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A Study of Tucatinib With Trastuzumab and mFOLFOX6 Versus Standard of Care Treatment in First-line HER2+ Metastatic Colorectal Cancer

An Open-label Randomized Phase 3 Study of Tucatinib in Combination With Trastuzumab and mFOLFOX6 Versus mFOLFOX6 Given With or Without Either Cetuximab or Bevacizumab as First-line Treatment for Subjects With HER2+ Metastatic Colorectal Cancer

Status
Recruiting
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT05253651
Acronym
MOUNTAINEER-03
Enrollment
400
Registered
2022-02-24
Start date
2022-10-24
Completion date
2029-07-27
Last updated
2026-03-16

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Colorectal Neoplasms

Keywords

Colorectal Cancer, CRC, Seattle Genetics

Brief summary

This study is being done to find out if tucatinib with other cancer drugs works better than standard of care to treat participants with HER2 positive colorectal cancer. This study will also determine what side effects happen when participants take this combination of drugs. A side effect is anything a drug does to the body besides treating your disease. Participants in this study have colorectal cancer that has spread through the body (metastatic) and/or cannot be removed with surgery (unresectable). Participants will be assigned randomly to the tucatinib group or standard of care group. The tucatinib group will get tucatinib, trastuzumab, and mFOLFOX6. The standard of care group will get either: * mFOLFOX6 alone, * mFOLFOX6 with bevacizumab, or * mFOLFOX6 with cetuximab mFOLFOX6 is a combination of multiple drugs. All of the drugs given in this study are used to treat this type of cancer.

Interventions

DRUGtucatinib

300mg given by mouth (orally) twice daily

DRUGtrastuzumab

8mg/kg loading dose will be given into the vein (IV; intravenously) on Cycle 1 day 1, followed by 6mg/kg given by IV every 3 weeks thereafter.

DRUGbevacizumab

5mg/kg given by IV every 2 weeks

DRUGcetuximab

400mg/m2 loading dose will be given by IV on Cycle 1 day 1, followed by 250mg/m2 given by IV weekly

DRUGoxaliplatin

85mg/m2 given by IV every 2 weeks. Component of mFOLFOX6.

DRUGleucovorin

400mg/ m2 given by IV every 2 weeks. Component of mFOLFOX6.

200mg/ m2 given by IV every 2 weeks. May be given in place of leucovorin. Component of mFOLFOX6.

DRUGfluorouracil

400mg/m2 given by IV bolus then 2400mg/m2 given by continuous IV infusion (over 46-48 hours) every 2 weeks. Component of mFOLFOX6.

Sponsors

Seagen, a wholly owned subsidiary of Pfizer
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Histologically and/or cytologically confirmed adenocarcinoma of the colon or rectum which is locally advanced unresectable or metastatic * Able to provide the most recently available formalin-fixed paraffin-embedded (FFPE) tumor tissue blocks (or freshly sectioned slides) obtained prior to treatment initiation to a central laboratory * If archival tissue is not available, a newly-obtained baseline biopsy of an accessible tumor lesion is required within 35 days prior to start of study treatment * HER2+ disease as determined by a tissue based assay performed at a central laboratory. * Participant has rat sarcoma viral oncogene homolog wild-type (RAS WT) disease as determined by local or central testing. For central RAS analysis, tissue sample must be analyzed within 1 year of biopsy date. * Radiographically measurable disease per RECIST v1.1 with: * At least one site of disease that is measurable and that has not been previously irradiated, or * If the participant has had previous radiation to the target lesion(s), there must be evidence of progression since the radiation * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * CNS Inclusion - based on contrast brain magnetic resonance imaging, participants may have any of the following: * No evidence of brain metastases * Previously treated brain metastases which are asymptomatic

Exclusion criteria

* Prior systemic anticancer therapy for colorectal cancer (CRC) in the locally advanced unresectable or metastatic setting; note that participants may have received a maximum of 2 doses of mFOLFOX6 in the locally advanced/unresectable or metastatic setting prior to randomization. * Note: May have received chemotherapy for CRC in the adjuvant setting if it was completed \>6 months prior to enrollment * Radiation therapy within 14 days prior to enrollment (or within 7 days in the setting of stereotactic radiosurgery) * Previous treatment with anti-HER2 therapy * Ongoing Grade 3 or higher neuropathy * Active or untreated gastrointestinal (GI) perforation at the time of screening.

Design outcomes

Primary

MeasureTime frameDescription
Progression-free survival (PFS) per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1) by Blinded Independent Central Review (BICR)Up to approximately 3 yearsThe time from the date of randomization to the BICR assessment of disease progression according to RECIST v1.1 or death from any cause

Secondary

MeasureTime frameDescription
Trough concentration (Ctrough)Approximately 4 monthsPK parameter
Incidence of adverse events (AEs)Through 30 days after the last study treatment; approximately 1 yearAny untoward medical occurrence in a clinical investigational participant administered a medicinal product and which does not necessarily have a causal relationship with this treatment.
Overall survival (OS)Up to approximately 6 yearsThe time from randomization to death from any cause
Confirmed objective response rate (cORR) per RECIST v1.1 by BICRUp to approximately 3 yearsThe proportion of participants with confirmed complete response (CR) or partial response (PR) according to RECIST v1.1, as assessed by BICR
PFS per RECIST v1.1 by investigator assessmentUp to approximately 3 yearsThe time from the date of randomization to the investigator assessment of disease progression according to RECIST v1.1 or death from any cause
cORR per RECIST v1.1 by investigator assessmentUp to approximately 3 yearsThe proportion of participants with confirmed CR or PR according to RECIST v1.1, as assessed by investigators
Duration of response (DOR) per RECIST v1.1 by BICRUp to approximately 3 yearsThe time from first documentation of objective response (CR or PR that is subsequently confirmed) to the first documentation of disease progression per RECIST v1.1 or death from any cause
DOR per RECIST v1.1 by investigator assessmentUp to approximately 3 yearsThe time from first documentation of objective response (CR or PR that is subsequently confirmed) to the first documentation of disease progression per RECIST v1.1 or death from any cause
Time to second progression or death (PFS2)Up to approximately 3 yearsThe time from randomization to disease progression on the next-line of therapy, or death from any cause
Change from baseline in European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC QLQC30) scoreThrough 30-37 days after the last study treatment; approximately 1 yearChange from baseline in European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) scores. Scale scores range from 0-100. For functioning and global health status/quality of life (QoL) scales, higher scores indicate better functioning or global health status/quality of life (QoL). For symptom scales, higher scores indicate greater symptom burden.
Incidence of dose alterationsThrough 30 days after the last study treatment; approximately 1 year
Time to meaningful change in EORTC QLQ30 scoreThrough 30-37 days after the last study treatment; approximately 1 yearThe time from baseline to the first onset of a ≥10-point changes in European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) scores. Scale scores range from 0-100. For functioning and global health status/QoL scales, higher scores indicate better functioning or global health status/QoL. For symptom scales, higher scores indicate greater symptom burden.

Countries

Argentina, Australia, Austria, Belgium, Brazil, Canada, Chile, China, France, Germany, Greece, Ireland, Italy, Japan, Netherlands, Norway, Poland, Portugal, Slovakia, South Korea, Spain, Switzerland, Taiwan, United Kingdom, United States

Contacts

CONTACTPfizer CT.gov Call Center
ClinicalTrials.gov_Inquiries@pfizer.com1-800-718-1021
STUDY_DIRECTORPfizer CT.gov Call Center

Pfizer

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Mar 17, 2026