MBrace Therapeutics Presents Preclinical Data Demonstrating Potential of Novel Antibody Drug Conjugate at 2023 San Antonio Breast Cancer Symposium

MBrace Therapeutics, Inc. ("MBrace"), a clinical-stage biopharmaceutical company devoted to improving the lives of cancer patients through the development of antibody-drug conjugates (ADCs) against novel oncology targets, today announced new preclinical data supporting ongoing development for lead investigational ADC therapeutic, MBRC-101, at the San Antonio Breast Cancer Symposium taking place December 5-9, 2023, in San Antonio, Texas.

"The data presented today further characterize the safety and activity of MBRC-101 and support its potential to effectively treat various solid tumors, including difficult-to-treat breast cancers," said Isan Chen, M.D., co-founder, president and chief executive officer at MBrace. "We are advancing our clinical evaluation of MBRC-101 in breast cancer, as well as for patients with other EphA5-expressing solid tumor cancers for whom there is a significant need for targeted treatment options."

MBRC-101 is composed of a humanized anti-EphA5 IgG1 antibody conjugated to monomethyl auristatin E (MMAE). In the data presented today, robust and selective EphA5 expression was detected in greater than 80% of triple negative breast cancer (TNBC) and greater than 80% of HR+ breast cancer tissue samples. EphA5 expression was not detected in adjacent, non-malignant breast tissue or normal breast.

Additionally, extensive in vitro testing showed that MBRC-101 binds to EphA5 exclusively, is rapidly internalized and is cytotoxic to cells expressing EphA5. Dramatic preclinical efficacy was observed in vivo, with weekly administration of intravenous MBRC-101 showing dose-dependent, robust, and reproducible anti-tumor activity in patient-derived xenograft murine models of TNBC. In addition, in preclinical models MBRC-101 was well tolerated at doses ranging from 10 mg/kg to 30 mg/kg. Toxicologic findings were attributed to the MMAE payload and not target-related. The highest non-severely toxic dose (HNSTD) was 10 mg/kg (HED = 3.2 mg/kg). At a dosage of 0.5 mg/kg, the safety margin was approximated at 15-fold based on projected human exposures.

The data presented are the results of research conducted both by MBrace, as well as in the laboratories of MBrace co-founders, Renata Pasqualini, Ph.D., Professor at Rutgers Cancer Institute of New Jersey and Chief of the Division of Cancer Biology at Rutgers New Jersey Medical School; and Wadih Arap, M.D., Ph.D., Professor and Chief of the Division of Hematology/Oncology and Director of the Rutgers Cancer Institute of New Jersey at University Hospital.

Details of the poster presentation are as follows:

Abstract Title: MBRC-101: a novel antibody-drug conjugate (ADC) targeting the membrane-associated tyrosine kinase receptor EphA5 in breast cancer
Presenter: Fernanda Staquicini, Ph.D., Director of Research & Development, MBrace Therapeutics
Presentation ID: P03-18-04
Spotlight Session: Poster Session 3
Session Date and Time: Thursday, December 7, 12:00 PM ? 2:00 PM CST
Location: Henry B. Gonzalez Convention Center, San Antonio, Texas
Published Abstract Number: 1580268

The poster is also available on the MBrace Therapeutics website at www.mbractetrx.com.

About MBRC-101

MBRC-101 is an investigational antibody drug conjugate (ADC) that uniquely targets the EphA5 receptor tyrosine kinase, which is present in multiple cancers including, but not limited to, breast, non-small cell lung (NSCLC), colorectal, gastric, and pancreatic cancers. MBRC-101 is currently being evaluated in the MBRC-101-001 Phase 1 clinical trial, a first-in-human, open-label, multi-center, dose escalation and dose expansion study enrolling patients with advanced metastatic solid tumors refractory to standard-of-care treatment. For more information about the MBRC-101-001 clinical trial and to review patient eligibility criteria visit clinicaltrials.gov (NCT06014658).

About MBrace Therapeutics

MBrace is a clinical stage pharmaceutical company focused on the development and commercialization of novel therapeutic agents for patients with cancer. MBrace develops innovative treatments for cancer patients by developing novel antibody-drug conjugates using the SPARTA technology pioneered by its founders. MBrace is headquartered in San Diego, CA, with research facilities at The Thomas O. Daniel Research Incubator in Summit, NJ. For additional information, please visit MBrace's website at www.mbracetrx.com.