A Study to Evaluate the Safety and Tolerability of TOS-358 in Women With HR+ HER2- Breast Cancer
This is not medical advice. AI-assisted translation — inaccuracies may occur. Always verify the original and consult your oncologist before taking any steps.
About the trial
The goal of this clinical trial is to evaluate the safety and efficacy of TOS-358 in women with HR+ HER2- metastatic breast cancer whose tumors have a mutation in PIK3CA and who meet all other study enrollment criteria. The main questions it aims to answer are: 1. Phase 1a: what is the maximum tolerated dose and recommended dose for phase 2? 2. Phase 1a: how safe and tolerable is TOS-358 at different dose levels when taken orally once or twice per day? 3. Phase 1b: how safe and effective is TOS-358 when given with standard of care medicines for HR+HER2- metastatic breast cancer (fulvestrant and CDK4/6i)
Original English text from ClinicalTrials.gov
Who can (and can't) join
✓ Qualifies
- •Zaawansowany, nawracający lub rozsiany rak piersi bez receptorów HER2, z receptorami hormonalnymi
- •Maksymalnie 3 poprzednie leczenia rozsianych zmian nowotworowych
- •Chęć i zdolność do podpisania świadomej zgody na udział w badaniu
- •Wiek 18 lat lub więcej
- •Potwierdzona mutacja lub zwiększona liczba kopii genu PIK3CA w certyfikowanym laboratorium
- •Mierzalne lub ocenialne zmiany nowotworowe
- •Dobry ogólny stan zdrowia (ocena ECOG 0 lub 1)
- •Spodziewana długość życia co najmniej 6 miesięcy
✗ Disqualifies
- •Cukrzyca typu 1 lub niekontrolowana cukrzyca typu 2
- •Aktywne przerzuty do mózgu
- •Mutacja genu PTEN
Simplified criteria — AI translation
Trial details
- Minimum age
- 18 Years
- Last updated (source)
- April 22, 2026
- Sex
- Female only
Therapies / drugs in trial
Locations (18)
Northwestern Memorial Hospital
Chicago, United States
Beth Israel Deaconess Medical Center
Boston, United States
Dana-Farber Cancer Institute
Boston, United States
Comprehensive Cancer Centers of Nevada
Las Vegas, United States
University of Pennsylvania
Philadelphia, United States
Sarah Cannon Cancer Center
Nashville, United States
Vanderbilt-Ingram Cancer Center
Nashville, United States
Texas Oncology - Flower Mound
Flower Mound, United States
Virginia Cancer Specialists
Fairfax, United States
NEXT Oncology - Hospital Quironsalud Barcelona - PPDS
Barcelona, Spain
START Barcelona HM Nou Delfos
Barcelona, Spain
Instituto de Investigacion Oncologica Vall dHebron (VHIO) - EPON
Barcelona, Spain
Hospital Clinico San Carlos
Madrid, Spain
START MADRID Hospital Universitario Fundacion Jimenez Diaz - EDOS
Madrid, Spain
START MADRID Hospital Universitario HM Sanchinarro - CIOCC
Madrid, Spain
Clinica Universidad de Navarra
Pamplona, Spain
NEXT Oncology - Hospital Quironsalud Madrid - PPDS
Pozuelo de Alarcón, Spain
Hospital Clinico Universitario de Valencia
Valencia, Spain
Trial contact
Clinical Trials
Contact information from ClinicalTrials.gov. Contact in English.
Data from ClinicalTrials.gov. AI-assisted translation, last sync: 7/1/2026.