Leukine (Sargramostim) for Parkinson's Disease

Parkinson's disease (PD) is a progressive and disabling neurological disorder involving the nigrostriatum and for which no cure is known. Evidence suggests that inflammation contributes, significantly, to the cause and/or progression of the disease. Studies in postmortem human brain, animal models, and human peripheral blood support the idea that the frequency and function of particular circulating T cell subsets are abnormal and worsen as disease progresses. This abnormality is linked specifically to increases in numbers of T effector neurodestructive cells (Teff) and to dysfunction of regulatory T cells (Treg) that control Teff. This imbalance tips the homeostatic balance to a pro-inflammatory profile with limited control. Nonetheless, whether such T cell deficits are a cause of PD or a reaction to it remains unknown. If these deficits are causal or exacerbative, then correcting the deficit could have significant positive effects on disease progression and could ameliorate nigrostriatal degeneration or its sequelae. Granulocyte macrophage colony stimulating factor (GM-CSF) is a potential immunomodulatory therapeutic for PD to increase Treg numbers or function and reduce or transform proinflammatory Teff responses, leading to neuroprotection of the nigrostriatum and improved clinical outcomes for disease. Recombinant human GM-CSF (sargramostim) is available as Leukine®. The purpose of this study is to determine if Leukine (sargramostim) can be safely administered to Parkinson's disease patients for an extended period of time (56 days).

In a previous study conducted at the University of Nebraska Medical Center (UNMC) using samples of whole blood, PD patients showed differences from caregiver controls according to results from complete blood count (CBC) with white blood cell (WBC) differential, fluorescence-activated cell sorting (FACS) analysis for T cell markers, and Treg functional assays. These immune aberrations correlated with motor dysfunction as determined by Parkinson's disease rating scale (UPDRS) part III assessments. In this pilot study, the effect of Leukine treatment on immune deficits in PD patients will be monitored. Immune cell analyses of whole blood, motor assessments, and physical examinations and blood analyses for safety, will be conducted before, during, and after Leukine or placebo treatment of PD patients, and using healthy controls during baseline data collection before drug treatment. Initially, 16 PD patients and 16 controls will be recruited. Subjects will be drawn from the previous study. Enrollment will be supplemented as needed with patients from Neurology Consultants of Nebraska-PC, UNMC Neurological Sciences, or recruitment through the American Parkinson's Disease Association. Enrollment will be staggered, and additional subjects will be recruited as needed to replace any withdrawing participants, with the goal of 32 subjects, 16 PD patients and 16 controls, completing the study.

At enrollment and repeating again at two 4-week intervals, whole blood from PD patients and controls will be obtained percutaneously using standard sterile techniques. CBC with WBC differential, FACS analysis for T cell markers, and Treg functional assays will be performed and used to calculate immune response profiles as a baseline for comparison after drug treatment. Blood chemistries will be analyzed including liver enzymes, electrolytes, blood urea nitrogen, creatinine, total protein, albumin and bilirubin levels, and anti-GM-CSF antibodies will be assessed in PD patients. PD patients will be evaluated by physical and clinical examinations, including UPDRS part III assessments for evaluation of motor function.

PD patients will then be randomized into two groups, placebo (n=8) and Leukine (n=8), and participation of the controls will end. Patients entered into the study will not have any noted co-morbid conditions including infection, inflammatory or cancerous diseases and will not be taking immunostimulatory or immunosuppressive medicines. Patients will continue to take medicines prescribed for the general treatment of PD, including, but not limited to, dopamine or dopamine agonists. There will be no history of prior surgeries linked to PD treatment. Patients will receive training for self-injection, and the treatment group will self-administer Leukine (6 µg/kg) by subcutaneous injection daily for eight weeks. The placebo group will self-administer saline as placebo. Every two weeks after the start of treatment and again 4 weeks after cessation of administration, all PD patients, receiving drug or placebo, will be evaluated by physical and clinical examinations, including UPDRS part III assessments. Every 2 weeks during Leukine treatment and again 4 weeks after cessation of drug, whole blood from PD patients will be obtained percutaneously using standard sterile techniques. At weeks 2, 4 and 8, results from CBC with WBC differential, FACS analysis for T cell markers, and Treg functional assays will be used to calculate immune response profiles and compared with baseline values. CBC with WBC differential, total T cell count, and blood chemistries will be analyzed every 2 weeks for evidence of potential toxicities, as well as 4 weeks after termination of Leukine treatment. Levels of anti-GM-CSF antibodies will be assessed for PD patients at enrollment and at 4 weeks intervals during drug treatment and 4 weeks after termination. Optional video recordings will be made at baseline, end of drug/placebo treatment and at follow-up.

An additional component of the study includes the development of magnetoencephalography (MEG) as a monitoring tool for PD. MEG provides a non-invasive method to study brain activity. Currently, there are not adequate assessment tools for monitoring disease progression or treatment protocols in PD. In preliminary experiments on PD patients and their caregivers, MEG data have indicated strong beta synchronization during rest in PD and milder beta desynchronization during movement preparation compared to age- and sex-matched controls. In this study, the amplitude of this pathological beta synchronization/desynchronization will be monitored to evaluate improvements in cortical brain function of PD patients treated with Leukine. MEG will be performed on PD patients and controls at the start of drug treatment, and on PD patients at the end of the drug treatment period and 4 weeks after drug is stopped.

Among the first 8 patients enrolled in the study, we have observed unexpected and statistically significant changes in the unified PD rating scale part III (UPDRS part III) clinical evaluations for motor function in half of the patients tested. This test, however, is viewed as subjective. To more objectively and analytically score motor functions, biomechanical assessments of the subject's mobility, postural balance, upper extremity motor control and resting state tremor will be performed on the remaining eight PD patients receiving Leukine or placebo. These assessments will occur at baseline, between 7 and 8 weeks of drug treatment, and at 4-5 weeks after cessation of drug treatment. Motor function tests are designed to provide an objective, computer generated score as measured by patient performance on each test. To investigate a possible mechanism for changes in motor function observed within two weeks of therapy, testing for plasma/serum neurotransmitters will be performed to include glutamate, glutamine, serotonin, acetylcholine, gamma-aminobutyric acid (GABA), norepinephrine and epinephrine. These measures will be performed on the last cohort of PD patients of the study before initiation of treatment, 8 weeks after treatment is initiated and at 4 weeks after cessation of drug treatment. The tests will be evaluated by enzyme-linked immunosorbent assay (ELISA) or by ultra-performance liquid chromatography (UPLC). A decision on which assay will be done for which neurotransmitter will be based on sensitivity and standard curve measures. Relationships between neurotransmitter levels and motor function will be determined. These tests are in addition to current ongoing and approved laboratory tests. Eligibility requirements are unchanged from those currently imposed. Measures of motor function and serum/plasma neurotransmitter concentrations will also be completed 4-5 weeks after cessation of treatment. The notion of exploring neurotransmitters in this study is based on role in motor function that include fatigue, bowel, sexual dysfunction and mood changes that are also observed in PD as well as that GM-CSF has been shown to affect neurotransmitter levels (96). This range of listed neurotransmitters was not investigated in the first part of this study and will require limited additional blood and assay resources for the last part of the investigation.