Dosing of QBS72S Begins for the Treatment of Brain Metastases of Breast Cancers

A phase 2, open-label clinical trial is evaluating treatment with QBS72S in patients with histologically-confirmed breast cancer that has developed brain metastases after a prior cytotoxic chemotherapy regimen.

Image Credit: © SciePro []

Image Credit: © SciePro []

About the Phase 2 Trial of QBS72S

Trial Name: A Phase IIa Study Assessing QBS72S For Treating Brain Metastases of Breast Cancer Identifier: NCT05305365

Sponsor: Melanie Hayden Gephart

Recruitment Contact: Monica Granucci, 650-388-8906,

Completion Date: August 2026

The first patient has been dosed with QBS72S in a phase 2 trial (NCT05305365) evaluating the agent for the treatment of brain metastases of breast cancers.1

"Breast cancer is one of the most common tumors to metastasize to the brain. Breast cancer brain metastases worsen prognosis, negatively affect quality of life, and currently available treatments are limited," said Melanie Hayden Gephart, MD, professor of Neurosurgery at Stanford Medicine, co-director of the Stanford Brain Tumor Center, and principal investigator of the phase 2 clinical study, in a press release. "QBS72S has shown promise in preclinical studies due to its targeted mechanism of action. I look forward to the opportunity to investigate this compound for patients in need."

When metastasized to the brain, most of the treatments for patients with breast cancer have limited efficacy. This is mostly due to the inability for current chemotherapeutics to cross the blood brain barrier in sufficient concentrations.

QBS72S is a novel, first-in-class chemotherapeutic agent that mimics an aromatic amino acid for cellular uptake by the amino acid transporter, L-type amino acid transporter 1 (LAT1). This enables QBS72S to cross the blood brain barrier and selectively target rapidly growing cancer cells. When QBS72S is inside the cell, double-stranded DNA breaks, which leads to cell death.

Currently, QBS72S is being evaluated in a phase 2 open-label clinical trial. In the study, the efficacy, safety, and tolerability of QBS72S is being assessed in patients with advanced, relapsed, metastatic breast cancer with central nervous system involvement. Approximately 35-40 patients will be included in the trial and treated with an intravenous infusion of QBS72S at 12 mg/m2 once a month.2

To be included in the study, patients must be aged 18 years and older with a histologically-confirmed breast cancer primary tumor that has developed brain metastases after a prior cytotoxic chemotherapy regimen. Patients must have a Karnofsky Performance Status of 60 or above, have received an MRI with contrast that supports the presence of parenchymal brain metastases or leptomeningeal disease, be on stable doses of corticosteroids and anticonvulsants for greater than or equal to 5 days prior to obtaining the baseline Gd-MRI of the brain, and have adequate bone marrow and liver function.

The primary end point of the study is overall response rate and clinical response as either a complete response or a partial response. Secondary end points include progression free survival, overall survival, duration of response, and adverse events. The study has an estimated completion date of August 2023.

In addition to the phase 2 trial for patients with brain metastases from breast cancer, investigators are also evaluating QBS72S for the treatment of glioblastoma in the phase 2 INSIGhT study (NCT02977780) at the Dana-Farber Cancer Institute.

"The treatment of brain metastases is a significant unmet need in oncology, as no approved therapies exist," said Gordon Ringold, PhD, chief executive officer of Quadriga BioSciences, in the press release. "With its ability to cross the blood brain barrier and target cancer cells, QBS72S has the potential to improve outcomes in these patients. We look forward to investigating this more closely with our colleagues at Stanford Medicine."

  1. Quadriga BioSciences announces dosing of first subject in phase 2 study evaluating QBS72S for brain metastases of breast cancer. News release. Quadriga BioSciences, Inc. April 11, 2023. Accessed April 11, 2023.
  2. Study assessing QBS72S for treating brain metastases of breast cancer. Updated January 31, 2023. Accessed April 11, 2023.
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