A Phase 1 interventional study of LY4257496 and Standard of Care Anticancer Therapies in Breast Neoplasms, Colorectal Neoplasms and Prostate Neoplasm, sponsored by Eli Lilly and Company. Recruiting at 33 sites in 7 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-04.
Sponsored by Eli Lilly and Company · Phase 1, Interventional, and Treatment
The main purpose of this study is to evaluate safety, tolerability, and efficacy of LY4257496 alone and as part of relevant standard of care (SOC) combination therapy in participants with Gastrin-releasing Peptide Receptor (GRPR)-positive advanced cancer, including but not limited to breast, colorectal, prostate, endometrial, esophageal, gastroesophageal (GE) junction, and gastric cancer. The study will also evaluate the safety, tolerability, and efficacy of LY4257529 to identify cancer with high levels of a protein called GRPR. This is a 2-part study. Participation could last up to 36 weeks or until your tumor progresses.
14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.
This study's planned enrollment of 421 is above the median of 72 across 10,896 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →Eli Lilly and Company is the lead sponsor of 2,106 studies on the registry; 152 are open to participants now.
Of its 536 completed or terminated interventional studies of FDA-regulated products, 357 (67%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Must be assessed by computed tomography (CT)/magnetic resonance imaging (MRI) to confirm at least 1 of the following:
Must have the following histologically or cytologically confirmed diagnosis:
For participants with breast cancer diagnosis, where possible, ER and HER2 status should be assessed from the most recent tissue taken at the time of presentation with recurrent or metastatic disease.
Exclusion Criteria:
Have known active virus (HBV). Exception: Individuals with chronic HBV if they:
Have known active virus (HCV). Exception: Individuals previously treated for HCV if they:
Have untreated (HIV) infection. Exception: Individuals who have well-controlled HIV infection/disease and they:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
RECIST
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HER2
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CD4 count
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LY4257496 administered intravenously (IV)
Drug: LY4257496 · Diagnostic Test: LY4257529
LY4257496 administered IV
Drug: LY4257496 · Diagnostic Test: LY4257529
Tumor specific cohort will receive LY4257496 alone or with standard of care anticancer therapy(ies)
Drug: LY4257496 · Drug: Standard of Care Anticancer Therapies · Diagnostic Test: LY4257529
Tumor specific cohort will receive LY4257496
Drug: LY4257496 · Diagnostic Test: LY4257529
Tumor specific cohort will receive LY4257496
Drug: LY4257496 · Diagnostic Test: LY4257529
Administered IV
Fulvestrant, Imlunestrant, Aromatase Inhibitors, Capecitabine, Abemaciclib
Administered IV at select sites
This study also gives Abemaciclib, Imlunestrant, Fulvestrant. No intervention listed here names it: that was found by reading the record.
Phase 1a Dose Escalation: Maximum Tolerated Dose of LY4257496
Time frame: From Cycle 1 Day 1 (C1D1) through 28 days after the first dose of study drug. Cycle = 28 days
Phase 1a Dose Optimization: Number of Dose Limiting Toxicities of LY4257496
Time frame: From Cycle 1 Day 1 (C1D1) through 28 days after the first dose of study drug. Cycle = 28 days
Phase 1b Dose Expansion and Optimization: Objective Response Rate (ORR): Percentage of Participants with Best Response of Complete Response (CR) or Partial Response (PR)
Time frame: From C1D1 through efficacy follow-up, estimated as Week 42. Cycle = 42 weeks
Phase 1a Dose Escalation and Optimization: ORR: Percentage of Participants with Best Response of CR or PR
Time frame: From C1D1 through efficacy follow-up, estimated as Week 42. Cycle = 42 weeks
Phase 1a Dose Escalation: Absorbed Dose Estimates (Gray (Gy)) of LY4257496 in Normal Organs
Time frame: From C1D1 through 30 days after the last dose of study drug dose. Cycle = 30 days
Phase 1a Dose Escalation and Optimization: Absorbed Dose Estimates (Gy) of LY4257529 in Normal Organs
Time frame: From end of injection at Screening, and at Day 30 through 1 day after injection
Phase 1a Dose Escalation Pharmacokinetics (PK): Maximum Drug Concentration (Cmax) of LY4257496
Time frame: From C1D1 through 30 days after the last dose of study drug dose. Cycle = 30 days
Phase 1a Dose Escalation and Optimization PK: Cmax of LY4257529
Time frame: From end of injection through 1 day after injection
Phase 1a Dose Escalation PK: Area Under the Curve (AUC) of LY4257496
Time frame: From C1D1 through 30 days after the last dose of study drug dose. Cycle = 30 days
Phase 1a Dose Escalation and Optimization PK: AUC of LY4257529
Time frame: From end of injection through 1 day after injection
Not enrolling at this site — choose another above.
Plan to share: No
Started Aug 2025 (actual). Primary completion is estimated for Apr 2030, 56 months after the start.
Of 388 industry-sponsored phase 1 interventional studies under Breast Neoplasms, half reached primary completion within 39 months of starting (the median), counting those still running; a quarter within 22 and three quarters within 56. This study's planned 56 months is above that.
Counting every sponsor, half of 759 studies reached it within 44 months; a quarter within 25 and three quarters within 66.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
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