臨床研究等提出・公開システム

Date of registration	July. 22, 2026
Last modified on	July. 22, 2026
Trial ID	jRCT2031260337

Scientific Title	A Global, Multicenter, Randomized, Double-Blinded, Placebo-Controlled, Phase 2 Study to Evaluate the Efficacy, Safety, and Tolerability of Efgartigimod PH20 SC in Adult and Adolescent Participants with Autoimmune Encephalitis (Polaris)
Public Title	A Study to Learn About How Well the Medicine Efgartigimod Works to Treat Autoimmune Encephalitis In Children 12 Years or Older and Adults (Polaris)

Contact for Scientific Queries	Name	jRCT Inquiry Receipt Center
	Affiliation	IQVIA Services Japan G.K.
	Address	Keikyu Dai-1 Building, 4-10-8 Takanawa Minato-ku, Tokyo, 108-0074
	Telephone	+81-3-6859-9500
	E-mail	JP-HAB40232-CL@iqvia.com
Contact for Public Queries	Name	jRCT Inquiry Receipt Center
	Affiliation	IQVIA Services Japan G.K.
	Address	Keikyu Dai-1 Building, 4-10-8 Takanawa Minato-ku, Tokyo, 108-0074
	Telephone	+81-3-6859-9500
	E-mail	JP-HAB40232-CL@iqvia.com

Recruitment status	Pending

Anticipated date of first enrollment		July. 22, 2026
Target sample size		17
Study Type		Interventional
Study Design	allocation	randomized controlled trial
	masking	double blind
	control	placebo control
	assignment	parallel assignment
	purpose	treatment purpose
Key inclusion & exclusion criteria	Inclusion Criteria	-Is at least 12 years of age. -Meeting at least the criteria for possible AIE according to the Graus criteria. -Part A: Must not have received prior treatment for AIE with PLEX or Ig (participants may have received glucocorticoids); and must not have received PLEX or Ig for any other medical condition in the last 3 months -Part B: Either completing Part A, or If directly entering Part B, must have received first-line treatment for AIE (i.e. corticosteroids, PLEX, and/or Ig) and have a CASE score of 3 or higher, or a score of 2 or higher in a single sub-item
	Exclusion Criteria	-Known anti-myelin oligodendrocyte glycoprotein (anti-MOG) antibody positivity. -Any medical condition that would interfere with an accurate assessment of clinical symptoms of AIE. -Recent major surgery (within 3 months of screening) or intention to have major surgery during the study, except for surgeries for AIE-related teratomas and thymomas. -History (within 12 months before screening) of current alcohol, drug (including recreational or prescribed cannabinoids), or medication abuse. -Psychiatric or cognitive impairment unrelated to AIE.
	Age Minimum	12age old over
	Age Maximum	No limit
	Gender	Both
Health Condition(s) or Problem(s) Studied		Autoimmune Encephalitis (AIE)
Intervention(s)		- Part A : participants will receive efgartigimod SC open label for 8 weeks. Subcutaneous administrations of efgartigimod PH20 SC given by prefilled syringe (PFS). For participants aged 12 to <18 years with body weight <=50 kg, the study drug will be administered by vial and syringe. - Part B: participants will receive either efgartigimod SC or placebo SC for 24 weeks. Subcutaneous administrations of efgartigimod PH20 SC or placebo given by prefilled syringe (PFS). For participants aged 12 to <18 years with body weight <=50 kg, the study drug will be administered by vial and syringe. - Part C : Participants who complete Part B will receive efgartigimod PH20 SC for 24 weeks. Subcutaneous administrations of efgartigimod PH20 SC given by prefilled syringe (PFS). For participants aged 12 to <18 years with body weight <=50 kg, the study drug will be administered by vial and syringe.
Primary Outcome(s)		Change in CASE score in the NMDAR population

Primary Sponsor	argenx BV

Secondary Sponsor

Secondary Sponsor

Name of Certified Review Board	Joint Institutional Review Board of Nihon University Itabashi Hospital, School of Medicine
Address	Oyaguchikami-cho 30-1, Itabashi-ku, Tokyo, Tokyo
Telephone	+81-3-3972-8111
Approval Status	Approval
Date of approval	June. 16, 2026

Plan to share IPD	No

Secondary ID(s)	NCT07583641
Issuing Authority	ClinicalTrials.gov

Countries of Recruitment（Except Japan）	U.S./Argentina/Australia/Belgium/France/Germany/Israel/Italy/Malaysia/(about 30countries)