Actively Recruiting
A Multicenter, Open-label, Phase 1/2, Dose-escalation and Subsequent Safety Extension Study of Subcutaneous KK8123 in Adult Patients With X-linked Hypophosphatemia
Led by Kyowa Kirin Co., Ltd. · Updated on 2025-11-14
24
Participants Needed
9
Research Sites
12 weeks
Total Duration
On this page
Sponsors
K
Kyowa Kirin Co., Ltd.
Lead Sponsor
K
Kyowa Kirin, Inc.
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are evaluating the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of KK8123 in adults with X-linked hypophosphatemia (XLH) through a Phase 1/2, multicenter, open-label, dose-escalation study. This first-in-human study aims to better understand how KK8123 behaves in the body and its effects on patients with this condition. The study is sponsored by Kyowa Kirin Co., Ltd. and includes an optional safety extension period. The study includes a Screening Period of up to 28 days, followed by Part 1, which is a Dose Escalation Period consisting of a planned Treatment Period and an Observation Period lasting 32 to 44 weeks. Part 2 is an optional Extension Period for additional safety evaluation. Participants receive subcutaneous doses of KK8123 at different levels, including low dose (single dose), mild dose (multiple doses), and high dose (multiple doses), with dosing confirmed for later cohorts. The study groups include several cohorts receiving escalating doses and an extension group. Participants will undergo multiple assessments during the study, including laboratory tests for hematology and clinical chemistry, measurement of serum phosphorus levels, echocardiograms, renal ultrasounds, and monitoring of vital signs such as heart rate and blood pressure. Researchers will track treatment-emergent adverse events (TEAEs) and measure KK8123 drug concentrations over time. Follow-up periods last up to 44 weeks in Part 1 and up to 52 weeks in Part 2. Participants are expected to adhere to study visit schedules and complete all assessments throughout their involvement.
CONDITIONS
Brief Title
A First-in-human Study of KK8123 in Adults With X-linked Hypophosphatemia
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Male or female patients aged 18 to 65 years inclusive at the time of signing the informed consent form.
- Body weight of at least 40 kg.
- Diagnosed with X-linked hypophosphatemia (XLH) as documented by the investigator.
- Fasting serum phosphorus level less than 2.5 mg/dL (0.81 mmol/L) at screening.
- Renal TmP/GFR less than 2.5 mg/dL (0.81 mmol/L) at screening.
- Estimated glomerular filtration rate (eGFR) of 60 mL/min or higher at screening.
- Corrected serum calcium level less than 10.8 mg/dL (2.7 mmol/L) at screening.
- Provide signed informed consent.
- Agree not to change diet and exercise regimen from one week prior to dosing to end of study.
- Negative pregnancy test at screening and willingness to have additional pregnancy tests during the study (female participants only).
- If taking chronic pain medications, stable regimen for at least 21 days before screening and willingness to maintain stable dose during the study (dose not exceeding 60 mg oral morphine equivalents/day).
- Willingness to use contraception during the study and for 5 months after last dose if sexually active and of childbearing potential.
- Willing and able to complete all study aspects, adhere to visits, and comply with assessments as judged by investigator.
You will not qualify if you...
- Use of burosumab within 7 months prior to informed consent.
- Positive test history for HIV antibody, hepatitis B surface antigen, or hepatitis C antibody at screening.
- History of hypersensitivity to any therapeutic monoclonal antibody ingredient.
- Active infection.
- Grade 3 or greater nephrocalcinosis confirmed by renal ultrasound.
- Uncontrolled diabetes mellitus at screening.
- History of known immunodeficiency.
- History of alcoholism or drug abuse.
- Blood donation within 60 days prior to screening.
- Use of investigational products or devices within 30 days prior to screening.
- Use of therapeutic monoclonal antibodies within 90 days prior to screening.
- Use of certain medications including pharmacologically active vitamin D, oral phosphate, aluminum hydroxide antacids, acetazolamide, thiazide diuretics, systemic corticosteroids within 14 days prior to screening.
- Use of medication to suppress parathyroid hormone within 2 months prior to screening.
- Use of denosumab within 6 months prior to screening.
- Use of oral bisphosphonates within 2 years prior to screening.
- Use of teriparatide or abaloparatide within 2 months prior to screening.
- Plasma intact parathyroid hormone ≥ 2.5 times upper limit of normal at screening.
- Planned or recommended orthopedic surgery during the study.
- Traumatic fracture or orthopedic surgery within 6 months prior to screening.
- Lactating participants.
- Current active and symptomatic COVID-19 infection at Day -1.
- Any condition that may increase risk of poor treatment compliance or study completion as judged by investigator.
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - Up to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person) for consent and screening assessments
Duration - 32 to 44 weeks
Participants receive subcutaneous doses of KK8123 during a dose escalation period, followed by an observation period to assess safety and effects.
Multiple visits for dosing and safety assessments over 32 to 44 weeks
Duration - Up to 52 weeks
Participants may enter an optional extension period with continued subcutaneous dosing of KK8123 to further monitor safety and treatment effects.
Ongoing visits for dosing and safety monitoring during the extension period
Trial Site Locations
Total: 9 locations
1
University of California - San Francisco
San Francisco, California, United States, 94158
Actively Recruiting
2
Yale Center for XLH/ Yale University School of Medicine
New Haven, Connecticut, United States, 06510
Actively Recruiting
3
Indiana University School of Medicine University Hospital
Indianapolis, Indiana, United States, 46202
Actively Recruiting
4
Mayo Clinic
Rochester, Minnesota, United States, 55905
Not Yet Recruiting
5
Vanderbilt University Medical Center
Nashville, Tennessee, United States, 37232
Actively Recruiting
6
Hoptial Bictre
Le Kremlin-Bicêtre, Paris, France, 94275
Actively Recruiting
7
Institute of Osteology and Biomechanics (IOBM)
Hamburg, Germany, 22529
Actively Recruiting
8
Universitaetsklinikum Wurzburg
Würzburg, Germany, 97074
Actively Recruiting
9
Hospital Universitario La Paz
Madrid, Spain, 28046
Actively Recruiting
Research Team
K
Kyowa Kirin
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
NON_RANDOMIZED
Model
SEQUENTIAL
Primary Purpose
TREATMENT
Number of Arms
5
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