A Phase 2 interventional study of Lapatinib and Letrozole in Breast Cancer, sponsored by Baylor Breast Care Center. Active, not recruiting at 8 sites in United States. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-03-12.
Sponsored by Baylor Breast Care Center · Phase 2, Interventional, and Treatment
Among 114 studies testing lapatinib in Breast Neoplasms — none open to participants now, 3 under way, 1 of them phase 3. Lapatinib · Breast Neoplasms.
Among the 114 studies testing lapatinib in Breast Neoplasms, this one is the 25th largest by enrollment, is one of 8 that started in 2011, is one of 60 in phase 2, and was the 71st registered.
14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.
This study's enrollment of 128 is above the median of 72 across 10,896 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →None of the 114 studies testing lapatinib in Breast Neoplasms is open now.
Lapatinib: first FDA approval 2007 (TYKERB), first EMA approval 2008. What it is approved for, and how studies give it, is on its page →
Of the 2,400 Breast Neoplasms studies recruiting now, 1,572 (66%) set no upper age limit and 591 (25%) stop at 75 or younger; 103 take children under 18; 214 take healthy volunteers.
This study: 18 Years and older · female · no healthy volunteers.
The full table on the hub →114 studies; the count open now beside each. This study's row is marked.
First in 2003; this study’s year is marked. 8 started in 2011.
Median enrollment 35 across the 114 interventional studies. Of the 99 that completed or were terminated, 50 (51%) have results posted.
48 of 114 have an industry lead sponsor. The 10 most frequent:
Baylor Breast Care Center is the lead sponsor of 16 studies on the registry; 1 is open to participants now.
16 studies in Breast Neoplasms by Baylor Breast Care Center: 1 open now, 3 under way, none of them phase 3. Of 12 finished, 6 (50%) have results posted.
Among the 16 studies in Breast Neoplasms by Baylor Breast Care Center, this one is the 2nd largest by enrollment, is the only one that started in 2011, is one of 13 in phase 2, and was the 13th registered.
Baylor Breast Care Center’s Breast Neoplasms studies by the year they started, since 1999.
None of the studies under way reaches primary completion within a year.
Among the 114 studies testing lapatinib in Breast Neoplasms, from their registry updates:
Nothing recorded among them since 2026-09-25.
Among Baylor Breast Care Center’s 16 in Breast Neoplasms:
Nothing recorded among them since 2026-09-25.
Breast cancer is the most common malignancy in the U.S. Targeted therapies such as tamoxifen have been revolutionary in reducing tumor recurrences and mortality in early breast cancer. Using this successful paradigm, there has been a continued search for other targeted biologic therapies directed at receptors with known potential for promoting tumor growth.
The estrogen receptor (ER) and/or the HER signaling pathways are the dominant drivers of cell proliferation and survival in the majority of human breast cancers. Molecular targets of these pathways provide the most effective therapies in appropriately selected patients. However, de novo and acquired resistance remain major obstacles to successful treatment, and understanding the molecular pathways responsible for this resistance would enable the discovery of new strategies to overcome it.
The superiority of multi-drug HER2-targeted therapy over single agent therapy has been demonstrated in the preclinical setting using mouse xenografts. Trastuzumab, pertuzumab, lapatinib, and gefitinib, represent a group of therapeutic agents that target the HER family by different molecular mechanisms. Used as single agents in the MCF7/HER2-18 xenograft model, these drugs restored or enhanced sensitivity to tamoxifen. However, tumor growth inhibition lasted only 2-3 months before resistance to treatments occurred. However, when gefitinib, a HER1 inhibitor, was added to the two-antibody (T+P) regimen to block signals from HER1 dimers, a complete disappearance of nearly all xenograft tumors was observed; moreover, there was evidence of complete tumor eradication in 50% of the mice. The combination of lapatinib + trastuzumab was also highly effective in eradication of tumor burden, with no evidence of re-growth after 200 days. These xenograft models demonstrate that multi-drug HER2-targeted therapy more effectively induces apoptosis and inhibits proliferation, thereby resulting in tumor regression. Furthermore, HER2 combination therapy appears to more effectively reduce levels of phosphorylated pAKT and MAPK, thus resulting in sustained tumor inhibition.
Breast cancer cells have certain characteristics or traits--these traits are called biomarkers. There are three biomarkers that help doctors decide which treatment to give any given patient. These biomarkers are the estrogen receptor (ER), progesterone receptor (PgR), and HER2 protein. Breast cancer cells that have a large number of estrogen or progesterone receptors are called ER and/or PgR positive. Cancers that are ER and/or PgR positive use the hormones estrogen and progesterone to help them grow. Not all breast cancers are ER or PgR positive. Patients are being asked to take part in this study that have a special type of breast cancer called HER2 positive breast cancer. HER2-positive breast cancer is a breast cancer that tests positive for a protein called human epidermal growth factor receptor-2 (HER2). HER2 is located on the outer surface of a cancer cell. The HER2 protein sends a signal to the inside of the cancer cells telling it to grow and divide.
Two medications that directly target this HER2 protein. One is called trastuzumab(Herceptin), and the other is called lapatinib (Tykerb). Both medications are FDA-approved for the treatment of women with HER2+ breast cancer. Each medication attaches to the protein so that it can no longer function. Once the protein stops working, the cancer cells can no longer make copies of themselves. This makes cancer shrink. Both drugs target HER2; however each drug works a little bit differently.
Some patients respond better to Herceptin, and some patients respond better to Tykerb. Right now, we are not sure why some patients respond to one drug but do not respond to the other drug. One possibility is that in some patients, the HER2 protein finds another way to send its message to the inside of the cell (similar to a road detour). For example, when one path is "closed" because the drug is blocking it, the HER2 protein finds a different way to send its signal. We think that we can completely block the HER2 protein by giving patients both Tykerb and Herceptin.
Some patients with HER positive breast cancer are also ER and/or PgR positive. Even after HER2 is completely blocked, these types of cancer cells can still grow by using the estrogen or progesterone receptor. If a patient is told they are ER and/or PgR positive, they will also take an anti-estrogen pill along with Tykerb and Herceptin. We think that we can stop cancer growth more completely by blocking both the HER2 protein and the ER/PR receptors.
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.
Exclusion Criteria:
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.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
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.
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.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
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.
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.
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
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.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
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.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
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.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
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.
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.
Leptomeningeal disease
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
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.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
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.
Participants will receive 24-weeks of lapatinib plus trastuzumab. Participants who are estrogen receptor (ER) and/or progesterone receptor (PR) positive will also receive endocrine therapy.
Drug: Lapatinib · Drug: Letrozole · Drug: Trastuzumab
Participants will receive 12-weeks of lapatinib plus trastuzumab. Participants who are estrogen receptor (ER) and/or progesterone receptor (PR) positive will also receive endocrine therapy.
Drug: Lapatinib · Drug: Letrozole · Drug: Trastuzumab
1000 mg of Lapatinib by mouth daily
Also known as: TyKerb
Letrozole, 2.5 mg by mouth daily (for hormone receptor positive participants only)
Also known as: Femara
6 mg/kg intravenously, every 3 weeks
Also known as: Herceptin
Pathologic Complete Response
Pathologic complete response was defined as no residual invasive cancer in the breast, after 12 or 24 weeks of lapatinib/trastuzumab with or without endocrine therapy. This outcome is based on patient's pathological report. We are not measuring the clinical response. Participants who have received at least one cycle of therapy (defined as one dose of trastuzumab and 21 days of lapatinib), and have had their response classified were evaluable.
Time frame: 12 or 24 week depending the arm assignment
Number of Participants With Adverse Events
the safety and tolerability of an extended regimen of lapatinib + trastuzumab, with or without endocrine therapy
Time frame: 12 week or 24 weeks depending on arm assignment
Total Pathologic Complete Response
pathologic complete response was defined as no residual invasive cancer in the breast and the axillary lymph nodes.
Time frame: 12 weeks or 24 weeks depending on arm assignment
Clinical Response
Time frame: 12 weeks or 24 weeks depending on arm assignment
Participants were recruited between October 2011 and July 2014 at 10 study sites: Baylor College of Medicine, UAB, University of Chicago, Johns Hopkins, Duke, Indiana University, Vanderbilt, MDACC, DFCI, and Mayo Clinic.
| Milestone | 24-week Arm | 12-week Arm |
|---|---|---|
| Started | 85 | 43 |
| Completed | 64 | 38 |
| Not completed | 21 | 5 |
| Withdrew: Lack of efficacy | 9 | 2 |
| Withdrew: Adverse event | 4 | 3 |
| Withdrew: Withdrawal by subject | 4 | 0 |
| Withdrew: Death | 1 | 0 |
| Withdrew: Ineligible | 3 | 0 |
Pathologic complete response was defined as no residual invasive cancer in the breast, after 12 or 24 weeks of lapatinib/trastuzumab with or without endocrine therapy. This outcome is based on patient's pathological report. We are not measuring the clinical response. Participants who have received at least one cycle of therapy (defined as one dose of trastuzumab and 21 days of lapatinib), and have had their response classified were evaluable.
| participants | 24-week Arm | 12-week Arm |
|---|---|---|
| pathologic complete response | 20 | 5 |
| non-complete pathologic response | 61 | 38 |
the safety and tolerability of an extended regimen of lapatinib + trastuzumab, with or without endocrine therapy
| participants | 24-week Arm | 12-week Arm |
|---|---|---|
| Number of Participants With Adverse Events | 61 | 26 |
pathologic complete response was defined as no residual invasive cancer in the breast and the axillary lymph nodes.
| participants | 24-week Arm | 12-week Arm |
|---|---|---|
| total complete pathologic response | 8 | 2 |
| not total complete pathologic response | 72 | 41 |
| participants | 24-week Arm | 12-week Arm |
|---|---|---|
| Complete response | 46 | 21 |
| Partial response | 10 | 13 |
| Stable disease | 2 | 3 |
| Progressive disease | 13 | 4 |
| Unknown | 10 | 2 |
Collected over 7 months. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| 24-week Arm | — | 3/85 (3.5%) | 61/85 (71.8%) |
| 12-week Arm | — | 1/43 (2.3%) | 26/43 (60.5%) |
| Event | 24-week Arm | 12-week Arm |
|---|---|---|
| Acute kidney injuryRenal and urinary disorders | 0/85 | 1/43 |
| HematuriaRenal and urinary disorders | 0/85 | 1/43 |
| Renal calculiRenal and urinary disorders | 0/85 | 1/43 |
| Urinary retentionRenal and urinary disorders | 0/85 | 1/43 |
| Cardiac arrestCardiac disorders | 1/85 | 0/43 |
| Elevated ASTHepatobiliary disorders | 1/85 | 0/43 |
| Breast infectionInfections and infestations | 1/85 | 0/43 |
| Event | 24-week Arm | 12-week Arm |
|---|---|---|
| DiarrheaGastrointestinal disorders | 30/85 | 14/43 |
| Aspartate aminotransferase increasedInvestigations | 23/85 | 7/43 |
| Alanine aminotransferase increasedInvestigations | 22/85 | 5/43 |
| Mucositis oralGastrointestinal disorders | 9/85 | 10/43 |
| Rash acneiformSkin and subcutaneous tissue disorders | 17/85 | 5/43 |
| FatigueGeneral disorders | 14/85 | 8/43 |
| Alkaline phosphatase increasedInvestigations | 12/85 | 3/43 |
| NuseaGeneral disorders | 11/85 | 6/43 |
| AnemiaBlood and lymphatic system disorders | 8/85 | 4/43 |
| AnorexiaMetabolism and nutrition disorders | 8/85 | 3/43 |
| Age, Continuous(years) | 24-week Arm | 12-week Arm | Total |
|---|---|---|---|
| Median | 50 (23 to 80) | 57 (38 to 88) | 52 (23 to 88) |
| Sex: Female, Male(Participants) | 24-week Arm | 12-week Arm | Total |
|---|---|---|---|
| Female | 85 | 43 | 128 |
| Male | 0 | 0 | 0 |
| Ethnicity (NIH/OMB)(Participants) | 24-week Arm | 12-week Arm | Total |
|---|---|---|---|
| Hispanic or Latino | 15 | 9 | 24 |
| Not Hispanic or Latino | 69 | 33 | 102 |
| Unknown or Not Reported | 1 | 1 | 2 |
| Race (NIH/OMB)(Participants) | 24-week Arm | 12-week Arm | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 3 | 2 | 5 |
| Native Hawaiian or Other Pacific Islander | 1 | 0 | 1 |
| Black or African American | 11 | 10 | 21 |
| White | 68 | 31 | 99 |
| More than one race | 1 | 0 | 1 |
| Unknown or Not Reported | 1 | 0 | 1 |
Plan to share: No
This study is active, not recruiting, as verified in Feb 2025. You cannot join it, but the record below documents what was studied.
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Studies of the drugs tested here: Lapatinib · Trastuzumab
Baylor Breast Care Center