Greenwich LifeSciences

What Greenwich LifeSciences does

Greenwich LifeSciences, Inc. (NASDAQ: GLSI) is a clinical-stage biopharmaceutical company founded in 2006 and headquartered in Stafford, Texas (registered in Delaware). The company is developing a single core asset, GLSI-100, a peptide immunotherapy that combines GP2 — a 9-amino-acid transmembrane peptide derived from the HER2/neu protein — with GM-CSF as an adjuvant, designed to stimulate an immune response that prevents metastatic breast cancer recurrences in HER2-positive patients who have completed standard-of-care trastuzumab-based therapy. The product is being evaluated in FLAMINGO-01, a prospective, randomized, double-blinded, multi-center Phase III trial enrolling up to 750 patients (approximately 500 HLA-A*02 patients randomized to GLSI-100 or placebo, plus up to 250 non-HLA-A*02 patients in an open-label arm) at 140-150 clinical sites across the United States and Europe, with the Steering Committee drawn from MD Anderson, Baylor, City of Hope, Northwestern, Harvard, Johns Hopkins and European networks including GEICAM, GBG, Unicancer and GIM. The company holds FDA Fast Track designation and patent protection extending through 2045, including recently filed claims covering non-HLA-A*02 patients.

The business model is pre-revenue and approval-gated: Greenwich monetizes through eventual commercialization of GLSI-100 (or a one-time licensing arrangement) following FDA approval, with management citing a potential revenue opportunity of up to $10 billion per year if the expanded patient population (including non-HLA-A*02 patients) is captured. Manufacturing capacity has been built and FDA-validated for the first commercial lot of GP2, with planned scale of 500,000-1 million vials per year, and the FDA-cited potential market exclusivity window extends to 12 years post-approval. The company has 1-10 employees, raising approximately $24.95M at its 2020 IPO and additional capital via ATM facilities (~$10.5M in Q1 2026 and ~$7M in January 2026), with a cash balance of approximately $10.5M as of March 31, 2026 and FY2025 operating cash burn of approximately $9.9M.

Customer positioning is narrow by design: HER2-positive (1+, 2+ or 3+ expression) breast cancer patients with residual disease or high-risk pathologic response post-surgery, totaling an estimated 88,000 new patients per year in the US and Europe for the HLA-A*02 subpopulation, with potential doubling to include the non-HLA-A*02 cohort. The Phase IIb trial, led by MD Anderson, demonstrated an 80% or greater reduction in metastatic breast cancer recurrence over five years compared to the 20-50% reduction achieved by existing HER2 therapies such as Herceptin and Kadcyla, supporting Phase III progression and DSMB recommendations to continue without modification.

Name

Greenwich LifeSciences

Legal name

Greenwich LifeSciences, Inc.

Website

https://greenwichlifesciences.com

Company type

Public

Founded year

2006

Operating status

Operating

Headcount range

1–10 employees

Short description

Greenwich LifeSciences is a clinical-stage biopharmaceutical company developing GLSI-100, a HER2/neu peptide immunotherapy (GP2 + GM-CSF) designed to prevent breast cancer recurrences in HER2-positive patients, currently in a global Phase III trial (FLAMINGO-01) at 150 sites across the US and Europe.

Ownership category

akta.pro rank

Product category

Biopharmaceuticals / Cancer Immunotherapy

NAICS

Biological Product (except Diagnostic) Manufacturing (325414), Research and Development in Biotechnology (except Nanobiotechnology) (541714), Research and Development in the Physical, Engineering, and Life Sciences (54171)

SIC

Biological Products, (No Disgnostic Substances) (2836), Pharmaceutical Preparations (2834), Services-Commercial Physical & Biological Research (8731)

akta.pro primary industry

Therapeutic Vaccines (cancer, chronic infection immunotherapy) (HLAAAEAB)

akta.pro secondary industries

Therapeutic Vaccines (e.g., Cancer/Chronic Infection) (HLAIAEAG), Breast Oncology (HLAKAFAJ), Vaccine Clinical Development & Regulatory Affairs (HLAIAEAM)

Keywords

• Breast cancer immunotherapy
• HER2-positive treatment
• Cancer vaccine development
• Biopharmaceutical clinical trials
• Immuno-oncology therapy

Headquarters

HQ city

Stafford

HQ country

United States

HQ region

North America

Offices1 record

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Technology or R&D, Personnel, Operations, Marketing or Sales, Others

Revenue model

1. GLSI-100 Commercialization: Pre-revenue clinical-stage biopharmaceutical company. Once FDA approved, GLSI-100 will be commercialized as an immunotherapy to prevent breast cancer recurrences. Potential revenue of up to $10 billion per year with expanded patient population including non-HLA-A*02 patients.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels5 records

Core offering

Greenwich LifeSciences develops GLSI-100, a cancer immunotherapy vaccine combining the HER2/neu-derived peptide GP2 with the immunoadjuvant GM-CSF, intended to prevent metastatic breast cancer recurrences in HER2-positive patients who have completed trastuzumab-based standard-of-care therapy. The candidate is currently in the global Phase III FLAMINGO-01 trial, with FDA Fast Track designation, and the company plans to scale commercial manufacturing to 500,000 to 1 million vials annually.

Product overview

Greenwich LifeSciences is a clinical-stage biopharmaceutical company with a single core product: GLSI-100, an immunotherapy vaccine combining GP2 peptide with GM-CSF. The company's product portfolio centers on this one therapy in development for preventing breast cancer recurrences. GLSI-100 is currently undergoing evaluation in the FLAMINGO-01 Phase III clinical trial. The company does not offer multiple products or a platform architecture; it is focused exclusively on advancing this one immunotherapy through clinical development.

Differentiator

Problem solved

Functional benefit

Brands

• GLSI-100: GP2 + GM-CSF immunotherapy product for preventing breast cancer recurrences in HER2-positive patients.

Products and services

• GLSI-100 GLSI-100 is a first-of-its-kind immunotherapy vaccine that combines GP2, a HER2/neu-derived 9-amino-acid transmembrane peptide, with GM-CSF (Granulocyte-Macrophage Colony Stimulating Factor). It is designed to activate the immune system to prevent metastatic breast cancer recurrences in HER2-positive patients who have previously undergone surgery and completed trastuzumab-based standard-of-care therapy. The product has FDA Fast Track designation and is being evaluated in the global Phase III FLAMINGO-01 trial across approximately 150 sites in the US and Europe.
• FLAMINGO-01 Phase III Clinical Trial FLAMINGO-01 is a prospective, randomized, double-blinded, multi-center Phase III clinical trial evaluating 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 includes approximately 500 HLA-A*02 patients randomized to GLSI-100 or placebo plus up to 250 non-HLA-A*02 patients in an open-label arm, with up to 750 patients planned to be treated across approximately 150 clinical sites.

Quantifiable outcome

• 80% or greater reduction in metastatic breast cancer recurrence rate over 5 years of follow-up compared to 20-50% reduction by other approved products
• +3 more outcomes

Named customers1 record

Segments1 record

Ideal customer profiles1 record

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature2 records

Partnerships

Nine partnerships are on record, tiered core.

• City of HopecoreStrategic or Co-development Partner · 20 March 2026Added as a new clinical site for FLAMINGO-01 Phase III trial expanding research efforts and access to treatment for high-risk breast cancer patients.
• Baylor College of MedicinecoreStrategic or Co-development PartnerLead institution for FLAMINGO-01 Phase III trial. Dr. Mothaffar F. Rimawi serves as key principal investigator representing the institution on the trial Steering Committee.
• City of Hope Comprehensive Cancer CentercoreStrategic or Co-development PartnerRecently added as new clinical site for FLAMINGO-01 trial. Dr. Hope S. Rugo serves on the trial Steering Committee.
• GEICAM (Spain)coreStrategic or Co-development PartnerSpanish breast cancer research network participating in FLAMINGO-01 trial. Dr. Miguel Martin serves as CEO of GEICAM and on the Steering Committee.
• GBG Forschungs GmbH (Germany)coreStrategic or Co-development PartnerGerman Breast Group participating in FLAMINGO-01 trial. Dr. Sibylle Loibl serves as CEO of GBG and on the Steering Committee.
• Unicancer (France)coreStrategic or Co-development PartnerFrench cancer research network participating in FLAMINGO-01 trial. Dr. Francois-Clement Bidard serves as Head of Breast Cancer Group at Institut Curie and on the Steering Committee.
• GIM (Italy)coreStrategic or Co-development PartnerItalian Group for Mammography screening participating in FLAMINGO-01 trial through clinical network partnerships.
• US Oncology/TRIO UScoreStrategic or Co-development PartnerUS oncology research network participating in FLAMINGO-01 trial. Dr. Joyce A. O'Shaughnessy represents the network on the Steering Committee.
• MD Anderson Cancer CentercoreStrategic or Co-development PartnerLed the completed Phase IIb clinical trial at 16 sites. Pivotal role in early development of GP2 immunotherapy showing 80% recurrence reduction.

Scale indicators9 records

Recent moves7 records

Expansion highlights5 records

Direct peers

• Puma Biotechnology: Markets Nerlynx (neratinib), an oral HER2-targeted therapy approved for extended adjuvant treatment of early-stage HER2-positive breast cancer. Directly comparable as an adjuvant/recurrence-prevention agent in HER2-positive patients post-trastuzumab.
• Seagen (Pfizer): Developed Tukysa (tucatinib) for HER2-positive metastatic breast cancer. Operates in the same HER2-positive treatment paradigm and provides a benchmark for clinical and commercial development in this indication.
• MacroGenics: Developed Margenza (margetuximab), a HER2-targeted antibody for metastatic HER2-positive breast cancer. Competes in the same HER2-positive breast cancer space, with overlapping patient population and treatment-line considerations.

Emerging players

• Syndax Pharmaceuticals: Develops oncology therapies including entinostat (HDAC inhibitor) in breast cancer combinations and is building a pipeline of immuno-oncology agents. Comparable as a small-cap clinical-stage oncology company pursuing combination and adjuvant breast cancer strategies.
• Gritstone bio: Develops neoantigen-based cancer vaccines (GRANITE, SLATE programs) using a prime/boost approach for solid tumors. Comparable as a small-cap cancer immunotherapy vaccine developer targeting tumor-specific immune activation.
• Moderna: Develops mRNA-based cancer vaccines (e.g., mRNA-4157/V940, individualized neoantigen therapy) with Merck. Comparable as a vaccine-platform oncology developer pursuing personalized immunotherapy approaches in solid tumors.
• BioNTech: Pioneers individualized mRNA cancer vaccines (e.g., BNT122/BNT211) and has a partnership with Roche on personalized cancer vaccines. Comparable as a next-generation cancer immunotherapy developer targeting solid tumors, including breast cancer programs.
• Bavarian Nordic: Develops therapeutic cancer vaccines including CV301 and is exploring immunotherapy combinations in oncology. Comparable as a smaller-cap biotech with therapeutic cancer vaccine programs targeting solid tumor indications.

Broad incumbents

• AstraZeneca / Daiichi Sankyo: Co-develop Enhertu (trastuzumab deruxtecan), an ADC approved for HER2-positive and HER2-low metastatic breast cancer. Represents the most threatening next-generation HER2 therapy and a direct competitive constraint on GLSI-100's recurrence-prevention positioning.
• Roche / Genentech: Markets Herceptin (trastuzumab), Kadcyla (ado-trastuzumab emtansine), and Phesgo, the dominant established HER2-positive breast cancer therapies. GLSI-100 is positioned as a complementary recurrence-prevention vaccine in this patient population treated with trastuzumab.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat4 records

Key risks6 records

Key highlights6 records

Customer concentration

• Xtwitter.com/GreenwichLS
• LinkedInlinkedin.com/company/greenwich-lifesciences-inc.

Revenue estimate

Valuation estimate

Number of profiles

Profiles3 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Greenwich LifeSciences