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GLSI-100

Phase 3

Breast Cancer | Monoclonal antibody | Oncology |Greenwich LifeSciences, Inc.|Last Updated: Jun 4, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
RandomizedDouble-BlindPLACEBO_CONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment750
FDA Designations
FAST_TRACK
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT05232916Phase 3 Study to Evaluate the Efficacy and Safety of HER2/Neu Peptide GLSI-100 (GP2 + GM-CSF) in HER2/Neu Positive SubjectsPHASE3 RECRUITING 750Aug 11, 2022Dec 1, 2026Jun 4, 2026179 United States, Belgium +8
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Study Endpoints
Primary Endpoints
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 Endpoints
Invasive Disease-free Survival (IDFS)
Median 4 years of follow-up (interim analysis planned)
Distant Disease-free Survival (DDFS)
Median 4 years of follow-up (interim analysis planned)
Overall Survival
Median 4 years of follow-up (interim analysis planned)
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Study Design & Arms
AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
0.9% Normal SalinePLACEBO_COMPARATOR0.9% 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-100EXPERIMENTALGLSI-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-labelEXPERIMENTALOpen-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)
Interventions
NameTypeDescription
PlaceboBIOLOGICAL0.9% Normal Saline
GLSI-100BIOLOGICAL500 mcg/mL GP2 and 125 mcg/mL GM-CSF
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Eligibility Criteria
Age Range18 Years — 100 Years
SexALL
Healthy VolunteersNo
Study Sites179

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 an...

Countries:United StatesBelgiumFranceGermanyIrelandItalyPolandPortugalRomaniaSpain
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Competitive Landscape -Breast Cancer 408 trials
CompanyTickerTrialsLead PhaseDrugs
Merck & Co., Inc.MRK12PHASE3Pembrolizumab, Paclitaxel, Doxorubicin, Epirubicin, Cyclophosphamide
AstraZeneca PLCAZN47PHASE3Fulvestrant, Capivasertib, Trastuzumab Deruxtecan, Paclitaxel, Trastuzumab
Gilead Sciences, Inc.GILD13PHASE3Sacituzumab Govitecan-hziy, Eribulin, Capecitabine Product, Gemcitabine, Vinorelbine
Eli Lilly and CompanyLLY27PHASE3Abemaciclib, Standard Adjuvant Endocrine Therapy, Imlunestrant, Tamoxifen, Anastrozole
BioNTech SE Sponsored ADRBNTX7PHASE3DB-1303/BNT323, T-DM1, Capecitabine, Paclitaxel, Nab-paclitaxel
Novartis AG Sponsored ADRNVS30PHASE3Ribociclib, Alpelisib, Fulvestrant, Trastuzumab, Pertuzumab
Olema Pharmaceuticals, Inc.OLMA5PHASE3Palazestrant, Fulvestrant, Anastrozole, Letrozole, Exemestane
Pfizer Inc.PFE34PHASE3ARV-471, Fulvestrant, PF-07220060, letrozole, abemaciclib
BeOne Medicines Ltd. Sponsored ADRONC6PHASE3BGB-43395, Letrozole, Abemaciclib, Palbociclib, Ribociclib
Jazz Pharmaceuticals Public Limited CompanyJAZZ3PHASE3Zanidatamab, Trastuzumab, Eribulin, Vinorelbine, Gemcitabine
Celcuity Inc.CELC3PHASE3Gedatolisib, Palbociclib, Fulvestrant, Alpelisib, Arm A: Gedatolisib + Palbociclib + Fulvestrant
Relay Therapeutics, Inc.RLAY2PHASE3RLY-2608, Capivasertib, Fulvestrant, Palbociclib, Ribociclib
GSK plc Sponsored ADRGSK2PHASE3Niraparib
Greenwich LifeSciences, Inc.GLSI1PHASE3GLSI-100
Bristol-Myers Squibb CompanyBMY5PHASE2Iza-bren, Nab-paclitaxel, Paclitaxel, Capecitabine, Carboplatin
BriaCell Therapeutics CorpBCTX2PHASE3SV-BR-1-GM, Cyclophosphamide, Interferon infiltration of the inoculation site, Retifanlimab, Treatment of Physician's Choice
Incyte CorporationINCY4PHASE2Ruxolitinib, Capecitabine, Regorafenib, Pembrolizumab, Axatilimab
Natera, Inc.NTRA3PHASE2Discontinuation of the anti-HER2 maintenance therapy
Puma Biotechnology, Inc.PBYI3PHASE2Neratinib, Loperamide, Colesevelam, Alisertib, Endocrine therapy
Immutep Ltd Sponsored ADRIMMP1PHASE2eftilagimod alpha, Paclitaxel
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Recent Changes (Last 90 Days)
LOWJun 4, 2026NCT05232916lastUpdatePostDate: changed
LOWJun 4, 2026NCT05232916lastUpdatePostDate: changed
LOWJun 4, 2026NCT05232916lastUpdatePostDate: changed
LOWJun 4, 2026NCT05232916lastUpdatePostDate: changed
LOWMay 26, 2026NCT05232916primaryCompletionDate: changed
LOWMay 24, 2026NCT05232916studyFirstPostDate: changed