Ankle OsteoarthritisPhase 1/2PhoenixNCT05092646
Evaluating Intra-articular Injection of Axolotl Ambient Compared to Saline in Subjects With Ankle Osteoarthritis
A Phase 1/2 study testing Axolotl Ambient in people with Ankle Osteoarthritis, run by Axolotl Biologix at 3 sites in United States.
Trial summary
A Double-blind, Multi-Center, Prospective, Randomized Placebo-controlled Pilot Study Evaluating Intra-articular Injection of Axolotl Ambient Compared to Saline in Subjects with Ankle Osteoarthritis. Read more about this study
- Who is it for?
- Ages 18 to 80 yearsHealthy volunteers can take part
- Conditions the study is for
- Ankle Osteoarthritis
- What is being tested?
- Axolotl Ambient
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 12 participants
- Where
- 3 sitesUnited States
- Study dates
- 1 Dec 2021to 10 Nov 2023
- Phase
- Phase 1/2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 18 to 80 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Signed written informed consent
- Willing to be randomized to either the investigational or control group
- Male or female at least 18 years of age and less than 80
- Clinical diagnosis of symptomatic tibiotalar (ankle) OA (primary idiopathic OA or post-traumatic OA), modified K-L grade 1-3a
- One ankle is the most symptomatic lower extremity joint and the only lower extremity joint currently planned for treatment
- Willing and able to comply with all study requirements including all postoperative clinical and radiographic evaluations
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- For women of childbearing potential (not post-menopausal for 12 months or surgically sterile), a urine pregnancy test with a negative result must be obtained at screening and on the day of procedure, prior to injection
- Male and female trial participants must commit to adequate birth control (e.g., surgically sterilized, oral contraceptive, two methods of barrier birth control, or abstinence) through the final follow-up
- Chronic ankle pain for ≥ 6 months
- SAOS Pain score ≥ 30 and ≤ 80 and AOS Function score ≥ 30 and ≤ 80
- Willing to discontinue all prescription and over-the-counter pain medications being used for ankle OA symptoms for the duration of the study, except for acetaminophen, which is not allowed for the 3 days preceding each scheduled follow-up visit and the day of the follow-up visit.
Who cannot join
- Previously received intra-articular injections in the index joint of Axolotl Ambient, bone marrow aspirate concentrate (BMAC), platelet-rich plasma (PRP), or other biologic-based products within the last 12 months.
- Modified K-L Grade 3b or 4 osteoarthritis of the index joint
- Diagnosis of ipsilateral peri-articular arthritis (e.g. subtalar joint) that the investigator determines may significantly confound the study results
- Received intra-articular hyaluronic acid injection in the index joint within the last 6 months
- Received intra-articular steroid injection in the index joint within the last 3 months
- Prior major surgical repair or reconstruction of the ankle that the investigator determines may significantly confound the study results
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- Baseline pain catastrophizing score ≥ 23
- Any surgery of the index ankle within the last 12 months
- Planned arthroscopy or other procedure on the ankle during the study
- Bilateral ankle OA requiring treatment of both ankles
- Pregnancy, breastfeeding, or woman of child-bearing potential not using adequate contraception
- Bone deficit
- Charcot foot disease
- Radiographic evidence of open epiphyses
- Systemic inflammatory condition
- Substantial vascular insufficiency
- Current treatment with anticoagulants
- Deformity in coronal, axial or sagittal plane greater the 30°
- Patients weighing less than 47 kg.
- BMI greater than 45 kg/m2
- Documented medical history of, or radiographic evidence of, a bone disease (e.g. severe osteoporosis or avascular necrosis) or other condition (e.g., osteolysis)
- Comorbidity that would limit the ability to administer any functional measurements
- Has at the time of injection, a systemic or local infection at the site of injection
- Medical condition, serious intercurrent illness, or extenuating circumstance that, in the opinion of the Investigator, would preclude participation in the study or potentially decrease survival or interfere with ambulation or rehabilitation (e.g., history of transient ischemic attack, stroke or liver disease)
- Known hypersensitivity to penicillin
- Known allergy to phenol red
- Currently receiving treatment with a drug known to interfere with bone or cartilage metabolism [e.g., systemic steroid therapy (topical steroid therapy is permissible), methotrexate]
- Medical condition requiring radiation, chemotherapy or immunosuppression
- Have an active history of malignancy (except for basal cell carcinoma of the skin)
- Has a history of autoimmune disease known to affect bone or cartilage. Examples include spondyloarthropathies (e.g., ankylosing spondylitis, Crohn's disease, and ulcerative colitis), Juvenile Arthritis, rheumatoid arthritis, Grave's disease, and Hashimoto's thyroiditis
- Has obvious or documented alcohol or illicit drug addictions
- Is a prisoner in a correctional institution/facility
- Actively involved in litigation or workman's compensation
- Has participated in clinical studies evaluating investigational devices, pharmaceuticals or biologics within 6 months of randomization
- Bedridden, confined to a wheelchair, or unable to walk 50 m without the help of a walker, crutches, or cane
- Is currently taking prescription pain medication for any conditions other than ankle osteoarthritis.
Trial locations and contacts
3 sites in 1 country.
United States3 sites
Injury Care Research
Boise, Idaho, 83713
OrthoCarolina Foot and Ankle Institute
Charlotte, North Carolina, 28207
Orthopedic Specialists of Louisiana
Shreveport, Louisiana, 71101
About this study
Official title: A Double-blind, Multi-Center, Prospective, Randomized Placebo-controlled Pilot Study Evaluating Intra-articular Injection of Axolotl Ambient Compared to Saline in Subjects With Ankle Osteoarthritis
A Double-blind, Multi-Center, Prospective, Randomized Placebo-controlled Pilot Study Evaluating Intra-articular Injection of Axolotl Ambient Compared to Saline in Subjects with Ankle Osteoarthritis. The goal of this pilot study and subsequent pivotal trial is to evaluate the safety and effectiveness of Axolotl Ambient intra-articular injection for ameliorating the pain and dysfunction associated with ankle OA.
Read the detailed description
This pilot study is a double-blind multi-center, prospective, randomized, placebo-controlled trial. Upon randomization, patients will receive 1 intraarticular injection of the investigational product or control fluid. Follow-up will be conducted at 4 weeks, 3 and 6 months, with 6 months serving as the primary endpoint. The primary outcomes will consist of patient reported outcomes of pain and functional assessment by the physician, specific to the foot and ankle. Subjects will be monitored for an additional 6 months to establish safety over a 1-year follow-up and evaluate the durability of benefit.
- Conditions
- Ankle Osteoarthritis
- Being tested
- Axolotl Ambient, "Drug/Placebo: 0.9% Normal Saline"
- Keywords
- Osteoarthritis, Biologic, Amniotic Fluid
- Medical subject headings
- Osteoarthritis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Axolotl AmbientBiological
Also called CA20
Axolotl Ambient is an allogeneic amniotic intra-articular injection therapy consisting of a growth factor and cytokine-rich fluid derived from human amnion cells.
"Drug/Placebo: 0.9% Normal Saline"Drug
"Drug/Placebo: 0.9% Normal Saline"
| Study group | Role | What they receive |
|---|---|---|
| Control Group | Placebo comparator | Single dose, 2.0 mL of 0.9% normal saline, administered via intra-articular injection administered to the affected tibiotalar joint. Receives: Drug: "Drug/Placebo: 0.9% Normal Saline" |
| Investigational Group | Experimental | Biological/Vaccine: Axolotl Ambient
Axolotl Ambient is an allogeneic amniotic intraarticular injection therapy consisting of a growth factor and cytokine-rich fluid derived from human amnion cells.
Other Names:
• CA20 Receives: Biological: Axolotl Ambient |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change From Baseline in Ankle Osteoarthritis Scale (AOS; 48 hr Recall) Pain Subscale
The Ankle Osteoarthritis Scale (AOS) pain subscale goes from 0 (No pain) -100 (The worst imaginable).
Measured: 4-weeks, 3-months, and 6-months
Change From Baseline for Ankle Osteoarthritis Scale (AOS; 48 hr Recall) Function Subscale
The Ankle Osteoarthritis Scale (AOS) functions subscale goes from 0 (No difficulty) -100 (So difficult, unable).
Measured: 4-week, 3 Months, 6-months
Change From Baseline for Foot and Ankle Outcome Score (FAOS) for Pain Subscale
A score of 100 represents no pain. A score of 0 constant pain.
Measured: 4-weeks, 3-months, 6-months
Change From Baseline for Foot and Ankle Outcome Score (FAOS) for Function Subscale
100 represents perfect health and 0 represents extreme problems and complete functional limitation. .
Measured: 4-weeks, 3-months, 6-months
Proportion of Patients Achieving Composite Clinical Success (CCS).
CCS defined as a patient meeting all of the three following criteria:
- Improvement in AOS (Pain and Function) or FAOS scores (Pain and ADL) of at least 20% from baseline
- No surgical intervention or prescription pain medications for ankle OA
- No treatment or procedure-related serious adverse events
Measured: 4-weeks, 3-months, 6-months
Secondary outcomes (7)
Incidence of Adverse Events
Proportion of subjects experiencing at least (1) adverse events.
Measured: Post-procedure follow-up assessments: 4 weeks (+/-7days), 3 Months (+/- 14 days), 6 Months (+/- 30 days), 12 Months (+/- 60 days), and unscheduled visits (up to 19 months)
FAOS Subscales Quality of Life (QoL)
0 (most severe problems) to 100 (no problems/best possible qualify of life)
Measured: 4-week, 3-month, 6-month
Visual Analog Scale (VAS) for Ankle Pain (Average During Last 48 Hours)
100 millimeter scale 0mm - No Pain and 100mm - Worst Imaginable Pain
Measured: 4 weeks, 3-months, 6-months
VAS Ankle Pain (Worst During Last 48 Hours)
100 millimeter scale 0mm - No Pain and 100mm - Worst Imaginable Pain
Measured: 4-weeks, 3-months, 6-months
EuroQOL-5 Dimension-5 Level (EQ-5D-5L) Quality of Life Scale
0 to 100 scale - 0 the worst health you can imagine to 100 the best health you can imagine.
Measured: 4-weeks, 3-months, 6-months
Working Status
Not working, unrelated to ankle Not working, related to ankle Working with major limitations related to ankle Working without limitations related to ankle
Measured: Baseline, 4-weeks, 3-months, 6-months
K-L Grade From Weightbearing X-ray at Baseline and 6 Months
Grade 2 Definite osteophytes with mild to moderate joint space narrowing; early radiographic OA Grade 3a Significant osteophytes and joint space narrowing, but greater than 50% of the joint space remains preserved Grade 3b Severe joint space narrowing with less than 50% remaining joint space, approaching end-stage disease but not completely bone-on-bone Grade 4 Near complete or complete loss of joint space with substantial deformity (end-stage OA)
Measured: Baseline, 6-months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Oct 2021
- Study start1 Dec 2021
- Primary completion10 Nov 2023
- Study completion10 Nov 2023
Why it stopped: This study was terminated by the Sponsor in December 2023 due to business considerations.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Ankle OsteoarthritisStudies 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 1/2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Randomized, Placebo-controlled, Double-blinded
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 12 participants (actual)
Sponsor and investigators
- Lead sponsor
- Axolotl Biologix
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Robert S. Kellar, PhD, Study director, Chief Science Officer (CSO)Aaron J. Tabor, PhD, CTBS, Study director, V.P. of Clinical Operations
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05092646
- Sponsor's protocol ID
- CA-2021-01
- Acronym
- Phoenix
- Status last verified
- Aug 2026
- First submitted
- 8 Oct 2021
- Last updated
- 7 Aug 2026
- Results posted
- Yes, on ClinicalTrials.gov
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Double-blind, Multi-Center, Prospective, Randomized Placebo-controlled Pilot Study Evaluating Intra-articular Injection of Axolotl Ambient Compared to Saline in Subjects With Ankle Osteoarthritis
- ClinicalTrials.gov ID
- NCT05092646
- Acronym / sponsor ID
- Phoenix / CA-2021-01
- Conditions
- Ankle Osteoarthritis
- Keywords
- Osteoarthritis, Biologic, Amniotic Fluid
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: This study was terminated by the Sponsor in December 2023 due to business considerations.
- Enrolment
- 12 participants (actual)
- Lead sponsor
- Axolotl BiologixIndustry (pharma, biotech, devices)
- Study start
- 1 Dec 2021 (actual)
- Primary completion
- 10 Nov 2023 (actual)
- Study completion
- 10 Nov 2023 (actual)
- First posted
- 25 Oct 2021 (actual)
- Results
- Posted 7 Aug 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A Double-blind, Multi-Center, Prospective, Randomized Placebo-controlled Pilot Study Evaluating Intra-articular Injection of Axolotl Ambient Compared to Saline in Subjects with Ankle Osteoarthritis. The goal of this pilot study and subsequent pivotal trial is to evaluate the safety and effectiveness of Axolotl Ambient intra-articular injection for ameliorating the pain and dysfunction associated with ankle OA.
Detailed description
This pilot study is a double-blind multi-center, prospective, randomized, placebo-controlled trial. Upon randomization, patients will receive 1 intraarticular injection of the investigational product or control fluid. Follow-up will be conducted at 4 weeks, 3 and 6 months, with 6 months serving as the primary endpoint. The primary outcomes will consist of patient reported outcomes of pain and functional assessment by the physician, specific to the foot and ankle. Subjects will be monitored for an additional 6 months to establish safety over a 1-year follow-up and evaluate the durability of benefit.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- Randomized, Placebo-controlled, Double-blinded
| Arm | Type | Receives |
|---|---|---|
| Control Group | Placebo comparator | Drug: "Drug/Placebo: 0.9% Normal Saline"Single dose, 2.0 mL of 0.9% normal saline, administered via intra-articular injection administered to the affected tibiotalar joint. |
| Investigational Group | Experimental | Biological: Axolotl AmbientBiological/Vaccine: Axolotl Ambient Axolotl Ambient is an allogeneic amniotic intraarticular injection therapy consisting of a growth factor and cytokine-rich fluid derived from human amnion cells. Other Names: • CA20 |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- Signed written informed consent
- Willing to be randomized to either the investigational or control group
- Male or female at least 18 years of age and less than 80
- Clinical diagnosis of symptomatic tibiotalar (ankle) OA (primary idiopathic OA or post-traumatic OA), modified K-L grade 1-3a
- One ankle is the most symptomatic lower extremity joint and the only lower extremity joint currently planned for treatment
Key exclusion criteria (36 listed)
- Previously received intra-articular injections in the index joint of Axolotl Ambient, bone marrow aspirate concentrate (BMAC), platelet-rich plasma (PRP), or other biologic-based products within the last 12 months.
- Modified K-L Grade 3b or 4 osteoarthritis of the index joint
- Diagnosis of ipsilateral peri-articular arthritis (e.g. subtalar joint) that the investigator determines may significantly confound the study results
- Received intra-articular hyaluronic acid injection in the index joint within the last 6 months
- Received intra-articular steroid injection in the index joint within the last 3 months
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 |
|---|---|---|
| Axolotl AmbientAlso: CA20Axolotl Ambient is an allogeneic amniotic intra-articular injection therapy consisting of a growth factor and cytokine-rich fluid derived from human amnion cells. | Biological | Investigational Group |
| "Drug/Placebo: 0.9% Normal Saline""Drug/Placebo: 0.9% Normal Saline" | Drug | Control Group |
Primary outcome
Change From Baseline in Ankle Osteoarthritis Scale (AOS; 48 hr Recall) Pain Subscale
Time frame: 4-weeks, 3-months, and 6-months
The Ankle Osteoarthritis Scale (AOS) pain subscale goes from 0 (No pain) -100 (The worst imaginable).
Change From Baseline for Ankle Osteoarthritis Scale (AOS; 48 hr Recall) Function Subscale
Time frame: 4-week, 3 Months, 6-months
The Ankle Osteoarthritis Scale (AOS) functions subscale goes from 0 (No difficulty) -100 (So difficult, unable).
Change From Baseline for Foot and Ankle Outcome Score (FAOS) for Pain Subscale
Time frame: 4-weeks, 3-months, 6-months
A score of 100 represents no pain. A score of 0 constant pain.
Change From Baseline for Foot and Ankle Outcome Score (FAOS) for Function Subscale
Time frame: 4-weeks, 3-months, 6-months
100 represents perfect health and 0 represents extreme problems and complete functional limitation. .
Proportion of Patients Achieving Composite Clinical Success (CCS).
Time frame: 4-weeks, 3-months, 6-months
CCS defined as a patient meeting all of the three following criteria: 1. Improvement in AOS (Pain and Function) or FAOS scores (Pain and ADL) of at least 20% from baseline 2. No surgical intervention or prescription pain medications for ankle OA 3. No treatment or procedure-related serious adverse events
7 secondary outcomes
Incidence of Adverse Events
Time frame: Post-procedure follow-up assessments: 4 weeks (+/-7days), 3 Months (+/- 14 days), 6 Months (+/- 30 days), 12 Months (+/- 60 days), and unscheduled visits (up to 19 months)
FAOS Subscales Quality of Life (QoL)
Time frame: 4-week, 3-month, 6-month
Visual Analog Scale (VAS) for Ankle Pain (Average During Last 48 Hours)
Time frame: 4 weeks, 3-months, 6-months
VAS Ankle Pain (Worst During Last 48 Hours)
Time frame: 4-weeks, 3-months, 6-months
EuroQOL-5 Dimension-5 Level (EQ-5D-5L) Quality of Life Scale
Time frame: 4-weeks, 3-months, 6-months
Working Status
Time frame: Baseline, 4-weeks, 3-months, 6-months
K-L Grade From Weightbearing X-ray at Baseline and 6 Months
Time frame: Baseline, 6-months
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Aug 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- 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. This study is not recruiting at the moment.
Robert S. Kellar, PhD study director
Chief Science Officer (CSO)
Aaron J. Tabor, PhD, CTBS study director
V.P. of Clinical Operations
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing Axolotl Ambient in people with Ankle Osteoarthritis, run by Axolotl Biologix at 3 sites in United States.
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 11 inclusion and 36 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: stopped early, as of the sponsor's last update on 7 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in United States. 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. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 7 Aug 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change From Baseline in Ankle Osteoarthritis Scale (AOS; 48 hr Recall) Pain Subscale (time frame: 4-weeks, 3-months, and 6-months). The study lists 5 primary outcomes in all. 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 7 Aug 2026.