Phase 3 Study to Evaluate the Efficacy and Safety of HER2/Neu Peptide GLSI-100 (GP2 + GM-CSF) in HER2/Neu Positive Subjects

Phase 3

Recruiting

• Conditions: Breast Cancer
• Interventions: Biological: Placebo; Biological: GLSI-100

• Registration Number: NCT05232916
• Lead Sponsor: Greenwich LifeSciences, Inc.

Brief 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.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2022-01-31
• Study First Submitted QC: 2022-01-31
• Study First Posted: 2022-02-10
• Study Start: 2022-08-11
• Status Verified: 2025-03
• Last Update Submitted: 2025-06-18
• Last Update Posted: 2025-06-24
• Primary Completion: 2026-12
• Study Completion: 2026-12-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 598

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
• 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

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 & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
0.9% Normal Saline	Placebo	0.9% normal saline in HLA-A\*02 positive and HER2/neu positive subjects administered intradermally every month for first 6 months then every 6 months for next 2.5 years (11 intradermal injections over 3 years)
GLSI-100	GLSI-100	GLSI-100 immunotherapy in HLA-A\*02 positive and HER2/neu positive subjects administered intradermally every month for first 6 months then every 6 months for next 2.5 years (11 intradermal injections over 3 years)
GLSI-100, Open-label	GLSI-100	Open-label arm: GLSI-100 immunotherapy in non-HLA-A\*02 positive and HER2/neu positive subjects administered intradermally every month for first 6 months then every 6 months for next 2.5 years (11 intradermal injections over 3 years)

Primary Outcome Measures

Name	Time	Method
Invasive Breast Cancer-free Survival (IBCFS)	Median 4 years of follow-up (interim analysis planned)	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.

Secondary Outcome Measures

Name	Time	Method
Invasive Disease-free Survival (IDFS)	Median 4 years of follow-up (interim analysis planned)	IDFS 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, second primary non-breast invasive cancer, or any cause mortality.
Distant Disease-free Survival (DDFS)	Median 4 years of follow-up (interim analysis planned)	DDFS will be defined as the time from the first dose of study medication to the time of distant disease recurrence or death.
Overall Survival	Median 4 years of follow-up (interim analysis planned)	Overall survival will be defined as the time from the first dose of study medication until death from any cause.
Quality of Life Questionnaire Core 30 (QLQ-C30)	Baseline and 36 months	European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core 30 (QLQ-C30)
Quality of Life FACT-GP5	Baseline and 36 months	FACT-GP5 to assess global side effect impact

Trial Locations

Locations (305)

Arizona Oncology Associates - Tucson; 🇺🇸 Tucson, Arizona, United States

Providence St. Jude Medical Center - Virginia K. Crosson Cancer Center; 🇺🇸 Fullerton, California, United States

University of California San Diego - Moores Cancer Center; 🇺🇸 La Jolla, California, United States

University of Southern California - Norris Comprehensive Cancer Center; 🇺🇸 Los Angeles, California, United States

Stanford Medicine Cancer Center - Stanford Women's Cancer Center; 🇺🇸 Palo Alto, California, United States

University of California San Francisco - Helen Diller Family Comprehensive Cancer Center; 🇺🇸 San Francisco, California, United States

University of California Los Angeles - Hematology / Oncology Parkside; 🇺🇸 Santa Monica, California, United States

PIH Health Hospital - Whittier Hospital; 🇺🇸 Whittier, California, United States

Rocky Mountain Cancer Centers; 🇺🇸 Denver, Colorado, United States

Yale Cancer Center - Smilow Cancer Hospital; 🇺🇸 New Haven, Connecticut, United States

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