Assessment of the impairment of the serotoninergic system during the prodromal phase of Parkinson’s disease in SNCA mutation carriers by PET using [11C]DASB and [11C]SB207145 : SerIAL-PD

Prior treatment

• Participation in investigational drug trials within 30 days prior to screening or within 5 half-life of investigational product whatever the longest
• Subjects treated with specific serotonin reuptake inhibitors, noradrenalin or serotonin reuptake inhibitors, tricyclic antidepressants, monoamine oxidase type A inhibitors, neuroleptics impacting the serotoninergic system or recreative drugs impacting the serotonergic system in the last 3 months

Other illness

• Contraindication to MRI such as claustrophobia, epilepsy, severe movement disorders or inability to lay flat that, in the investigator's judgment, precludes the subject's safe participation in and completion of the study. Subjects with a history of working with metal (using grinders, etc.) should have a safety check for residual metal fragments in their eyes to avoid damage from the magnetic fields.
• Active disease which could interfere with study conduct as per investigator’s judgement
• For participants undergoing optional skin sampling: any contraindication to this procedure including : - Anticoagulant or antiplatelet therapy, - History of hemostasis disorders, - Bleeding risk verified by a coagulation test
• Presence or known medical history of clinically significant neurological disorder other than PD
• Implanted devices such as stimulators, spinal rods, aneurysm clips, cardiac pacemaker, hearing device, metallic contraceptive device, insulin pump, artificial implants, peripheral or neuronal stimulator, intravenous catheter that would interfere with MRI interpretation
• Known Hypersensitivity to ioflupane or to any excipients of DaTSCAN®

Lab values

• For participants undergoing optional lumbar puncture (LP): Any contraindication to LP procedures, including but not limited to: a. Known or suspected structural abnormality of the lumbar spine, including but not limited to X-ray, MRI, or myelographic evidence of significant lumbar spine abnormalities, or other anatomical factors at or near the LP site that, in the opinion of the Investigator, may interfere with the performance of the LP, render repeated LPs difficult, or increase the risk of the procedure for the participant. b. Presence of risk for increased or uncontrolled bleeding and/or risk of bleeding that is not managed optimally and might place a participant at an increased risk for intraoperative or postoperative bleeding. These could include, but are not limited to, anatomical factors at or near the LP site (e.g., vascular abnormalities, neoplasms, or other abnormalities), known underlying disorders of the coagulation cascade, platelet function, or platelet count (e.g., hemophilia, von Willebrand’s disease, liver disease), clinically significant abnormal lab values increasing the risk of bleeding regarding platelets count, INR or PT or aPTT. - Low platelet count (below 50,000 cells/μL)(Hemostasis test must be done 72h max prior to the LP. A medical prescription will be sent to the participant to check whether his/her coagulation level is in accordance with this intervention.), - Screening values of International Normalized Ratio (INR), Prothrombin time (PT), or Activated Partial Thromboplastin Time (APTT) that are not within normal ranges (determined by the laboratory performing the analyses), - Taking any antiplatelet medication (e.g., aspirin >81 mg daily, clopidogrel, or nonsteroidal anti-inflammatory drugs [NSAIDs]) within 7 days prior to the planned LP or anticipated need for antiplatelet medication within 48 hours after an LP, - Taking anticoagulant medication (warfarin, heparinoids, and direct coagulation factor inhibitors, e.g., apixaban, dabigatran, rivaroxaban) c. Presence of intracranial hypertension d. Puncture site infections e. Patients treated with Deep Brain Stimulation.
• Pregnant and lactating women; Women of childbearing potential (WOCBP) tested positive in serum or urine pregnancy test (The following may be considered as highly effective contraception: progestogen-only or combined (estrogen and progestogen containing) hormonal contraception, intrauterine device, intrauterine hormone-releasing system, bilateral tubal occlusion, vasectomized partner (if the 22/58 SerIAL-PD_Protocol_V1.0_18032025 partner is the sole sexual partner of the WOCBP participant for the duration of the study) or abstinence (depending on the participant's lifestyle)).

Other

• Any factor which might create an unjustified risk for the participant
• Minors or subjects benefiting from laws aimed at protecting vulnerable adults: subjects being deprived of liberty by judicial or administrative decision, subjects under guardianship /curatorship.
• Participant within the exclusion period in the National Register for participants of the French Ministry of Health.
• Contraindication to PET imaging or DaTSCAN®
• Significant brain abnormalities that could interfere with accurate brain imaging analysis
• Impaired comprehension interfering with an informed consent in the opinion of the investigator
• WOCBP without a highly effective contraception

• Males and females with an age range of 18–80 years at the time of signing the informed consent
• Participant affiliated with or beneficiary of a French social security system or of such a regime
• Diagnosis of PD according to the 2015 Movement Disorder Society criteria, with bradykinesia AND at least ONE of the following: muscular rigidity, or resting tremor; with no other suspected cause of Parkinsonism for Symptomatic PD patients with and without SNCA mutation
• With documented point mutation or multiplication (i.e., duplication/triplication) mutation on the α-synuclein gene (SNCA) for Symptomatic PD patients with and without SNCA mutation
• Or without documented mutation in the SNCA gene for Symptomatic PD patients with and without SNCA mutation
• First degree relative of a PD patient with a known point mutation or multiplication in the SNCA gene (parent, sibling, or child) for Relatives of SNCA gene mutation carriers, without a diagnosis of PD
• Asymptomatic for PD symptoms, and not meeting Diagnosis of PD according to the 2015 Movement Disorder Society criteria for Healthy controls and Relatives of SNCA gene mutation carriers, without a diagnosis of PD
• Able to perform the assessments planned for the study (including brain imaging) according to investigator opinion
• Informed consent obtained from the patient or/ and a legal representative when appropriate
• For subjects taking any of the following drugs (Neuroleptics, metoclopramide, alpha methyldopa, methylphenidate, reserpine, or amphetamine derivative) must be willing and medically able to hold the medication for at least 5 half-lives before DaTSCAN imaging.