A Phase 2 interventional study of U3-1402 in Metastatic Breast Cancer and Locally Advanced Breast Cancer, sponsored by SCRI Development Innovations, LLC. Completed at 11 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-22.
Sponsored by SCRI Development Innovations, LLC · Phase 2, Interventional, and Treatment
This study is to evaluate safety and efficacy of an antibody drug conjugate U3-1402 (patritumab deruxtecan) in patients with locally advanced or metastatic breast cancer (MBC).
U3-1402 (Patritumab Deruxtecan) is an antibody drug conjugate comprising a recombinant fully human anti HER3 monoclonal antibody linked to a linker containing topoisomerase I inhibitor. This is a phase II study of U3-1402 (patritumab deruxtecan) in subjects with MBC. The study will be conducted in 3 parts (Part A , Part B, and Part Z). All enrolled subjects in Part A will undergo pretreatment biopsies to determine if subjects with particular biomarker expression (ER/PR/HER2/HER3) show preliminary efficacy. Part B will enroll subgroups of participants that are metastatic, hormone receptor-positive (HR+) HER2-negative or triple-negative (mTNBC) regardless of HER3 expression that were defined from Part A analysis. Part Z will enroll participants with HER2- positive (HER2+) MBC.
14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.
This study's enrollment of 121 is above the median of 72 across 10,896 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →SCRI Development Innovations, LLC is the lead sponsor of 179 studies on the registry; 5 are open to participants now.
Of its 15 completed or terminated interventional studies of FDA-regulated products, 15 (100%) have results posted.
Counted across the registry records on this site, refreshed daily.
Eligibility Criteria:
Inclusion criteria for Part A and B (-negative) and Part Z (HER2-positive) cohorts:
Has adequate organ function within 7 days before the start of study treatment, defined as:
Exclusion Criteria
Patients who meet any of the following criteria will be excluded from study entry:
Exclusion criteria for Parts A and B (HER2-negative) and Part Z (HER2-positive) cohorts:
Treatment with any of the following:
Clinically severe pulmonary compromise (based on Investigator's assessment) resulting from intercurrent pulmonary illnesses including, but not limited to:
OR prior pneumonectomy
Uncontrolled or significant cardiovascular disorder prior to Cycle 1 Day 1, including:
Psychological, familial, sociological, or geographical conditions that do not permit compliance with the protocol and/or follow-up procedures outlined in the protocol
Additional exclusion criteria only for Parts A and B (HER2-negative) cohorts:
Part B patients only: Prior treatment with trastuzumab deruxtecan, sacituzumab govitecan, and/or datopotamab deruxtecan with any of the following:
Additional exclusion criteria only for Part Z (HER2-positive) cohort:
Treatment with any of the following:
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.
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.
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.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
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.
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
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 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.
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 protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
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.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
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.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
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.
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.
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.
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.
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.
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.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
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.
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
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.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
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.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
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.
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.
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.
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.
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.
Line of therapy
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
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.
Brain metastases
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
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.
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.
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.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
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.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
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.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
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.
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.
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.
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.
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.
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.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
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.
CTCAE grade
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
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.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
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.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
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.
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 5.6 mg/kg U3-1402 (Patritumab Deruxtecan) intravenously on day 1 every 3 weeks. All participants will undergo pre-treatment biopsies. (An archival tissue sample taken within two months of treatment should be provided if it is not medically feasible to provide a pre-treatment biopsy). Up to 60 HER2-negative participants will be enrolled into this arm.
Drug: U3-1402
Participants will receive 5.6 mg/kg U3-1402 intravenously on day 1 every 3 weeks. Part B will enroll 20 participants with metastatic hormone-receptor positive (HR+) HER2-negative cancer and 20 participants with metastatic triple-negative breast cancer (mTNBC), regardless of HER3 expression.
Drug: U3-1402
Participants will receive 5.6 mg/kg U3-1402 (Patritumab Deruxtecan) intravenously on day 1 every 3 weeks. Part Z will enroll an additional 21 participants with HER2+ MBC.
Drug: U3-1402
All subjects will receive 5.6 mg/kg U3-1402 (Patritumab Deruxtecan) intravenously on day 1 of every 3 weeks. One cycle is defined as 3 weeks.
Also known as: Patritumab Deruxtecan
Overall Response Rate (ORR) in Participants With HER2-negative MBC (Part A and Part B)
Overall Response Rate (ORR) is defined as the percentage of participants with confirmed complete response (CR) or partial response (PR) out of all treated participants. Confirmed response is two consecutive CR or PR at least 4 weeks apart according to RECIST v1.1 criteria. CR=disappearance of all target and non-target lesions. PR=at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of lesion diameters.
Time frame: Assessed every 6 weeks for the first 6 months then every 9 weeks thereafter until disease progression or death or study discontinuation, up to 45 months.
Progression-Free Survival at 6 Months (PFS-6) in Participants With HER2-negative MBC (Part A and Part B)
Progression-Free Survival at 6 months (PFS-6) is defined as the rate of patients who survive progression-free for at least 6 months per RECIST version (v) 1.1. Per RECIST V1.1, progressive disease is defined as a ≥20% increase in target lesions and ≥5mm increase in size from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions.
Time frame: Assessed every 6 weeks for the first 6 months then every 9 weeks thereafter until disease progression or death or study discontinuation, up to 45 months.
Incidence of Treatment- Emergent Adverse Events to Assess Safety and Tolerability
The safety and tolerability of U3-1402 (Patritumab Deruxtecan) was assessed through the analysis of the reported incidence of treatment-emergent AEs. Treatment-emergent AEs are those with an onset on or after the initiation of study therapy up to 40 days after last day of treatment, and will be graded according to NCI CTCAE 5.0.
Time frame: Every 3 weeks, up to 45 months.
Duration of Response (DOR)
Duration of response (DOR) is calculated only for participants who experienced a Complete Response (CR) or Partial Response (PR) per RECIST V1.1 and is defined as the median number of months of duration from the first documented response \[complete response (CR) or partial response (PR)\] to the date of disease progression (PD) according to the RECIST V1.1 criteria or death due to any cause. Per RECIST V1.1, CR=disappearance of all target lesions, PR=at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of target lesion diameters, PD is ≥20% increase in target lesions and ≥5mm from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions. Kaplan-Meier estimates were used to calculate the 95% confidence intervals for duration of response.
Time frame: Assessed every 6 weeks for the first 6 months then every 9 weeks thereafter until disease progression or death or study discontinuation, up to 45 months.
Progression-Free Survival (PFS)
Progression Free Survival (PFS) is defined as the time from start of study treatment to the date of the first documented disease progression (PD) according to the RECIST V1.1 criteria or death due to any cause. Per RECIST V1.1, PD is ≥20% increase in target lesions and ≥5mm increase from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions.
Time frame: Assessed every 6 weeks for the first 6 months then every 9 weeks thereafter until disease progression or death or study discontinuation, up to 45 months.
Clinical Benefit Rate (CBR)
CBR is defined as the rate of participants with complete response (CR), partial response (PR), or best overall response of stable disease (SD) for ≥ 6 months according to the RECIST v 1.1 criteria. Per RECIST V1.1: A CR is defined as the disappearance of all target and non-target lesions. A PR is defined as ≥30% decrease in the sum of diameters of target lesions from the baseline sum. A SD is defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease (PD).
Time frame: Assessed every 6 weeks for the first 6 months then every 9 weeks thereafter until disease progression or death or study discontinuation, up to 45 months.
Overall Response Rate (ORR) in Participants With HER2-positive (HER2+) MBC After Progression on Trastuzumab Deruxtecan: Part Z
Overall Response Rate (ORR) is defined as the percentage of participants with confirmed complete response (CR) or partial response (PR) out of all treated participants. Confirmed response is two consecutive CR or PR at least 4 weeks apart according to RECIST v1.1 criteria. CR=disappearance of all target and non-target lesions. PR=at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of lesion diameters.
Time frame: Assessed every 6 weeks for the first 6 months then every 9 weeks thereafter until disease progression or death or study discontinuation, up to 45 months.
Progression-Free Survival at 6 Months (PFS-6) in Participants With HER2-positive (HER2+) MBC: Part Z
Progression-Free Survival at 6 months (PFS-6) is defined as the rate of patients who survive progression-free for at least 6 months per RECIST version (v) 1.1. Per RECIST V1.1, progressive disease is defined as a ≥20% increase in target lesions and ≥5mm increase in size from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions.
Time frame: Assessed every 6 weeks for the first 6 months then every 9 weeks thereafter until disease progression or death or study discontinuation, up to 45 months.
| Milestone | Part A | Part B | Part Z |
|---|---|---|---|
| Started | 60 | 40 | 21 |
| Completed | 0 | 0 | 0 |
| Not completed | 60 | 40 | 21 |
| Withdrew: Disease progression by recist v1.1 | 38 | 28 | 18 |
| Withdrew: Clinical progression/symptomatic deterioration | 5 | 3 | 2 |
| Withdrew: Adverse event | 13 | 2 | 0 |
| Withdrew: Withdrawal by subject | 3 | 4 | 0 |
| Withdrew: Non-compliance to protocol | 0 | 0 | 1 |
| Withdrew: Physician decision | 1 | 3 | 0 |
Overall Response Rate (ORR) is defined as the percentage of participants with confirmed complete response (CR) or partial response (PR) out of all treated participants. Confirmed response is two consecutive CR or PR at least 4 weeks apart according to RECIST v1.1 criteria. CR=disappearance of all target and non-target lesions. PR=at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of lesion diameters.
| percentage of participants | Part A | Part B |
|---|---|---|
| Overall Response Rate (ORR) in Participants With HER2-negative MBC (Part A and Part B) | 35 (23.1 to 48.4) | 5 (0.6 to 16.9) |
Progression-Free Survival at 6 months (PFS-6) is defined as the rate of patients who survive progression-free for at least 6 months per RECIST version (v) 1.1. Per RECIST V1.1, progressive disease is defined as a ≥20% increase in target lesions and ≥5mm increase in size from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions.
| percentage of participants | Part A | Part B |
|---|---|---|
| Progression-Free Survival at 6 Months (PFS-6) in Participants With HER2-negative MBC (Part A and Part B) | 43.3 (30.6 to 56.8) | 10.0 (2.8 to 23.7) |
The safety and tolerability of U3-1402 (Patritumab Deruxtecan) was assessed through the analysis of the reported incidence of treatment-emergent AEs. Treatment-emergent AEs are those with an onset on or after the initiation of study therapy up to 40 days after last day of treatment, and will be graded according to NCI CTCAE 5.0.
| Participants | Part A | Part B | Part Z |
|---|---|---|---|
| Incidence of Treatment- Emergent Adverse Events to Assess Safety and Tolerability | 60 | 39 | 21 |
Duration of response (DOR) is calculated only for participants who experienced a Complete Response (CR) or Partial Response (PR) per RECIST V1.1 and is defined as the median number of months of duration from the first documented response \[complete response (CR) or partial response (PR)\] to the date of disease progression (PD) according to the RECIST V1.1 criteria or death due to any cause. Per RECIST V1.1, CR=disappearance of all target lesions, PR=at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of target lesion diameters, PD is ≥20% increase in target lesions and ≥5mm from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions. Kaplan-Meier estimates were used to calculate the 95% confidence intervals for duration of response.
| months | Part A | Part B | Part Z |
|---|---|---|---|
| Duration of Response (DOR) | 7.5 (5.4 to 10.3) | 3.6 (2.8 to NA) | 4.3 (NA to NA) |
Progression Free Survival (PFS) is defined as the time from start of study treatment to the date of the first documented disease progression (PD) according to the RECIST V1.1 criteria or death due to any cause. Per RECIST V1.1, PD is ≥20% increase in target lesions and ≥5mm increase from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions.
| months | Part A | Part B | Part Z |
|---|---|---|---|
| Progression-Free Survival (PFS) | 7.2 (4.0 to 10.2) | 2.6 (1.4 to 3.7) | 1.4 (1.3 to 3.1) |
CBR is defined as the rate of participants with complete response (CR), partial response (PR), or best overall response of stable disease (SD) for ≥ 6 months according to the RECIST v 1.1 criteria. Per RECIST V1.1: A CR is defined as the disappearance of all target and non-target lesions. A PR is defined as ≥30% decrease in the sum of diameters of target lesions from the baseline sum. A SD is defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease (PD).
| percentage of participants | Part A | Part B | Part Z |
|---|---|---|---|
| Clinical Benefit Rate (CBR) | 48.3 (35.2 to 61.6) | 5.0 (0.6 to 16.9) | 4.8 (0.1 to 23.8) |
Overall Response Rate (ORR) is defined as the percentage of participants with confirmed complete response (CR) or partial response (PR) out of all treated participants. Confirmed response is two consecutive CR or PR at least 4 weeks apart according to RECIST v1.1 criteria. CR=disappearance of all target and non-target lesions. PR=at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum of lesion diameters.
| percentage of participants | Part Z |
|---|---|
| Overall Response Rate (ORR) in Participants With HER2-positive (HER2+) MBC After Progression on Trastuzumab Deruxtecan: Part Z | 4.8 (0.1 to 23.8) |
Progression-Free Survival at 6 months (PFS-6) is defined as the rate of patients who survive progression-free for at least 6 months per RECIST version (v) 1.1. Per RECIST V1.1, progressive disease is defined as a ≥20% increase in target lesions and ≥5mm increase in size from smallest sum, appearance of any new lesions, or unequivocal progression of non-target lesions.
| percentage of participants | Part Z |
|---|---|
| Progression-Free Survival at 6 Months (PFS-6) in Participants With HER2-positive (HER2+) MBC: Part Z | 0 (0.0 to 16.1) |
Collected over Serious and/or other adverse events were assessed from the date of first dose to 40 days after last dose of study treatment, up to 45 months. All-Cause Mortality was monitored from date of consent up until progression of disease or death, up to 45 months.. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Part A | 7/60 (11.7%) | 12/60 (20%) | 60/60 (100%) |
| Part B | 4/40 (10%) | 7/40 (17.5%) | 39/40 (97.5%) |
| Part Z | 3/21 (14.3%) | 5/21 (23.8%) | 21/21 (100%) |
| Event | Part A | Part B | Part Z |
|---|---|---|---|
| NeutropeniaBlood and lymphatic system disorders | 0/60 | 0/40 | 1/21 |
| NauseaGastrointestinal disorders | 1/60 | 0/40 | 1/21 |
| VomitingGastrointestinal disorders | 1/60 | 1/40 | 1/21 |
| Procedural haemorrhageInjury, poisoning and procedural complications | 0/60 | 0/40 | 1/21 |
| Brain oedemaNervous system disorders | 0/60 | 0/40 | 1/21 |
| DyspnoeaRespiratory, thoracic and mediastinal disorders | 1/60 | 0/40 | 1/21 |
| PneumonitisRespiratory, thoracic and mediastinal disorders | 2/60 | 0/40 | 0/21 |
| Febrile neutropeniaBlood and lymphatic system disorders | 1/60 | 1/40 | 0/21 |
| Abdominal painGastrointestinal disorders | 0/60 | 1/40 | 0/21 |
| AscitesGastrointestinal disorders | 0/60 | 1/40 | 0/21 |
| Event | Part A | Part B | Part Z |
|---|---|---|---|
| NauseaGastrointestinal disorders | 33/60 | 17/40 | 11/21 |
| FatigueGeneral disorders and administration site conditions | 29/60 | 15/40 | 5/21 |
| DiarrhoeaGastrointestinal disorders | 26/60 | 9/40 | 7/21 |
| VomitingGastrointestinal disorders | 21/60 | 11/40 | 4/21 |
| AlopeciaSkin and subcutaneous tissue disorders | 21/60 | 2/40 | 1/21 |
| AnaemiaBlood and lymphatic system disorders | 20/60 | 8/40 | 4/21 |
| Neutrophil count decreasedInvestigations | 13/60 | 13/40 | 7/21 |
| HypokalaemiaMetabolism and nutrition disorders | 19/60 | 8/40 | 5/21 |
| White blood cell count decreasedInvestigations | 8/60 | 12/40 | 4/21 |
| ConstipationGastrointestinal disorders | 15/60 | 7/40 | 5/21 |
| Age, Continuous(Years) | Part A | Part B | Part Z | Total |
|---|---|---|---|---|
| Median | 58 (32 to 80) | 57 (29 to 78) | 56 (36 to 81) | 57 (29 to 81) |
| Sex: Female, Male(Participants) | Part A | Part B | Part Z | Total |
|---|---|---|---|---|
| Female | 59 | 40 | 21 | 120 |
| Male | 1 | 0 | 0 | 1 |
| Race (NIH/OMB)(Participants) | Part A | Part B | Part Z | Total |
|---|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 | 0 |
| Asian | 6 | 3 | 2 | 11 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 | 0 |
| Black or African American | 6 | 4 | 4 | 14 |
| White | 46 | 31 | 14 | 91 |
| More than one race | 0 | 0 | 0 | 0 |
| Unknown or Not Reported | 2 | 2 | 1 | 5 |
| Region of Enrollment(Participants) | Part A | Part B | Part Z | Total |
|---|---|---|---|---|
| United States | 60 | 40 | 21 | 121 |
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Studies of the drug tested here: Patritumab deruxtecan
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