A Phase 3 interventional study of BNT323/DB-1303 and Doxorubicin in Endometrial Cancer, sponsored by BioNTech SE. Recruiting at 214 sites in 27 countries. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by BioNTech SE · Phase 3, Interventional, and Treatment
The study is divided into two cohorts (Cohort 1 and Cohort 2), to which participants will be enrolled based on the amount of human epidermal growth factor receptor 2 (HER2) in their tumor sample.
In Cohort 1, the main goal is to assess how well BNT323 (also known as DB-1303) or chemotherapy (doxorubicin or paclitaxel [or docetaxel, if participants cannot take paclitaxel]) works by determining the progression-free survival (PFS) of participants who have been previously treated with immune checkpoint inhibitors (ICIs).
In Cohort 2, the main goal is to assess how well BNT323 works by determining the objective response rate (ORR), that is, the percentage of participants whose tumor shrinks (partial response) or disappears (complete response) after treatment.
The safety of BNT323 will also be assessed by following the occurrence of unfavorable/adverse effects that are seen after treatment. Other measures include the pharmacokinetics of BNT323 (or how BNT323 moves through and out of the body), the body's immune response, and the impact on quality of life.
This is an open-label, randomized, multi-site, Phase III, interventional clinical study designed to determine the efficacy and safety of BNT323 compared with investigator's choice of single agent chemotherapy in previously treated participants with recurrent endometrial cancer (including HER2 1+ or 2+ score as determined using a centralized immunohistochemistry [IHC] analysis method), whose disease has progressed on at least one line of platinum-based therapy and ICI (Cohort 1). In addition, participants with recurrent endometrial cancer with HER2 IHC 3+ score will be enrolled in a BNT323 monotherapy arm (Cohort 2) to further investigate the efficacy and safety of BNT323.
In Cohort 1, participants will be randomized 2:1 to receive either BNT323/DB-1303 or investigator's choice of single agent chemotherapy, preferably doxorubicin or paclitaxel (or docetaxel if contraindicated to paclitaxel and available at the site) until Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) defined progressive disease (PD) unless there is unacceptable toxicity, withdrawal of consent, or another criterion for discontinuation is met.
In Cohort 2, participants will receive BNT323 monotherapy until RECIST v1.1 defined PD unless there is unacceptable toxicity, withdrawal of consent, or another criterion for discontinuation is met.
The study consists of a screening period, a treatment period, a safety follow-up period, an efficacy follow-up period, and a long-term survival follow-up. The expected treatment duration per participant is \~6 months, followed by an anticipated long-term survival follow-up period of up to 53 months.
1,425 studies on the registry are indexed under Endometrial Neoplasms; 473 are open to participants now.
This study's planned enrollment of 480 is above the median of 71 across 1,026 interventional studies indexed under Endometrial Neoplasms.
Browse Endometrial Neoplasms studies →BioNTech SE is the lead sponsor of 76 studies on the registry; 25 are open to participants now.
Of its 33 completed or terminated interventional studies of FDA-regulated products, 26 (79%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Have confirmed endometrial cancer that:
Have recurrent endometrial cancer and meet any of the following:
Key Exclusion Criteria:
NOTE: Other protocol defined Inclusion/Exclusion criteria apply.
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.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
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.
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.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
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.
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.
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.
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.
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.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
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.
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.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
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.
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.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
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.
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.
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.
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.
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.
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.
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.
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.
Drug: BNT323/DB-1303
Single agent chemotherapy (either doxorubicin or paclitaxel) per investigator's choice. Participants with contraindications to paclitaxel may receive docetaxel as an alternative (if available at the site).
Drug: Doxorubicin · Drug: Paclitaxel · Drug: Docetaxel
Drug: BNT323/DB-1303
Drug page: Trastuzumab pamirtecan
intravenous (IV) infusion
Also known as: trastuzumab pamirtecan
IV bolus or infusion
IV infusion
IV infusion
Cohort 1: PFS assessed by blinded independent central review (BICR) in participants with HER2 IHC 1+/2+ recurrent endometrial cancer
By treatment arm. Defined as the time from randomization to the first objective tumor progression (per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 2: ORR assessed by BICR in participants with HER2 IHC 3+ recurrent endometrial cancer
Defined as the proportion of participants with a CR or PR (per RECIST v1.1) as best overall response with confirmation.
Time frame: Up to approximately 53 months
Cohort 1: Overall survival (OS) in participants with HER2 IHC 1+/2+ recurrent endometrial cancer
By treatment arm. Defined as the time from randomization to death from any cause.
Time frame: Up to approximately 53 months
Cohort 1: PFS assessed by the investigator in participants with HER2 IHC 1+/2+ recurrent endometrial cancer
By treatment arm. Defined as the time from randomization to the first objective tumor progression (per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 1: ORR assessed by BICR in participants with HER2 IHC 1+/2+ recurrent endometrial cancer
By treatment arm. Defined as the proportion of participants with a CR or PR (per RECIST v1.1) as best overall response with confirmation.
Time frame: Up to approximately 53 months
Cohort 1: ORR assessed by the investigator in participants with HER2 IHC 1+/2+ recurrent endometrial cancer
By treatment arm. Defined as the proportion of participants with a CR or PR (per RECIST v1.1) as best overall response with confirmation.
Time frame: Up to approximately 53 months
Cohort 1: Duration of response (DoR) assessed by BICR in participants with HER2 IHC 1+/2+ recurrent endometrial cancer
By treatment arm. Defined as the time from first objective response (CR or PR per RECIST v1.1) to first occurrence of objective tumor progression (PD per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 1: DoR assessed by the investigator in participants with HER2 IHC 1+/2+ recurrent endometrial cancer
By treatment arm. Defined as the time from first objective response (CR or PR per RECIST v1.1) to first occurrence of objective tumor progression (PD per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 1: Percentage of participants with HER2 IHC 1+/2+ recurrent endometrial cancer with occurrence of treatment-emergent adverse events (TEAEs)
By treatment arm. TEAEs including Grade ≥3, serious, and fatal TEAEs by relationship.
Time frame: Up to 35 days after the last dose of study treatment
Cohort 1: Percentage of participants with HER2 IHC 1+/2+ recurrent endometrial cancer with occurrence of TEAEs leading to drug interruption, dose reduction, or discontinuation of study treatment.
By treatment arm.
Time frame: Up to 35 days after the last dose of study treatment
Cohort 2: ORR assessed by the investigator participants with HER2 IHC 3+ recurrent endometrial cancer
Defined as the proportion of participants in whom a CR or PR (per RECIST v1.1) is observed as best overall response with confirmation.
Time frame: Up to approximately 53 months
Cohort 2: DoR assessed by BICR in participants with HER2 IHC 3+ recurrent endometrial cancer
Defined as the time from first objective response (CR or PR per RECIST v1.1) to first occurrence of objective tumor progression (PD per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 2: DoR assessed by the investigator in participants with HER2 IHC 3+ recurrent endometrial cancer
Defined as the time from first objective response (CR or PR per RECIST v1.1) to first occurrence of objective tumor progression (PD per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 2: PFS assessed by BICR in participants with HER2 IHC 3+ recurrent endometrial cancer
Defined as the time from the first dose of study treatment to the first objective tumor progression (per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 2: PFS assessed by the investigator in participants with HER2 IHC 3+ recurrent endometrial cancer
Defined as the time from the first dose of study treatment to the first objective tumor progression (per RECIST v1.1) or death from any cause, whichever occurs first.
Time frame: Up to approximately 53 months
Cohort 2: OS in participants with HER2 IHC 3+ recurrent endometrial cancer
Defined as the time from the first dose of trial treatment to death from any cause.
Time frame: Up to approximately 53 months
Cohort 2: Percentage of participants with HER2 IHC 3+ recurrent endometrial cancer with occurrence of TEAEs
BNT323 monotherapy. TEAEs including Grade ≥3, serious, and fatal TEAEs by relationship.
Time frame: Up to 35 days after the last dose of study treatment
Cohort 2: Percentage of participants with HER2 IHC 3+ recurrent endometrial cancer with occurrence of TEAEs leading to drug interruption, dose reduction, or discontinuation of study treatment.
Time frame: Up to 35 days after the last dose of study treatment
Showing the first 100 of 214 sites across 27 countries. Choose a country and city above to see the rest.
Plan to share: No
Started Jun 2025 (actual). Primary completion is estimated for Mar 2028, 33 months after the start.
Of 44 phase 3 interventional studies under Endometrial Neoplasms, half reached primary completion within 53 months of starting (the median), counting those still running; a quarter within 45 and three quarters within 126. This study's planned 33 months is below that.
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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Studies of the drug tested here: Trastuzumab pamirtecan