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RecruitingInterventionalPhase 3

A Randomized, Multicenter, Placebo-controlled, Phase 3 Study to Evaluate the Efficacy and Safety of HER2/Neu Peptide GLSI-100 (GP2 + GM-CSF) in HER2/Neu Positive Subjects With Residual Disease or High-Risk PCR After Both Neoadjuvant and Postoperative Adjuvant Trastuzumab-based Therapy (FLAMINGO-01)

NCT ID: NCT05232916Sponsor: Greenwich LifeSciences, Inc.Last updated: 2026-06-04

Summary

This is a prospective, randomized, double-blinded, placebo-controlled, multi-center, Phase 3 study of GLSI-100 immunotherapy in HLA-A\*02 positive and HER2/neu positive subjects who are at high risk for disease recurrence and have completed both neoadjuvant and postoperative adjuvant standard of care therapy. Treatment consists of 6 intradermal injections, Primary Immunization Series (PIS), over the first 6 months of treatment and 5 booster intradermal injections spaced 6 months apart. A third open-label arm will explore GLSI-100 immunotherapy in non-HLA-A\*02 positive and HER2/neu positive subjects.

Arms & interventions

  • BiologicalPlacebo

    0.9% Normal Saline

  • BiologicalGLSI-100

    500 mcg/mL GP2 and 125 mcg/mL GM-CSF

Outcome measures

Primary

  • Invasive Breast Cancer-free Survival (IBCFS)

    IBCFS is defined as the time from the first dose of study medication until the date of ipsilateral invasive breast cancer recurrence, ipsilateral local-regional invasive breast cancer recurrence, distant recurrence, contralateral invasive breast cancer, or any cause mortality.

    Time frame: Median 4 years of follow-up (interim analysis planned)

Secondary

  • Invasive Disease-free Survival (IDFS)

    Time frame: Median 4 years of follow-up (interim analysis planned)

  • Distant Disease-free Survival (DDFS)

    Time frame: Median 4 years of follow-up (interim analysis planned)

  • Overall Survival

    Time frame: Median 4 years of follow-up (interim analysis planned)

  • Quality of Life Questionnaire Core 30 (QLQ-C30)

    Time frame: Baseline and 36 months

  • Quality of Life FACT-GP5

    Time frame: Baseline and 36 months

Eligibility criteria

Sex: AllAge: 18 Years to 100 YearsHealthy volunteers: No
Inclusion Criteria: * HLA-A\*02-positive, unless being enrolled in the third non-HLA-A\*02 arm * Histologically confirmed diagnosis of HER2/neu positive primary breast cancer for all tumors biopsied (multifocal, multicentric, or synchronous contralateral disease) * Completion of both neoadjuvant and adjuvant trastuzumab-based standard of care breast cancer therapy * Stage I, II, or III at presentation with pathologic evidence of residual invasive carcinoma in the breast or axillary lymph nodes (residual disease) at surgery following completion of neoadjuvant therapy -OR- Stage III at presentation with pathologic complete response (pCR) at surgery following completion of neoadjuvant therapy * The subject can begin study therapy within one year of completion of adjuvant trastuzumab-based therapy and any other standard therapies, but, study therapy can be administered concurrently with endocrine therapy. * No clinical evidence of residual or persistent breast cancer per treating physician assessment * ECOG 0-2 * Adequate organ function * Negative pregnancy test or evidence of post-menopausal status * If of childbearing potential, willing to use a form of highly effective contraception * Subject must both reside in and have been treated for their cancer in the country in which the clinical site is located. Exclusion Criteria: * Stage IV cancer or metastatic breast cancer at any time * Inflammatory breast cancer * Receiving other investigational agents * Receiving chemotherapy * Requiring long-term systemic treatment with corticosteroids or other immunosuppressive therapy * History of immunodeficiency or active autoimmune disease * A history of serious allergic reactions, including anaphylaxis, to human granulocyte-macrophage colony-stimulating factors such as sargramostim, yeast-derived products, or any component of the investigational product * Other malignancies except adequately treated in situ carcinoma of the cervix or basal cell or squamous cell carcinoma of the skin * Active infection * Known HIV infection with a detectable viral load within 6 months of the anticipated start of treatment. Note: Subjects on effective antiretroviral therapy with an undetectable viral load within 6 months of the anticipated start of treatment are eligible for this trial.

Study locations (51)

Southern Cancer Center

Mobile, Alabama, 36607

Not Yet Recruiting
Michael Meshad · Principal Investigator

City of Hope - Cancer Center Phoenix

Goodyear, Arizona, 85338

Recruiting
Jenny Sanchez · Contact
Felicia Lewis · Contact
Hope Rugo, MD · Principal Investigator

Tucson Medical Center HealthCare

Tucson, Arizona, 85704

Recruiting
Stacey Kimbell, R.N. · Contact
Aisha Ahmed, MD · Principal Investigator

City of Hope - Duarte Cancer Center

Duarte, California, 91010

Recruiting
Jenny Sanchez · Contact
Felicia Lewis · Contact
Hope Rugo, MD · Principal Investigator

Providence St. Jude Medical Center - Virginia K. Crosson Cancer Center

Fullerton, California, 92835

Recruiting
Linda Gozar · Contact
Monica E Lee, MD · Principal Investigator

City of Hope - Orange County Lennar Foundation Cancer Center

Irvine, California, 92618

Recruiting
Jenny Sanchez · Contact
Felicia Lewis · Contact
Hope Rugo, MD · Principal Investigator

University of California San Diego - Moores Cancer Center

La Jolla, California, 92093

Recruiting
Sauntee Braddock · Contact
Rebecca Shatsky, MD · Principal Investigator

University of Southern California - Norris Comprehensive Cancer Center

Los Angeles, California, 90033

Active Not Recruiting

Stanford Medicine Cancer Center - Stanford Women's Cancer Center

Palo Alto, California, 74304

Recruiting
Michelle Narayan Brauer · Contact
Fauzia Riaz, MD · Principal Investigator

University of California San Francisco - Helen Diller Family Comprehensive Cancer Center

San Francisco, California, 94158

Recruiting
Amy Deluca · Contact
Laura Huppert, MD · Principal Investigator

University of California Los Angeles - Hematology / Oncology Parkside

Santa Monica, California, 90404

Recruiting
Monica Rocha · Contact
Aashni Master, DO · Principal Investigator

PIH Health Hospital - Whittier Hospital

Whittier, California, 90602

Recruiting
Kristine Bradbury · Contact
Lisa Wang, MD · Principal Investigator

Rocky Mountain Cancer Centers

Denver, Colorado, 80220

Recruiting
Jennifer Hege · Contact
Mabel Mardones, MD · Principal Investigator

Yale Cancer Center - Smilow Cancer Hospital

New Haven, Connecticut, 06511

Recruiting
Adam Blanchard · Contact
Michael DiGiovanna, MD, PhD · Principal Investigator

Johns Hopkins Medicine - Kimmel Cancer Center-Sibley Memorial Hospital

Washington D.C., District of Columbia, 20016

Recruiting
Hayden Chae, RN · Contact
Cesar Santa-Maria, MD · Principal Investigator

University of Miami - Sylvester Comprehensive Cancer Center

Miami, Florida, 33146

Recruiting
Maria Ferrer-Guerra · Contact
Elisa Krill-Jackson, MD · Principal Investigator

Moffitt Cancer Center

Tampa, Florida, 33612

Recruiting
Julian Guerrero · Contact
Aixa Soyano Muller, MD · Principal Investigator

City of Hope - Cancer Center Atlanta

Newnan, Georgia, 30265

Recruiting
Jenny Sanchez · Contact
Felicia Lewis · Contact
Hope Rugo, MD · Principal Investigator

Northwestern University - Northwestern Memorial Hospital

Chicago, Illinois, 60611

Recruiting
William Gradishar, MD · Principal Investigator

City of Hope - Cancer Center Chicago

Zion, Illinois, 60099

Recruiting
Jenny Sanchez · Contact
Felicia Lewis · Contact
Hope Rugo, MD · Principal Investigator

Maryland Oncology Hematology

Annapolis, Maryland, 21401

Recruiting
Gloria Seho-Ahiable · Contact
Jeanine Werner, MD · Principal Investigator

Massachusetts General Hospital Cancer Center

Boston, Massachusetts, 02114

Recruiting
MGH Cancer Center New Patient Access Team · Contact
Laura Spring, MD · Principal Investigator

Minnesota Oncology

Maple Grove, Minnesota, 55369

Recruiting
Kayla McDonald · Contact
Nicole Jacobi, MD · Principal Investigator

Siteman Cancer Center - Washington University Medical Campus

St Louis, Missouri, 63110

Recruiting
Tracy Summa · Contact
Faisal Fa'ak, MD · Principal Investigator

Nebraska Cancer Specialists

Omaha, Nebraska, 68114

Recruiting
Heather Cordes · Contact
Mary Heurter Wells, MD · Principal Investigator

Nebraska Medicine - University of Nebraska Medical Center

Omaha, Nebraska, 68198

Recruiting
Meghana Kesireddy, MBBS · Principal Investigator

Comprehensive Cancer Centers of Nevada

Henderson, Nevada, 89052

Recruiting
Lindsay Kondo · Contact
Stephani Christensen, MD · Principal Investigator

Cooper University Health Care

Camden, New Jersey, 08103

Active Not Recruiting

New York Oncology Hematology

Albany, New York, 12065

Recruiting
Josephine Faruol · Contact
Karen Tedesco, MD · Principal Investigator

New York-Presbyterian - Columbia University Irving Medical Center

New York, New York, 10032

Recruiting
Julia McGuinness, MD · Principal Investigator

Stony Brook University Cancer Center

Stony Brook, New York, 11794

Recruiting
Pushpa Talanki · Contact
Jules Cohen, MD · Principal Investigator

Oncology Hematology Care

Cincinnati, Ohio, 45211

Recruiting
Douglas Hart · Contact
Patrick Ward, MD, PhD · Principal Investigator

Hematology Oncology Associates

Medford, Oregon, 97504

Not Yet Recruiting
Cho, MD · Principal Investigator

Compass Oncology - Northwest Cancer Specialists

Tigard, Oregon, 97223

Recruiting
Jennifer Thompson · Contact
Jay Andersen, MD · Principal Investigator

Redeemer Health - Holy Redeemer Hospital

Meadowbrook, Pennsylvania, 19046

Recruiting
Nadine Varney · Contact
Rabia Cattie, MD · Principal Investigator

Sidney Kimmel Comprehensive Cancer Center - Thomas Jefferson University Hospital

Philadelphia, Pennsylvania, 19107

Recruiting
Maysa Abu-Khalaf, MD · Principal Investigator

Tennessee Cancer Specialists

Knoxville, Tennessee, 37909

Not Yet Recruiting
R. David Schumaker, MD · Principal Investigator

SCRI Oncology Partners

Nashville, Tennessee, 37203

Not Yet Recruiting
Denise A Yardley, MD · Principal Investigator

Texas Oncology - Austin

Austin, Texas, 78745

Recruiting
Sara Manning · Contact
Kathryn Hudson, MD · Principal Investigator

Texas Oncology - Dallas Presbyterian Hospital

Dallas, Texas, 75231

Recruiting
Nancy Jones · Contact
Cynthia Osborne, MD · Principal Investigator

Texas Oncology - Baylor Charles A. Sammons Cancer Center

Dallas, Texas, 75246

Recruiting
Christine Terraciano · Contact
Cynthia Osborne, MD · Principal Investigator

The University of Texas Southwestern Medical Center

Dallas, Texas, 75390

Recruiting
Meredith Carter · Contact
Nisha Unni, MD · Principal Investigator

Baylor College of Medicine - Dan L. Duncan Comprehensive Cancer Center

Houston, Texas, 77057

Recruiting
Maria Rodriguez · Contact
Mothaffar Rimawi, MD · Principal Investigator

The University of Texas Health Sciences Center at San Antonio - Mays Cancer Center

San Antonio, Texas, 78229

Recruiting
Epp Goodwin · Contact
Virginia Kaklamani, MD · Principal Investigator

Texas Oncology - San Antonio Medical Center

San Antonio, Texas, 78240

Recruiting
Shannon Syring · Contact
Emmalind Aponte, MD · Principal Investigator

Texas Oncology - Gulf Coast

Sugar Land, Texas, 77479

Recruiting
Melissa Howell · Contact
Jorge Darcourt, MD · Principal Investigator

Texas Oncology - Tyler

Tyler, Texas, 75702

Recruiting
Shelly Maxfield · Contact
Nanna Sulai, MD · Principal Investigator

University of Utah - Huntsman Cancer Institute

Salt Lake City, Utah, 84112

Recruiting
Janna Espinosa · Contact
Mei Wei, MD · Principal Investigator

Virginia Cancer Specialists

Fairfax, Virginia, 22031

Recruiting
Carrie Friedman · Contact
Shruti Tiwari, MD · Principal Investigator

Virginia Oncology Associates

Norfolk, Virginia, 23502

Not Yet Recruiting
Nino Balanchivadze, MD · Principal Investigator

Shenandoah Oncology

Winchester, Virginia, 22601

Not Yet Recruiting
Kristine Reed, MD · Principal Investigator