A Phase 3 interventional study of Biospecimen Collection and Brachytherapy in Endometrial Endometrioid Adenocarcinoma, Stage I Uterine Corpus Carcinoma or Carcinosarcoma AJCC v8 and Stage II Uterine Corpus Carcinoma or Carcinosarcoma AJCC v8, sponsored by National Cancer Institute (NCI). Active, not recruiting at 280 sites in 2 countries. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-02.
Sponsored by National Cancer Institute (NCI) · Phase 3, Interventional, and Treatment
This phase III trial compares whether the addition of pembrolizumab to radiation therapy is more effective than radiation therapy alone in reducing the risk of cancer coming back (recurrence) in patients with newly diagnosed stage I-II endometrial cancer. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Radiation therapy uses high energy x-rays to kill tumor cells and shrink tumors. The addition of pembrolizumab to radiation treatment may be more effective than radiation treatment alone in reducing cancer recurrence.
PRIMARY OBJECTIVE:
I. To compare the 3-year recurrence-free survival of women with high intermediate risk (HIR) stage I/II mismatch repair deficient (dMMR) endometrioid endometrial cancer treated with radiation and pembrolizumab (MK-3475) versus radiation alone.
SECONDARY OBJECTIVES:
I. To describe the safety and tolerability of concurrent pembrolizumab (MK-3475) and radiation compared to radiation alone in patients with MMR deficient high intermediate risk endometrial cancer (HIR EC).
II. To describe the recurrence patterns in each group. III. To measure recurrence free survival at 5 years in each group. IV. To estimate disease specific overall survival in each group. V. To determine whether the addition of pembrolizumab (MK-3475) to radiation, compared with radiation alone is associated with decreased quality of life at 6- and 24-weeks, as measured with the Functional Assessment of Cancer Therapy (FACT)-Endometrial (En) Trial Outcome Index (TOI), increased gastrointestinal (GI) symptoms as measured with the GI subscale, and increased fatigue as measured with the Patient Reported Outcomes Measurement Information System (PROMIS)-Fatigue scale (short form).
VI. To validate the Functional Assessment of Cancer Therapy-Immune Checkpoint Modulator (FACT-ICM) subscale, which assesses in cancer patients on immunotherapy.
VII. To evaluate the ability of ctDNA to predict outcomes in the experimental and control groups.
CORRELATIVE/TERTIARY OBJECTIVES:
I. To explore the baseline tumor genetic and microenvironment parameters predictive of clinical benefit or resistance to immunotherapy.
II. To determine whether the addition of pembrolizumab (MK-3475) to radiation, compared with radiation alone, is associated with decreased quality of life as measured with the Functional Assessment of Cancer Therapy-Immune Checkpoint Modulator (FACT-ICM subscale) and more self-reported bother from side effects as measured with a single item GP5 "I am bothered by side effects," a question from the FACT-En TOI.
OUTLINE: Patients are randomized to 1 of 2 arms.
ARM I: Patients undergo pelvic external beam radiation therapy (EBRT) daily for 5-6 weeks and vaginal brachytherapy completed within 7 days after completion of EBRT in the absence of disease progression or unacceptable toxicity.
ARM II: Patients undergo EBRT and brachytherapy as in Arm I. Within 7 days prior to the start of radiation therapy, patients also receive pembrolizumab intravenously (IV) over 30 minutes on day 1. Treatment with pembrolizumab repeats every 6 weeks for up to 1 year (9 cycles) in the absence of disease progression or unacceptable toxicity.
Patients in both arms also undergo collection of blood samples and computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, or x-ray imaging throughout the trial.
After completion of study treatment, patients are followed up every 3 months for 2 years and then every 6 months for 3 years.
60 studies on the registry are indexed under Carcinosarcoma; 12 are open to participants now.
This study's enrollment of 164 is above the median of 48 across 52 interventional studies indexed under Carcinosarcoma.
Browse Carcinosarcoma studies →National Cancer Institute (NCI) is the lead sponsor of 3,556 studies on the registry; 336 are open to participants now.
Of its 411 completed or terminated interventional studies of FDA-regulated products, 373 (91%) 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.
Patients must have:
Stage I endometrioid endometrial cancer and a combination of age and risk factors as listed below:
Age \< 50 and 3 risk factors
Risk factors:
Stage II endometrioid endometrial cancer
Exclusion Criteria:
Patients who have a diagnosis of immunodeficiency or are receiving systemic steroid therapy or any other form of therapy within 7 days prior to registration:
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.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
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.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
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 yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
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.
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.
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.
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.
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
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.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
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.
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.
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.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Absolute neutrophil count (ANC)
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
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.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
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.
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.
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.
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.
PD-1, PD-L1 and checkpoint inhibitors
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
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.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
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.
Patients undergo pelvic EBRT daily for 5-6 weeks and vaginal brachytherapy completed within 7 days after completion of EBRT in the absence of disease progression or unacceptable toxicity. Patients also undergo collection of blood samples and CT scans, MRI scans, or x-ray imaging throughout the trial.
Procedure: Biospecimen Collection · Radiation: Brachytherapy · Procedure: Computed Tomography · Radiation: External Beam Radiation Therapy · Procedure: Magnetic Resonance Imaging · Other: Quality-of-Life Assessment · Other: Questionnaire Administration · Procedure: X-Ray Imaging
Patients undergo EBRT and brachytherapy as in Arm I. Within 7 days prior to the start of radiation therapy, patients also receive pembrolizumab IV over 30 minutes on day 1. Treatment with pembrolizumab repeats every 6 weeks for up to 1 year (9 cycles) in the absence of disease progression or unacceptable toxicity. Patients also undergo collection of blood samples and CT scans, MRI scans, or x-ray imaging throughout the trial.
Procedure: Biospecimen Collection · Radiation: Brachytherapy · Procedure: Computed Tomography · Radiation: External Beam Radiation Therapy · Procedure: Magnetic Resonance Imaging · Biological: Pembrolizumab · Other: Quality-of-Life Assessment · Other: Questionnaire Administration · Procedure: X-Ray Imaging
Undergo collection of blood
Also known as: Biological Sample Collection, Biospecimen Collected, Sample Collection, Specimen Collection
Undergo vaginal brachytherapy
Also known as: Brachytherapy, NOS, Internal Radiation, Internal Radiation Brachytherapy, Internal Radiation Therapy, Radiation Brachytherapy, Radiation, Internal
Undergo CT
Also known as: CAT, CAT Scan, Computed Axial Tomography, Computerized Axial Tomography, Computerized axial tomography (procedure), Computerized Tomography, Computerized Tomography (CT) scan, CT, CT Scan, Diagnostic CAT Scan, Diagnostic CAT Scan Service Type, tomography
Undergo EBRT
Also known as: Definitive Radiation Therapy, EBRT, External Beam Radiation, External Beam Radiotherapy, External Beam Radiotherapy (conventional), External Beam RT, external radiation, External Radiation Therapy, external-beam radiation, Radiation, External Beam, Teleradiotherapy, Teletherapy, Teletherapy Radiation
Undergo MRI
Also known as: Magnetic Resonance, Magnetic Resonance Imaging (MRI), Magnetic resonance imaging (procedure), Magnetic Resonance Imaging Scan, Medical Imaging, Magnetic Resonance / Nuclear Magnetic Resonance, MR, MR Imaging, MRI, MRI Scan, MRIs, NMR Imaging, NMRI, Nuclear Magnetic Resonance Imaging, sMRI, Structural MRI
Given IV
Also known as: BCD-201, GME 751, GME751, Keytruda, Lambrolizumab, MK 3475, MK-3475, MK3475, Pembrolizumab Biosimilar BCD-201, Pembrolizumab Biosimilar GME751, Pembrolizumab Biosimilar QL2107, Pembrolizumab Biosimilar RPH-075, Pembrolizumab Biosimilar SB27, QL2107, RPH 075, RPH-075, RPH075, SB 27, SB-27, SB27, SCH 900475, SCH-900475, SCH900475
Ancillary studies
Also known as: Quality of Life Assessment
Ancillary studies
Undergo x-rays
Also known as: Conventional X-Ray, Diagnostic Radiology, Medical Imaging, X-Ray, Plain film radiographs, Radiographic Imaging, Radiographic imaging procedure (procedure), Radiography, RG, Static X-Ray, X-Ray
3 year recurrence-free survival
Patients with evidence of surviving recurrence-free for at least 3 years were classified as treatment successes. Patients who withdrew before 3 years or had a recurrence or death within 3 years were classified as treatment failures.
Time frame: Time from study entry (randomization) to the time of withdrawal, death, or cancer recurrence, assessed at 3 years
Incidence of adverse events
Will be assessed by Common Terminology Criteria for Adverse Events (CTCAE) by treatment regimen. Will be evaluated descriptively using frequencies and percentages and will be reported using tables. Differences between treatment arms will be assessed through absolute deviations and contingency table analyses. All patients who receive treatment, will be evaluated for toxicity. Toxicities by type and maximum grade over the course of treatment and follow up will be summarized and by date of occurrence (acute toxicity and late adverse effects).
Time frame: 12 months
Recurrence patterns
The cumulative incidences of vaginal recurrence, pelvic recurrence, retroperitoneal, and distant recurrence from endometrial cancer will be estimated within treatment regimen. Treatments will be compared graphically using Kaplan-Meier estimates of the survival function.
Time frame: 5 years
5 year recurrence free survival
Proportions will be compared by treatment using Fisher's exact test. This analysis may be delayed until the data are mature.
Time frame: Time from study entry (randomization) to the time of cancer recurrence, assessed at 5 years
Overall survival
Will be estimated using the Kaplan Meier method and treatment comparisons will be made using a stratified log-rank test.
Time frame: Duration of time from study entry to time of death or the date of last contact, assessed up to 5 years
Patient-reported outcomes
Will be assessed by questionnaire.
Time frame: Up to 2 years after starting treatment
Impact of circulating tumor deoxyribonucleic acid (ctDNA) on treatment outcomes
Will examine the association between ctDNA and 2- year (or 3-year) progression free survival in a 2-stages of analysis.
Time frame: Up to 5 years
Potential transformations of the severity of adverse events
An example of potential transformation of the severity of adverse events is whether or not the patient experienced \>= grade 3 events. It will be assessed by CTCAE and treatment regimen.
Time frame: 12 months
Biomarker analysis
Will assess baseline genetic characteristics (e.g. mutations) and microenvironment parameters, treatment, and interactions between treatment and biomarkers in a Cox regression.
Time frame: Baseline
Functional Assessment of Cancer Therapy (FACT)-Immune Checkpoint Modulator (ICM) subscale
Treatment differences in the FACT-ICM subscale and self-reported bother from side effects will be explored using a linear mixed model for repeated measures, adjusted for the baseline score.
Time frame: Up to 2 years after starting treatment
Showing the first 100 of 280 sites across 2 countries. Choose a country and city above to see the rest.
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes — NCI is committed to sharing data in accordance with NIH policy. For more details on how clinical trial data is shared, access the link to the NIH data sharing policy page.
Data sharing details ↗ · grants.nih.gov
Ran from Apr 2020 to primary completion in Dec 2025, 68 months.
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This study is active, not recruiting, as verified in Feb 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Pembrolizumab
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