Greenwich Lifesciences Stock Price, News & Analysis

Greenwich LifeSciences, Inc. (Nasdaq: GLSI) is a clinical-stage biopharmaceutical company in the pharmaceutical preparation manufacturing industry. The company is focused on developing GLSI-100, an immunotherapy intended to prevent breast cancer recurrences, and on conducting its Phase III clinical trial known as FLAMINGO-01 (NCT05232916). According to company disclosures and press releases, GLSI-100 combines GP2, a 9 amino acid transmembrane peptide of the HER2/neu protein, with GM-CSF. HER2/neu is a cell surface receptor protein expressed in a variety of common cancers, including a large proportion of breast cancers.

Greenwich LifeSciences states that FLAMINGO-01 is designed to evaluate the safety and efficacy of GLSI-100 in HER2 positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant trastuzumab-based treatment. The trial is led by Baylor College of Medicine and includes clinical sites in the United States and Europe from university-based hospitals and academic and cooperative networks, with plans disclosed by the company to open up to 150 sites globally.

GLSI-100 and the FLAMINGO-01 Trial Design

In company communications, GLSI-100 is described as GP2 plus GM-CSF. GP2 is characterized as a 9 amino acid transmembrane peptide of the HER2/neu protein, which is expressed in many cancers and in an estimated 75% of breast cancers at low (1+), intermediate (2+), and high (3+ or over-expressor) levels. The combination with GM-CSF is intended to stimulate an immune response against HER2-expressing cancer cells. The FLAMINGO-01 Phase III trial includes double-blinded randomized arms and an open label arm:

• Approximately 500 HLA-A*02 patients are planned to be randomized to GLSI-100 or placebo in double-blinded arms.
• Up to 250 patients of other HLA types (non-HLA-A*02) are planned to be treated with GLSI-100 in a third, open label arm.
• The trial has been designed to detect a hazard ratio of 0.3 in invasive breast cancer-free survival, with 28 events required and an interim analysis for superiority and futility planned when at least 14 events have occurred.

The company reports that FLAMINGO-01 has screened more than 1,000 patients across approximately 40 U.S. sites and 100 European sites, with a screening rate of about 600 patients per year. Greenwich LifeSciences has also disclosed plans and regulatory approvals to expand the trial into multiple European countries, including Spain, France, Germany, Italy, Poland, Romania, Ireland, Portugal, Belgium, and Austria, in addition to the U.S.

Clinical Data and Development History

Greenwich LifeSciences highlights prior clinical data from a Phase IIb trial of GLSI-100 in HLA-A*02 breast cancer patients. In this prospective, randomized, single-blinded, placebo-controlled, multi-center study led by MD Anderson Cancer Center, 46 HER2/neu 3+ over-expressor patients were treated with GLSI-100 and 50 placebo patients received GM-CSF alone. The company reports that, after 5 years of follow-up, there was an 80% or greater reduction in metastatic breast cancer recurrence rate in the GLSI-100–treated HER2/neu 3+ patients who were treated, followed, and remained disease free over the first 6 months. The primary immunization series (PIS), consisting of the first 6 GLSI-100 injections over the first 6 months, was associated with a peak immune response at 6 months, and the company describes the safety profile as well tolerated with no reported serious adverse events attributable to treatment in the Phase IIb and earlier Phase I studies.

In FLAMINGO-01, Greenwich LifeSciences reports that the 250-patient non-HLA-A*02 open label arm has been fully enrolled, with all patients receiving GLSI-100. Preliminary analyses disclosed by the company indicate an approximately 80% reduction in recurrence rate in this arm after completion of the PIS, based on comparisons to expected historical recurrence rates and internal comparisons of recurrence rates before and after the PIS. The company emphasizes that these results are preliminary, based on data that are not yet complete or fully reviewed, and that final outcomes may differ.

Regulatory Status and Fast Track Designation

The company has announced that the U.S. Food and Drug Administration granted Fast Track designation for GLSI-100 in the HLA-A*02 patient population. The designation, as quoted by the company, applies to GLSI-100 for the treatment of patients with HLA-A*02 genotype and HER2-positive breast cancer who have completed standard of care HER2/neu targeted therapy, with the goal of improving invasive breast cancer-free survival. Greenwich LifeSciences notes that Fast Track designation may enable more frequent communication with the FDA, potential use of rolling review for a future Biologic License Application, and possible eligibility for other expedited review mechanisms if criteria are met.

Corporate Governance and Exchange Listing

Greenwich LifeSciences is incorporated as Greenwich LifeSciences, Inc. and its common stock trades on Nasdaq under the symbol GLSI. The company holds annual meetings of stockholders, as described in its definitive proxy statements and related Form 8-K filings. For example, an 8-K dated December 18, 2025 reports the results of the 2025 Annual Meeting of Stockholders, including the election of directors and ratification of the appointment of MaloneBailey LLP as the independent registered public accounting firm for the fiscal year ended December 31, 2025.

In a separate Form 8-K dated July 24, 2025, the company disclosed that its audit committee approved the dismissal of RBSM LLP as its independent registered public accounting firm and the engagement of MaloneBailey LLP to audit the company’s consolidated financial statements for the year ended December 31, 2025. The filing notes that RBSM’s prior reports did not contain adverse opinions or disclaimers of opinion and describes identified material weaknesses in internal control over financial reporting, as discussed in the company’s periodic reports.

Breast Cancer and HER2/neu Context

In its public communications, Greenwich LifeSciences cites widely used breast cancer statistics to frame the potential clinical setting for GLSI-100. The company notes that 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. It also states that HER2 (human epidermal growth factor receptor 2) is expressed in about 75% of breast cancers at varying levels (low, intermediate, and high). These figures are presented by the company as context for the potential population in which GLSI-100 and the FLAMINGO-01 trial are being studied.

Business Focus

Based on the available information, Greenwich LifeSciences’ business model centers on the clinical development and potential future commercialization of GLSI-100 as an immunotherapy product candidate. The company’s disclosures focus on clinical trial execution, regulatory strategy, and intellectual property around the use of GLSI-100 in specific patient populations, including HLA-A*02 and non-HLA-A*02 HER2-positive breast cancer patients. The company also discusses financing approaches, such as at-the-market (ATM) offerings, and partnering strategies in its press releases, but detailed revenue-generating activities beyond development are not described in the provided materials.

Key Points for Investors and Observers

• GLSI is a clinical-stage biopharmaceutical company; its main asset, GLSI-100, is in Phase III development and is not described in the sources as an approved therapy.
• The company’s primary clinical program, FLAMINGO-01, targets HER2-positive breast cancer patients who have completed trastuzumab-based therapy and had residual disease or high-risk pathologic complete response at surgery.
• GLSI-100 has received FDA Fast Track designation in the HLA-A*02 genotype population, which may affect the regulatory pathway.
• Preliminary open label data in non-HLA-A*02 patients and prior Phase IIb results in HLA-A*02 patients, as reported by the company, suggest substantial reductions in recurrence rates, but the company explicitly cautions that preliminary Phase III data are not predictive of final outcomes.
• The company remains listed on Nasdaq and continues to file proxy materials, 8-Ks, and other reports with the SEC, reflecting ongoing corporate governance and reporting obligations.

All information above is drawn from company press releases and SEC filings provided in the source data and reflects how Greenwich LifeSciences describes its own operations, clinical programs, and regulatory status.