Adaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastases

Abstract Background Breast cancer is the most common cause of cancer death among women and frequently metastasizes to the brain. Up to 30% of patients with breast-to-brain metastases will develop leptomeningeal disease (LMD), with poor survival, rapid neurologic decline, and no durable treatment opt...

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Main Authors: Rukayat Taiwo, Paul M. Harary, Thy T. H. Trinh, Monica Granucci, Sophie Bertrand, Brandon Carlson-Clarke, Sophia B. Chernikova, Kate Therkelsen, Mili Arora, Michelle E. Melisko, Michael Iv, Hannes Vogel, Summer Han, Christine Xie, Susie Brain, Vivian Lee, Krishna L. Bharani, Seema Nagpal, Melanie Hayden Gephart
Format: Article
Language:English
Published: BMC 2025-08-01
Series:BMC Cancer
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Online Access:https://doi.org/10.1186/s12885-025-14282-x
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author Rukayat Taiwo
Paul M. Harary
Thy T. H. Trinh
Monica Granucci
Sophie Bertrand
Brandon Carlson-Clarke
Sophia B. Chernikova
Kate Therkelsen
Mili Arora
Michelle E. Melisko
Michael Iv
Hannes Vogel
Summer Han
Christine Xie
Susie Brain
Vivian Lee
Krishna L. Bharani
Seema Nagpal
Melanie Hayden Gephart
author_facet Rukayat Taiwo
Paul M. Harary
Thy T. H. Trinh
Monica Granucci
Sophie Bertrand
Brandon Carlson-Clarke
Sophia B. Chernikova
Kate Therkelsen
Mili Arora
Michelle E. Melisko
Michael Iv
Hannes Vogel
Summer Han
Christine Xie
Susie Brain
Vivian Lee
Krishna L. Bharani
Seema Nagpal
Melanie Hayden Gephart
author_sort Rukayat Taiwo
collection DOAJ
description Abstract Background Breast cancer is the most common cause of cancer death among women and frequently metastasizes to the brain. Up to 30% of patients with breast-to-brain metastases will develop leptomeningeal disease (LMD), with poor survival, rapid neurologic decline, and no durable treatment options. The novel agent QBS72S, also known as QBS10072S, is designed to leverage the high expression of L-type amino acid transporter 1 (LAT1) on breast cancer cells and the blood-brain barrier. By conjugating an amino acid analogue with a DNA alkylating moiety, QBS72S can exploit LAT1 for specific delivery into the brain and metastatic tumor cells. Methods We designed a single-arm, Phase 2a study to test the preliminary efficacy and safety of QBS72S for breast-to-brain metastasis in two distinct cohorts: intraparenchymal metastasis (Cohort 1; no LMD), and LMD (Cohort 2; with or without intraparenchymal metastasis). The primary endpoint is overall response rate across evaluable participants in Cohort 1. Secondary endpoints include progression-free survival, overall survival, duration of response, and treatment-related adverse events in Cohort 1. Exploratory endpoints include correlation of LAT1 expression in formalin-fixed paraffin-embedded samples with treatment response, CSF pharmacokinetics, perfusion MRI, and novel CSF-based biomarkers. Discussion Adaptive clinical trial design enables rapid enrollment and tailored endpoints for patient cohorts with baseline disparate outcomes. Our LAT1 staining protocol will allow ongoing trials in glioblastoma (NCT02977780) and future studies in brain metastases to correlate LAT1 expression to drug efficacy. Our exploratory endpoints may facilitate identification of more rapid and reliable biomarkers of LMD treatment response and resistance. Trial registration ClinicalTrials.gov NCT05305365.
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spelling doaj-art-c86cde2c2f1a419e82a9e8a14f2e0f482025-08-20T04:02:55ZengBMCBMC Cancer1471-24072025-08-0125111310.1186/s12885-025-14282-xAdaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastasesRukayat Taiwo0Paul M. Harary1Thy T. H. Trinh2Monica Granucci3Sophie Bertrand4Brandon Carlson-Clarke5Sophia B. Chernikova6Kate Therkelsen7Mili Arora8Michelle E. Melisko9Michael Iv10Hannes Vogel11Summer Han12Christine Xie13Susie Brain14Vivian Lee15Krishna L. Bharani16Seema Nagpal17Melanie Hayden Gephart18Department of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterDepartment of Neurology and Neurological Sciences, Stanford Cancer InstituteDivision of Hematology and Oncology, University of California, Davis Comprehensive Cancer Center, University of California, Davis School of MedicineDivision of Hematology/Oncology, Department of Medicine, University of California, San FranciscoDepartment of Radiology, Stanford University School of MedicineDepartment of Pathology, Stanford University School of MedicineQuantitative Sciences Unit, Stanford University School of MedicineDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterPatient Advocate, Komen Advocates in SciencePatient Advocate, Komen Advocates in ScienceDepartment of Pathology, Stanford University School of MedicineDepartment of Neurology and Neurological Sciences, Stanford Cancer InstituteDepartment of Neurosurgery, Stanford University School of Medicine, Stanford Cancer CenterAbstract Background Breast cancer is the most common cause of cancer death among women and frequently metastasizes to the brain. Up to 30% of patients with breast-to-brain metastases will develop leptomeningeal disease (LMD), with poor survival, rapid neurologic decline, and no durable treatment options. The novel agent QBS72S, also known as QBS10072S, is designed to leverage the high expression of L-type amino acid transporter 1 (LAT1) on breast cancer cells and the blood-brain barrier. By conjugating an amino acid analogue with a DNA alkylating moiety, QBS72S can exploit LAT1 for specific delivery into the brain and metastatic tumor cells. Methods We designed a single-arm, Phase 2a study to test the preliminary efficacy and safety of QBS72S for breast-to-brain metastasis in two distinct cohorts: intraparenchymal metastasis (Cohort 1; no LMD), and LMD (Cohort 2; with or without intraparenchymal metastasis). The primary endpoint is overall response rate across evaluable participants in Cohort 1. Secondary endpoints include progression-free survival, overall survival, duration of response, and treatment-related adverse events in Cohort 1. Exploratory endpoints include correlation of LAT1 expression in formalin-fixed paraffin-embedded samples with treatment response, CSF pharmacokinetics, perfusion MRI, and novel CSF-based biomarkers. Discussion Adaptive clinical trial design enables rapid enrollment and tailored endpoints for patient cohorts with baseline disparate outcomes. Our LAT1 staining protocol will allow ongoing trials in glioblastoma (NCT02977780) and future studies in brain metastases to correlate LAT1 expression to drug efficacy. Our exploratory endpoints may facilitate identification of more rapid and reliable biomarkers of LMD treatment response and resistance. Trial registration ClinicalTrials.gov NCT05305365.https://doi.org/10.1186/s12885-025-14282-xBreast cancerLeptomeningeal diseaseChemotherapyExpression profilingLiquid biopsy
spellingShingle Rukayat Taiwo
Paul M. Harary
Thy T. H. Trinh
Monica Granucci
Sophie Bertrand
Brandon Carlson-Clarke
Sophia B. Chernikova
Kate Therkelsen
Mili Arora
Michelle E. Melisko
Michael Iv
Hannes Vogel
Summer Han
Christine Xie
Susie Brain
Vivian Lee
Krishna L. Bharani
Seema Nagpal
Melanie Hayden Gephart
Adaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastases
BMC Cancer
Breast cancer
Leptomeningeal disease
Chemotherapy
Expression profiling
Liquid biopsy
title Adaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastases
title_full Adaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastases
title_fullStr Adaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastases
title_full_unstemmed Adaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastases
title_short Adaptive cohort design and LAT1 expression scale: study protocol for a Phase 2a trial of QBS72S in breast cancer brain metastases
title_sort adaptive cohort design and lat1 expression scale study protocol for a phase 2a trial of qbs72s in breast cancer brain metastases
topic Breast cancer
Leptomeningeal disease
Chemotherapy
Expression profiling
Liquid biopsy
url https://doi.org/10.1186/s12885-025-14282-x
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