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OncoMatch/Clinical Trials/NCT05683418

A Study to Evaluate the Safety and Tolerability of TOS-358 in Adults With HR+ Breast Cancer and Other Select Solid Tumors

Is NCT05683418 recruiting? Yes, currently enrolling (May 2026). This Phase 1 trial studies TOS-358 for squamous cell carcinoma of head and neck.

Phase 1RecruitingTotus MedicinesNCT05683418Data as of May 2026

Treatment: TOS-358The goal of this clinical trial is to evaluate the safety of TOS-358 in adults with select solid tumors who meet study enrollment criteria. The main questions it aims to answer are: 1. what is the maximum tolerated dose and recommended dose for phase 2? 2. how safe and tolerable is TOS-358 at different dose levels when taken orally once or twice per day?

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Extracted eligibility criteria

Cancer type

Head and Neck Squamous Cell Carcinoma

Endometrial Cancer

Breast Carcinoma

Urothelial Carcinoma

Biomarker criteria

Required: PIK3CA amplification

Required: PIK3CA mutation

Performance status

ECOG 0–1(Restricted strenuous activity)

Prior therapy

Cannot have received: PI3K inhibitor

Exception: breast cancer patients

For non-breast cancer: prior treatment with any PI3K, AKT, or mTOR inhibitor, or any agent whose mechanism of action is to inhibit the PI3K-AKT-mTOR pathway

Cannot have received: AKT inhibitor

Exception: breast cancer patients

For non-breast cancer: prior treatment with any PI3K, AKT, or mTOR inhibitor, or any agent whose mechanism of action is to inhibit the PI3K-AKT-mTOR pathway

Cannot have received: mTOR inhibitor

Exception: breast cancer patients

For non-breast cancer: prior treatment with any PI3K, AKT, or mTOR inhibitor, or any agent whose mechanism of action is to inhibit the PI3K-AKT-mTOR pathway

Cannot have received: PI3K-AKT-mTOR pathway inhibitor

Exception: breast cancer patients

For non-breast cancer: prior treatment with any PI3K, AKT, or mTOR inhibitor, or any agent whose mechanism of action is to inhibit the PI3K-AKT-mTOR pathway

Lab requirements

Blood counts

adequate bone marrow function within 14 days prior to first dose of investigational product

Kidney function

adequate kidney function within 14 days prior to first dose of investigational product

Liver function

adequate liver function within 14 days prior to first dose of investigational product

Structured fields extracted by AI. May contain errors — verify against the official protocol.

US trial sites

  • University of Southern California, Norris Comprehensive Cancer Center · Los Angeles, California
  • Northwestern Memorial Hospital · Chicago, Illinois
  • Massachusetts General Hospital Cancer Center · Boston, Massachusetts
  • Beth Israel Deaconess Medical Center · Boston, Massachusetts
  • Dana-Farber Cancer Institute · Boston, Massachusetts

Showing up to 5 US sites. See all sites on ClinicalTrials.gov →

Could you qualify for this trial?

Enter your biomarker results to see how this trial's eligibility criteria match your specific cancer profile.

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