Clinical trial · Interventional
A Study to Evaluate the Safety and Tolerability of TOS-358 in Women With HR+ HER2- Breast Cancer
A Study to Evaluate the Safety and Tolerability of the Covalent Phosphoinositide-3-Kinase (PI3K)-Alpha Inhibitor, TOS-358, in Adult Subjects With Select Solid Tumors
- Source
- ClinicalTrials.gov
- Retrieved
- Sep 8, 2026
- Layer
- normalized (units and labels harmonized; values unchanged)
- Run
- ING-CLINICALTRIALS-20260908-000001
Summary
Brief summary (as posted)
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
Conditions (1)
Free-text conditions as registered, with the CancerIndex entity they were reconciled to and the match type.
| Condition (as posted) | Mapped entity | Match | Confidence |
|---|---|---|---|
| HR+/HER2-negative Breast Cancer | — | UNRESOLVED | — |
Interventions
Interventions (4)
| Intervention | Type | Mapped drug | Match |
|---|---|---|---|
| Fulvestrant | Drug | Fulvestrant | ALIAS |
| Palbociclib | Drug | Palbociclib | ALIAS |
| Ribociclib | Drug | Ribociclib | ALIAS |
| TOS-358 | Drug | — | UNRESOLVED |
Design
Arms and outcomes
Arms (3)
- type
- EXPERIMENTAL
- label
- TOS-358 + fulvestrant
- description
- TOS-358 + fulvestrant at standard dosing
- interventionNames
- Drug: TOS-358
- Drug: Fulvestrant
- type
- EXPERIMENTAL
- label
- TOS-358 + fulvestrant + CDK4/6i
- description
- TOS-358 + fulvestrant + CDK4/6i
- interventionNames
- Drug: TOS-358
- Drug: Fulvestrant
- Drug: Palbociclib
- Drug: Ribociclib
- type
- EXPERIMENTAL
- label
- TOS-358
Eligibility
Eligibility (as posted)
- Sex
- Female
- Minimum age
- 18 Years
Show eligibility criteria text
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
References
Publications (0)
Data not yet available