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Study of Tersolisib (STX-478) for Advanced Solid Tumors

This study is testing a new drug called STX-478, alone and with other cancer medicines, for people with advanced solid tumors, including breast cancer. STX-478 works by targeting a specific protein called PI3Kα, which can be mutated in some cancers. Researchers want to see how safe STX-478 is and if it can shrink tumors. You might be eligible if you have an advanced solid tumor with a PI3Kα mutation. The study will measure side effects and how many people's tumors shrink or disappear over 12 months. This study is currently recruiting up to 880 participants.

Study design
This is a multi-part, open-label (meaning you and your doctors will know what treatment you are receiving) Phase 1/2 study. It plans to enroll up to 880 participants.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
The study will measure how many participants' tumors respond to treatment at 12 months.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT05768139

First-in-Human Study of Tersolisib (STX-478) as Monotherapy and in Combination With Other Antineoplastic Agents in Participants With Advanced Solid Tumors

Recruiting
PHASE1Ages 18+InterventionalTreatment
Eli Lilly and Company
~880 participants
Updated 2026-07-07 on ClinicalTrials.gov
What's tested:STX-478FulvestrantRibociclibPalbociclibLetrozoleAnastrozole

At a glance

Recruiting sites
59 of 65 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Number of participants who experience at least 1 Dose Limiting Toxicity (DLT)
Measured over First 28 days of treatment
+4 more outcomes measured

Conditions

Breast Cancer
Solid Tumors, Adult

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Where it's being run

65 sites across 25 states
Spain12
Italy9
France6
Texas5
Japan4
California2
Florida2
Massachusetts2

Study leadership

  • Call 1-877-CTLILLY (1-877-285-4559) or 1-317-615-4559 Mon - Fri 8 AM - 8 PM Eastern time (UTC/GMT - 5 hours, EST) · STUDY_DIRECTOR · Eli Lilly and Company

Who to contact

Trial questions or participation questions: 1-877-CTLILLY (1-877-285-4559) or
[email protected]
1-317-615-4559
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Has an advanced or refractory solid tumor malignancy that is metastatic or locally advanced and unresectable (as specified by Cohort)
Has a new or recent tumor biopsy (collected at screening, if feasible) or will provide an adequate tissue sample prior to screening
Has a tumor that harbors a documented PI3Kα mutation (cohort specific criterion for cohort-specific mutation types)
Is ≥18 years of age at the time of signing the ICF
Has an ECOG performance status score of 0 or 1 at screening
Has adequate organ function as defined per protocol

Exclusion

Has history (within ≤2 years before screening) of a solid tumor or hematological malignancy that is histologically distinct from the cancers being studied
Has symptomatic brain or spinal metastases
Has an established diagnosis of uncontrolled diabetes mellitus (defined as HbA1c ≥8% and/or FBG ≥140 mg/dL \[7.7 mmol/L\] and/or requiring or required insulin).
Has had prior treatment with PI3K/AKT/mTOR inhibitor(s), except in certain circumstances
Has had treatment with any local or systemic antineoplastic therapy or investigational anticancer agent within 14 days or 4 half-lives, whichever is longer, prior to the initiation of study treatment up to a maximum washout period of 28 days. Endocrine therapy does not require a washout period if the patient is enrolling in a cohort with the same combination endocrine therapy.
Has toxicities from previous anticancer therapies that have not resolved to baseline levels or CTCAE grade ≤1, with the exception of alopecia and peripheral neuropathy.
Has had radiotherapy within 14 days before the initiation of study treatment

What this trial measures

  • Number of participants who experience at least 1 Dose Limiting Toxicity (DLT)First 28 days of treatment
  • Proportion of participants who experience at least 1 DLT during the first 28 days of treatmentFirst 28 days of treatment
  • Objective response rate (ORR) defined as the percentage of participants with partial response or complete response based on RECIST 1.112 months
  • Incidence of TEAEs/SAEs ≥ grade 212 months
  • Frequency of TEAEs according to CTCAE v5.0 criteria12 months