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Clinical Trials in Spain / NCT05683418
Recruiting Phase 1

A Study to Evaluate the Safety and Tolerability of TOS-358 in Women With HR+ HER2- Breast Cancer

NCT05683418 · tracked via the Priya Life Science Spain tracker
Sponsor
Totus Medicines
Phase
Phase 1
Started
2023-02-15
Last updated
2026-04-22

Condition(s) studied

HR+/HER2-negative Breast Cancer

Investigational drug(s) / intervention(s)

TOS-358Fulvestrant →Palbociclib →Ribociclib →

TOS-358: Covalent Phosphoinositide-3-Kinase (PI3K)-alpha Inhibitor

Fulvestrant: Intramuscular SERD at standard doses

Palbociclib: CDK4/6 inhibitor at standard doses

Ribociclib: CDK4/6 inhibitor at standard doses

Study summary

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)

Eligibility

Sex
FEMALE
Min age
18 Years
Max age
—
Healthy volunteers
No
Key Inclusion Criteria * Locally advanced, recurrent, or metastatic HR +/HER2- breast cancer * Up to 3 prior lines of therapy for metastatic disease * Willing and able to provide written informed consent for this study * Adults ≥ 18 years old at time of consent * Known PIK3CA mutations or amplifications as determined at a CAP/CLIA-certified or equivalently accredited diagnostic laboratory using a validated test * Measurable or evaluable disease by RECIST 1.1 * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Life expectancy ≥ 6 months, as determined by the investigator * Adequate bone marrow, liver, and kidney function within 14 days prior to first dose of investigational product * Fasting plasma glucose \<= 140 mg/dL AND hemoglobin A1c (HbA1c) \<= 7.0% * Available archived or fresh tumor tissue sample for detection of PIK3CA mutation by central laboratory test Key Exclusion Criteria * Has an established diagnosis of diabetes mellitus type 1 or has uncontrolled diabetes mellitus type 2 * Known active central nervous system (CNS) metastases * PTEN mutations

Primary outcome measure(s)

  • Determine the rate of dose-limiting toxicities (DLTs) — First 21 days of treatment
  • Incidence and severity of adverse events (AEs) and specific laboratory abnormalities graded according to NCI CTCAE v5 — Start of treatment to 30 days after last dose

Trial sites (18)

FacilityCityRegionStatus
Northwestern Memorial Hospital Chicago Illinois Recruiting
Beth Israel Deaconess Medical Center Boston Massachusetts Recruiting
Dana-Farber Cancer Institute Boston Massachusetts Recruiting
Comprehensive Cancer Centers of Nevada Las Vegas Nevada Recruiting
University of Pennsylvania Philadelphia Pennsylvania Recruiting
Sarah Cannon Cancer Center Nashville Tennessee Recruiting
Vanderbilt-Ingram Cancer Center Nashville Tennessee Recruiting
Texas Oncology - Flower Mound Flower Mound Texas Recruiting
Virginia Cancer Specialists Fairfax Virginia Recruiting
NEXT Oncology - Hospital Quironsalud Barcelona - PPDS Barcelona Spain Recruiting
START Barcelona HM Nou Delfos Barcelona Spain Recruiting
Instituto de Investigacion Oncologica Vall dHebron (VHIO) - EPON Barcelona Spain Recruiting
Hospital Clinico San Carlos Madrid Spain Recruiting
START MADRID Hospital Universitario Fundacion Jimenez Diaz - EDOS Madrid Spain Recruiting
START MADRID Hospital Universitario HM Sanchinarro - CIOCC Madrid Spain Recruiting
Clinica Universidad de Navarra Pamplona Spain Recruiting
NEXT Oncology - Hospital Quironsalud Madrid - PPDS Pozuelo de Alarcón Spain Recruiting
Hospital Clinico Universitario de Valencia Valencia Spain Recruiting

On this site

📄 Ibrance (palbociclib) drug profile → 📄 Kisqali (ribociclib) drug profile →
Official registry record

This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.

View NCT05683418 on ClinicalTrials.gov ↗ ← All trials in Spain