Sapanisertib and Serabelisib (PIKTOR) in Various Combinations in Patients With HR+/HER2- Advanced/Metastatic Breast Cancer

April 27, 2026 updated by: Faeth Therapeutics

Open-Label Umbrella Study to Evaluate Safety and Efficacy of Sapanisertib and Serabelisib (PIKTOR) in Various Combinations in Patients With HR+/HER2- Advanced or Metastatic Breast Cancer

The study is a Phase 1b/2, multi-center, open-label, dose escalation trial evaluating the safety and preliminary efficacy of sapanisertib and serabelisib (PIKTOR) with fulvestrant and/or other anticancer therapies in participants with HR+/HER2- advanced/metastatic breast cancer.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The study is a Phase 1b/2, multi-center, open-label, dose escalation trial evaluating the safety and preliminary efficacy of sapanisertib and serabelisib (PIKTOR) with fulvestrant and/or other anticancer therapies in participants with HR+/HER2- advanced/metastatic breast cancer.

Study Type

Interventional

Enrollment (Estimated)

32

Phase

  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90025
        • Recruiting
        • START Los Angeles
    • Oregon
      • Springfield, Oregon, United States, 97477
        • Recruiting
        • Oncology Associates of Oregon
    • Tennessee
      • Nashville, Tennessee, United States, 37203
        • Recruiting
        • SCRI Oncology Partners

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Histologically confirmed diagnosis of HR+/HER2- breast cancer.
  • Documented evidence of advanced or recurrent disease that is not amenable to surgery/radiation for curative intent.
  • Participant has received at least one prior systemic therapy.
  • At least 1 measurable or evaluable target lesion according to RECIST v1.1
  • Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 1 at Screening.
  • Non-pregnant, non-lactating females who are postmenopausal, surgically sterile or who agree to use effective contraceptive methods.

Exclusion Criteria:

  • Participants with triple-negative breast cancer.
  • Participants with central nervous system metastases are not eligible, unless they have completed local therapy and have discontinued the use of corticosteroids for this indication for at least 4 weeks before starting treatment in this study.
  • Active malignancy (except for breast cancer, definitively treated in-situ carcinomas [e.g., breast, cervix, bladder], or basal or squamous cell carcinoma of the skin) within the past 24 months prior to treatment. Fully resected localized malignancies are eligible.
  • Gastric feeding tube (gastrostomy tube), gastrointestinal malabsorption, gastrointestinal anastomosis, bowel obstruction, or any other condition that might affect the absorption of study treatment.
  • Significant cardiovascular impairment.
  • Active, uncontrolled infection.
  • Concurrent participation in another therapeutic clinical trial.
  • Prior radiation therapy within 21 days prior to start of study treatment.
  • Participants who have received a prior PI3K, AKT, mTORC1/2, or dual PI3K/mTOR inhibitor.
  • Strong CYP3A4 inhibitors, strong CYP1A2 inhibitors or CYP1A2 inducers, or clinically significant CYP3A4 inducers within 7 days before the first dose of study intervention, or participants who require treatment with strong CYP3A4 inhibitors or inducers during the study.
  • Prolongation of QTc interval to >480 ms.
  • Type 1 or Type 2 diabetes mellitus on insulin.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Cohort A1 - Sapanisertib and serabelisib (PIKTOR) with fulvestrant
Subjects will receive doses of sapanisertib and serabelisib (PIKTOR) administered orally and fulvestrant administered intramuscularly.
Drug: Serabelisib
Serabelisib is a selective, small molecule inhibitor of PI3Kα.
Drug: Sapanisertib
Sapanisertib is a small molecule inhibitor of the mammalian mTOR serine/threonine kinase.
Drug: Fulvestrant
Fulvestrant is a first-in-class SERD.
Experimental: Cohort A2 - Sapanisertib and serabelisib (PIKTOR) with fulvestrant
Subjects will receive doses of sapanisertib and serabelisib (PIKTOR) at a higher dose than Cohort A1 administered orally and fulvestrant administered intramuscularly.
Drug: Serabelisib
Serabelisib is a selective, small molecule inhibitor of PI3Kα.
Drug: Sapanisertib
Sapanisertib is a small molecule inhibitor of the mammalian mTOR serine/threonine kinase.
Drug: Fulvestrant
Fulvestrant is a first-in-class SERD.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Safety and tolerability of drugs by assessment of adverse events (AEs) / serious adverse events (SAEs)
Time Frame: 2 years
Graded according to the National Cancer Institute (NCI CTCAE v5.0).
2 years

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Objective Response Rate (ORR)
Time Frame: Up to 2 years.
Defined as the proportion of participants from the Response-Evaluable population who have confirmed best overall response of either CR or PR according to RECIST v1.1 as confirmed by the Investigator.
Up to 2 years.
Progression Free Survival (PFS)
Time Frame: Up to 5 years.
Defined as the time from first dose to the date of the first evidence of disease progression or death.
Up to 5 years.
Progression Free Survival (PFS) at 6 months
Time Frame: 6 months
Defined as the progression free survival (PFS) rate at 6 months.
6 months
Overall Survival (OS)
Time Frame: Up to 5 years.
Defined as the time from first dose to the date of death due to any cause.
Up to 5 years.
Clinical Benefit Rate (CBR)
Time Frame: Up to 5 years.
Defined as the percentage of participants from the All Treated population who achieve CR, PR, or SD.
Up to 5 years.
Duration of Response (DoR)
Time Frame: Up to 5 years.
Defined for participants with a confirmed CR or PR as the time from response to the date of first evidence of disease progression or death.
Up to 5 years.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Faeth Therapeutics

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

April 1, 2026

Primary Completion (Estimated)

May 1, 2029

Study Completion (Estimated)

May 1, 2033

Study Registration Dates

First Submitted

April 17, 2026

First Submitted That Met QC Criteria

April 27, 2026

First Posted (Actual)

April 30, 2026

Study Record Updates

Last Update Posted (Actual)

April 30, 2026

Last Update Submitted That Met QC Criteria

April 27, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • FTH-PIK-101

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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