Prospective and Longitudinal Assessment of FDOPA Activity in a Patient Undergoing Stem Cell Transplantation for Parkinson’s Disease

1055 Introduction: Putaminal stem cell transplantation is a new investigational approach in treatment of Parkinson’s disease. This new treatment modality is currently offered to select patients within clinical trial framework at few academic institutions in United States. Fluorine-18-flurodopa (FDOPA) is a fluorinated form of L-DOPA and used as a positron emitting radiotracer to assess the functional state of the nigrostriatal dopaminergic pathway among other indications. Methods: A 71-year-old male with medically refractory Parkinson9s disease on multi-agent therapy regimen underwent initial left side stereotactic autologous putaminal dopamine neuron transplantation followed by right side transplantation 6 month later. Dopamine neurons were derived from autologous induced pluripotent stem cells (iPSC). The patient underwent initial pre-procedural baseline FDOPA scan and 4 subsequent scans in 6-8 months intervals. Time point of the 5 FDOPA scans relative to putaminal iPSC implantations were 4 months prior and 3, 11, 17 and 23 months after the left side iPSC implantation. For the right side the scans were at 10 and 3 months prior and 5, 11 and 17 months after right side iPSC implantation. A standard dose of 10 mCi (370MBq) F-18 L-DOPA was administered with image acquisition 60 minutes post injection. Visual qualitative as well as quantitative assessment using the neuroQ™ software were carried out. The uptake in the striatum was calculated relative to the occipital cortex and striatal-to-occipital ratios were obtained.Results: Visual inspection demonstrated diminished bilateral putamen tracer activity, particularly in the posterior aspects across all studies. The tracer activity of bilateral caudate nuclei were relatively preserved, compared with other visualized basal ganglia structures. Based on stability of quantitative measurements of caudate nuclei over time, posterior putamen-to-caudate ratios were used as best index of interval change after treatment. The posterior putamen to caudate ratios for the left side were calculated as 0.82, four months prior to iPSC transplantation and 0.72, 0.68, 0.78, and 0.80 three, eleven, seventeen, and twenty-three months after iPSC transplantation, respectively. For the right side, the posterior putamen-to-caudate ratios were calculated as 0.82 and 0.79, ten and three months prior to iPSC transplantation and 0.76, 0.65 and 0.73, five, eleven and seventeen months after iPSC transplantation, respectively. After initial decline of posterior putamen-to-caudate ratios bilaterally, there was a trend towards increase of metabolic activity as assessed by the posterior putamen-to-caudate ratios bilaterally, beginning at the 17-month post-treatment F-DOPA study for each side. A depiction of the timeline and quantitative measurements is represented in figure 1. Figure 2 illustrates the visual assessment of bilateral putaminal activity. Subjectively, patient is reporting improvement of symptoms on continued multi-agent therapy. Conclusion: Putaminal stem cell transplantation is a promising new therapy approach for Parkinson’s disease. FDOPA brain positron emission tomography can serve as an accurate and objective assessment tool for response to therapy in this indication.