Table 2.

Monoclonal antibodies and vaccines, plasma therapy, cell therapy, gene therapy, and herbal extracts in phase I, II, or III clinical trials for PD treatment. The data are based on the trial status (ongoing, updated, or discontinued) on ClinicalTrials.gov (https://clinicaltrials.gov) that is active as of 16 June 2021.

Therapeutic Strategy	Classification	Name	PD Subjects	Trial Status	Reasons for Discontinuation	Sponsor	ClinicalTrials.gov Identifier and Reference
Anti-α-synuclein aggregation therapy	Monoclonal antibody	ABBV-0805	Idiopathic PD	Phase I discontinued	Withdrawn due to strategic considerations.	AbbVie	NCT04127695
Anti-α-synuclein aggregation therapy	Vaccine Short synthetic peptides	AFFITOPE® PD01A	Early stage PD	Phase I	Not applicable	Affiris AG	NCT01568099 [45]
Anti-α-synuclein aggregation therapy	Monoclonal antibody IgG1 protein produced from memory B cells	BIIB054	PD patients	Phase II discontinued	Terminated due to lack of efficacy.	Biogen	NCT03318523
Anti-α-synuclein aggregation therapy	Monoclonal antibody	PRX002 (Prasinezumab/ RO7046015)	Idiopathic PD	Phase I	Not applicable	Prothena Biosciences Limited	NCT02157714 [43]
Anti-α-synuclein aggregation therapy	Monoclonal antibody	PRX002 (Prasinezumab/ RO7046015)	Early stage PD	Phase II	Not applicable	Hoffmann-La Roche	NCT03100149 [43]
Convalescent plasma therapy	Young plasma infusions	Infusions of young plasma	Moderate-stage PD	Phase I	Not applicable	Stanford University	NCT02968433 [58]
Cell-based therapy	Injection cultured human retinal pigment epithelial cells into both hemispheres	Spheramine/ BAY86-5280	Advanced-stage PD	Phase II discontinued	Terminated. The trial was completed, and only the lifelong extended follow-up phase was discontinued after 12 years.	Bayer	NCT00206687 [62]
Cell-based therapy	Xenotransplantation of immunoprotected (alginate-encapsulated) choroid plexus cells in the brain	NTCELL	Idiopathic PD	Phase I/II	Not applicable	Living Cell Technologies	NCT01734733
Cell-based therapy	Xenotransplantation of immunoprotected (alginate-encapsulated) choroid plexus cells in the brain	NTCELL	Idiopathic PD	Phase II	Not applicable	Living Cell Technologies	NCT02683629
Cell-based therapy	Neuronal progenitor stem cells	Adult neuronal progenitor stem cell	PD	Phase II discontinued	The study was withdrawn before participants were enrolled.	Rajavithi Hospital	NCT00927108
Cell-based therapy	Embryonic dopamine cell implant	Embryonic dopamine cell implant surgery	Idiopathic PD	Phase III	Not applicable	University of Colorado, Denver	NCT00038116 [73]
Gene therapy	AAV2-GDNF delivered to the putamen	AAV2-GDNF	Mild to moderate and moderate to severe PD	Phase I	Not applicable	Brain Neurotherapy Bio, Inc.	NCT04167540
Gene therapy	Surgical infusion of AAV-GAD into the subthalamic nucleus	Glutamic acid decarboxylase (GAD) gene therapy	Advanced-stage PD	Phase I	Not applicable	Neurologix, Inc.	NCT00195143 [80]
Gene therapy	Adeno-associated virus delivery of neurturin gene in the substantia nigra and putamen	CERE-120	Idiopathic PD	Phase I/II	Not applicable	Sangamo Therapeutics	NCT00985517 [81]
Gene therapy	Glucocerebrosidase gene therapy by intra cisterna magna administration	PR001A	Moderate to severe PD	Phase I/IIa	Not applicable	Prevail Therapeutics	NCT04127578
Gene therapy	AAV2-neurturin gene therapy	CERE-120	Idiopathic PD	Phase II	Not applicable	Sangamo Therapeutics (Ceregene)	NCT00400634 [83]
Antioxidants and botanical-based medication	Plant-based herbal dry powder	Hypoestoxide	PD	Phase I/II	Not applicable	Adesola Ogunniyi, University of Ibadan	NCT04858074
Antioxidants and botanical-based medication	Plant-based herbal extract	WIN-1001X	Early stage PD	Phase II	Not applicable	Medi Help Line	NCT04220762