Study: NCT04042701

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Trastuzumab deruxtecan (DS-8201a)
Description: Part 1: Two dose levels of DS-8201a (3.2 mg/kg Q3W and 5.4 mg/kg Q3W via intravenous (IV) infusion will be administered for the dose escalation part of the study in combination with pembrolizumab.~Part 2: Once Part 1 of the study is complete and a RDE for DS-8201a has been established, Part 2 will begin. All participants will receive DS-8201a at the RDE in combination with pembrolizumab.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Trastuzumab deruxtecan (DS-8201a)
Description: Part 1: Two dose levels of DS-8201a (3.2 mg/kg Q3W and 5.4 mg/kg Q3W via intravenous (IV) infusion will be administered for the dose escalation part of the study in combination with pembrolizumab.~Part 2: Once Part 1 of the study is complete and a RDE for DS-8201a has been established, Part 2 will begin. All participants will receive DS-8201a at the RDE in combination with pembrolizumab.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Trastuzumab deruxtecan (DS-8201a)
Description: Part 1: Two dose levels of DS-8201a (3.2 mg/kg Q3W and 5.4 mg/kg Q3W via intravenous (IV) infusion will be administered for the dose escalation part of the study in combination with pembrolizumab.~Part 2: Once Part 1 of the study is complete and a RDE for DS-8201a has been established, Part 2 will begin. All participants will receive DS-8201a at the RDE in combination with pembrolizumab.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Trastuzumab deruxtecan (DS-8201a)
Description: Part 1: Two dose levels of DS-8201a (3.2 mg/kg Q3W and 5.4 mg/kg Q3W via intravenous (IV) infusion will be administered for the dose escalation part of the study in combination with pembrolizumab.~Part 2: Once Part 1 of the study is complete and a RDE for DS-8201a has been established, Part 2 will begin. All participants will receive DS-8201a at the RDE in combination with pembrolizumab.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Trastuzumab deruxtecan (DS-8201a)
Description: Part 1: Two dose levels of DS-8201a (3.2 mg/kg Q3W and 5.4 mg/kg Q3W via intravenous (IV) infusion will be administered for the dose escalation part of the study in combination with pembrolizumab.~Part 2: Once Part 1 of the study is complete and a RDE for DS-8201a has been established, Part 2 will begin.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Pembrolizumab
Description: All participants will receive pembrolizumab (200 mg Q3W) via intravenous (IV) infusion prior to DS-8201a in Parts 1 and 2 of the study.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Pembrolizumab
Description: All participants will receive pembrolizumab (200 mg Q3W) via intravenous (IV) infusion prior to DS-8201a in Parts 1 and 2 of the study.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Pembrolizumab
Description: All participants will receive pembrolizumab (200 mg Q3W) via intravenous (IV) infusion prior to DS-8201a in Parts 1 and 2 of the study.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Pembrolizumab
Description: All participants will receive pembrolizumab (200 mg Q3W) via intravenous (IV) infusion prior to DS-8201a in Parts 1 and 2 of the study.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Pembrolizumab
Description: All participants will receive pembrolizumab (200 mg Q3W) via intravenous (IV) infusion prior to DS-8201a in Parts 1 and 2 of the study.