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

NCT05683418 · Status: RECRUITING · Phase: PHASE1 · Type: INTERVENTIONAL · Enrollment: 241

Last updated 2026-04-22

No results posted yet for this 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)

Conditions

  • HR+/HER2-negative Breast Cancer

Interventions

DRUG

TOS-358

Covalent Phosphoinositide-3-Kinase (PI3K)-alpha Inhibitor

DRUG

Fulvestrant

Intramuscular SERD at standard doses

DRUG

Palbociclib

CDK4/6 inhibitor at standard doses

DRUG

Ribociclib

CDK4/6 inhibitor at standard doses

Sponsors & Collaborators

  • Totus Medicines

    lead INDUSTRY

Principal Investigators

  • Zelanna Goldberg, MD · Totus Medicines

Study Design

Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Model
PARALLEL

Eligibility

Min Age
18 Years
Sex
FEMALE
Healthy Volunteers
No

Timeline & Regulatory

Start
2023-02-15
Primary Completion
2027-12-31
Completion
2027-12-31
FDA Drug
Yes

Countries

  • United States
  • Spain

Study Locations

More Related Trials

Entities

Drugs

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT05683418 on ClinicalTrials.gov