Although nilotinib is safe and tolerable in patients with moderate or advanced Parkinson’s disease, it may not affect the disease’s symptoms, according to investigators. Nevertheless, other drugs that – like nilotinib – inhibit tyrosine kinase (c-Abl) may have a neuroprotective effect, they added. The study was presented online as part of the American Academy of Neurology’s 2020 Science Highlights.
Research using preclinical models of Parkinson’s disease has indicated that nilotinib offers neuroprotection. Tanya Simuni, MD, the Arthur C. Nielsen Jr., Research Professor of Parkinson’s Disease and Movement Disorders at Northwestern University in Chicago, and colleagues conducted a prospective study to evaluate the safety and tolerability of oral nilotinib in patients with moderate or advanced Parkinson’s disease. The investigators also sought to examine nilotinib’s symptomatic effect, as measured by the Movement Disorder Society–Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part III. In addition, Dr. Simuni and colleagues analyzed the drug’s effect on progression of disability, as measured by various other Parkinson’s disease scales. The study’s exploratory outcomes included cognitive function, quality of life, pharmacokinetic profile, and a battery of serum and spinal fluid biomarkers.
The researchers conducted their randomized, double-blind, placebo-controlled, parallel-group study at 25 sites in the United States. They randomized 76 patients with Parkinson’s disease in approximately equal groups to a daily dose of placebo, 150 mg of nilotinib, or 300 mg of nilotinib. Safety visits occurred monthly. Patient assessments occurred at 3 months and at 6 months, which was the end of the treatment period. Patients presented off study medication at 1 month and 2 months after the end of the treatment period.
Treatment Did Not Change Dopamine Levels
Baseline demographics and disease characteristics were balanced between groups. Mean age was about 66 years in the placebo group, 61 years in the 150-mg group, and 67 years in the 300-mg group. The proportion of male participants was 64% in the placebo group, 60% in the 150-mg group, and 81% in the 300-mg group. Disease duration was 9 years in the placebo group, approximately 9 years in the 150-mg group, and approximately 12 years in the 300-mg group. Mean MDS-UPDRS total on score was 46 in the placebo group, 47 in the 150-mg group, and 52 in the 300-mg group.
Tolerability was 84% in the placebo group, 76% in the in the 150-mg group, and 77% in the 300-mg group. The sole treatment-related serious adverse event, arrhythmia, occurred in one patient in the 300-mg group. The rate of any adverse event was 88% in the placebo group, 92% in the 150-mg group, and 88% in the 300-mg group. The rate of any serious adverse event was 8% in the placebo group and 4% in each nilotinib group.
From baseline to 1 month, MDS-UPDRS part III on scores decreased by 0.49 points in the placebo group, increased by 2.08 in the 150-mg group, and increased by 4.67 in the 300-mg group. Differences in other secondary measures (e.g., change in MDS-UPDRS part III on scores from baseline to 6 months and change in MDS-UPDRS part III off score from baseline to 6 months) were not statistically significant.
At 3 months, CSF levels of nilotinib were well below the threshold for c-Abl inhibition (approximately 11 ng/mL). The arithmetic mean levels were 0.91 ng/mL in the 150-mg group and 1.69 ng/mL in the 300-mg group. Nilotinib also failed to alter CSF levels of dopamine or its metabolites at 3 months. Dr. Simuni and colleagues did not see significant differences between treatment groups in the exploratory outcomes of cognitive function and quality of life.
“Nilotinib is not an optimal molecule to assess the therapeutic potential of c-Abl inhibition for Parkinson’s disease,” the investigators concluded.
Nilotinib May Be an Inappropriate Candidate
The data “suggest that the hypothesis wasn’t tested, since the CSF and serum concentration of the drug were insufficient for enzyme inhibition,” said Peter LeWitt, MD, Sastry Foundation Endowed Chair in Neurology and professor of neurology at Wayne State University, Detroit. “A higher dose or a more CNS-penetrant drug would be needed for adequate testing of the hypothesis that c-Abl inhibition could provide disease modification.”
Nilotinib might not be an appropriate drug for this investigation, he continued. “There may be better choices among c-Abl inhibitors for penetration into the CNS, such as dasatinib, or for increased potency of effect, such as imatinib.”
Sun Pharma Advanced Research Company is conducting a clinical trial of KO706, another c-Abl inhibitor, added Dr. LeWitt, who is a researcher in that trial and an editorial adviser to Neurology Reviews. “The studies published recently in JAMANeurologyby Pagan et al. claiming target engagement with nilotinib in Parkinson’s disease patients need to be contrasted with the results of the current investigation. Disease modification with c-Abl inhibition continues to be a promising therapeutic avenue, but both positive and negative study results need careful reassessment and validation.”
The Michael J. Fox Foundation, the Cure Parkinson’s Trust, and Van Andel Research Institute funded the study. Novartis provided the study drug and placebo. The investigators reported no conflicts of interest.
SOURCE: Simuni T et al. AAN 2020. Abstract 43617.
This story originally appeared on MDedge.com.