have bradykinesia (slowed movements). To date, 32 sites in the U.S. are active, 59 patients are enrolled, another 19 are in pre-enrollment screening, and 54 others are being evaluated for eligibility, the company reported.

The trial is testing the safety and tolerability of risvodetinib, given once daily as a gelatin capsule at a dose of 50, 100, or 200 mg for 12 weeks (about three months), compared with a placebo. Patients who complete this trial part are invited to enter a one-year extension study, where the estimated 30 placebo-group patients will start on risvodetinib at its highest daily dose, Inhibikase reports on its 201 trial website.

It also is assessing the treatment’s efficacy at easing disease symptoms via changes over time in patients’ motor and nonmotor function, using the MDS Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) parts 2 and 3 combined.

Risvodetinib showing reasonable safety in untreated patients

To date, 10 mild and one moderate adverse events considered possibly related to the treatment were reported by 14% of study participants. While the trial is ongoing, investigators are blinded as to who is receiving the treatment and who is randomized to a placebo.

Fifteen assessments of motor, nonmotor, and gastrointestinal function are performed at baseline (at study entry) and every month after dosing starts. These assessments cannot be interpreted, however, until the trial ends and its findings are unblinded, so comparisons can be made between treatment and placebo groups.

Researchers previously analyzed unblinded data covering 11 participants dosed before the trial was placed on a two-month clinical hold by the U.S. Food and Drug Administration (FDA), due to safety concerns regarding the medication’s higher dose. The early December 2022 hold was lifted in late January 2023, after the company provided the additional safety and pharmacological data requested by the FDA.

Data covering three of those patients, all treated at high dose, showed risvodetinib at 200 mg once daily was safe. Findings also showed that treatment could improve motor function and daily life activities in people with previously untreated Parkinson’s.

The therapy also was seen to reach steady levels in the body after up to five days, without serious side effects at any of the three doses tested.

A previous Phase 1 trial (NCT04350177) of single and multiple ascending therapy doses given to healthy adults and Parkinson’s patients showed the treatment to be safe and well tolerated, with no serious side effects reported.

Findings in that earlier trial helped in the design and dose selection of the Phase 2 study, which is due to fully conclude in January 2025.