Mast Cell Treatment in Post-tick Bite Illness (PTBI)

April 6, 2026 updated by: University of North Carolina, Chapel Hill

A Phase II Pilot Study to Assess the Safety and Tolerability of Mast Cell Treatment in Post-tick Bite Illness

This is a Phase II double-blinded study to assess the safety, tolerability, and feasibility of the mast cell stabilizing medications ketotifen and cromolyn compared to participants receiving standard of care treatment with fexofenadine alone in participants who have persistent symptoms of mast cell activation following a documented tick-borne illness (Ehrlichiosis, Rocky Mountain Spotted Fever, Alpha-gal Syndrome).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This Phase II study is designed as a randomized, double-blind study to assess the safety, tolerability, and feasibility of mast cell-directed therapy using ketotifen, cromolyn and fexofenadine vs fexofenadine alone in participants who have post-tick bite illness. The study is a 2 arm, 4-month trial preceded by a 14 day run-in period of fexofenadine for all screened and consented participants. At the end of 14 days, participants will be re-administered the mast cell activation symptom screening questionnaire and those who have a greater than 20% increase in symptom improvement score during 14 days of fexofenadine will be considered meaningfully better and not be randomized due to not needing further treatment. Randomized participants (n=50) will be assigned 2:1 by study pharmacy to receive either fexofenadine 180mg daily or ketotifen 1 mg twice daily (starting dose) + cromolyn 200mg three times daily + fexofenadine 180 mg daily. After 30 days, ketotifen will be increased to 2 mg twice daily and remain at that dose until trial completion.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
50

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • North Carolina
      • Chapel Hill, North Carolina, United States, 27514

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • In order to be eligible to participate in this study, an individual must meet all of the following criteria:

    • Ability to understand and provide informed consent in English (a translator will not be present during screening, consent or follow-up visits)
    • Age 21-65 years old and of any gender, race, and ethnicity at the time of the initial visit.
    • History of Ehrlichiosis and/or Rocky Mountain Spotted Fever (RMSF) within the last 36 months diagnosed and treated by a healthcare provider more than 6 months previously with current symptoms causing clinically significant distress or impairment in functioning as measured by a mast cell symptom scale score >88 ± 9

  • OR - History of alpha-gal syndrome (AGS) with an alpha-gal Immunoglobulin E (IgE) >0.1 IU/mL and managed on an appropriate avoidance diet for more than 6 months previously with current symptoms causing clinically significant distress or impairment in functioning as measured by a mast cell symptom scale score >88 ± 9

    • Females of childbearing potential must have a negative pregnancy test prior to study entry
    • Ability to refrain from diphenhydramine ("Benadryl") during the study period

Exclusion Criteria:

  • Any individual who meets one or more of the following criteria will be excluded from participation:

    • History of allergy, intolerance or hypersensitivity to fexofenadine, cromolyn or ketotifen (as documented by self-report and/or medical chart review)
    • History of a prior course of ketotifen and/or cromolyn within 12 months before enrollment
    • Inability or unwillingness to give written informed consent or comply with study protocol
    • Pregnant (urine testing) or planning to become pregnant during the course of this study
    • Use of omalizumab within 6 months of enrollment
    • Use of systemic steroids for any reason within 28 days of study entry
    • Use of zileuton within 14 days of study entry
    • Have past or current medical problems or findings from physical exam or laboratory testing not listed above, which in the opinion of the investigator, may pose additional risks from participation in the study or which may interfere with the ability to comply with study requirements
    • Suicidal ideation with intent in the last 6 months or suicidal behavior in the last year as assessed by the Columbia-suicide severity rating scale
    • Current serious unstable medical illness
    • Ongoing or planned other therapies to address post-tick bite illness (PTBI) symptoms during the course of this study

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Fexofenadine Monotherapy
Participants receive fexofenadine 180 mg orally once daily for 4 months following a 14-day open-label run-in period
Drug: fexofenadine
Fexofenadine is a second-generation H1 antihistamine administered orally at a dose of 180 mg once daily
Other Names:
  • Allegra
Experimental: Mast Cell-Directed Combination Therapy
Participants receive ketotifen plus cromolyn plus fexofenadine for 4 months following a 14-day open-label run-in period. Ketotifen is administered orally at 1 mg twice daily with dose escalation to 2 mg twice daily after 30 days. Cromolyn is administered orally at 200 mg three times daily, and fexofenadine is administered orally at 180 mg once daily.
Drug: fexofenadine
Fexofenadine is a second-generation H1 antihistamine administered orally at a dose of 180 mg once daily
Other Names:
  • Allegra
Drug: Ketotifen
Ketotifen is a mast cell stabilizer and H1 antihistamine administered orally at 1 mg twice daily, with dose escalation to 2 mg twice daily after 30 days.
Drug: Cromolyn Sodium
Cromolyn sodium is a mast cell stabilizer administered orally at a dose of 200 mg three times daily.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in Mast Cell Activation Symptom Score
Time Frame: Baseline, after 4 months of intervention
Symptoms will be assessed using the mast cell activity symptom scale, which is based on the American Academy of Allergy, Asthma and Immunology scale but with modifications to include neuro/psych symptoms. The construct is a Likert metric with participants ranking symptoms based on categories of frequency, severity and impact to daily life ("bothersome"). Each item is rated on a 4-point scale from 1 ("not at all") to 4 ("extremely") resulting in a range of 63 - 252. Higher scores are correlated with worse symptoms.
Baseline, after 4 months of intervention

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in General Symptoms Questionnaire-30 (GSQ-30) Total Score
Time Frame: Baseline, after 4 months of intervention
The General Symptoms Questionnaire-30 (GSQ-30) is a 30-item patient-reported outcome measure designed to assess multi-system symptom burden. Each item is rated on a 5-point Likert scale from 0 ("not at all") to 4 ("very much"), resulting in a total score ranging from 0 to 120. Higher scores indicate greater symptom burden.
Baseline, after 4 months of intervention

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of North Carolina, Chapel Hill

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Columbia University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Scott Commins, University of North Carolina

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 30, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 6, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 6, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 13, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 13, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 6, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 24-0990

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Deidentified individual data that supports the results will be shared beginning 9 to 36 months following publication provided the investigator who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with UNC.

IPD Sharing Time Frame

beginning 9 and continuing for 36 months following publication

IPD Sharing Access Criteria

Investigator has approved IRB, IEC, or REB and an executed data use/sharing agreement with UNC.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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