# A Study of Tucatinib vs. Placebo in Combination With Ado-trastuzumab Emtansine (T-DM1) for Patients With Advanced or Metastatic HER2+ Breast Cancer

> **NCT03975647** · PHASE3 · ACTIVE_NOT_RECRUITING · sponsor: **Seagen, a wholly owned subsidiary of Pfizer** · enrollment: 466 (actual)

## Conditions studied

- HER2-positive Breast Cancer

## Interventions

- **DRUG:** tucatinib
- **DRUG:** placebo
- **DRUG:** T-DM1

## Key facts

- **NCT ID:** NCT03975647
- **Lead sponsor:** Seagen, a wholly owned subsidiary of Pfizer
- **Sponsor class:** INDUSTRY
- **Phase:** PHASE3
- **Study type:** INTERVENTIONAL
- **Status:** ACTIVE_NOT_RECRUITING
- **Start date:** 2019-10-02
- **Primary completion:** 2023-06-29
- **Final completion:** 2029-03-10
- **Target enrollment:** 466 (ACTUAL)
- **Last updated:** 2026-03-30


## Primary source

ClinicalTrials.gov registry: https://clinicaltrials.gov/study/NCT03975647

## Citation

> US National Library of Medicine, ClinicalTrials.gov registration NCT03975647, "A Study of Tucatinib vs. Placebo in Combination With Ado-trastuzumab Emtansine (T-DM1) for Patients With Advanced or Metastatic HER2+ Breast Cancer". Retrieved via AI Analytics 2026-06-03 from https://api.ai-analytics.org/clinical/NCT03975647. Licensed CC0.

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