Greenwich LifeSciences is advancing its Phase III clinical trial FLAMINGO-01, evaluating GLSI-100 as an immunotherapy to prevent breast cancer recurrences in HER2-positive patients. The company announced that Noble Capital Markets has initiated equity research coverage, underscoring growing investor interest in this novel therapeutic approach.
Phase III Trial Design and Objectives
FLAMINGO-01 (NCT05232916) is designed to evaluate the safety and efficacy of GLSI-100 (GP2 + GM-CSF) in HER2-positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and have completed both neoadjuvant and postoperative adjuvant trastuzumab-based treatment.
The trial employs a robust three-arm design with approximately 500 HLA-A*02 patients randomized to GLSI-100 or placebo in double-blinded arms, while up to 250 patients of other HLA types will receive GLSI-100 in a third arm. This approach allows for comprehensive evaluation across different patient populations while maximizing the therapeutic potential for eligible patients.
Statistical Power and Endpoints
The trial has been designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, representing a 70% reduction in recurrence risk. The study requires 28 events to reach statistical significance, with an interim analysis for superiority and futility planned when at least 14 events have occurred.
The statistical design provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater, ensuring adequate sensitivity to detect clinically meaningful differences between treatment groups.
Global Clinical Infrastructure
Led by Baylor College of Medicine, the trial currently includes US and European clinical sites from university-based hospitals and academic and cooperative networks. The company plans to expand to up to 150 sites globally, demonstrating the scale and international scope of this pivotal study.
Mechanism of Action and Target Population
GLSI-100 is based on GP2, a 9 amino acid transmembrane peptide of the HER2 protein. HER2 is a cell surface receptor protein expressed in a variety of common cancers, including 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels.
This broad expression pattern represents a significant therapeutic opportunity, as one in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors currently in the United States.
Clinical Development Strategy
The immunotherapy approach targets breast cancer recurrence prevention in patients who have previously undergone surgery, addressing a critical unmet medical need in post-surgical care. By focusing on patients who have completed standard trastuzumab-based treatment, GLSI-100 aims to provide additional protection against disease recurrence in this high-risk population.
The company's focus on HER2-positive breast cancer with residual disease or high-risk pathologic complete response represents a well-defined patient population with established clinical need for additional therapeutic interventions to prevent recurrence.
