Malignant Neoplasm of Breast
Conditions
Keywords
HER2, Breast cancer, Oncology, Antibody drug conjugate, ADC
Brief summary
This study will look at the effect on the QTc interval and pharmacokinetics after multiple dosing in subjects with HER2-expressing metastatic and/or unresectable breast cancer.
Interventions
DRUGDS-8201a
DS-8201a is supplied as a lyophilized powder which is reconstituted for infusion
Sponsors
AstraZeneca
Daiichi Sankyo Co., Ltd.
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
20 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Has a pathologically documented unresectable or metastatic breast cancer with HER2 expression (immunohistochemistry \[IHC\] 3+, IHC 2+, IHC 1+ and/or in situ hybridization \[ISH\] +) that is refractory to or intolerable with standard treatment, or for which no standard treatment is available * Has a left ventricular ejection fraction (LVEF) ≥ 50% * Has an Eastern Cooperative Oncology Group performance status (ECOG PS) score of 0 or 1
Exclusion criteria
* Has a medical history of myocardial infarction within 6 months before enrollment * Has a medical history of ventricular arrhythmias, other than rare occasional premature ventricular contractions * Has uncontrolled or significant cardiovascular disease
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days) | Maximum serum concentration (Cmax) of DS-8201a and total anti-HER2 antibody was assessed. |
| Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days) | Area under the concentration versus-time curve from time 0 to the last quantifiable concentration (AUClast) and during the dosing interval (AUCtau) of DS-8201a and total anti-HER2 antibody were assessed. |
| Pharmacokinetic Parameters Area Under the Concentration-Time Curve of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days) | Area under the concentration versus-time curve from time 0 to the last quantifiable concentration (AUClast) and during the dosing interval (AUCtau) were assessed. |
| Changes in QTcF After Treatment With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Screening (within 7 days before enrollment) up to Cycle 3 Day 15 (each cycle is 21 days) | The number of participants with notable electrocardiogram changes meeting predefined criteria is being reported. |
| Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days) | Maximum serum concentration (Cmax) of MAAA-1181 was assessed. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever occurs first), up to approximately 12 months post-dose | Adverse events (AEs) were to be coded using MedDRA Version 20.1 and assigned severity grades based on Common Terminology Criteria for Adverse Events (CTCAE) Version 4.03. A treatment-emergent adverse event (TEAE) was defined as an AE that occurred, having been absent before the first dose of study drug, or had worsened in severity or seriousness after initiating the study drug until 47 days after last dose of study drug. |
| Objective Response Rate Based on The Investigator's Assessment (Unconfirmed) Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever occurs first), up to 12 months post-dose | Objective response rate (ORR) was defined as unconfirmed complete response (CR) and partial response (PR) as assessed by the investigator based on Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1. CR was defined as a disappearance of all target lesions and PR was defined as at least a 30% decrease in the sum of diameters of target lesions. |
Countries
Japan
Participant flow
Recruitment details
A total of 51 participants who met all inclusion criteria and no exclusion criteria were enrolled and treated at 7 sites in Japan.
Pre-assignment details
The 6.4 mg/kg DS-8201a dose was chosen for this study based on the efficacy, safety, and pharmacokinetic profiles established in an earlier Phase 1 trial.
Participants by arm
| Arm | Count |
|---|---|
| DS-8201a Participants who received 6.4 mg/kg of DS-8201a as an intravenous (IV) infusion once every 3 weeks on Day 1 of each 21-day cycle. | 51 |
| Total | 51 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | Adverse Event | 12 |
| Overall Study | Clinical progression | 2 |
| Overall Study | Progressive disease per RECIST v1.1 | 33 |
| Overall Study | Withdrawal by Subject | 4 |
Baseline characteristics
| Characteristic | DS-8201a |
|---|---|
| Age, Continuous | 55.9 years STANDARD_DEVIATION 10.48 |
| Age, Customized <65 | 38 Participants |
| Age, Customized ≥65 | 13 Participants |
| Age, Customized >75 | 1 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 51 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 0 Participants |
| Region of Enrollment Japan | 51 participants |
| Sex: Female, Male Female | 51 Participants |
| Sex: Female, Male Male | 0 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 51 |
| other Total, other adverse events | 51 / 51 |
| serious Total, serious adverse events | 9 / 51 |
Outcome results
Primary
Changes in QTcF After Treatment With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
The number of participants with notable electrocardiogram changes meeting predefined criteria is being reported.
Time frame: Screening (within 7 days before enrollment) up to Cycle 3 Day 15 (each cycle is 21 days)
Population: QTc and QTcF were assessed in the Cardiac Analysis Set.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| DS-8201a | Changes in QTcF After Treatment With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Maximum change from baseline in QTcF: >30 ms | 3 Participants |
| DS-8201a | Changes in QTcF After Treatment With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Maximum change from baseline in QTcF: >60 ms | 0 Participants |
Primary
Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
Area under the concentration versus-time curve from time 0 to the last quantifiable concentration (AUClast) and during the dosing interval (AUCtau) of DS-8201a and total anti-HER2 antibody were assessed.
Time frame: Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days)
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUClast, DS-8201: Cycle 1 | 677 ug*d/mL | Standard Deviation 143 |
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUClast, Total Anti-HER2 antibody: Cycle 1 | 753 ug*d/mL | Standard Deviation 190 |
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUCtau, DS-8201: Cycle 1 | 677 ug*d/mL | Standard Deviation 141 |
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUCtau, DS-8201: Cycle 3 | 905 ug*d/mL | Standard Deviation 189 |
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUCtau, Total Anti-HER2 antibody: Cycle 1 | 752 ug*d/mL | Standard Deviation 185 |
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUCtau, Total Anti-HER2 antibody: Cycle 3 | 1030 ug*d/mL | Standard Deviation 256 |
Primary
Pharmacokinetic Parameters Area Under the Concentration-Time Curve of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
Area under the concentration versus-time curve from time 0 to the last quantifiable concentration (AUClast) and during the dosing interval (AUCtau) were assessed.
Time frame: Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days)
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUClast, MAAA-1181a: Cycle 1 | 39.3 ng*d/mL | Standard Deviation 11.3 |
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUCtau, MAAA-1181a: Cycle 1 | 39.0 ng*d/mL | Standard Deviation 11.2 |
| DS-8201a | Pharmacokinetic Parameters Area Under the Concentration-Time Curve of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | AUCtau, MAAA-1181a: Cycle 3 | 41.5 ng*d/mL | Standard Deviation 13.8 |
Primary
Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
Maximum serum concentration (Cmax) of DS-8201a and total anti-HER2 antibody was assessed.
Time frame: Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days)
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | DS-8201: Cycle 1 | 179 ug/mL | Standard Deviation 112 |
| DS-8201a | Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | DS-8201: Cycle 3 | 154 ug/mL | Standard Deviation 23.3 |
| DS-8201a | Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Total Anti-HER2 antibody: Cycle 1 | 165 ug/mL | Standard Deviation 110 |
| DS-8201a | Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Total Anti-HER2 antibody: Cycle 3 | 142 ug/mL | Standard Deviation 27 |
Primary
Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
Maximum serum concentration (Cmax) of MAAA-1181 was assessed.
Time frame: Cycles 1 and 3: Day 1: before infusion (BI), end of infusion (EOI), 2 hours, 4 hours, 7 hours; Days 2 and 4: 24 hours, 72 hours; Days 8 and 15; Cycle 2: Day 1 BI, EOI; Cycles 4, 6, and 8: Day 1 BI and EOI (each cycle is 21 days)
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | MAAA-1181a: Cycle 1 | 12.6 ng/mL | Standard Deviation 4.49 |
| DS-8201a | Pharmacokinetic Parameters of Maximum Serum Concentration (Cmax) of MAAA-1181 After Cycle 1 and Cycle 3 Treatments With DS-8201a in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | MAAA-1181a: Cycle 3 | 9.60 ng/mL | Standard Deviation 3.89 |
Secondary
Objective Response Rate Based on The Investigator's Assessment (Unconfirmed) Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
Objective response rate (ORR) was defined as unconfirmed complete response (CR) and partial response (PR) as assessed by the investigator based on Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1. CR was defined as a disappearance of all target lesions and PR was defined as at least a 30% decrease in the sum of diameters of target lesions.
Time frame: Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever occurs first), up to 12 months post-dose
Population: Response was assessed in the Efficacy Analysis Set.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| DS-8201a | Objective Response Rate Based on The Investigator's Assessment (Unconfirmed) Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | 2 Participants |
| HER2 Low | Objective Response Rate Based on The Investigator's Assessment (Unconfirmed) Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | 18 Participants |
Secondary
Objective Response Rate Based on The Investigator's Assessment (Unconfirmed) Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
Objective response rate (ORR) was defined as unconfirmed complete response (CR) and partial response (PR) as assessed by the investigator based on Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1. CR was defined as a disappearance of all target lesions and PR was defined as at least a 30% decrease in the sum of diameters of target lesions.
Time frame: Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever occurs first), up to 38 months post-dose
Population: Response was assessed in the Efficacy Analysis Set.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| DS-8201a | Objective Response Rate Based on The Investigator's Assessment (Unconfirmed) Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | 2 Participants |
| HER2 Low | Objective Response Rate Based on The Investigator's Assessment (Unconfirmed) Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | 23 Participants |
Secondary
Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer
Adverse events (AEs) were to be coded using MedDRA Version 20.1 and assigned severity grades based on Common Terminology Criteria for Adverse Events (CTCAE) Version 4.03. A treatment-emergent adverse event (TEAE) was defined as an AE that occurred, having been absent before the first dose of study drug, or had worsened in severity or seriousness after initiating the study drug until 47 days after last dose of study drug.
Time frame: Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever occurs first), up to approximately 12 months post-dose
Population: Treatment-emergent adverse events (TEAEs) were assessed in the Safety Analysis Set.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Any TEAEs | 51 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Gastrointestinal Disorders | 45 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Nausea | 42 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Vomiting | 20 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Constipation | 16 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Stomatitis | 16 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Diarrhoea | 14 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Investigations | 45 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Neutrophil count decreased | 36 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | White blood cell count decreased | 31 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Platelet count decreased | 20 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Lymphocyte count decreased | 13 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Alanine aminotransferase increased | 12 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Aspartate aminotransferase increased | 12 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Blood and Lymphatic System Disorders | 30 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Anaemia | 30 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Skin and Subcutaneous Tissue Disorders | 27 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Alopecia | 21 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | General Disorders and Administration Site Conditions | 25 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Fatigue | 11 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Infections and Infestations | 21 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Nasopharyngitis | 11 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Metabolism and Nutrition Disorders | 19 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Decreased appetite | 16 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Nervous System Disorders | 15 Participants |
| DS-8201a | Treatment-Emergent Adverse Events of Any Grade by System Organ Classes and Preferred Term Following DS-8201a Treatment in Participants With HER2-expressing Metastatic and/or Unresectable Breast Cancer | Respiratory, Thoracic, and Mediastinal Disorders | 12 Participants |