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Can a Two-Drug combo outsmart Treatment-Resistant breast cancer?

NCT ID NCT05262400

Disease control Sponsor: Pfizer Source: ClinicalTrials.gov ↗

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing This study
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Sep 14, 2026 · Last updated Sep 15, 2026 · Updated 1 time

Summary

Researchers are testing two experimental oral drugs, PF-07220060 and PF-07104091, combined with standard hormone therapy in people with advanced breast cancer and other solid tumors. The trial has two parts: one that finds the safest dose and another that tests the combination in specific breast cancer types. Participants take the study medicines by mouth for about two years while doctors monitor safety and look for signs the treatment works.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
two experimental oral drugs, PF-07220060 and PF-07104091, given with standard hormone therapy
What this could lead to
If the combination works, it could offer a new oral treatment option for people with advanced breast cancer whose disease has stopped responding to standard therapies.
What could go wrong
This is an early-phase trial with a small number of participants, so safety and effectiveness are still unknown. The drugs may cause side effects or fail to shrink tumors, and results may not apply to everyone.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 1/2

Runs two stages together: safety and dose first, then whether the treatment works.

Participants

235 people

The number who actually took part.

Started

Mar 2022

Expected to finish

Feb 2027

An estimate. End dates often move.

Lead sponsor

A company

The lead sponsor is a pharmaceutical, biotech, or medical-device company.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 years and older

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria * Part 1: Breast Cancer (BC) * HR+, HER2- BC * Refractory HR-positive/HER2-positive BC * Part 1: Solid Tumors other than BC * Part 2: * HR-positive/HER2-negative BC * Lesion: * Part 1: evaluable lesion (including skin or bone lesion only) * Part 2: measurable lesion per RECIST v1.1 * Prior systemic Treatment * Part 1: HR-positive/HER2-negative BC * At least 1 line of SOC, including CDK4/6 inhibitor therapy and Endocrine Therapy, for advanced or metastatic disease. * Prior chemotherapy in the metastatic setting is allowed. * Part 1: HR-positive/HER2-positive BC * At least 1 prior treatment of approved HER2 targeting therapy. * Part 1: Solid Tumors other than BC * Participants with no standard therapy available or for which no local regulatory approved standard therapy is available that would confer significant clinical benefit in the medical judgement of the investigator. * Part 2A: At least 1 prior systemic therapy for advanced or metastatic disease, including CDK4/6 inhibitor treatment and ET. * Parts 2B: At least 1 prior endocrine therapy for advanced or metastatic disease. Progression during treatment or within 12 months of completion of adjuvant endocrine therapy is acceptable. * Part 2B: Up to 1 prior line of chemotherapy for advanced/metastatic disease is allowed. * General Inclusion Criteria * Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0 or 1 * Adequate renal, liver, and bone marrow function * Resolved acute effects of any prior therapy to baseline severity Exclusion Criteria: * All Study Parts: Permanent treatment discontinuation from prior CDK 4 and/or CDK2 inhibitor due to treatment related toxicity. * Part 2B and 1C: Prior treatment with any CDK 4/6 inhibitor, or SERDs (e.g. fulvestrant), or everolimus, or any agent whose mechanism of action is to inhibit the PI3K-mTOR pathway for advanced disease. * Parts 2B and 2C: Prior treatment with any CDK4/6 inhibitor for advanced disease. * Parts 2B and 2C: Prior treatment with an investigational endocrine therapy for advanced disease. * Part 2C: Prior neoadjuvant or adjuvant treatment with a nonsteroidal aromatase inhibitor AI (ie, anastrozole or letrozole) with disease recurrence while on or within 12 months of completing treatment. * Part 2C: Any prior systemic treatment for advanced disease. * Prior irradiation to \>25% of the bone marrow * Current use of drugs which have a risk for QTc prolongation * Current use or anticipated need for food or drugs that are known strong CYP3A4/5, strong UGT2B7 or UGT1A9 inhibitors or inducers * Participation in other studies involving investigational drug(s) within 4 weeks prior to study entry * Participants with any other active malignancy within 3 years prior to enrollment except for adequately treated basal cell or squamous cell skin cancer, or carcinoma in situ of the cervix, Bowen's disease * Major surgery within 4 weeks prior to study entry * Radiation therapy within 4 weeks prior to study entry. * Clinically important hypertension * Known or suspected hypersensitivity to PF-07220060, PF-07104091, letrozole, fulvestrant, or goserelin (or equivalent to induce chemical menopause if applicable) * Known abnormalities in coagulation. Anticoagulation with subcutaneous heparin or prophylactic doses of anticoagulant are allowed * Known active uncontrolled or symptomatic central nervous system (CNS) metastases * Active inflammatory GI disease * Current use or anticipated need for Proton Pump Inhibitors (PPI) within 14 days prior to first dose of the study intervention * Previous high-dose chemotherapy requiring stem cell rescue * Participants with active, uncontrolled bacterial, fungal, or viral infection, including hepatitis B virus (HBV), hepatitis C virus (HCV), and known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) related illness * Other protocol specific exclusion criteria may apply

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Conditions

The condition(s) this trial relates to.

breast cancer breast neoplasm hormone receptor-positive breast cancer triple-positive breast carcinoma

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Breast cancer Solid tumors

Contacts and locations

Locations

  • Administrative Address: UCLA Hematology/Oncology

    Los Angeles, California, 90095, United States

  • Centro Gaucho Integrado De Oncologia, Hematologia, Ensino E Pesquisa

    Porto Alegre, Rio Grande do Sul, 90110-270, Brazil

  • Centro Oncologico Korben

    Buenos Aires, 1426, Argentina

  • Centro de Pesquisa Clínica - Área Administrativa

    Porto Alegre, Rio Grande do Sul, 90850-170, Brazil

  • Clinica Viedma S. A

    Viedma, Río Negro Province, R8500ACE, Argentina

  • Clínica Universitaria Reina Fabiola

    Córdoba, X50004FHP, Argentina

  • Clínica de Pesquisas e Centro de Estudos em Oncologia Ginecológica e Mamária Ltda

    São Paulo, 01317-000, Brazil

  • Complex Oncology Center - Plovdiv EOOD

    Plovdiv, 4004, Bulgaria

  • Complex Oncology Center - Vratsa

    Vratsa, 3000, Bulgaria

  • FARMOVS

    Bloemfontein, Free State, 9301, South Africa

  • Fakultni nemocnice Bulovka

    Prague, Praha 8, 180 81, Czechia

  • Fakultni nemocnice Olomouc

    Olomouc, Olomouc Region, 779 00, Czechia

  • Fudan University Shanghai Cancer Center

    Shanghai, Shanghai Municipality, 200032, China

  • Fundación CORI para la Investigación y Prevención del Cáncer

    La Rioja, F5300COE, Argentina

  • Fundação Pio XII - Hospital de Câncer de Barretos

    Barretos, São Paulo, 14784400, Brazil

  • Hospital Clínic de Barcelona

    Barcelona, Catalunya [cataluña], 08036, Spain

  • Hospital Universitari Vall d'Hebron

    Barcelona, Barcelona [barcelona], 08035, Spain

  • Hospital Universitario "Dr. Jose Eleuterio Gonzalez"

    Monterrey, Nuevo León, 64460, Mexico

  • Hospital Universitario 12 de Octubre

    Madrid, Madrid, Comunidad de, 28041, Spain

  • Hospital Universitario HM Sanchinarro

    Madrid, Madrid, Comunidad de, 28050, Spain

  • Hospital Universitario Virgen Del Rocio

    Seville, 41013, Spain

  • Instituto Nacional de Cancerologia

    Mexico City, Mexico City, 14080, Mexico

  • Massachusetts General Hospital

    Boston, Massachusetts, 02114, United States

  • Multiprofile Hospital for Active Treatment Serdikamed EOOD

    Sofia, Sofia (stolitsa), 1632, Bulgaria

  • Mérida Investigación Clínica

    Mérida, Yucatán, 97125, Mexico

  • ONCOSITE - Centro de Pesquisa Clinica em Oncologia

    Ijuí, Rio Grande do Sul, 98700-000, Brazil

  • Ronald Reagan UCLA Medical Center

    Los Angeles, California, 90095, United States

  • START Midwest

    Grand Rapids, Michigan, 49546, United States

  • Saint Luke's Cancer Institute

    Kansas City, Missouri, 64111, United States

  • Sir Run Run Shaw Hospital of Zhejiang University School of Medicine

    Hangzhou, Zhejiang, 310016, China

  • Specialized Hospital for Active Treatment of Oncology - Haskovo

    Haskovo, 6300, Bulgaria

  • Swedish Medical Center

    Seattle, Washington, 98104, United States

  • Swedish Medical Center

    Seattle, Washington, 98122, United States

  • Texas Oncology-Baylor Charles A. Sammons Cancer Center

    Dallas, Texas, 75246, United States

  • The First Hospital of Jilin University

    Changchun, Jilin, 130021, China

  • The University of Texas MD Anderson Cancer Center

    Houston, Texas, 77030, United States

  • Tianjin Medical University Cancer Institute & Hospital

    Tianjin, Tianjin Municipality, 300060, China

  • UCLA Hematology / Oncology-Parkside

    Santa Monica, California, 90404, United States

  • UCLA Hematology/Oncology

    Los Angeles, California, 90095, United States

  • UCLA Hematology/Oncology-Santa Monica

    Santa Monica, California, 90404, United States

  • Vseobecna fakultni nemocnice v Praze

    Prague, 12808, Czechia

  • Všeobecná fakultní nemocnice v Praze

    Prague, 12808, Czechia

  • West China Hospital, Sichuan University

    Chengdu, Sichuan, 610041, China

  • Wits Clinical Research

    Johannesburg, Gauteng, 2193, South Africa

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