A Phase I Study to Evaluate the Safety and Preliminary Efficacy of [225Ac]Ac-DOTATATE Injection Combined With Tislelizumab in the Maintenance Treatment Period for Patients of Extensive-stage Small Cell Lung Cancer (ES-SCLC) With Somatostatin Receptors (SSTR)+ as First-line Treatment

This is a phase I study to evaluate the safety and preliminary efficacy of [225Ac]Ac-DOTATATE injection combined with tislelizumab in the maintenance treatment period for patients of extensive-stage small cell lung cancer (ES-SCLC) with somatostatin receptors (SSTR)+ as first-line treatment.Patients with ES-SCLC who have completed the induction therapy of first-line standard treatment and are yet to enter the maintenance treatment period are planned to be enrolled.

Study Overview

• Status: Recruiting
• Conditions: SCLC, Extensive Stage
• Intervention / Treatment: Drug: [225Ac]Ac-DOTATATE

• Study Type: Interventional
• Enrollment (Estimated): 24
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Zhi Yang; Phone Number: 010-88196196; Email: pekyz@163.com

Study Locations

• China
  • Beijing Municipality
    • Beijing, Beijing Municipality, China, 100000
      • Recruiting
      • Peking University Cancer Hospital & Institute
      • Contact: Zhi Yang; Phone Number: 010-88196196; Email: pekyz@163.com

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Patients must have the ability to understand and sign an approved informed consent form (ICF).
2. Patients must be >= 18 and <＝80 years of age.
3. Extensive-stage small cell lung cancer that requires histopathological or cytological confirmation.
4. Presence of at least 1 measurable site of disease (based on RECIST 1.1).
5. ECOG score of 0 or 1.
6. SSTR-PET positive.

7. Sufficient bone marrow capacity and organ function:

   Serum creatinine ≤1.5×ULN or creatinine clearance ≥50 ml/min (Cockcroft Gault formula).

   Hemoglobin≥90g/L, neutrophil count ≥1.5×10^9/L, platelets≥100×10^9/L. Serum total bilirubin ≤1.5×ULN. Serum albumin ≥30g/L. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≤ 2.5×ULN，or ALT/AST≤5×ULN with liver metastases.

   Partially activated prothrombin time (APTT) ≤1.5 x ULN.

8. Subjects of childbearing potential voluntarily use an effective method of contraception, such as condoms, oral or injectable contraceptives, IUDs, etc., during treatment and within 6 months of the last use of the trial drug.

Exclusion Criteria:

1. Pregnant or lactating females.
2. Received systemic antitumor therapy such as targeted therapy, immunotherapy, antitumor herbal therapy, chemotherapy within 4 weeks prior to initiation of study treatment.
3. Uncontrolled congestive heart failure.
4. uncontrolled diabetes mellitus, including baseline fasting glucose > 2 x ULN.
5. Known hypersensitivity to Lutetium[177Lu] Oxodotreotide Injection or [225Ac]Ac-DOTATATE Injection and their excipients.
6. Other treatment options (e.g., chemotherapy, targeted therapy) that, in the opinion of the investigator, are more appropriate for the patient than the treatment provided in the study based on the patient's disease characteristics.
7. Unsuitable for the study for any reason, in the opinion of the investigator.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: [225Ac]Ac-DOTATATE; The subjects received the [225Ac]Ac-DOTATATE injection combined with tislelizumab. The tislelizumab was administered at a fixed dose of 200mg on day 1, and was given every 3 weeks. The [225Ac]Ac-DOTATATE injection was administered once every 6 (±1) weeks, with a maximum of 4 administrations.

Drug: [225Ac]Ac-DOTATATE; During the dose escalation phase, the "3+3" dose escalation method was adopted. There were two dose groups: the single-dose administration dose of the first dose group was 90 kBq/kg, and that of the second dose group was 120 kBq/kg.During the dose expansion phase, the subjects received the RP2D dose of the [225Ac]Ac-DOTATATE injection. The administration method, combination therapy, etc. were all the same as those in the dose escalation phase.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
During the dose escalation phase, the efficacy of [225Ac]Ac-DOTATATE injection at the RP2D dose for maintenance treatment in first-line therapy for SSTR-positive ES-SCLC patients when used in combination with tislelizumab was evaluated.	Incidence and severity of adverse events (AEs) DLT MTD RP2D	6 months after last dose administration
During the dose expansion phase, the efficacy of [225Ac]Ac-DOTATATE injection at the RP2D dose for maintenance treatment in first-line therapy for SSTR-positive ES-SCLC patients when used in combination with tislelizumab was evaluated.	PFS	12 months after last dose administration

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
During the dose escalation phase, the efficacy of [225Ac]Ac-DOTATATE injection for use as a maintenance treatment in the first-line therapy of SSTR-positive ES-SCLC patients when combined with tislelizumab was evaluated.	PFS	12 months after last dose administration
During the dose escalation phase, the efficacy of [225Ac]Ac-DOTATATE injection for use as a maintenance treatment in the first-line therapy of SSTR-positive ES-SCLC patients when combined with tislelizumab was evaluated.	ORR	12 months after last dose administration
During the dose escalation phase, the efficacy of [225Ac]Ac-DOTATATE injection for use as a maintenance treatment in the first-line therapy of SSTR-positive ES-SCLC patients when combined with tislelizumab was evaluated.	DCR	12 months after last dose administration
During the dose escalation phase, the efficacy of [225Ac]Ac-DOTATATE injection for use as a maintenance treatment in the first-line therapy of SSTR-positive ES-SCLC patients when combined with tislelizumab was evaluated.	OS	12 months after last dose administration
During the dose expansion phase, other efficacy endpoint indicators will be evaluated.	PFS since the first-line treatment	12 months after last dose administration
During the dose expansion phase, other efficacy endpoint indicators will be evaluated.	ORR	12 months after last dose administration
During the dose expansion phase, other efficacy endpoint indicators will be evaluated.	DCR	12 months after last dose administration
During the dose expansion phase, other efficacy endpoint indicators will be evaluated.	OS	12 months after last dose administration
During the dose expansion phase, the safety is evaluated.	Incidence and severity of adverse events (AEs)	6 months after last dose administration

Collaborators and Investigators

• Sponsor: Peking University Cancer Hospital & Institute

Study record dates

Study Major Dates

• Study Start (Actual): January 20, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): June 30, 2028

Study Registration Dates

• First Submitted: January 18, 2026
• First Submitted That Met QC Criteria: February 9, 2026
• First Posted (Actual): February 17, 2026

Study Record Updates

• Last Update Posted (Actual): February 17, 2026
• Last Update Submitted That Met QC Criteria: February 9, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: IIT-XT024-1-02

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