Adenocarcinoma, Gastric, Neoplasm, Breast
Conditions
Keywords
Stomach cancer, Cancer where the esophagus meets the stomach, Human epidermal growth factor 2, HER2, Breast Cancer, Adenocarcinoma, Gastroesophageal Junction (GEJ), Gastric Cancer, Antibody drug conjugate (ADC), Oncology
Brief summary
HER2-positive cancer is a cancer that tests positive for a protein called human epidermal growth factor receptor 2 (HER2). HER2 promotes the growth of certain cancer cells. This study will test DS-8201a (trastuzumab deruxtecan), a HER2-targeted antibody and topoisomerase I inhibitor conjugate. The safety and tolerability profile of DS-8201a will be assessed in Chinese patients with certain types of stomach and breast cancer that test positive for HER2. It also will test how DS-8201a moves within the body (pharmacokinetics).
Detailed description
The expected time from the first subject's enrollment until the last subject's enrollment is approximately 8 months. The screening period is 28 days and each cycle of treatment is 21 days. The number of treatment cycles is not fixed in this study. Subjects who continue to derive clinical benefit from the study drug in the absence of withdrawal of consent, progressive disease (PD), or unacceptable toxicity may continue the study drug.
Interventions
DRUGDS-8201a
An antibody drug conjugate
Sponsors
AstraZeneca
Daiichi Sankyo Taiwan Ltd., a Daiichi Sankyo Company
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 gastric or GEJ adenocarcinoma, or breast cancer, with HER2 expression \[immunohistochemistry (IHC) 3+, 2+, or 1+ and/or in situ hybridization (ISH) +\] 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 * Has any other history or condition that might compromise: 1. Safety of the participant or offspring 2. Safety of study staff 3. Analysis of Results
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever came first), up to approximately 5 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI | Maximum concentration (Cmax) of MAAA-1181a was assessed. |
| Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI | Area under the serum concentration-time curve during dosing interval (AUCtau) of DS-8201a and total anti-HER2 antibody was assessed. |
| Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI | Area under the serum concentration-time curve during dosing interval (AUCtau) of MAAA-1181a was assessed. |
| Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI | Maximum concentration (Cmax) of DS-8201a and total anti-HER2 antibody was assessed. |
| Objective Response Rate (Unconfirmed) As Assessed in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever came first), up to approximately 5 months post-dose | Objective response rate (ORR; defined as participants who achieved CR and PR) was 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. |
| Disease Control Rate (Unconfirmed) As Assessed in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever came first), up to approximately 5 months post-dose | Disease control rate (DCR; defined as participants who achieved CR, PR, and SD) was 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, PR was defined as at least a 30% decrease in the sum of diameters of target lesions, and SD was defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD defined as at least a 20% increase in the sum of diameters of target lesions. |
| Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever came first), up to approximately 5 months post-dose | Best overall response (BOR) was assessed by the investigator based on Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1. Complete response (CR) was defined as a disappearance of all target lesions, PR was defined as at least a 30% decrease in the sum of diameters of target lesions, and stable disease (SD) was defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease (PD; at least a 20% increase in the sum of diameters of target lesions. |
Countries
Taiwan
Participant flow
Recruitment details
A total of 12 participants who met all inclusion criteria and no exclusion criteria were enrolled and received treatment in Taiwan.
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 DS-8201a administered by intravenous infusion on Day 1 of each cycle, once every 3 weeks. | 12 |
| Total | 12 |
Baseline characteristics
| Characteristic | DS-8201a |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 1 Participants |
| Age, Categorical Between 18 and 65 years | 11 Participants |
| Age, Continuous | 54.8 years STANDARD_DEVIATION 8.73 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 12 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 Taiwan | 12 participants |
| Sex: Female, Male Female | 12 Participants |
| Sex: Female, Male Male | 0 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 12 |
| other Total, other adverse events | 12 / 12 |
| serious Total, serious adverse events | 2 / 12 |
Outcome results
Primary
Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan)
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 came first), up to approximately 5 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 Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any TEAE | 12 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any drug-related TEAE | 12 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any TEAE of CTCAE Grade ≥3 | 7 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any drug-related TEAE of CTCAE Grade ≥3 | 6 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any serious TEAE | 2 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any drug-related serious TEAE | 1 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any serious TEAE of CTCAE Grade ≥3 | 2 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any drug-related serious TEAE of CTCAE Grade ≥3 | 1 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any TEAE leading to drug withdrawal | 0 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any TEAE leading to dose reduction | 2 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any drug-related TEAE leading to dose reduction | 2 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any TEAE leading to dose interruption | 5 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any drug-related TEAE leading to dose interruption | 5 Participants |
| DS-8201a | Treatment-emergent Adverse Events Following Treatment With DS-8201a (Trastuzumab Deruxtecan) | Any TEAE leading to death | 0 Participants |
Secondary
Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer
Best overall response (BOR) was assessed by the investigator based on Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1. Complete response (CR) was defined as a disappearance of all target lesions, PR was defined as at least a 30% decrease in the sum of diameters of target lesions, and stable disease (SD) was defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for progressive disease (PD; at least a 20% increase in the sum of diameters of target lesions.
Time frame: Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever came first), up to approximately 5 months post-dose
Population: Response was assessed in the Response Evaluable Set.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| DS-8201a | Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Complete response (CR) | 0 Participants |
| DS-8201a | Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Partial response (PR) | 4 Participants |
| DS-8201a | Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Stable disease (SD) | 7 Participants |
| DS-8201a | Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Non-Complete Response (CR)/Non-Progressive Disease (PD) | 0 Participants |
| DS-8201a | Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Progressive Disease (PD) | 0 Participants |
| DS-8201a | Best Overall Response By The Investigator's Assessment (Unconfirmed) in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | Non-evaluable (NE) | 0 Participants |
Secondary
Disease Control Rate (Unconfirmed) As Assessed in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer
Disease control rate (DCR; defined as participants who achieved CR, PR, and SD) was 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, PR was defined as at least a 30% decrease in the sum of diameters of target lesions, and SD was defined as neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD defined as at least a 20% increase in the sum of diameters of target lesions.
Time frame: Baseline up to withdrawal of consent, progressive disease, or unacceptable toxicity (whichever came first), up to approximately 5 months post-dose
Population: Response was evaluated in the Response Evaluable Set.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| DS-8201a | Disease Control Rate (Unconfirmed) As Assessed in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | 11 Participants |
Secondary
Objective Response Rate (Unconfirmed) As Assessed in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer
Objective response rate (ORR; defined as participants who achieved CR and PR) was 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 came first), up to approximately 5 months post-dose
Population: Response was evaluated in the Response Evaluable Set.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| DS-8201a | Objective Response Rate (Unconfirmed) As Assessed in Participants With HER2-Positive Advanced and/or Refractory Gastric, Gastroesophageal Junction Adenocarcinoma, or Breast Cancer | 4 Participants |
Secondary
Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan)
Area under the serum concentration-time curve during dosing interval (AUCtau) 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | DS-8201a, Cycle 1 | 631 ug*d/mL | Standard Deviation 173 |
| DS-8201a | Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | DS-8201a, Cycle 3 | 991 ug*d/mL | Standard Deviation 109 |
| DS-8201a | Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | Total Anti-HER2 antibody, Cycle 1 | 821 ug*d/mL | Standard Deviation 312 |
| DS-8201a | Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | Total Anti-HER2 antibody, Cycle 3 | 1180 ug*d/mL | Standard Deviation 208 |
Secondary
Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan)
Area under the serum concentration-time curve during dosing interval (AUCtau) of MAAA-1181a 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | MAAA-1181a, Cycle 1 | 36.1 ng*d/mL | Standard Deviation 9.71 |
| DS-8201a | Pharmacokinetic Parameter of Area Under the Serum Concentration-time Curve During Dosing Interval (AUCtau) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | MAAA-1181a, Cycle 3 | 41.3 ng*d/mL | Standard Deviation 5.06 |
Secondary
Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan)
Maximum 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | DS-8201a, Cycle 1 | 157 ug/mL | Standard Deviation 19.1 |
| DS-8201a | Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | DS-8201a, Cycle 3 | 163 ug/mL | Standard Deviation 19.5 |
| DS-8201a | Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | Total Anti-HER2 antibody, Cycle 1 | 150 ug/mL | Standard Deviation 22.6 |
| DS-8201a | Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | Total Anti-HER2 antibody, Cycle 3 | 154 ug/mL | Standard Deviation 16.6 |
Secondary
Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan)
Maximum concentration (Cmax) of MAAA-1181a 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; Cycles 2, 4, 6 and 8, Day 1: BI and EOI
Population: Pharmacokinetic parameters were assessed in the Pharmacokinetic Analysis Set.
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| DS-8201a | Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | MAAA-1181a, Cycle 1 | 11.9 ng/mL | Standard Deviation 3.79 |
| DS-8201a | Pharmacokinetic Parameter of Maximum (Peak) Observed Serum Concentration (Cmax) of MAAA-1181a Following Cycle 1 and Cycle 3 Treatment With DS-8201a (Trastuzumab Deruxtecan) | MAAA-1181a, Cycle 3 | 9.01 ng/mL | Standard Deviation 1.36 |