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

Phase 1

Recruiting

• Conditions: Squamous Cell Carcinoma of Head and Neck; Endometrial Cancer; HR+/HER2-negative Breast Cancer; Bladder Cancer
• Interventions: Drug: TOS-358

• Registration Number: NCT05683418
• Lead Sponsor: Totus Medicines

Brief Summary

The 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?

Detailed Description

This study will be conducted in two parts: a dose finding portion to determine the maximum tolerated dose and recommended phase 2 dose (RP2D) of TOS-358 administered orally on once a day (QD) and twice daily (BID) schedules, and a dose expansion portion to evaluate safety and tolerability in tumor-specific cohorts administered TOS-358 at the recommended phase 2 dose and schedule.

Adult subjects with histologically confirmed diagnosis of hormone receptor-positive (HR+), human epidermal growth factor receptor 2 (HER2) negative breast cancer, squamous cell carcinoma of the head and neck, cancer of the bladder, or endometrial cancer with known PIK3CA mutations or amplifications and who meet all of the eligibility criteria will be enrolled in the study.

In the dose finding portion of the study, TOS-358 will be evaluated as a single-agent at multiple dose levels administered orally until disease progression, unacceptable toxicity, or until meeting any other reason for discontinuation as specified in the protocol.

Study Timeline

• Study First Submitted: 2022-11-12
• Study First Submitted QC: 2023-01-05
• Study First Posted: 2023-01-13
• Study Start: 2023-02-15
• Status Verified: 2025-07
• Last Update Submitted: 2025-07-17
• Last Update Posted: 2025-07-22
• Primary Completion: 2026-12
• Study Completion: 2026-12-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 241

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
TOS-358 Single Agent Arm	TOS-358	Multiple doses of TOS-358 for oral administration.

Primary Outcome Measures

Name	Time	Method
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 Locations

Locations (18)

University of Southern California, Norris Comprehensive Cancer Center; 🇺🇸 Los Angeles, California, United States

Northwestern Memorial Hospital; 🇺🇸 Chicago, Illinois, United States

Massachusetts General Hospital Cancer Center; 🇺🇸 Boston, Massachusetts, United States

Beth Israel Deaconess Medical Center; 🇺🇸 Boston, Massachusetts, United States

Dana-Farber Cancer Institute; 🇺🇸 Boston, Massachusetts, United States

Stephenson Cancer Center; 🇺🇸 Oklahoma City, Oklahoma, United States

University of Pennsylvania; 🇺🇸 Philadelphia, Pennsylvania, United States

Vanderbilt-Ingram Cancer Center; 🇺🇸 Nashville, Tennessee, United States

Virginia Cancer Specialists, PC; 🇺🇸 Fairfax, Virginia, United States

NEXT Oncology - Hospital Quironsalud Barcelona - PPDS; 🇪🇸 Barcelona, Spain

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