Ex Vivo Evaluation of JAK-inhibitor and Gene Therapeutical Approach in JAK-STAT Related Disorders (JAKarta)

Ex Vivo Evaluation of JAK-inhibitor and Gene Therapeutical Approach in JAK-STAT Related Disorders (JAKarta Study)

The investigators want to study the JAK-inhibitors and their impact on the immune system and evaluate the potential of a gene-therapeutic strategy

Study Overview

• Status: Recruiting
• Conditions: Primary Immunodeficiency Diseases (PID)
• Intervention / Treatment: Diagnostic test: blood sampling

Detailed Description

The investigators want to study ex vivo the effect of JAK-inhibitors on the transcriptional profile and immune cell landscape in patients with inborn errors of the JAK-STAT pathway and the ex vivo evaluation of the feasibility of a gene therapeutic approach for STAT1 GOF. Following aspects will be compared:

• To study pSTAT, transcriptional profile and cytokine production on bulk and sorted peripheral blood cell populations following stimulation in the presence or absence of different jakinibs
• To evaluate to what extent jakinibs can normalize the transcriptional in different cell types (or not and identify blind spots of this treatment strategy)
• To evaluate ex vivo the impact of a gene therapeutic approach for STAT1 GOF.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rik Schrijvers, MD, PhD; Phone Number: +3216342985; Email: rik.schrijvers@uzleuven.be

Study Locations

• Belgium
  • Vlaams-Brabant
    • Leuven, Vlaams-Brabant, Belgium, 3000
      • Recruiting
      • University Hospitals Leuven,
      • Contact: Cecilia Iglesias Herrero, MPharm; Email: cecilia.iglesiasherrero@kuleuven.be

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Cases (A): adult patients presenting with a genetically confirmed or highly suspected disorder leading to an exagerated JAK-STAT pathway.
• Controls (B): participants eligible for inclusion in this study must fall in one of the following categories:
• Healthy controls (without immune-mediated disease)

Exclusion Criteria:

• Children (< 18 years at time of recruitment)
• Persons unable or unwilling to give informed consent

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Patients with a monogenic IEI with an hyperactive JAK-STAT pathway; Adult patients presenting with a genetically confirmed or highly suspected disorder leading to an exagerated JAK-STAT pathway.	Diagnostic test: blood sampling; Blood/serum samples will be collected during routine clinical visits at the time of planned peripheral venous blood sampling. Samples will be processed and either used immediately (flow cytometry-based cell sorting, gDNA extraction, in vitro functional assays, primary cell culture or single-cell applications) or stored for later analysis.
Other: Healthy controls; Healthy controls (without immune-mediated disease)	Diagnostic test: blood sampling; Blood/serum samples will be collected during routine clinical visits at the time of planned peripheral venous blood sampling. Samples will be processed and either used immediately (flow cytometry-based cell sorting, gDNA extraction, in vitro functional assays, primary cell culture or single-cell applications) or stored for later analysis.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in STAT phosphorylation levels in peripheral blood mononuclear cells (PBMCs) after cytokine stimulation with and without JAK inhibitor exposure	Quantification via Median fluorescence intensity (MFI) of phosphorylated STAT1, STAT3, and STAT5 using multiparameter flow cytometry in bulk PBMCs and sorted T cells, B cells, NK cells, and monocyte subsets after standardized cytokine stimulation (e.g., IFNα, IFNγ, IL-6, IL-2) with or without JAK inhibitor exposure. Outcomes reported as fold-change relative to baseline.	From time of inclusion to 24 months
Change in transcriptional profiles of immune cell subsets during JAK inhibitor treatment	Differential gene expression assessed by single-cell RNA sequencing of PBMCs. Outcome is reported as the number of differentially expressed genes (adjusted p<0.05) at different sampling timepoints (n=3)	From time of inclusion to 24 months
Impact of ex vivo gene therapeutic correction in STAT1 gain-of-function patient-derived PBMCs	On-target editing efficiency measured as percentage of corrected alleles by targeted sequencing.	24 months from inclusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mutation-specific differences in response to JAK inhibitor treatment	Comparison of cytokine-induced phosphorylation (MFI of pSTAT1, pSTAT3, pSTAT5) and transcriptional responses (differential expression and pathway enrichment) between patients harboring distinct STAT1 gain-of-function variants. Outcomes reported as half-inhibitory concentration IC50 and area under the curve AUC in comparison to baseline	From time of inclusion to 24 months
Impact of our gene therapeutic approach on cell viability	Cell viability will be measured with MTT-assay	From time of inclusion to 24 months
Off target events in our ex vivo gene therapeutic approach	Off-target events detected by GUIDE-seq and confirmed by amplicon sequencing.	24 months
Transcriptional correction of our ex vivo gene therapeutic approach	Transcriptional correction measured by single-cell RNA sequencing (fold-change of interferon pathway gene expression).	24 months
Functional differentiation capacity of gene therapy-corrected cells	Functional differentiation capacity of corrected cells assessed by flow cytometry (percentages of T, B, NK, and monocyte subsets).	24 months

Collaborators and Investigators

• Sponsor: prof. dr. Rik Schrijvers
• Collaborators: Research Foundation - Flanders (Fonds Wetenschappelijk Onderzoek)
• Investigators: Principal Investigator: Rik Schrijvers, MD, PhD, UZ Leuven

Publications and helpful links

General Publications

• Staels F, Roosens W, Giovannozzi S, Moens L, Bogaert J, Iglesias-Herrero C, Gijsbers R, Bossuyt X, Frans G, Liston A, Humblet-Baron S, Meyts I, Van Aelst L, Schrijvers R. Case report: Myocarditis in congenital STAT1 gain-of function. Front Immunol. 2023 Mar 20;14:1095595. doi: 10.3389/fimmu.2023.1095595. eCollection 2023.
• Giovannozzi S, Demeulemeester J, Schrijvers R, Gijsbers R. Transcriptional Profiling of STAT1 Gain-of-Function Reveals Common and Mutation-Specific Fingerprints. Front Immunol. 2021 Feb 17;12:632997. doi: 10.3389/fimmu.2021.632997. eCollection 2021.
• Giovannozzi S, Lemmens V, Hendrix J, Gijsbers R, Schrijvers R. Live Cell Imaging Demonstrates Multiple Routes Toward a STAT1 Gain-of-Function Phenotype. Front Immunol. 2020 Jun 9;11:1114. doi: 10.3389/fimmu.2020.01114. eCollection 2020.

Study record dates

Study Major Dates

• Study Start (Actual): November 21, 2024
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): December 1, 2030

Study Registration Dates

• First Submitted: June 25, 2025
• First Submitted That Met QC Criteria: November 28, 2025
• First Posted (Estimated): December 3, 2025

Study Record Updates

• Last Update Posted (Estimated): December 3, 2025
• Last Update Submitted That Met QC Criteria: November 28, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: gene therapy; JAK inhibitors; STAT1 gain-of-function
• Additional Relevant MeSH Terms: Genetic Diseases, Inborn; Immune System Diseases; Immunologic Deficiency Syndromes; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Primary Immunodeficiency Diseases; Investigative Techniques; Specimen Handling; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Punctures; Surgical Procedures, Operative; Blood Specimen Collection
• Other Study ID Numbers: S69751; G054022N (Other Grant/Funding Number: Fonds Wetenschapelijk Onderzoek Flanders (FWO))

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: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No