A Phase III Study of KHN939 in Chinese Patients With Moderate-to-Severe Inactive Thyroid Eye Disease (Halo-2)

A Multicenter, Randomized, Double-masked, Placebo-Controlled Phase III Clinical Study to Evaluate the Efficacy and Safety of KHN939 in the Treatment of Moderate-to-Severe Inactive Thyroid Eye Disease (TED) in China.

This is a multicenter, randomized, double-masked, placebo-controlled Phase 3 study to evaluate the efficacy, safety, immunogenicity, and population pharmacokinetic (PopPK) characteristics of KHN939 in Chinese patients with moderate-to-severe inactive thyroid eye disease (TED). Approximately 117 participants who meet the study eligibility criteria will be randomized in a 2:1 ratio (stratified by smoking status) to receive 8 infusions of KHN939 or placebo q3W.

Study Overview

• Status: Not yet recruiting
• Conditions: Thyroid Eye Disease
• Intervention / Treatment: Drug: KHN939; Drug: Placebo

• Study Type: Interventional
• Enrollment (Estimated): 117
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Zhili Niu; Phone Number: +86-028-87516260; Email: niuzhili@cnkh.com

Study Locations

• China
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 200135
      • Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University
      • Contact: Study Team; Phone Number: +86-028-87509966/87508866; Email: khn939_trial@cnkh.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Aged 18-70 years (inclusive) at the time of signing the informed consent form (ICF), male or female
2. Weight between 45 kg and 100 kg (inclusive)

3. Diagnosed with moderate-to-severe inactive TED:

   • proptosis ≥18 mm, accompanied by at least one of the following: (a) eyelid retraction ≥2 mm; (b) moderate to severe soft tissue involvement; (c) intermittent or continuous diplopia
   • CAS ≤ 2 points in each eye
   • CAS ≤ 2 in each eye for 6 months prior to screening (based on medical records); or meets all of the following criteria for ≥ 6 months prior to screening (based on patient self-report or medical records): no progression of proptosis, no new-onset or progressive TED-related diplopia, no new-onset inflammatory TED symptoms
   • The time since initial TED diagnosis is ≥ 2 years and < 10 years prior to screening (documented by patient history or medical records)
4. Female participants of childbearing potential must have a negative serum pregnancy test during screening and agree to use an effective method of contraception from screening until 90 days after the last dose of the study drug. (Note: Women of non-childbearing potential, defined as surgically sterile or postmenopausal, are exempt.)Male participants must agree to use birth control from screening until at least 90 days after the dose of study drug.
5. Able to comply with all protocol-required procedures, examinations, and symptom reporting

Exclusion Criteria:

1. Known hypersensitivity to any component of the study drug formulation, or prior hypersensitivity to any monoclonal antibodies
2. Proptosis at Day 1 (pre-dose) that has decreased by ≥2 mm relative to screening

3. Ocular conditions:

   • Prior or investigator-assessed diagnosis of dysthyroid optic neuropathy (DON) at screening
   • Corneal involvement in the study eye without improvement after appropriate treatment
   • Prior orbital radiotherapy or surgery for TED in the study eye (including orbital decompression, strabismus correction, eyelid correction)
   • Requires immediate or planned ophthalmic surgical intervention during the study period
   • Has any pre-existing ocular condition (e.g., high myopia, anticipated cataract surgery) that, as determined by the investigator, would preclude study participation or complicate the interpretation of study results

4. Prior/concomitant treatments:

   • Use of oral or intravenous glucocorticoids within 30 days prior to screening
   • Periorbital/periocular corticosteroid injection within 90 days of screening
   • Oral or IV non-steroidal immunosuppressants within 90 days of screening
   • Corticosteroid or non-steroidal immunosuppressant eye drops within 7 days of screening
   • Received teprotumumab or teprotumumab N01 at any time prior to screening
   • Received anti-CD20 antibody therapy within 12 months prior to screening
   • Received anti-interleukin-6 receptor (anti-IL-6R) antibody therapy within 6 months prior to screening
   • Received any other investigational therapy for TED at any time prior to screening (including, but not limited to, biologics targeting IGF-1R, FcRn, or TSHR)
   • Received any other monoclonal antibody therapy within 90 days prior to screening
   • Need for selenium or vitamin supplementation for TED treatment from 21 days pre-dose through study end (multivitamins are permitted)

5. Medical history/conditions:

   • Medical conditions that contraindicate study drug use, including: suspected or confirmed inflammatory bowel disease (IBD), coagulopathy, Cerebrovascular accident (CVA) or transient ischemic attack (TIA) within 180 days, acute myocardial infarction (MI), unstable angina, or CABG/PCI within 180 days, severe arrhythmia, or severe systemic infection
   • Malignancy (treated or untreated) within 5 years prior to screening, except for the following cured or non-metastatic conditions: cutaneous squamous cell carcinoma (SCC) or basal cell carcinoma (BCC), cervical or prostate carcinoma in situ (CIS), papillary thyroid carcinoma
   • Uncontrolled diabetes (HbA1c ≥8.0% at screening, or initiation of a new diabetes medication, or a >10% dose adjustment to an existing diabetes medication within 60 days prior to screening)
   • Poorly controlled thyroid function: defined as FT3 or FT4 deviating ≥50% from local laboratory normal range (≥1.5×ULN or ≤0.5×LLN)
   • Uncontrolled hypertension: defined as SBP ≥160 mmHg or DBP ≥100 mmHg; renal artery stenosis; or other evidence of clinically unstable blood pressure
   • 12-lead ECG with a heart rate <50 or >100 bpm and evidence of active cardiac disease; or any screening ECG abnormality that, in the investigator's opinion, confounds subsequent interpretation, particularly QTcF >450 ms in males or >470 ms in females

6. Laboratory exclusions at screening:

   • Alanine aminotransferase (ALT) >3 × ULN
   • Aspartate aminotransferase (AST) >3 × ULN
   • Serum creatinine(Cr) ≥1.5 × ULN, or glomerular filtration rate (GFR) <30 mL/min/1.73 m² (MDRD formula)
7. Clinically significant ear disease, prior ear surgery, hearing impairment, or abnormal pure-tone audiometry (defined as a mean bone conduction threshold ≥25 dB at 0.5, 1, 2, 4 kHz, or ≥40 dB at any frequency)
8. Positive for HBsAg with HBV-DNA >1000 IU/mL or currently receiving anti-HBV therapy; positive for HIV antibody or HCV antibody; or active syphilis
9. Participation in any drug, vaccine, or device clinical trial within 3 months prior to screening, or currently within follow-up or within 5 half-lives of another study
10. Female subjects who are pregnant or lactating
11. Any other condition deemed by the investigator as inappropriate for study participation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: KHN939 20 mg/kg; 8 infusions of KHN939 q3W for a total of 21 weeks	Drug: KHN939; Intravenous (IV) infusion: 20 mg/kg every 3 weeks (Q3W) for a total of 8 doses over 21 weeks
Placebo Comparator: Placebo; 8 infusions of placebo q3W for a total of 21 weeks	Drug: Placebo; Intravenous (IV) infusion: placebo every 3 weeks (Q3W) for a total of 8 doses over 21 weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The proptosis responder rate of the study eye	Defined as percentage of subjects with a ≥ 2mm reduction from Baseline in proptosis in the study eye, without deterioration [≥ 2 mm increase] of proptosis in the non-study eye at Week 24. Proptosis assessment: amount of protrusion of the eye from the orbital rim measured by Hertel exophthalmometer.	Week 24

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proptosis responder rate in the study eye	See primary outcome measure description for details.	Week 12
Change from baseline in proptosis measurement of the study eye	See primary outcome measure description for details.	week 12, week 24
Change in Quality of Life (GO-QoL) Scores	The GO-QoL is a 16-item self-administered questionnaire divided into 2 subsets and used to assess the perceived effects of TED by the subjects on (i) their daily physical activity as it relates to visual function, and (ii) psychosocial functioning. The range of the GO-QoL overall transformed scores is 0 to 100, where higher values correspond to better quality of life.	week 12, week 24
Change from baseline in Clinical Activity Score (CAS) in the study eye	The CAS, based on the 7-item European Group on Graves' Ophthalmopathy (EUGOGO) amendment, was used to evaluate clinical activity. The CAS ranges from 0 to 7, where higher scores indicate greater disease activity (worse outcome).	week 12, week 24
Change from baseline in diplopia score	Diplopia will be evaluated using the Gorman Subjective Diplopia Scale. The total score ranges from a minimum value of 0 to a maximum value of 3 (0 = no diplopia; 1 = intermittent diplopia; 2 = inconstant diplopia; 3 = constant diplopia). Higher scores mean a worse outcome (more severe diplopia condition).	week 12, week 24
Percentage of subjects with a CAS value of 0 or 1 in the study eye		week 12, week 24
Proptosis responder rate in the non-study eye		week 12, week 24
Change from baseline in proptosis measurement in the non-study eye		week 12, week 24
Change from baseline in ocular motility of the study eye		week 12, week 24
The number, incidence, severity, and relevance to study drugs or treatments of all ocular and other systemic AEs, TEAEs, AESIs, and SAEs		From the Screening period through study completion, with each participant completing all study visits over approximately 28 weeks, comprising a Screening Period (up to 4 weeks), a Treatment Period (21 weeks), and a Safety Follow-up Period (3 weeks).
Incidence of anti-drug antibodies (ADA) and neutralizing antibodies (NAbs)		Up to Week 24
Serum Drug Concentration	Serum drug concentrations will be collected at the following scheduled time points: Pre-dose (within 1 hour before infusion) and end-of-infusion (within 5 minutes after infusion completion) at Dose 1 (Week 0/Day 1), Dose 2 (Week 3), Dose 3 (Week 6), and Dose 5 (Week 12); A single sample at Week 1 (Day 8); A single sample at Week 24 or at early termination Serum concentration data from all sampling time points will be used to develop a population pharmacokinetic (PopPK) model and characterize the pharmacokinetics of KHN939.	Pre-dose and end-of-infusion at Doses 1, 2, 3, and 5, with additional samples at Week 1 and Week 24 (or early termination), up to Week 24
Change from Baseline in Diplopia Questionnaire (DQ) Score	The Diplopia Questionnaire (DQ) will be used to evaluate the severity and impact of diplopia. Total scores range from 0 to 100, with higher scores indicating greater symptom severity and a more significant negative impact on daily life (representing a worse outcome).	Week 12, Week 24

Collaborators and Investigators

• Sponsor: Beijing Kanghong Biological Medicine Co., Ltd.

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: July 10, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 23, 2026
• Last Update Submitted That Met QC Criteria: July 22, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Endocrine System Diseases; Genetic Diseases, Inborn; Autoimmune Diseases; Immune System Diseases; Eye Diseases; Eye Diseases, Hereditary; Graves Disease; Exophthalmos; Orbital Diseases; Goiter; Hyperthyroidism; Thyroid Diseases; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Graves Ophthalmopathy
• Other Study ID Numbers: KHN939-60102

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No