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

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: Not yet recruiting
• Conditions: Post-tick Bite Illness; Mast Cell Stabilizer
• Intervention / Treatment: Drug: fexofenadine; Drug: Ketotifen; Drug: Cromolyn Sodium

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: Interventional
• Enrollment (Estimated): 50
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Scott P Commins, MD, PhD; Phone Number: 919-537-3306; Email: scommins@email.unc.edu
• Study Contact Backup: Name: Julie Vorobiov; Email: alphagalstudy@med.unc.edu

Study Locations

• United States
  • North Carolina
    • Chapel Hill, North Carolina, United States, 27514
      • University of North Carolina
      • Contact: Study Coordinator; Phone Number: 800-594-8624; Email: alphagalstudy@med.unc.edu

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Change in Mast Cell Activation Symptom Score	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

Outcome Measure	Measure Description	Time Frame
Change in General Symptoms Questionnaire-30 (GSQ-30) Total Score	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

• Sponsor: University of North Carolina, Chapel Hill
• Collaborators: Columbia University
• Investigators: Principal Investigator: Scott Commins, University of North Carolina

Study record dates

Study Major Dates

• Study Start (Estimated): April 30, 2026
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): January 1, 2027

Study Registration Dates

• First Submitted: April 6, 2026
• First Submitted That Met QC Criteria: April 6, 2026
• First Posted (Actual): April 13, 2026

Study Record Updates

• Last Update Posted (Actual): April 13, 2026
• Last Update Submitted That Met QC Criteria: April 6, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: mast cell stabilizer; post-tick bite illness; alpha-gal syndrome
• Additional Relevant MeSH Terms: red meat allergy; Sulfur Compounds; Organic Chemicals; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Pyrans; Piperidines; Thiophenes; Benzopyrans; Chromones; Cromolyn Sodium; Ketotifen; fexofenadine
• Other Study ID 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