Tucatinib / Trastuzumab / Capecitabine · Phase 2 Trial

A Study of Tucatinib (MK-7119) in Combination With Trastuzumab and Capecitabine in Participants With Previously Treated Locally Advanced Unresectable or Metastatic Human Epidermal Growth Factor Receptor 2 Positive (HER2+) Breast Carcinoma (MK-7119-001)

ClinicalTrials.gov · September 10, 2026

Preliminary Why this matters to you Expert discussion

Early or partial results. Treat as a signal, not a conclusion.

AI Summary

This is a Phase 2 trial registry record documenting a planned study of tucatinib combined with trastuzumab and capecitabine in 66 heavily pretreated patients with HER2+ breast cancer. No efficacy or safety results are posted in this registry record. The primary hypothesis is that confirmed objective response rate will exceed 20% by RECIST v1.1 independent review, but no outcome data are available to evaluate this claim.

What was studied

Phase 2, Interventional, Single Group, Open label, Treatment purpose. Breast Cancer; age from 20 Years. Intervention: Tucatinib + Trastuzumab + Capecitabine. n = 66. 28 sites: Japan, South Korea, Taiwan.

Key findings

Safety

This is a registry record only; no results are reported and no efficacy or safety outcomes can be assessed.

Who this may help

The source did not state who this applies to in practice.

Plain-language summary

This is a Phase 2 clinical trial registry record with no reported results; it describes a planned study of tucatinib combination therapy in heavily pretreated HER2+ breast cancer.

Study design

As stated by the source record.

MethodsPrimary outcome measure: Confirmed Objective Response Rate(cORR) Per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 Determined by Independent Central Review (ICR): Japanese Participants (assessed at From date of first dose until first documented disease progression or start of…)

DesignPhase 2, Interventional, Single Group, Open label, Treatment purpose

PopulationBreast Cancer; age from 20 Years

Sample size66

InterventionTucatinib + Trastuzumab + Capecitabine

Setting28 sites: Japan, South Korea, Taiwan

Reported figures

Quoted from the source exactly as published.

Planned enrollment66

Study phasePhase 2

Primary outcome measureConfirmed Objective Response Rate (cORR) per RECIST v1.1 by Independent Central Review

Primary hypothesis thresholdcORR greater than 20%

Follow-up duration (maximum)17.8 months from first dose until disease progression or new anticancer therapy

Caveats

This is a registry record only; no results are reported and no efficacy or safety outcomes can be assessed.
Sample size (66) is typical for Phase 2 but insufficient to establish definitive efficacy.
No control arm or comparator treatment specified in the study design.
Outcome data, including whether the primary hypothesis threshold of cORR > 20% was met, are not provided in this registry entry.

Evidence assessment

Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.

Study design

moderate

Phase 2 interventional trial with independent central review of primary endpoint.

Directness

strong

Studies previously treated metastatic HER2+ breast cancer with clinically relevant comparator hypothesis.

Consistency

insufficient

No results reported in registry record; consistency cannot be assessed.

Risk of bias

moderate

Primary endpoint assessed by independent central review; no blinding or control arm specified.

Sample adequacy

limited

Planned enrollment 66 participants; sample size for Phase 2 but not powered for definitive conclusion.

What is missing. This record has no key findings. That is a gap in the analysis, not a judgement about the study.

Source abstract

Registry record from ClinicalTrials.gov (NCT04721977). This is a study registration, not published results. Lead sponsor: Pfizer. Recruitment status: ACTIVE_NOT_RECRUITING. Phase: PHASE2. Study type: INTERVENTIONAL. Enrollment: 66 participants (ACTUAL). Conditions: Breast Cancer. Interventions: DRUG: Tucatinib; BIOLOGICAL: Trastuzumab; DRUG: Capecitabine. Primary outcome measures: Confirmed Objective Response Rate(cORR) Per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 Determined by Independent Central Review (ICR): Japanese Participants , From date of first dose until first documented disease progression or start of new anticancer therapy, whichever occurred first (maximum up to 17.8 months). Brief summary: The goal of this study is to evaluate the efficacy and safety of tucatinib in combination with trastuzumab and capecitabine in participants with unresectable locally advanced or metastatic HER2+ breast cancer who have had prior treatment with taxane anti-cancer agent, trastuzumab, pertuzumab and trastuzumab emtansine (T-DM1). The primary hypothesis is that the confirmed objective response rate (cORR) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) as determined by independent central review (ICR) for the combination of tucatinib, trastuzumab and capecitabine, is greater than 20%.

Follow from this

Taken from the source record, never inferred. Follow any of these and new work involving them reaches your briefing.

TucatinibNCT04721977TrastuzumabCapecitabineBreast CancerPfizer