Basket Study of Tucatinib and Trastuzumab in Solid Tumors With HER2 Alterations

Study summary

This trial studies how well tucatinib works for solid tumors that make either more HER2 or a different type of HER2 than usual (HER2 alterations) The solid tumors studied in this trial have either spread to other parts of the body (metastatic) or cannot be removed completely with surgery (unresectable). All participants will get both tucatinib and trastuzumab. People with hormone-receptor positive breast cancer will also get a drug called fulvestrant. The trial will also look at what side effects happen. A side effect is anything a drug does besides treating cancer.

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Key things to know

Main goalTreatment

This describes the study’s primary purpose.

What is being studiedtucatinib and trastuzumab

Plus 1 other study approaches.

Who it may be forHER2 · Early-stage or resectable · Metastatic or stage IV

These are broad labels—not an eligibility decision.

Checked against the public recordLast updated Aug 21, 2026 · Source: ClinicalTrials.gov

Is enrollment open?Active Not Recruiting

The study is underway but is not accepting new participants.

What kind of study?Phase 2

Interventional

Where is it offered?108 U.S. locations

Locations may change over time.

Who runs it?Seagen, a wholly owned subsidiary of Pfizer

Study sponsor

Study overview

What this study is about

Purpose: Treatment
Study type: Interventional
Phase: Phase 2
Sponsor: Seagen, a wholly owned subsidiary of Pfizer
Interventions being studied: Drug: tucatinib; Drug: trastuzumab; Drug: fulvestrant

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How this study is categorized

These labels come from structured fields and exact terms in the public record.

Disease setting

Early-stage or resectable→Metastatic or stage IV→

Biomarkers

HER2→

Treatment approach

Surgery→

Public criteria

Who may be able to participate

The sponsor separates these requirements into two groups. You do not need to interpret them alone—use them to guide a conversation with the study team.

Requirements people may need to meetInclusion criteria

Histologically or cytologically confirmed diagnosis of locally-advanced unresectable or metastatic solid tumor, including primary brain tumors
Participants with non-squamous NSCLC must have progressed during or after standard treatment or for which no standard treatment is available
Participants with other disease types must have progressed during or after ≥1 prior line of systemic therapy for locally-advanced unresectable or metastatic disease
Disease progression during or after, or intolerance of, the most recent line of systemic therapy
Disease demonstrating HER2 alterations (overexpression/amplification or HER2 activating mutations), as determined by local or central testing processed in a Clinical Laboratory Improvement Amendments (CLIA)- or International Organization for Standardization (ISO) accredited laboratory, according to one of the following:
HER2 overexpression/amplification from fresh or archival tumor tissue or blood
Known activating HER2 mutations detected in fresh or archival tumor tissue or blood
Have measurable disease per RECIST v1.1 criteria according to investigator assessment
Have Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1

Reasons someone may not be able to joinExclusion criteria

Participants with breast cancer, gastric or gastroesophageal junction adenocarcinoma, or CRC whose disease shows HER2 amplification/overexpression.
Previous treatment with HER2-directed therapy; participants with uterine serous carcinoma or HER2-mutated gastric or gastroesophageal junction adenocarcinoma without HER2-overexpression/amplification may have received prior trastuzumab
Known hypersensitivity to any component of the drug formulation of tucatinib or trastuzumab (drug substance, excipients, murine proteins), or any component of the drug formulation of fulvestrant in participants with HR+ HER2-mutated breast cancer
History of exposure to a 360 mg/m² doxorubicin-equivalent or \>720 mg/m\^2 epirubicin-equivalent cumulative dose of anthracyclines
Treatment with any systemic anti-cancer therapy, radiation therapy, major surgery, or experimental agent within ≤3 weeks of first dose of study treatment or are currently participating in another interventional clinical trial. There are additional inclusion and

Important: This is the sponsor’s public criteria, not a determination of eligibility. The study team must review your individual situation.

Study sites

U.S. locations

HonorHealthPhoenix, Arizona
HonorHealthTempe, Arizona
The University of Arizona Cancer Center-North CampusTucson, Arizona
City of Hope at Huntington BeachHuntington Beach, California
City of Hope at Irvine Sand CanyonIrvine, California
Koman Family Outpatient PavilionLa Jolla, California
UC San Diego Medical Center - La Jolla (Jacobs Medical Center / Thornton Pavilion)La Jolla, California
UC San Diego Moores Cancer Center- Investigational Drug ServicesLa Jolla, California
UC San Diego Moores Cancer CenterLa Jolla, California
City of Hope at Long Beach WorshamLong Beach, California
City of Hope at Long Beach ElmLong Beach, California
City of Hope at Newport Beach LidoNewport Beach, California

Source and freshness
Processed from ClinicalTrials.gov. Last public update: Aug 21, 2026. Always confirm current availability with the study team.

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