A Phase I Study of CS5007 in Participants With Advanced Solid Tumors

A Phase I, Dose-Escalation and Dose-Expansion Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Anti Tumor Activities of CS5007, a Novel EGFR and HER3 Bispecific Antibody-Drug Conjugate, in Participants With Advanced Solid Tumors

This is a first-in-human (FIH), open-label, and multi-center Phase I study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of CS5007 as monotherapy in participants with advanced solid tumors. The study is comprised of a Phase Ia dose escalation and Phase Ib dose expansion.

Study Overview

• Status: Not yet recruiting
• Conditions: Advanced Solid Tumors
• Intervention / Treatment: Drug: CS5007

• Study Type: Interventional
• Enrollment (Estimated): 310
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Sean Yao; Phone Number: +86 18616365940; Email: yaosheng@cstonepharma.com

Study Locations

• Australia
  • Queensland
    • South Brisbane, Queensland, Australia, 4101
      • Icon Cancer Centre South Brisbane
      • Principal Investigator: Jermaine Coward
  • Western Australia
    • Nedlands, Western Australia, Australia, 6009
      • Linear Clinical Research
      • Principal Investigator: Wee Chin
• China
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 200030
      • Shanghai Chest Hospital
      • Principal Investigator: Shun Lu
      • Principal Investigator: Ziming Li

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Evidence of a personally signed and dated informed consent document.
• Willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.
• Being ≥ 18 years of age on the day of signing informed consent.
• Pathologically or cytologically confirmed, unresectable advanced solid tumors.
• Participants must have at least one measurable lesion according to RECIST Version1.1.
• Eastern Cooperative Oncology Group (ECOG) Performance Score of 0 or 1.
• Adequate organ function.
• Life expectancy ≥ 3 months.
• Fertile men and women of childbearing potential must agree to use an effective method of birth control from providing signed consent and for 180 days after the last study drug administration

Exclusion Criteria:

• Has disease that is suitable for local treatment administered with curative intent.
• Has a history of a second malignancy active within the previous 3 years except for locally curable cancers that have been apparently cured.
• Known primary central nervous system (CNS) tumor or solid tumor CNS metastasis that is symptomatic, untreated, or requires therapy.
• Has life-threatening bleeding event or severe bleeding within 3 months prior to first dose.
• Has uncontrolled pleural effusion, pericardial effusion, or ascites.
• Has immune deficient disease or received systemic immunosuppressive treatment.
• Has intestinal obstruction,or history of inflammatory bowel disease,or chronic diarrhea.
• Has history of (non-infectious) interstitial lung disease/pneumonitis that required steroids.
• Has active infections requiring systemic therapy.
• Has significant cardiovascular disease or cerebrovascular accident within specified timeframes prior to first dose.
• Insufficient washout from prior anti-tumor therapy.
• Received live vaccine within 28 days prior to first dose.
• History of allogeneic organ or hematopoietic stem cell transplantation.
• History of hypersensitivity to excipients of study drug or any monoclonal antibody.
• Any toxic effects of prior therapy unresolved to Grade ≤1.
• Active alcohol or drug abuse.
• Pregnant or breastfeeding women.
• Other acute or chronic medical or psychiatric conditions that may increase risk or interfere with study results, in the investigator's judgment.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dose Escalation; Participants will be administered escalating doses of CS5007.	Drug: CS5007; CS5007 will be administered via intravenous (IV) infusion on Day 1 of repeated 21-day cycles (Q3W).
Experimental: Dose Expansion; Participants will be administered the recommended dose(s) of CS5007 according to dose-escalation data.	Drug: CS5007; CS5007 will be administered via intravenous (IV) infusion on Day 1 of repeated 21-day cycles (Q3W).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
[Dose Expansion] Objective response rate (ORR) evaluated by investigators per RECIST v1.1		Up to approximately 2 years
[Dose Escalation] Maximum tolerated dose (MTD) of CS5007	Participants will receive CS5007 via intravenous (IV) infusion on Day 1 of repeated 21-day cycles (Q3W). The MTD will be determined, if any, by the number of participants who experience a dose limiting toxicity (DLT).	Cycle 1 (Up to 21 Days)
[Dose Escalation] Tentative recommended Phase II dose (RP2D) of CS5007	The selection of tentative RP2D will be based on consideration of overall safety information together with available pharmacokinetic, pharmacodynamic, and efficacy data. The tentative RP2D may be the MTD or a lower dose within the tolerable dose range.	Up to approximately 2 years
[Dose Escalation] The incidence and severity of adverse events (AEs)		Up to approximately 2 years

Secondary Outcome Measures

Outcome Measure	Time Frame
[Dose Escalation] Objective response rate (ORR) evaluated by investigators per RECIST v1.1	Up to approximately 2 years
[Dose Escalation & Expansion] Area under the curve (AUC) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Maximum concentration (Cmax) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Time to maximum concentration (Tmax) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Elimination half-life (t1/2) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Clearance (CL) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Volume of distribution (Vz) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Trough concentration (Ctrough) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Accumulation ratio (R) of CS5007	Up to approximately 2 years
[Dose Escalation & Expansion] Number of participants with anti-CS5007 antibodies	Up to approximately 2 years
[Dose Escalation & Expansion] Duration of response (DOR) evaluated by investigators per RECIST v1.1	Up to approximately 2 years
[Dose Escalation & Expansion] Disease control rate (DCR) evaluated by investigators per RECIST v1.1	Up to approximately 2 years
[Dose Expansion] The incidence and severity of adverse events (AEs)	Up to approximately 2 years

Collaborators and Investigators

• Sponsor: CStone Pharmaceuticals

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): January 1, 2028
• Study Completion (Estimated): January 1, 2029

Study Registration Dates

• First Submitted: May 28, 2026
• First Submitted That Met QC Criteria: May 28, 2026
• First Posted (Actual): June 3, 2026

Study Record Updates

• Last Update Posted (Actual): June 3, 2026
• Last Update Submitted That Met QC Criteria: May 28, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: EGFR; Phase I; Advanced Solid Tumors; HER3; Bispecific Antibody-Drug Conjugate
• Other Study ID Numbers: CS5007-101

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: No
• Studies a U.S. FDA-regulated device product: No