NCT05768139 · Eli Lilly and Company
First-in-Human Study of STX-478 as Monotherapy and in Combination With Other Antineoplastic Agents in Participants With Advanced Solid Tumors
What this study is about
Study STX-478-101 is a multipart, where both patients and doctors know the treatment given, phase 1/2 study evaluating the safety, tolerability, how the drug moves through the body (PK), and preliminary antitumor activity of STX-478 (LY4064809) in participants with advanced solid tumors with P13Ka mutations.
View original scientific description
Study STX-478-101 is a multipart, open-label, phase 1/2 study evaluating the safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity of STX-478 (LY4064809) in participants with advanced solid tumors with P13Ka mutations. Part 1 will evaluate STX-478 as monotherapy in participants with advanced solid tumors. Part 2 will evaluate STX-478 therapy as combination therapy with fulvestrant in participants with hormone receptor positive (HR+) breast cancer.
Interventions
DRUG
STX-478
STX-478 is a mutant-selective PI3Kα inhibitor
DRUG
Fulvestrant
Fulvestrant
DRUG
Ribociclib
Ribociclib
DRUG
Palbociclib
Palbociclib
DRUG
Letrozole
Letrozole
DRUG
Anastrozole
Anastrozole
DRUG
Exemestane
Exemestane
DRUG
Tamoxifen
Tamoxifen
DRUG
Abemaciclib
Abemaciclib
DRUG
Imlunestrant
Imlunestrant
DRUG
Metformin
Metformin
Primary outcome measures
Number of participants who experience at least 1 Dose Limiting Toxicity (DLT)
Time frame: First 28 days of treatment
Proportion of participants who experience at least 1 DLT during the first 28 days of treatment
Time frame: First 28 days of treatment
Objective response rate (ORR) defined as the percentage of participants with partial response or complete response based on RECIST 1.1
Time frame: 12 months
Incidence of TEAEs/SAEs ≥ grade 2
Time frame: 12 months
Frequency of TEAEs according to CTCAE v5.0 criteria
Time frame: 12 months
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Has an advanced or refractory solid tumor malignancy that is metastatic or locally advanced and unresectable (as specified by Cohort) 2. Has a new or recent tumor biopsy (collected at screening, if feasible) or will provide an adequate tissue sample prior to screening 3. Has a tumor that harbors a documented PI3Kα mutation (cohort specific criterion for cohort-specific mutation types) 4. Is ≥18 years of age at the time of signing the ICF 5. Has an ECOG performance status score of 0 or 1 at screening 6. Has adequate organ function as defined per protocol Key
Exclusion criteria
- Has history (within ≤2 years before screening) of a solid tumor or hematological malignancy that is histologically distinct from the cancers being studied 2. Has symptomatic brain or spinal metastases 3. 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). 4. Has had prior t
Where
- Los Angeles, California
- San Francisco, California
- Aurora, Colorado
- New Haven, Connecticut
- Lake Mary, Florida
- Tampa, Florida
- Atlanta, Georgia
- Iowa City, Iowa
- New Orleans, Louisiana
- Boston, Massachusetts
- Detroit, Michigan
- Grand Rapids, Michigan
And 13 more locations — see the full list below.
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jul 7, 2026 · Source of record for eligibility and locations