Treatment of Participants With Primary or Secondary Progressive Multiple Sclerosis (IMPACT-MS)

A Phase 1/2a, Open-Label, Dose-Escalation Study to Evaluate the Safety and Preliminary Efficacy of TRX319 in Subjects With Primary or Secondary Progressive Multiple Sclerosis

The goal of this clinical trial is to treat male and female participants with two types of Multiple Sclerosis (MS) called primary progressive or secondary progressive MS.

The main questions the trial aims to answer are the following:

• Is TRX319 safe when administered to patients with progressive forms of MS?
• At what dose does TRX319 work the best to treat participants with primary and or secondary progressive MS?
• Is pre-conditioning (with Bendamustine) needed to allow TRX319 to better treat participants with primary and/or secondary progressive MS?

Participants will be asked to be on study for up 1 year and may receive up to 3 total administrations of TRX319. While on study, participants will have blood tests and other assessments (MRI scans and lumbar punctures) done to understand the safety of TRX319 and how it may benefit their multiple sclerosis.

Study Overview

• Status: Recruiting
• Conditions: Multiple Sclerosis; Primary Progressive Multiple Sclerosis; Secondary Progressive Multiple Sclerosis (SPMS); Multiple Sclerosis (MS) Primary Progressive; Multiple Sclerosis (MS) Secondary Progressive
• Intervention / Treatment: Biological: TRX319; Drug: Bendamustine

• Study Type: Interventional
• Enrollment (Estimated): 39
• Phase: Phase 2; Phase 1

Contacts and Locations

• Study Contact: Name: Tr1X Clinical Trials; Phone Number: 858-283-7879; Email: Tr1xClinicalTrials@Tr1x.bio
• Study Contact Backup: Name: Study Team; Email: Tr1xClinicalTrials@Tr1x.bio

Study Locations

• United States
  • Kansas
    • Kansas City, Kansas, United States, 66160
      • Recruiting
      • University of Kansas Medical Center
      • Contact: Sharon Lynch; Phone Number: 913-588-6980; Email: SLYNCH@kumc.edu
  • Missouri
    • St Louis, Missouri, United States, 63110
      • Recruiting
      • Washington University, St. Louis
      • Contact: Susan Sommer; Phone Number: 314-362-3293; Email: foxs@wustl.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Clinical diagnosis of MS with evidence of PPMS or SPMS according to 2025 McDonald criteria.
2. Expanded Disability Status Scale (EDSS) range ≥ 2.5 to ≤ 6.5.
3. Evidence of clinical disability progression within 2 years prior to enrollment.
4. Documented presence of CSF-restricted OCBs and/or elevated IgG index and/or κ free light chain.
5. Males and females ≥ 18 and ≤ 65 years of age at time of consent.
6. Evidence of adequate organ function
7. Women of child bearing potential have a negative pregnancy test at screening.
8. Contraceptive use by all participants while on study.
9. Participants must be able to understand, consent, and be willing and able to complete all specified procedures and visits.
10. Positive varicella zoster virus titer. Participants who test seronegative for varicella zoster virus IgG antibodies need to complete vaccination ≥ 4 weeks prior to TRX319 infusion.
11. Participants must be willing to refrain from donating blood for 1 year after TRX319 infusion.

Exclusion Criteria:

1. MS clinical stability on disease modifying therapy.
2. Clinical relapse of MS in the 1 year prior to study entry.
3. Diseases other than MS to explain the first demyelinating event, including aquaporin 4 IgG or myelin oligodendrocyte glycoprotein-IgG seropositivity.
4. Prior treatment with CAR-T or gene therapy product directed at any target.
5. Prior treatment with mitoxantrone, cladribine (or other chemotherapies), or alemtuzumab within 2 years prior to TRX319 dose.
6. Prior treatment with CD20-depleting antibodies within 3 months and prior treatment with Bruton's tyrosine kinase inhibitor (BTKi) and sphingosine 1 phosphate (S1P) modulators within 1 month of TRX319 dose.
7. Plan to or have received live, attenuated vaccines less than 4 weeks (28 days) prior to TRX319 infusion, and other vaccines less than 2 weeks (14 days) prior to TRX319 infusion.
8. Serologic status reflecting active hepatitis B or C infection.
9. Positive serology for human immunodeficiency virus (HIV).
10. History of progressive multifocal leukoencephalopathy.
11. Untreated active, or active with documented completed treatment but without a negative chest X-ray that shows no evidence of active tuberculosis, or latent tuberculosis.
12. Primary immunodeficiency as defined by a known genetic disorder.
13. History of splenectomy.
14. Impaired cardiac function or clinically significant cardiac disease.
15. Previous or concurrent malignancy.
16. Prior organ transplant, or allogeneic hematopoietic stem cell transplantation or recipient of peripheral blood products < 3 years prior to TRX319 infusion.
17. Major surgery within 4 weeks prior or planned within 4 weeks after TRX319 administration.
18. History of any other neurologic disorder or medical condition the Investigator considers would increase the risk for the participant, including seizure disorders.
19. Life-threatening allergies, hypersensitivity, or documented intolerance to TRX319 drug product excipients.
20. Subjects that are pregnant, breast feeding or aim to become pregnant during the study period (Subjects must agree to use a highly effective method of contraception).
21. Serious and/or uncontrolled medical condition that, in the Investigator's judgment, would cause unacceptable safety risk, interfere with study procedures or results, or compromise compliance with the protocol.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cohort 2; Dose level 2	Biological: TRX319; TRX319 is an investigational research cell therapy that may treat and provide long term relief to individuals suffering from Primary Progressive Multiple Sclerosis and/or Secondary Progressive Multiple Sclerosis.
Experimental: Cohort 1; Dose Level 1	Biological: TRX319; TRX319 is an investigational research cell therapy that may treat and provide long term relief to individuals suffering from Primary Progressive Multiple Sclerosis and/or Secondary Progressive Multiple Sclerosis.
Experimental: Cohort 1A; Dose Level 1 with pre-conditioning	Biological: TRX319; TRX319 is an investigational research cell therapy that may treat and provide long term relief to individuals suffering from Primary Progressive Multiple Sclerosis and/or Secondary Progressive Multiple Sclerosis.; Drug: Bendamustine; Administration of bendamustine prior to TRX319 infusion
Experimental: Cohort 2A; Dose Level 2 with pre-conditioning	Biological: TRX319; TRX319 is an investigational research cell therapy that may treat and provide long term relief to individuals suffering from Primary Progressive Multiple Sclerosis and/or Secondary Progressive Multiple Sclerosis.; Drug: Bendamustine; Administration of bendamustine prior to TRX319 infusion
Experimental: Cohort 3; Dose Level 3	Biological: TRX319; TRX319 is an investigational research cell therapy that may treat and provide long term relief to individuals suffering from Primary Progressive Multiple Sclerosis and/or Secondary Progressive Multiple Sclerosis.
Experimental: Cohort 3A; Dose level 3 with pre-conditioning	Biological: TRX319; TRX319 is an investigational research cell therapy that may treat and provide long term relief to individuals suffering from Primary Progressive Multiple Sclerosis and/or Secondary Progressive Multiple Sclerosis.; Drug: Bendamustine; Administration of bendamustine prior to TRX319 infusion

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To assess the safety and tolerability of TRX319 infusion in subjects with Primary Progressive or Secondary Progressive Multiple Sclerosis.	Number of participants with severity of treatment-emergent adverse events (TEAEs) and treatment-emergent serious adverse events (TESAEs); Rate of Adverse Events of Special Interest (AESIs) in participants; The safety of TRX319 determined by negative Replication Competent Lentivirus (RCL) at approximately 3-months, 6-months, and 12-months	From baseline until 12 months post TRX319 Infusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To characterize target engagement via reduction of Oligoclonal bands (OCB) and/or normalization of cerebral spinal fluid (CSF) Immunoglobulin G (IgG) index	Reduction of OCB in CSF; Reduction and/or normalization of CSF IgG index	From baseline until 12 months post TRX319 Infusion
To evaluate the effects of TRX319 on disease progression/reactivation by gadolinium-enhancing MRI	No increase in gadolinium-enhanced T1-weighted lesions and no new or enlarging T1- or T2-weighted lesions in brain and cervical spinal cord	From baseline until 12 months post TRX319 Infusion
To evaluate disease response, as measured by the Neurostatus Expanded Disability Status Scale (EDSS)	Measure of disease response based on change in disability and walking score at Weeks 12, 24, 36, and 48.	From baseline to approximately 12 months post TRX319 infusion

Collaborators and Investigators

• Sponsor: Tr1X, Inc.

Study record dates

Study Major Dates

• Study Start (Estimated): March 1, 2026
• Primary Completion (Estimated): August 1, 2028
• Study Completion (Estimated): January 1, 2029

Study Registration Dates

• First Submitted: March 9, 2026
• First Submitted That Met QC Criteria: March 12, 2026
• First Posted (Actual): March 17, 2026

Study Record Updates

• Last Update Posted (Actual): March 19, 2026
• Last Update Submitted That Met QC Criteria: March 17, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Multiple Sclerosis; MS; SPMS; Autoimmune; Secondary Progressive; PPMS; Primary Progressive; Tr1X; TRX319-01; IMPACT-MS; Impact MS
• Additional Relevant MeSH Terms: Nervous System Diseases; Pathologic Processes; Chronic Disease; Disease Attributes; Autoimmune Diseases; Immune System Diseases; Demyelinating Autoimmune Diseases, CNS; Autoimmune Diseases of the Nervous System; Demyelinating Diseases; Pathological Conditions, Signs and Symptoms; Multiple Sclerosis; Multiple Sclerosis, Chronic Progressive; Organic Chemicals; Heterocyclic Compounds; Benzimidazoles; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Hydrocarbons; Acids, Acyclic; Carboxylic Acids; Nitrogen Mustard Compounds; Mustard Compounds; Hydrocarbons, Halogenated; Butyrates; Bendamustine Hydrochloride
• Other Study ID Numbers: TRX319-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No