Osteoarthritis of the KneePhase 3NCT06549686
A Phase III Study of CLS2901C in Patients With Osteoarthritis of the Knee
A Phase 3 study testing CLS2901C (human [allogeneic] chondrocyte sheets) in people with Osteoarthritis of the Knee, run by CellSeed Inc. at 6 sites in Japan.
Trial summary
To evaluate the efficacy and safety of CLS2901C human allogenic chondrocyte sheets used in the osteotomy + RMSC group compared to in the osteotomy alone group of patients with osteoarthritis of the knee (OAK). Read more about this study
- Who is it for?
- Ages 20 to 79 years
- Conditions the study is for
- Osteoarthritis of the Knee
- What is being tested?
- CLS2901C (human [allogeneic] chondrocyte sheets)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 96 participants
- Where
- 6 sitesJapan
- Study dates
- 20 Oct 2023to 31 Jul 2031
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 20 to 79 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Male or female aged 20 to 79 years at informed consent.
- Diagnosis of OAK classified as Kellgren-Lawrence (K-L) Grade 2 to 4 based on plain lower extremity X-ray.
- OAK eligible for proximal tibial osteotomy based on the following criteria: Range of motion (ROM): >=120 degree flexion, <=5 degree extension
- Preoperative cartilage defect of the femoral condyle/trochlear groove or medial tibial condyle with an area of >=4 cm2 per defect site.
- Total defect area of <=21 cm2 in individuals with multiple cartilage defects.
- Body mass index (BMI) <30.
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- No coexisting ligament injury requiring surgery, and no meniscal injury requiring suturing or surgical repair other than partial resection, in the target knee.
- No history of ligament reconstruction, meniscal suturing, total meniscectomy or bone marrow stimulation, and no history of treatment with regenerative medicine products (including investigational products), cell processing products（including PRP） or gene therapy, in the target knee.
- No history of treatment with hyaluronic acid products and/or opioid for severe pain in the target knee within 1 month prior to informed consent.
- No history of treatment with corticosteroid products and/or immunosuppressive drug in the target knee within 3 months prior to informed consent.
- No history of platelet-rich plasma (PRP) therapy within 6 months prior to informed consent.
- Non-smoker; provided, however, that smokers will be eligible for study entry if they consent to abstain from smoking from 3 months prior to proximal tibial osteotomy or proximal tibial osteotomy+RMSC until postoperative bone healing.
- Written informed consent to participate in the study on a voluntary basis.
- No history of treatment with radiofrequency ablation of peripheral nerves in the knee joint within 1 year prior to informed consent.
- No history of proximal tibial osteotomy in the non-target knee.
- No history of treatment using mesenchymal stem cells, mesenchymal stromal cells, or stem cell culture supernatant.
Who cannot join
- Requires surgical treatment of the non-target knee during the study period.
- Any coexisting illness that would interfere with surgery under general anesthesia or that would affect knee surgery.
- Systemic inflammatory disease such as rheumatoid arthritis.
- Systemic Active infectious disease such as bacterial, fungal or viral infection.
- 6) Serious disease such as liver disorder, renal disorder, heart disease, lung disease, blood disease or metabolic disease that would make the patient unsuitable for study entry in the opinion of the investigator.
- 7) Diagnosed or suspected malignant tumor or history of malignant tumor within the past 5 years.
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- 8) Uncontrolled psychiatric disorder. 9) Poorly-controlled diabetes (HbA1c: >7.0%). 10) septic arthritis of the target knee. 11) Women who are pregnant or breastfeeding, or women of childbearing potential. Women of childbearing potential must agree to use the following contraceptive methods (i.e., contraceptives and medical devices that are approved/certified in Japan) or to abstain completely from sexual intercourse from the time of informed consent and for the study duration (excluding the follow-up period) in order to be eligible for study entry. (a) Primary contraceptive methods: Oral contraceptives, intrauterine devices (IUDs) including progesterone-releasing systems. (b) Adjunctive contraceptive methods: Condoms Use of a primary contraceptive method is mandatory, whereas use of the adjunctive contraceptive method must be in conjunction with a primary contraceptive method. Given that oral contraceptive doses can be missed and that their effects may be diminished when used concomitantly with other medications or dietary health supplements, subjects should consider changing their primary contraceptive method.
- 12) Received treatment as part of another clinical study within the past 6 months, currently participating in another clinical study, or planning to participate in another clinical study while also participating in the present study.
- 13) Known history of hypersensitivity to antibiotics (benzylpenicillin potassium, streptomycin sulfate, amphotericin B).
- 14) Known history of hypersensitivity to bovine-derived materials. 15) Any other reason the investigator deems the subject unsuitable for study entry.
Trial locations and contacts
6 sites in 1 country. Contact the study team or a site near you to ask about taking part.
6 sites in 1 country
Japan6 sites, 6 recruiting
- Recruiting
Juntendo University Hospital
Bunkyō-Ku, Tokyo, 113-8431
- Recruiting
Ebina General Hospital/Ebina Medical Plaza
Ebina, Kanagawa, 243-0433
- Recruiting
Tokai University Hospital
Isehara, Kanagawa, 259-1193
- Recruiting
Yokohama Sekishinkai Hospital
Yokohama, Kanagawa, 230-0062
- Recruiting
Yokohama City University Medical Center
Yokohama, Kanagawa, 232-0024
- Recruiting
Yokohama Minami Kyousai Hospital
Yokohama, Kanagawa, 236-0037
About this study
Official title: A Phase III Study Evaluating the Efficacy and Safety of CLS2901C in Patients With Osteoarthritis of the Knee
To evaluate the efficacy and safety of CLS2901C human allogenic chondrocyte sheets used in the osteotomy + RMSC group compared to in the osteotomy alone group of patients with osteoarthritis of the knee (OAK).
Read the detailed description
The investigational human cellular based product is a cell sheet made by culturing and growing chondrocytes taken from cartilage tissue derived from patients with polydactyly. To evaluate the efficacy and safety of CLS2901C human allogenic chondrocyte sheets used in the osteotomy + RMSC group compared to in the osteotomy alone group of patients with osteoarthritis of the knee (OAK). Safety is evaluated by the rate of adverse events and malfunctions. The evaluation period for each group will be approximately 14.5 months, and after the completion of the 52-week evaluation, patients who are available for follow-up will continue to be examined and observed for 5 years after sheets transplantation.
- Conditions
- Osteoarthritis of the Knee
- Being tested
- CLS2901C (human [allogeneic] chondrocyte sheets)
- Medical subject headings
- Osteoarthritis, Knee
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CLS2901C (human [allogeneic] chondrocyte sheets)Biological
CLS2901C (human [allogeneic] chondrocyte sheets)
| Study group | Role | What they receive |
|---|---|---|
| the osteotomy monotherapy group | No intervention | the osteotomy monotherapy |
| the osteotomy + RMSC combination therapy group | Experimental | the osteotomy + RMSC combination therapy
*RMSC combination therapy R: Resection of unhealthy tissue MS: Marrow arrow Stimulating＝MSCs Recruitment C: Covered by Chondrocyte sheets Receives: Biological: CLS2901C (human [allogeneic] chondrocyte sheets) |
What is being measured
The primary outcome is the main question the study is designed to answer.
KOOS 4 score (The Knee injury and Osteoarthritis Outcome 4 score)
Absolute change from baseline KOOS4 (Pain, Symptoms, ADL, QOL) score at postoperative Week 52. The four patient-relevant subscales of KOOS are scored separately: KOOS Pain (9items); KOOS Symptoms (7 items); KOOS ADL (17 items); KOOS QOL (4 items). A Likert scale is used and all items have five possible answer options scored from 0 (No Problems) to 4 (Extreme Problems). Scores are transformed to a 0-100 scale, with zero representing extreme knee problems and 100 representing no knee problems as is common in orthopaedic assessment scales and generic measures.
Measured: 52 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Aug 2024
- Study start20 Oct 2023
- Primary completion31 Dec 2028 (estimated)
- Study completion31 Jul 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Osteoarthritis of the KneeStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 96 participants (estimated)
Sponsor and investigators
- Lead sponsor
- CellSeed Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Manabu Ishizuka, Study director, CellSeed Inc.
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06549686
- Sponsor's protocol ID
- CLS2901-OAK-01
- Status last verified
- Jul 2026
- First submitted
- 8 Aug 2024
- Last updated
- 9 Jul 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 9 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase III Study Evaluating the Efficacy and Safety of CLS2901C in Patients With Osteoarthritis of the Knee
- ClinicalTrials.gov ID
- NCT06549686
- Acronym / sponsor ID
- CLS2901-OAK-01
- Conditions
- Osteoarthritis of the Knee
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 96 participants (estimated)
- Lead sponsor
- CellSeed Inc.Industry (pharma, biotech, devices)
- Study start
- 20 Oct 2023 (actual)
- Primary completion
- 31 Dec 2028 (estimated)
- Study completion
- 31 Jul 2031 (estimated)
- First posted
- 12 Aug 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
To evaluate the efficacy and safety of CLS2901C human allogenic chondrocyte sheets used in the osteotomy + RMSC group compared to in the osteotomy alone group of patients with osteoarthritis of the knee (OAK).
Detailed description
The investigational human cellular based product is a cell sheet made by culturing and growing chondrocytes taken from cartilage tissue derived from patients with polydactyly. To evaluate the efficacy and safety of CLS2901C human allogenic chondrocyte sheets used in the osteotomy + RMSC group compared to in the osteotomy alone group of patients with osteoarthritis of the knee (OAK). Safety is evaluated by the rate of adverse events and malfunctions. The evaluation period for each group will be approximately 14.5 months, and after the completion of the 52-week evaluation, patients who are available for follow-up will continue to be examined and observed for 5 years after sheets transplantation.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| the osteotomy monotherapy group | No intervention | –the osteotomy monotherapy |
| the osteotomy + RMSC combination therapy group | Experimental | Biological: CLS2901C (human [allogeneic] chondrocyte sheets)the osteotomy + RMSC combination therapy *RMSC combination therapy R: Resection of unhealthy tissue MS: Marrow arrow Stimulating＝MSCs Recruitment C: Covered by Chondrocyte sheets |
Who may qualify
- Ages
- 20 to 79 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (16 listed)
- Male or female aged 20 to 79 years at informed consent.
- Diagnosis of OAK classified as Kellgren-Lawrence (K-L) Grade 2 to 4 based on plain lower extremity X-ray.
- OAK eligible for proximal tibial osteotomy based on the following criteria: Range of motion (ROM): >=120 degree flexion, <=5 degree extension
- Preoperative cartilage defect of the femoral condyle/trochlear groove or medial tibial condyle with an area of >=4 cm2 per defect site.
- Total defect area of <=21 cm2 in individuals with multiple cartilage defects.
Key exclusion criteria (10 listed)
- Requires surgical treatment of the non-target knee during the study period.
- Any coexisting illness that would interfere with surgery under general anesthesia or that would affect knee surgery.
- Systemic inflammatory disease such as rheumatoid arthritis.
- Systemic Active infectious disease such as bacterial, fungal or viral infection.
- 6) Serious disease such as liver disorder, renal disorder, heart disease, lung disease, blood disease or metabolic disease that would make the patient unsuitable for study entry in the opinion of the investigator.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| CLS2901C (human [allogeneic] chondrocyte sheets)CLS2901C (human [allogeneic] chondrocyte sheets) | Biological | the osteotomy + RMSC combination therapy group |
Primary outcome
KOOS 4 score (The Knee injury and Osteoarthritis Outcome 4 score)
Time frame: 52 weeks
Absolute change from baseline KOOS4 (Pain, Symptoms, ADL, QOL) score at postoperative Week 52. The four patient-relevant subscales of KOOS are scored separately: KOOS Pain (9items); KOOS Symptoms (7 items); KOOS ADL (17 items); KOOS QOL (4 items). A Likert scale is used and all items have five possible answer options scored from 0 (No Problems) to 4 (Extreme Problems). Scores are transformed to a 0-100 scale, with zero representing extreme knee problems and 100 representing no knee problems as is common in orthopaedic assessment scales and generic measures.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Jul 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Manabu Ishizuka study director
CellSeed Inc.
6 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing CLS2901C (human [allogeneic] chondrocyte sheets) in people with Osteoarthritis of the Knee, run by CellSeed Inc. at 6 sites in Japan.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 16 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 9 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 6 sites in Japan. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Chikako Sato (+81-03-6380-7490, cs.clinicaldevelopment@cellseed.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
KOOS 4 score (The Knee injury and Osteoarthritis Outcome 4 score) (time frame: 52 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Jul 2026.