Quadriga BioSciences Announces Encouraging Interim Phase II Results of LAT1-targeted QBS72S in Breast Cancer Patients with Leptomeningeal Disease

• Leptomeningeal disease (LMD) is a deadly cancer complication with no approved treatments and a 2–4 month expected survival
• Phase IIa interim data show 1-, 3-, and 12-month survival of 90%, 60%, and 40% in QBS72S-treated patients
• Radiographic and symptom improvements were observed, including two long-term responders
• QBS72S was well tolerated in heavily pre-treated patients; Findings support continued development to address a critical unmet need in metastatic breast cancer

LOS ALTOS, Calif., Dec. 3, 2025 /PRNewswire/ -- Quadriga BioSciences, a clinical-stage oncology company developing QBS72S (formerly QBS10072S) for the targeted treatment of cancer, announced positive Phase IIa interim clinical data presented at the 7th Quadrennial World Federation of Neuro-Oncology Societies and 30th Annual Meeting of the Society for Neuro-Oncology (WFNOS–SNO), held November 19–23, 2025, at the Hawaii Convention Center in Honolulu, Hawaii. In an oral session, data were presented from a single-arm, open-label study conducted by the Department of Neurosurgery at the Stanford University School of Medicine that evaluated the safety and efficacy of QBS72S, a novel chemotherapeutic designed to cross the blood–brain barrier via the L-type amino acid transporter 1 (LAT1). The results showed that QBS72S produced both radiographic and symptomatic improvement in breast cancer patients with leptomeningeal disease (LMD).

"The Phase IIa results provide important early clinical signals that reinforce the potential of QBS72S to meaningfully impact outcomes for patients with LMD," said Gordon Ringold, Ph.D., CEO of Quadriga BioSciences. "Seeing radiographic stability alongside improvements in neurologic and physical symptoms, as well as survival beyond 12 months in 4 out of 10 patients, is very encouraging. These findings underscore the promise of our therapeutic approach and strengthen our commitment to advancing QBS72S as a treatment option for patients with LMD, for which there are no approved treatment alternatives."

LMD is a serious complication of advanced breast cancer in which cancer cells spread to the membranes surrounding the brain and spinal cord, leading to significant neurologic symptoms, rapid clinical decline, and a poor prognosis.

"Breast cancer is one of the most common solid tumors to spread to the brain, and LMD represents a serious and challenging complication for patients," said Ron Weitzman, M.D., CMO of Quadriga BioSciences  "Available treatment options remain limited, in part due to challenges with drug delivery across the blood-brain barrier. The clinical findings presented at WFNOS–SNO suggest that QBS72S reaches the cancer cells and may offer meaningful benefit for patients with advanced metastatic disease. These data support continued evaluation of QBS72S as a targeted therapeutic candidate for LMD, an area of significant unmet need."

These results reinforce Quadriga Biosciences' commitment to advancing QBS72S toward a potential therapeutic option for patients with leptomeningeal disease and other central nervous system manifestations of metastatic breast cancer.

Reference: Abstract ID: CTNI-71, Oral Presentation

Title: Interim analysis of a phase IIa trial of LAT1-targeted QBS72S in breast cancer leptomeningeal disease
Authors:Brandon Carlson-Clarke, Sahara Rout, Meaghan Roy-O'Reilly, Rukayat Taiwo, Paul M. Harary, Monica Granucci, Sophia B. Chernikova, Thy T.H. Trinh, Sophie Bertrand, Kate Therkelsen, Summer Han, Bo Gu, Gordon Ringold, Jaymes Holland, Ron Weitzman, Seema Nagpal, Melanie Hayden Gephart

About QBS72S
QBS72S is a novel, first-in-class chemotherapeutic agent that mimics an aromatic amino acid for cellular uptake by the amino acid transporter LAT1 (L-type amino acid transporter 1) thereby enabling the drug to cross the blood brain barrier (BBB) as well as to selectively target numerous types of rapidly growing cancer cells. Once inside the cell QBS72S causes double-stranded DNA breaks resulting in cell death. Most aggressive cancers express high LAT1, which is commonly associated with poor prognoses.1

About the Study
The Phase 2 open-label clinical trial is designed to assess the safety, tolerability and efficacy of QBS72S in patients with brain metastases from breast cancer. The study will recruit up to 35 patients with the primary objective of determining preliminary efficacy through overall response rate. Secondary endpoints include measurement of progression free survival, overall survival, duration of response, and adverse events.

Please refer to www.clinicaltrials.gov [NCT05305365] for additional clinical trial details.

About Quadriga BioSciences
Quadriga BioSciences is a clinical-stage oncology company developing QBS10072S (QBS72S), a novel, first-in-class chemotherapeutic agent that exploits the amino acid transporter LAT1, enabling the drug to cross the blood brain barrier (BBB) as well as to selectively target numerous types of rapidly growing cancer cells. Our technology is based on the discovery that many aggressive forms of cancer cells overexpress LAT1 on their cell surfaces for the intake of nutrients to support rapid tumor growth and proliferation. Our mission is to develop safer and more effective treatments for patients with cancer.

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

Contact Information

General Inquiries
info@quadrigabiosciences.com
+1 (650) 917 9098

Media Inquiries
Tony Russo
Russo Partners
tony.russo@russopartnersllc.com
+1 (212) 845 4251

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SOURCE Quadriga BioSciences, Inc.