Liquid Biopsy Monitoring Of EGFR T790M in Advanced Non-Small Cell Lung Cancer (LBM-T790M)

March 17, 2026 updated by: Soumaya RAMMEH, Faculty of Medicine of Tunis

Longitudinal Liquid Biopsy Monitoring of EGFR T790M Resistance in Advanced Non-Small Cell Lung Cancer: Real-World Data From Tunisia

The goal of this retrospective observational study is to assess the clinical utility of plasma-based EGFR testing for detection and longitudinal monitoring of the acquired T790M resistance mutation in patients with advanced EGFR-mutated non-small cell lung cancer (NSCLC) treated with first- or second-generation EGFR tyrosine kinase inhibitors in routine clinical practice in Tunisia.

The main questions it aims to answer are:

  • What is the detection rate of EGFR T790M mutation in plasma at the time of disease progression?
  • Does repeated liquid biopsy increase the cumulative detection of T790M?
  • Is T790M emergence associated with baseline clinical and molecular characteristics?
  • Is T790M status associated with progression-free survival? Participants underwent plasma sampling for circulating tumor DNA analysis during follow-up, and clinical and molecular data were retrospectively collected from medical records to evaluate mutation dynamics and outcomes.

Study Overview

Status

Completed

Conditions

Detailed Description

Acquired resistance to first- and second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in advanced EGFR-mutated non-small cell lung cancer (NSCLC) is most commonly mediated by the secondary EGFR T790M mutation. Identification of this resistance mechanism is clinically relevant, as it may guide subsequent treatment strategies. However, repeat tissue biopsy at disease progression is often limited by tumor inaccessibility, patient condition, or procedural risk. Plasma-based analysis of circulating tumor DNA (ctDNA) offers a minimally invasive alternative for molecular reassessment.

This retrospective real-world study evaluates the implementation of plasma EGFR testing for the detection of acquired T790M mutation in routine clinical practice in Tunisia. The study focuses on the detection rate of T790M at progression, the added value of repeated liquid biopsy sampling in initially negative cases, and the relationship between T790M emergence and baseline clinical or molecular characteristics.

In addition, longitudinal patterns of T790M appearance, persistence, or loss across serial plasma samples are explored to better understand resistance dynamics under TKI selective pressure. The association between T790M status and progression-free survival is also assessed.

By integrating molecular results with longitudinal clinical follow-up, this study seeks to characterize real-world patterns of acquired resistance and to evaluate the practical contribution of plasma-based EGFR testing to therapeutic decision-making.

Study Type

Observational

Enrollment (Actual)

70

Contacts and Locations

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

Study Locations

  • Tunisia
      • Tunis, Tunisia, 1007
        • Pathology Department, Charles Nicolle Hospital of Tunis

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

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

This study included patients with advanced non-small cell lung cancer consulting in different hospitals in Tunisia (The Military Hospital of Tunis, Salah Azaiez Institute, Abderhamen Mami Hospital, Jendouba Hospital, Charles Nicolle Hospital of Tunis...) and referred to the Pathology Department of Charles Nicolle Hospital of Tunis for EGFR T790M monitoring using liquid biopsy.

Description

Inclusion Criteria:

  • Confirmed advanced (stage IIIB/IV) non-small cell lung cancer
  • Documented activating EGFR mutations
  • Disease progression on first- or second-generation EGFR TKIs

Exclusion Criteria:

  • Prior treatment with third-generation EGFR TKIs before plasma sampling
  • Lack of follow-up clinical data

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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Detection rate of EGFR T790M mutation in plasma at disease progression
Time Frame: From initiation of first- or second-generation EGFR-TKI therapy until the first documented radiological disease progression at which plasma EGFR T790M testing is performed, assessed up to 36 months.
Proportion of patients with detectable T790M in plasma at the time of radiological progression.
From initiation of first- or second-generation EGFR-TKI therapy until the first documented radiological disease progression at which plasma EGFR T790M testing is performed, assessed up to 36 months.
Proportion of participants with newly detected EGFR T790M on repeat liquid biopsy after an initial negative plasma result
Time Frame: From the initial negative plasma EGFR T790M result at radiological disease progression until detection of T790M on repeat liquid biopsy testing during follow-up, assessed up to 36 months.
Incremental T790M detection rate in patients with initially negative plasma results who underwent additional testing.
From the initial negative plasma EGFR T790M result at radiological disease progression until detection of T790M on repeat liquid biopsy testing during follow-up, assessed up to 36 months.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Association of T790M emergence with baseline characteristics
Time Frame: Baseline defined at the time of initiation of first- or second-generation EGFR-TKI therapy, before treatment exposure
Correlation of T790M status with clinical and molecular features at baseline.
Baseline defined at the time of initiation of first- or second-generation EGFR-TKI therapy, before treatment exposure
Progression-free survival by T790M status
Time Frame: From initiation of first- or second-generation EGFR-TKI therapy until the first radiologically confirmed disease progression, assessed up to 36 months.
Comparison of progression-free survival in patients with versus without T790M detected in plasma.
From initiation of first- or second-generation EGFR-TKI therapy until the first radiologically confirmed disease progression, assessed up to 36 months.

Collaborators and Investigators

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

Sponsor

Faculty of Medicine of Tunis

Collaborators

Hopital Charles Nicolle

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 (Actual)

March 1, 2023

Primary Completion (Actual)

December 30, 2025

Study Completion (Actual)

December 30, 2025

Study Registration Dates

First Submitted

March 5, 2026

First Submitted That Met QC Criteria

March 11, 2026

First Posted (Actual)

March 16, 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

Additional Relevant MeSH Terms

Other Study ID Numbers

  • LB-T790M-TN

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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