NCT05768139

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

First-in-Human Study of STX-478, a Mutant-Selective PI3Kα Inhibitor as Monotherapy and in Combination With Other Antineoplastic Agents in Participants With Advanced Solid Tumors

• Status: Recruiting
• Phase: Phase 1 / Phase 2
• Study type: Interventional
• Enrollment: 720 (estimated)
• Sponsor: Eli Lilly and Company · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

Study STX-478-101 (LY4064809) 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. Part 3 will evaluate STX-478 as combination therapy with endocrine therapy (aromatase inhibitors, fulvestrant or imlunestrant) and a CDK4/6 Inhibitor (either Ribociclib, Palbociclib or Abemaciclib) in participants with HR+ breast cancer. Each study part will include a 28-day screening period, followed by treatment with STX-478 monotherapy or combination therapy.

Conditions

• Breast Cancer
• Solid Tumors, Adult

Interventions

Type	Name	Description
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

Timeline

• Start date: 2023-04-17
• Primary completion: 2030-07-01
• Completion: 2030-07-01
• First posted: 2023-03-14
• Last updated: 2026-03-02

Locations

67 sites across 9 countries: United States, Belgium, France, Germany, Ireland, Italy, Japan, Netherlands, Spain

Regulatory

• FDA-regulated drug study