Study to Evaluate SBRT for EGFR Mutant NSCLC Patients Receiving Osimertinib (CULTRO)

Study Overview
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Brief Summary
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Phase II Study to Evaluate the Impact of SBRT (Stereotactic Body Radiation Therapy) and/or SRS (Stereotactic Radiosurgery) on Oligoresidual Disease in EGFR Mutation Patients Treated with Osimertinib as First-Line Systemic Intervention. All candidates must exhibit a partial response after 12 weeks of treatment with the third-generation tyrosine kinase inhibitor (alone or in combination with chemotherapy) and a maximum of five (5) residual lesions in a maximum of two (2) organs. The primary outcome will be progression-free survival (PFS), and secondary outcomes will include overall survival (OS), proportion of patients without progression at months 12 and 36, safety, and overall response rate (ORR). Additionally, an exploratory analysis will be conducted on the prognostic value of liquid biopsy (supplementary information), considering baseline presence of mutations (determined by Next Generation Sequencing tests) and reduction or negativization of allelic fraction (AF).

Detailed Description
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Phase II study with a single-stage Fleming design based on a normal approximation to the binomial distribution, with a one-sided type I error of 10% and a power of 90% to detect 30 events related to disease progression. Under the alternative hypothesis to detect a 35% improvement in PFS, 35 patients are required to be recruited over 22 months, with a minimum median follow-up of 14 months. An interim analysis will be conducted to determine early termination of the study using a Lan-DeMets monitoring boundary and an O'Brien-Fleming stopping rule. The interim analysis will be performed when 20 out of the expected 30 events have been observed. Employing the O'Brien-Fleming statistic, the critical value for the Z-score in the interim analysis (to stop and reject the null hypothesis) will be 1.054, and the critical value for the Z-score to stop and reject the alternative (futility) will be -0.204.

Official Title
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Phase II Study to Evaluate the Efficacy and Safety of SBRT as an Adjunctive Intervention for Oligoresidual Disease in EGFR Mutant NSCLC With First-Line Osimertinib Treatment

Conditions
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EGFR G719X, EGF-R Positive Non-Small Cell Lung Cancer, Non Small Cell Lung Cancer, EGFR Exon 19 Deletion, EGFR Exon 21 Mutation

Intervention / Treatment
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* Radiation: Stereotactic Body Radiation Therapy SBRT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Be older than 18 years of age. Be capable of giving informed consent to participate in the study. Have histological confirmation compatible with EGFR mutant non-small cell lung cancer (NSCLC) and metastatic disease (with or without histological confirmation of metastatic lesions). Have confirmation of the presence of common EGFR mutations (exon 19 deletion, L858R/exon 21, or G719X) through any locally and internationally accepted standard tests. Have received at least 12 weeks of Osimertinib treatment (with or without the addition of chemotherapy based on FLAURA2 study results after discussion with the investigative team). Have a partial response defined by RECIST 1.1 criteria. Have a maximum of 5 residual tumor lesions in up to 2 organs suitable for treatment with Stereotactic Ablative Radiotherapy (SABR). Have the following imaging and clinical tests within 4 weeks before study entry: Contrast-enhanced brain MRI. Chest/abdomen/pelvis CT scan, with or without bone scan (at the investigator's discretion) if PET-CT was not performed. 18-FDG PET-CT. Spinal MRI for patients with vertebral or paravertebral metastases. Electrocardiogram (EKG) and transthoracic echocardiogram. Complete blood count and standard blood chemistry. Negative pregnancy test for fertile women within 4 weeks prior to starting radiotherapy. Liquid biopsy for assessment of tumor allelic fraction (baseline). ECOG performance status 0-2. All sites of oligoresidual disease must be safely treatable according to the following criteria: All brain lesions must be treatable with SRS. The maximum size for extracranial lesions will be up to 6 cm, with exceptions for bone metastases which may include lesions larger than 6 cm at the discretion of the investigative medical team (e.g., ribs, scapula, or pelvis). Life expectancy >6 months. Not eligible for surgical treatment. Osimertinib treatment must be suspended 48 hours before the start of ablative therapy and cannot be initiated within 48 hours of receiving the last fraction. In patients receiving SBRT for central lung lesions, the suspension time for Osimertinib may be extended up to 5 days before and after ablative therapy. Patients may have previously received treatments such as radiofrequency or microwave ablation for oligoresidual lesions, but imaging must demonstrate that the lesion persists and is treatable with SABR. Metastatic tumor lesions that received initial treatment with radiosurgery cannot be included for SABR treatment. If initial treatment was conventional radiotherapy, SABR could be considered if safe to administer. In this case, the ablative therapy must be discussed by the investigative team. The eligibility and prognosis criteria will be reviewed by the multidisciplinary thoracic tumor board at CTIC Centro de Tratamiento e Investigación Sobre Cáncer Luis Carlos Sarmiento Angulo. Exclusion Criteria: Severe comorbidities contraindicating radiation therapy. Bone metastases in the femur with a high risk of fracture. Complete response to Osimertinib treatment (no oligoresidual disease for ablative treatment). Inability to treat all oligoresidual lesions with ablative intent. History of pneumonitis or functionally limiting interstitial lung disease. It may be considered limiting if the patient is unable to perform DLCO maneuvers or if adjusted DLCO is less than 35% of predicted, PaO2 at Bogotá altitude with FiO2 21% is less than or equal to 50 mmHg. Clinical or radiological evidence of symptomatic spinal cord compression. Dominant brain metastatic disease requiring surgical management (e.g., imminent herniation or hydrocephalus). Candidate for a clinical trial with an experimental drug. Inability to receive Osimertinib with minimal adherence. Oligoresidual involvement in peritoneum, pleura, or bone marrow (non-measurable disease). Leptomeningeal involvement (presumed based on imaging findings or confirmed by cerebrospinal fluid cytology). Pregnant or breastfeeding women.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 99 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Radiation<br>A total of 35 patients diagnosed and treated at CTIC Centro de Tratamiento e Investigación Sobre Cáncer Luis Carlos Sarmiento Angulo. | Radiation: Stereotactic Body Radiation Therapy SBRT<br>* This is a non-randomized Phase II study in which all patients receive the experimental treatment with Stereotactic Ablative Radiotherapy (SABR) to residual tumor lesions (up to 5 residual metastatic lesions in a maximum of 2 organs) following 12 weeks of systemic treatment with Osimertinib. The study aims to enroll 35 patients diagnosed and treated at CTIC Centro de Tratamiento e Investigación Sobre Cáncer Luis Carlos Sarmiento Angulo.<br>* Other names: Stereotactic radiosurgery SRS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Progression-Free Survival | Time from the initiation of systemic treatment (Osimertinib) to disease progression or death. This outcome is not influenced by second-line interventions and allows for the estimation of the relative efficacy of the treatment and its Hazard Ratio (HR) | Month 12 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Overall Response Rate (ORR) | Proportion of patients with partial or complete response following the implementation of SBRT. This measurement does not include stable disease | Month 12 | 
| Overall Survival (OS) | Time from diagnosis, the first day of systemic treatment, and implementation of SBRT to death from any cause or last follow-up | Month 12 | 
| Progression-Free Time (PFT) | Time from the execution of SBRT to objective tumor progression, excluding death | Month 12 | 
| Adverse Events and Safety | Adverse events will be graded using the Common Terminology Criteria for Adverse Events (CTCAE) version 5 from the National Cancer Institute (NCI) US | Month 12 |