Quadriga BioSciences Announces Publication of Phase 2 QBS72S Data in Neuro-Oncology for Breast Cancer Leptomeningeal Disease

LOS ALTOS, Calif., Nov. 3, 2026 /PRNewswire/ -- Quadriga BioSciences Inc., a clinical-stage oncology company developing QBS72S for the targeted treatment of cancer, today announced the publication in Neuro-Oncology, the official journal of the Society for Neuro-Oncology, of the results from a Phase 2, single-arm, open-label clinical trial (NCT05305365) of QBS72S in patients with breast cancer leptomeningeal disease (LMD).

The peer-reviewed article, titled "Phase 2 test of QBS72S for breast cancer leptomeningeal disease," reports results from 10 patients treated with QBS72S and evaluated for safety, efficacy, and pharmacokinetics, as well as exploratory analyses of LAT1 expression and observation of cerebrospinal fluid (CSF) concentration.

LMD is a severe complication of metastatic breast cancer in which tumor cells spread to the CSF and leptomeninges surrounding the brain and spinal cord. Patients' overall survival is 2-4 months from time of diagnosis, and treatment remains challenging in part because many systemic therapies achieve limited exposure within the central nervous system (CNS). QBS72S is a first-in-class bifunctional molecule designed to target LAT1, a transporter expressed at the blood-brain barrier and overexpressed in many cancers, with the potential to facilitate CNS delivery while preferentially targeting LAT1-expressing cancer cells.

Key Study Findings Include:

• Clinical activity: QBS72S was detected at significant levels in the CSF of treated patients. Three of 10 patients (30%) achieved radiographic response and disease stability. Two patients experienced disease control lasting more than six months, with progression-free survival of 7.4 and 6.4 months, respectively, accompanied by improvements in physical and neurologic symptoms.
• Survival observations: Overall survival rates at one, four and twelve months were 90%, 60% and 40%, respectively. Survival was recorded from the initiation of therapy, not from the time of diagnosis. At the data cut-off, four patients remained alive, each more than 12 months after initiating treatment with QBS72S.
• Safety and tolerability: The majority of adverse events were hematologic or gastrointestinal and low to moderate in severity. Grade 4 lymphopenia occurred in 40% of patients and Grade 3 neutropenia in 20%, with no febrile neutropenia reported. Three patients experienced adverse events considered possibly related to QBS72S, including two cases of symptomatic cerebral edema, both occurring in patients with extensive prior whole-brain radiation therapy.
• Potential biomarker opportunity: CSF cell-free RNA analysis showed significantly higher LAT1 (SLC7A5) expression in patients with breast cancer LMD compared with non-cancer controls, supporting further investigation of CSF cfRNA as a potential method for evaluating LAT1 expression.

"Publication of these results in Neuro-Oncology marks an important milestone for the QBS72S program and adds to the clinical foundation supporting its continued development," said Gordon Ringold, Ph.D., Chief Executive Officer of Quadriga BioSciences. "QBS72S was designed to leverage LAT1 as a differentiated approach to treating cancers involving the central nervous system, and we believe these Phase 2 data provide important insights that can help guide the next stage of the program. Our focus now is on building on these findings and advancing QBS72S for patients with leptomeningeal disease and other difficult-to-treat cancers."

The publication places these observations in the context of the broader clinical challenge of treating leptomeningeal disease and the need for therapies capable of addressing disease within the central nervous system.

"Patients with breast cancer leptomeningeal disease are facing an aggressive cancer complication with limited therapeutic options, and historically have been excluded from clinical trials," said Melanie Hayden Gephart, M.D., M.A.S., Professor of Neurosurgery at Stanford University, study investigator and corresponding author of the publication.

"The radiographic and symptomatic improvements observed in patients, together with the favorable tolerability profile of QBS72S, are encouraging, particularly in a patient population with limited treatment options and significant unmet medical needs. These early clinical findings are further supported by the detection of QBS72S in cerebrospinal fluid and associated biomarker evidence, reinforcing the scientific rationale for continued evaluation of QBS72S and LAT1-targeted therapeutic strategies."

The article was published online in Neuro-Oncology on August 7, 2026, and is available at DOI 10.1093/neuonc/noag177.

About the Study

The Phase 2a, single-arm, single-center, open-label clinical trial (NCT05305365), conducted at Stanford University, evaluated QBS72S in breast cancer patients with LMD. Participants receive QBS72S intravenously at 18 mg/m² once monthly until disease progression or treatment discontinuation.

The published results include 10 patients with breast cancer LMD who received at least one dose of QBS72S, with data through December 10, 2024. The study focused on safety, efficacy, and pharmacokinetics, with progression-free survival, overall survival and duration of response as secondary endpoints. Exploratory analyses evaluated LAT1 expression by tumor immunohistochemistry and by CSF cell-free RNA sequencing, CSF concentrations of QBS72S were also observed.

For additional information about the clinical trial, please visit ClinicalTrials.gov and reference NCT05305365.

About Quadriga BioSciences

Quadriga BioSciences is a clinical-stage oncology company developing QBS72S, a novel, first-in-class chemotherapeutic agent that exploits the amino acid transporter LAT1, enabling the drug to cross the blood-brain barrier while selectively targeting numerous types of rapidly growing cancer cells. Quadriga's technology is based on the discovery that many aggressive forms of cancer overexpress LAT1 on their cell surfaces to support the increased nutrient requirements associated with rapid tumor growth and proliferation. The Company's mission is to develop safer and more effective treatments for patients with cancer.

For more information, please visit www.quadrigabiosciences.com.

NIH Funding Acknowledgment

Research reported in this release was supported by the National Cancer Institute of the National Institutes of Health under award numbers R44CA257579 and U54CA261717. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Additional support for the study was provided by Quadriga BioSciences, the California Breast Cancer Research Program, Metavivor and Stanford Spark/Spectrum.

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SOURCE Quadriga BioSciences Inc.