Focus of the Study: Safety of XFB19Phase 1NCT05361733
A First in Human Study of the Safety, Tolerability, and the Physiologically Based Pharmacokinetics of XFB19 in Healthy Adult Volunteers.
A Phase 1 study testing XFB19 in people with Focus of the Study: Safety of XFB19, run by Xfibra, Inc. at 1 site in United States.
Trial summary
Xfibra, Inc. is conducting a Phase 1, randomized, double-blind, placebo-controlled, first-in-human study of the safety, tolerability, and physiologically-based pharmacokinetics (PK) of single and multiple ascending doses of XFB19 in healthy adult volunteers. Read more about this study
- Who is it for?
- Ages 18 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- Focus of the Study: Safety of XFB19
- What is being tested?
- XFB19
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 40 participants
- Where
- 1 siteUnited States
- Study dates
- 17 Feb 2026to 15 Dec 2026
- Phase
- Phase 1
- 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 18 to 55 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Must have given written informed consent before any study-related activities are carried out and must be able to understand the full nature and purpose of the study, including possible risks and adverse effects.
- Adult males and females, 18 to 55 years of age (inclusive) at screening.
- Body mass index ≥ 18.0 and ≤ 35.0 kg/m2 with a body weight ≥ 45 kg at screening.
- Be non-smokers (including tobacco, e-cigarettes, and marijuana) for at least 1 month prior to first investigational drug administration.
- Medically healthy without clinically significant abnormalities (in the opinion of the Investigator) at the Screening Visit and prior to dosing including:
- Physical examination without any clinically significant findings
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- Systolic blood pressure in the range of 90 to 160 mmHg (inclusive) and diastolic blood pressure in the range of 50 to 95 mmHg (inclusive) after 5 minutes rest in supine position
- Heart rate (HR) in the range of 40 to 100 bpm (inclusive) after 5 minutes rest in supine position
- Body temperature (tympanic or oral) in the range of 35.5°C to 37.7°C (inclusive)
- No clinically significant findings in serum chemistry, hematology, coagulation, and urinalysis tests
- Triplicate 12-lead ECGs (taken after the volunteer has been supine for at least 5 minutes) with QT intervals corrected using Fridericia's method (QTcF) ≤ 450 msec for males and ≤ 470 msec for females and no clinically significant abnormalities
- Female volunteers must:
- Be of nonchildbearing potential, i.e., surgically sterilised (hysterectomy, bilateral salpingectomy, bilateral tubal ligation, bilateral oophorectomy at least 6 weeks before screening) or postmenopausal (defined as no menses for 12 months without an alternative medical cause and a follicle-stimulating hormone [FSH] level > 40 IU/L at the Screening Visit) OR
- If of childbearing potential, must agree not to donate ova, not to attempt to become pregnant, and, if engaging in sexual intercourse with a male partner, must agree to use an acceptable method of contraception from the time of signing the participant informed consent form (PICF) until at least 30 days after the last dose of the study drug
- Male volunteers must agree not to donate sperm, and, if engaging in sexual intercourse with a female partner who could become pregnant, must agree to use an acceptable method of contraception from the time of signing the consent form until at least 30 days after the last dose of study drug.
- Have suitable venous access for blood sampling.
- Be willing and able to comply with all study assessments and adhere to the protocol schedule and restrictions.
Who cannot join
- History or presence of any clinically significant (as determined by the PI) cardiovascular, pulmonary, hepatic, renal, hematological, gastrointestinal, endocrine, immunologic, dermatologic, or neurological disease, including any acute illness or major surgery, within the past 3 months.
- Current infection that requires systemically absorbed antibiotic, antifungal, antiparasitic, or antiviral medications.
- Any history of malignant disease in the last 5 years (excluding surgically resected skin squamous cell or basal cell carcinoma).
- Presence of clinically relevant immunosuppression from, but not limited to, immunodeficiency conditions such as common variable hypogammaglobulinemia.
- Use of or plans to use systemic immunosuppressive (e.g., corticosteroids, methotrexate, azathioprine, cyclosporine) or immunomodulating medications (e.g., interferon) during the study or within 3 months prior to the first study drug administration.
- History of risk factors for torsade de pointes (including a family history of long QT syndrome or sudden cardiac death) or a known arrythmia.
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- Liver function test (LFT) results > 1.5 times the upper limit of normal (ULN) for gamma glutamyl transferase (GGT), bilirubin (total, conjugated, and unconjugated), alkaline phosphatase (ALP), aspartate aminotransferase (AST), or alanine aminotransferase (ALT). Volunteers with bilirubin, ALP and/or ALT/AST above the limits specified may be included, at the discretion of the Investigator, if the levels are unaccompanied by clinical signs.
- Positive test results for human immunodeficiency virus (HIV-1 or HIV-2) antibodies, hepatitis C virus (HCV) antibodies, or hepatitis B surface antigen (HBsAg) at the Screening Visit. Patients with HCV antibodies, or HBsAg could be included if the viral load for HCV or hepatitis B are negative.
- Positive test result for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via polymerase chain reaction or commercially validated antigen test, per site's standard clinical procedure.
- Presence of sequelae of gastrointestinal, liver, kidney, or other conditions known to interfere with the absorption, distribution, metabolism, or excretion of drugs.
- Estimated creatinine clearance (CrCl) < 60 mL/min using the Cockcroft-Gault formula or serum creatinine more than 1.5 x ULN.
- History of substance abuse or alcohol abuse (defined as more than 10 standard drinks per week or regularly consuming more than 4 standard drinks per day where 1 standard drink is 10 g of pure alcohol and equivalent to 285 mL beer [4.9% Alc./Vol], 100 mL wine [12% Alc./Vol], or 30 mL spirit [40% Alc./Vol]) within 12 months prior to the Screening Visit.
- Positive drugs of abuse or alcohol breath test results at the Screening Visit or at CRU check in (Day -1) (repeat tests allowed if false positive suspected). Non-habitual use and agreement to refrain from using any THC/CBD products during the study is allowed.
- Use of any prescription or over the counter (OTC) medication (including herbal products, diet aids, and hormone supplements) within 10 days or 5 half-lives of the medication (whichever is longer) prior to the first study drug administration, excepting use of contraceptives and occasional use of acetaminophen (up to 1 g every 8 hours or 3 g per day maximum).
- Demonstrated clinically significant (required intervention, e.g., emergency room visit, epinephrine administration) allergic reactions (e.g., food, drug, or atopic reactions, asthmatic episodes) which, in the opinion of the Investigator, would interfere with the volunteer's ability to participate in the study.
- Known hypersensitivity to any of the study drug ingredients.
- Use of any vaccinations within 10 days prior to first study drug administration.
- For women of childbearing potential, a positive serum pregnancy test at the Screening Visit or a positive urine pregnancy test (with confirmatory positive serum pregnancy test) at CRU check-in (Day -1).
- Currently breastfeeding.
- Donation of blood or plasma or loss of whole blood of more than 500 mL within 30 days prior to first study drug administration or receipt of a blood transfusion within 2 months prior to first study drug administration.
- Participation in another clinical study of an investigational drug within 30 days or 5 half-lives of the investigational agent (whichever is longer) prior to the first study drug administration.
- Any other condition or prior therapy that in the opinion of the Investigator would make the volunteer unsuitable for this study, including inability to cooperate fully with the requirements of the study protocol or likelihood of noncompliance with any study requirements.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
AMR Clinical
Knoxville, Tennessee, 37920
About this study
Official title: A Phase 1, Randomized, Double-Blind, Placebo-Controlled, First-in-Human Study of the Safety, Tolerability, and Pharmacokinetics of Single and Multiple Ascending Doses of XFB19 in Healthy Adult Volunteers.
Xfibra, Inc. is conducting a Phase 1, randomized, double-blind, placebo-controlled, first-in-human study of the safety, tolerability, and physiologically-based pharmacokinetics (PK) of single and multiple ascending doses of XFB19 in healthy adult volunteers.
Read the detailed description
Xfibra, Inc. is conducting this clinical research study to test a potential new drug called XFB19 that is being developed for inflammatory/fibrotic diseases.
Although current medications are available to improve health and survival in patients with inflammatory/fibrotic diseases no specific pharmacotherapy has proven curative against Acute Respiratory Distress Syndrome (ARDS), liver cirrhosis , or Idiopathic Pulmonary Fibrosis (IPF). The advantages of XFB19 over currently available therapies are its target specificity, in that it only affects a carefully selected target which may allow recovery from inflammatory/fibrotic diseases, and potentially reverse tissue fibrosis.
Although many laboratory and animal studies have been completed, this is the first time XFB-19 is being tested in humans. Therefore, side effects in humans are unknown.
This study will be conducted in two parts - Part A (single dose) and Part B (multiple dosing). The purpose and main goals of this study are:
- To determine whether XFB19 is safe and well tolerated in humans
- To determine a safe dose of XFB19 to be used in future studies in patients.
- To test how much XFB19 gets into the blood and how long it takes to be cleared from the body
- To measure the activity of XFB19 in blood.
XFB19 is considered experimental because it has not yet been approved by the FDA (Food and Drug Administration) in the USA, or any other regulatory agency responsible for approving medicines. There may be risks in taking this experimental drug that are unknown.
- Conditions
- Focus of the Study: Safety of XFB19
- Being tested
- XFB19, Placebo
- Keywords
- human C/EBPβ-Thr266, XFB19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
XFB19Drug
The site-specific phosphorylation of the CCAAT/enhancer binding protein β (C/EBPβ) on Threonine266 (phospho-C/EBPβThr266) is critical for the priming and activation pathways, signals 1 and 2 of the NLRP3 inflammasome, that result in its full induction, causal to systemic inflammation critical to the morbidity and mortality of inflammatory/fibrotic diseases.
Phospho-C/EBPβThr266 is also essential for the mesenchymal myofibroblastic cell cycle checkpoint failure and transition that results in the inappropriate tissue repair and pathological tissue fibrosis.
XFB19 is a first-in-class, rationally-designed drug. It is homeostatic, and in preclinical studies, effectively, safely, and selectively inhibits phospho-C/EBPβThr266, the pathological inflammatory-fibrotic complications of NLRP3 inflammasome activation and synergistic myofibroblastic transition, reversing the pathology towards homeostasis, and fulfilling the precision medicine objectives.
PlaceboDrug
No active ingredient drug use to blind participants and investigators
| Study group | Role | What they receive |
|---|---|---|
| XFB19 administered SC. | Experimental | Part A: XFB19 SC injection at the following dose levels:
* Cohort A1: 5 mg (or placebo vehicle , same volume)
* Cohort A2: 10 mg (or placebo vehicle , same volume)
* Cohort A3: 20 mg (or placebo vehicle , same volume)
Part B: XFB19 SC injection at the 2 highest acceptable dose levels from Part A:
* Cohort B1: second highest acceptable dose level from Part A (or placebo vehicle , same volume)
* Cohort B2: highest acceptable dose level from Part A (or placebo vehicle , same volume) Receives: Drug: XFB19 |
| Placebo | Placebo comparator | 10 healthy volunteers will be randomized and assigned to the Placebo arm in Part A (Cohorts A1, A2 and A3) and Part B (Cohorts B1 and B2). Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of participants with adverse events
Number of participants with adverse events (using the CTCAE v5.0 grading scale), with abnormal laboratory tests results (hematology, serum chemistry, coagulation, and urinalysis), abnormal vital signs, abnormal ECG parameters, and abnormal physical examination findings.
Measured: During admission to the clinical unit (up to 10 days)
Heart Rate (assessed by ECG)
ECG parameters include the following:
Heart Rate
Measured: During admission to the clinical unit (up to 10 days)
Rhythm (assessed by ECG)
ECG parameters include the following:
Rhythm
Measured: During admission to the clinical unit (up to 10 days)
P wave (assessed by ECG)
ECG parameters include the following:
P wave
Measured: During admission to the clinical unit (up to 10 days)
PR interval (assessed by ECG)
ECG parameters include the following:
PR interval
Measured: During admission to the clinical unit (up to 10 days)
QRS complex (assessed by ECG)
ECG parameters include the following:
QRS complex
Measured: During admission to the clinical unit (up to 10 days)
ST segment (assessed by ECG)
ECG parameters include the following:
ST segment
Measured: During admission to the clinical unit (up to 10 days)
T wave (assessed by ECG)
ECG parameters include the following:
T wave
Measured: During admission to the clinical unit (up to 10 days)
QT interval (assessed by ECG)
ECG parameters include the following:
QT interval
Measured: During admission to the clinical unit (up to 10 days)
Cardiac axis (assessed by ECG)
ECG parameters include the following:
Cardiac axis
Measured: During admission to the clinical unit (up to 10 days)
J-point (assessed by ECG)
ECG parameters include the following:
J-point
Measured: During admission to the clinical unit (up to 10 days)
Secondary outcomes (10)
Maximum observed concentration (Cmax)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- Cmax
Measured: During admission to the clinical unit (up to 10 days)
Time to Cmax (Tmax)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- Tmax
Measured: During admission to the clinical unit (up to 10 days)
Trough concentration (Ctrough)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- Ctrough (predose Day 7 in Part B only)
Measured: During admission to the clinical unit (up to 10 days)
Area under the plasma drug concentration-time curve (AUC0-tlast).
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- Area under the plasma drug concentration-time curve from time zero to the time of last quantifiable concentration (AUC0-tlast)
Measured: During admission to the clinical unit (up to 10 days)
Apparent terminal elimination half-life (t1/2)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- t1/2
Measured: During admission to the clinical unit (up to 10 days)
Apparent terminal elimination half-life (t1/2)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- Apparent terminal elimination half-life (t1/2)
Measured: During admission to the clinical unit (up to 10 days)
Terminal elimination rate constant (λz)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- λz
Measured: During admission to the clinical unit (up to 10 days)
Total apparent body clearance (CL/F)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- CL/F
Measured: During admission to the clinical unit (up to 10 days)
Apparent volume of distribution (Vz/F)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- Vz/F
Measured: During admission to the clinical unit (up to 10 days)
Apparent steady state volume of distribution (Vss/F)
XFB19 PK endpoints include (but are not limited to) the following after the single dose in Part A and/or the first and last doses in Part B as indicated:
- Vss/F
Measured: During admission to the clinical unit (up to 10 days)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 May 2022
- Study start17 Feb 2026
- Primary completion15 Sep 2026 (estimated)
- Study completion15 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Focus of the Study: Safety of XFB19Studies 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
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- In Part A, 24 healthy volunteers will be enrolled in a total of 3 cohorts (Cohorts A1 to A3) with ascending doses of XFB19: 5mg (Cohort A1), 10mg (Cohort A2), and 20mg (Cohort A3). Each cohort will enroll 8 participants with 6 participants randomized to receive XFB19 and 2 participants randomized to receive placebo. In Part B, 16 healthy volunteers will be enrolled in a total of 2 cohorts (Cohorts B1 and B2). Each cohort will enroll 8 participants with 6 participants randomized to receive XFB19 and 2 participants randomized to receive placebo. Cohorts B1 and B2 will accept the second highest and highest XFB19 doses for evaluation from Part A.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Xfibra, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- PharPoint Research, Inc., Safe Harbor Pharmacovigilance
- Responsible party
- Sponsor
- Investigators
- Martina M Buck, Ph.D., Study chair, Xfibra, Inc.
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05361733
- Sponsor's protocol ID
- XFB19-101
- Other IDs
- HT94252510985 (Log # PR241349)
- Status last verified
- Apr 2026
- First submitted
- 8 Apr 2022
- Last updated
- 1 May 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: No at this time, as Xfibra, Inc. will evaluate data internally and may share data at a later time period.
Publications
Buck M, Chojkier M. A ribosomal S-6 kinase-mediated signal to C/EBP-beta is critical for the development of liver fibrosis. PLoS One. 2007 Dec 26;2(12):e1372. doi: 10.1371/journal.pone.0001372.
PubMed 18159255Buck M, Chojkier M. C/EBPbeta associates with caspase 8 complex proteins and modulates apoptosis in hepatic stellate cells. J Clin Gastroenterol. 2007 Nov-Dec;41 Suppl 3:S295-9. doi: 10.1097/MCG.0b013e31814927d5.
PubMed 17975479Buck M, Chojkier M. C/EBPbeta-Thr217 phosphorylation signaling contributes to the development of lung injury and fibrosis in mice. PLoS One. 2011;6(10):e25497. doi: 10.1371/journal.pone.0025497. Epub 2011 Oct 5.
PubMed 21998664Buck M, Poli V, Hunter T, Chojkier M. C/EBPbeta phosphorylation by RSK creates a functional XEXD caspase inhibitory box critical for cell survival. Mol Cell. 2001 Oct;8(4):807-16. doi: 10.1016/s1097-2765(01)00374-4.
PubMed 11684016Buck M, Solis-Herruzo J, Chojkier M. C/EBPbeta-Thr217 Phosphorylation Stimulates Macrophage Inflammasome Activation and Liver Injury. Sci Rep. 2016 Apr 12;6:24268. doi: 10.1038/srep24268.
PubMed 27067260
Study at a glance
From the registry record, last updated by the sponsor on 1 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1, Randomized, Double-Blind, Placebo-Controlled, First-in-Human Study of the Safety, Tolerability, and Pharmacokinetics of Single and Multiple Ascending Doses of XFB19 in Healthy Adult Volunteers.
- ClinicalTrials.gov ID
- NCT05361733
- Acronym / sponsor ID
- XFB19-101
- Conditions
- Focus of the Study: Safety of XFB19
- Keywords
- human C/EBPβ-Thr266, XFB19
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- Xfibra, Inc.Industry (pharma, biotech, devices)
- Collaborators
- PharPoint Research, Inc., Safe Harbor Pharmacovigilance
- Study start
- 17 Feb 2026 (actual)
- Primary completion
- 15 Sep 2026 (estimated)
- Study completion
- 15 Dec 2026 (estimated)
- First posted
- 5 May 2022 (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.
Xfibra, Inc. is conducting a Phase 1, randomized, double-blind, placebo-controlled, first-in-human study of the safety, tolerability, and physiologically-based pharmacokinetics (PK) of single and multiple ascending doses of XFB19 in healthy adult volunteers.
Detailed description
Xfibra, Inc. is conducting this clinical research study to test a potential new drug called XFB19 that is being developed for inflammatory/fibrotic diseases.
Although current medications are available to improve health and survival in patients with inflammatory/fibrotic diseases no specific pharmacotherapy has proven curative against Acute Respiratory Distress Syndrome (ARDS), liver cirrhosis , or Idiopathic Pulmonary Fibrosis (IPF). The advantages of XFB19 over currently available therapies are its target specificity, in that it only affects a carefully selected target which may allow recovery from inflammatory/fibrotic diseases, and potentially reverse tissue fibrosis.
Although many laboratory and animal studies have been completed, this is the first time XFB-19 is being tested in humans. Therefore, side effects in humans are unknown.
This study will be conducted in two parts - Part A (single dose) and Part B (multiple dosing). The purpose and main goals of this study are:
- To determine whether XFB19 is safe and well tolerated in humans
- To determine a safe dose of XFB19 to be used in future studies in patients.
- To test how much XFB19 gets into the blood and how long it takes to be cleared from the body
- To measure the activity of XFB19 in blood.
XFB19 is considered experimental because it has not yet been approved by the FDA (Food and Drug Administration) in the USA, or any other regulatory agency responsible for approving medicines. There may be risks in taking this experimental drug that are unknown.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- In Part A, 24 healthy volunteers will be enrolled in a total of 3 cohorts (Cohorts A1 to A3) with ascending doses of XFB19: 5mg (Cohort A1), 10mg (Cohort A2), and 20mg (Cohort A3). Each cohort will enroll 8 participants with 6 participants randomized to receive XFB19 and 2 participants randomized to receive placebo. In Part B, 16 healthy volunteers will be enrolled in a total of 2 cohorts (Cohorts B1 and B2). Each cohort will enroll 8 participants with 6 participants randomized to receive XFB19 and 2 participants randomized to receive placebo. Cohorts B1 and B2 will accept the second highest and highest XFB19 doses for evaluation from Part A.
| Arm | Type | Receives |
|---|---|---|
| XFB19 administered SC. | Experimental | Drug: XFB19Part A: XFB19 SC injection at the following dose levels: * Cohort A1: 5 mg (or placebo vehicle , same volume) * Cohort A2: 10 mg (or placebo vehicle , same volume) * Cohort A3: 20 mg (or placebo vehicle , same volume) Part B: XFB19 SC injection at the 2 highest acceptable dose levels from Part A: * Cohort B1: second highest acceptable dose level from Part A (or placebo vehicle , same volume) * Cohort B2: highest acceptable dose level from Part A (or placebo vehicle , same volume) |
| Placebo | Placebo comparator | Drug: Placebo10 healthy volunteers will be randomized and assigned to the Placebo arm in Part A (Cohorts A1, A2 and A3) and Part B (Cohorts B1 and B2). |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (17 listed)
- Must have given written informed consent before any study-related activities are carried out and must be able to understand the full nature and purpose of the study, including possible risks and adverse effects.
- Adult males and females, 18 to 55 years of age (inclusive) at screening.
- Body mass index ≥ 18.0 and ≤ 35.0 kg/m2 with a body weight ≥ 45 kg at screening.
- Be non-smokers (including tobacco, e-cigarettes, and marijuana) for at least 1 month prior to first investigational drug administration.
- Medically healthy without clinically significant abnormalities (in the opinion of the Investigator) at the Screening Visit and prior to dosing including:
Key exclusion criteria (22 listed)
- History or presence of any clinically significant (as determined by the PI) cardiovascular, pulmonary, hepatic, renal, hematological, gastrointestinal, endocrine, immunologic, dermatologic, or neurological disease, including any acute illness or major surgery, within the past 3 months.
- Current infection that requires systemically absorbed antibiotic, antifungal, antiparasitic, or antiviral medications.
- Any history of malignant disease in the last 5 years (excluding surgically resected skin squamous cell or basal cell carcinoma).
- Presence of clinically relevant immunosuppression from, but not limited to, immunodeficiency conditions such as common variable hypogammaglobulinemia.
- Use of or plans to use systemic immunosuppressive (e.g., corticosteroids, methotrexate, azathioprine, cyclosporine) or immunomodulating medications (e.g., interferon) during the study or within 3 months prior to the first study drug administration.
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 |
|---|---|---|
| XFB19The site-specific phosphorylation of the CCAAT/enhancer binding protein β (C/EBPβ) on Threonine266 (phospho-C/EBPβThr266) is critical for the priming and activation pathways, signals 1 and 2 of the NLRP3 inflammasome, that result in its full induction, causal to systemic inflammation critical to the morbidity and mortality of inflammatory/fibrotic diseases. Phospho-C/EBPβThr266 is also essential for the mesenchymal myofibroblastic cell cycle checkpoint failure and transition that results in the inappropriate tissue repair and pathological tissue fibrosis. XFB19 is a first-in-class, rationally-designed drug. It is homeostatic, and in preclinical studies, effectively, safely, and selectively inhibits phospho-C/EBPβThr266, the pathological inflammatory-fibrotic complications of NLRP3 inflammasome activation and synergistic myofibroblastic transition, reversing the pathology towards homeostasis, and fulfilling the precision medicine objectives. | Drug | XFB19 administered SC. |
| PlaceboNo active ingredient drug use to blind participants and investigators | Drug | Placebo |
Primary outcome
Number of participants with adverse events
Time frame: During admission to the clinical unit (up to 10 days)
Number of participants with adverse events (using the CTCAE v5.0 grading scale), with abnormal laboratory tests results (hematology, serum chemistry, coagulation, and urinalysis), abnormal vital signs, abnormal ECG parameters, and abnormal physical examination findings.
Heart Rate (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: Heart Rate
Rhythm (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: Rhythm
P wave (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: P wave
PR interval (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: PR interval
QRS complex (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: QRS complex
ST segment (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: ST segment
T wave (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: T wave
QT interval (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: QT interval
Cardiac axis (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: Cardiac axis
J-point (assessed by ECG)
Time frame: During admission to the clinical unit (up to 10 days)
ECG parameters include the following: J-point
10 secondary outcomes
Maximum observed concentration (Cmax)
Time frame: During admission to the clinical unit (up to 10 days)
Time to Cmax (Tmax)
Time frame: During admission to the clinical unit (up to 10 days)
Trough concentration (Ctrough)
Time frame: During admission to the clinical unit (up to 10 days)
Area under the plasma drug concentration-time curve (AUC0-tlast).
Time frame: During admission to the clinical unit (up to 10 days)
Apparent terminal elimination half-life (t1/2)
Time frame: During admission to the clinical unit (up to 10 days)
Apparent terminal elimination half-life (t1/2)
Time frame: During admission to the clinical unit (up to 10 days)
Terminal elimination rate constant (λz)
Time frame: During admission to the clinical unit (up to 10 days)
Total apparent body clearance (CL/F)
Time frame: During admission to the clinical unit (up to 10 days)
Apparent volume of distribution (Vz/F)
Time frame: During admission to the clinical unit (up to 10 days)
Apparent steady state volume of distribution (Vss/F)
Time frame: During admission to the clinical unit (up to 10 days)
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 1 May 2026.
- Background: PubMed 18159255Buck M, Chojkier M. A ribosomal S-6 kinase-mediated signal to C/EBP-beta is critical for the development of liver fibrosis. PLoS One. 2007 Dec 26;2(12):e1372. doi: 10.1371/journal.pone.0001372.
- Background: PubMed 17975479Buck M, Chojkier M. C/EBPbeta associates with caspase 8 complex proteins and modulates apoptosis in hepatic stellate cells. J Clin Gastroenterol. 2007 Nov-Dec;41 Suppl 3:S295-9. doi: 10.1097/MCG.0b013e31814927d5.
- Background: PubMed 21998664Buck M, Chojkier M. C/EBPbeta-Thr217 phosphorylation signaling contributes to the development of lung injury and fibrosis in mice. PLoS One. 2011;6(10):e25497. doi: 10.1371/journal.pone.0025497. Epub 2011 Oct 5.
- Background: PubMed 11684016Buck M, Poli V, Hunter T, Chojkier M. C/EBPbeta phosphorylation by RSK creates a functional XEXD caspase inhibitory box critical for cell survival. Mol Cell. 2001 Oct;8(4):807-16. doi: 10.1016/s1097-2765(01)00374-4.
- Background: PubMed 27067260Buck M, Solis-Herruzo J, Chojkier M. C/EBPbeta-Thr217 Phosphorylation Stimulates Macrophage Inflammasome Activation and Liver Injury. Sci Rep. 2016 Apr 12;6:24268. doi: 10.1038/srep24268.
- Individual participant dataSharing planned: No. No at this time, as Xfibra, Inc. will evaluate data internally and may share data at a later time period.
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.
Martina M Buck, Ph.D. study chair
Xfibra, Inc.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing XFB19 in people with Focus of the Study: Safety of XFB19, run by Xfibra, Inc. at 1 site 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 17 inclusion and 22 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 1 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site 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 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.
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 Mario Chojkier, M.D. (858-864-3588, mchojkier@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of participants with adverse events (time frame: During admission to the clinical unit (up to 10 days)). The study lists 11 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05361733, which also lists 5 linked publications.
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 1 May 2026.