68Ga-SorB PET/CT Imaging in Patients With Solid Tumors (SORB-PET)

A Prospective, Single-Center, Open-Label Exploratory Study of 68Ga-SorB PET/CT Imaging for the Diagnosis of Sortilin-Positive Solid Tumors

This prospective, single-center, open-label exploratory diagnostic study aims to evaluate the safety, feasibility, and diagnostic performance of the novel Sortilin-targeted PET tracer 68Ga-SorB in patients with solid tumors. Eligible participants with confirmed or suspected melanoma, hepatocellular carcinoma, lung cancer, pancreatic cancer, breast cancer, or ovarian cancer will undergo 68Ga-SorB PET/CT imaging. The imaging findings will be compared with standard-of-care 18F-FDG PET/CT, using pathology results and/or clinical follow-up as the reference standard.

The primary objectives are to evaluate the safety and tolerability of 68Ga-SorB, assess imaging feasibility, and characterize tumor uptake using quantitative PET parameters, including SUVmax and tumor-to-background ratio (TBR). Secondary exploratory objectives include comparing lesion detection between 68Ga-SorB PET/CT and 18F-FDG PET/CT, assessing diagnostic sensitivity and specificity, evaluating imaging characteristics across different tumor types, and exploring the correlation between Sortilin expression and tracer uptake. This study will provide preliminary clinical evidence supporting the development of Sortilin-targeted molecular imaging and future theranostic applications.

Study Overview

• Status: Recruiting
• Conditions: Breast Cancer; Hepatocellular Carcinoma; Pancreatic Cancer; Ovarian Cancer; Lung Cancer; Melanoma (Skin Cancer)
• Intervention / Treatment: Diagnostic test: 68Ga-SorB PET/CT

Detailed Description

Background Sortilin is a type I transmembrane receptor belonging to the VPS10 receptor family. It is highly expressed in a variety of malignancies, including melanoma, hepatocellular carcinoma, lung cancer, pancreatic cancer, breast cancer, and ovarian cancer, while showing relatively low expression in most normal tissues. Due to its tumor-specific expression pattern and efficient receptor-mediated internalization, Sortilin has emerged as a promising molecular target for cancer imaging and targeted theranostic applications.

Although ^18F-FDG PET/CT is widely used for oncologic imaging, its diagnostic performance may be limited by nonspecific uptake in inflammatory lesions, resulting in false-positive findings. Therefore, a more tumor-specific PET tracer may improve lesion detection and diagnostic accuracy.

Study Design This is a prospective, single-center, open-label, exploratory diagnostic imaging study designed to evaluate the clinical performance of the novel Sortilin-targeted PET radiotracer ^68Ga-SorB. Approximately 40-50 adult patients with confirmed or suspected melanoma, hepatocellular carcinoma, lung cancer, pancreatic cancer, breast cancer, pancreatic cancer, or ovarian cancer will be enrolled. All participants will undergo ^68Ga-SorB PET/CT imaging according to the study protocol. Standard-of-care ^18F-FDG PET/CT performed within the predefined time window will be used as the comparator whenever available.

Histopathological findings and/or clinical and imaging follow-up will serve as the reference standard for evaluating diagnostic performance.

Study Objectives The primary objectives are to evaluate the safety and tolerability of ^68Ga-SorB, assess imaging feasibility, and characterize tracer biodistribution and tumor uptake using quantitative PET parameters, including SUVmax and tumor-to-background ratio (TBR).

Secondary exploratory objectives include comparison of lesion detection between ^68Ga-SorB PET/CT and ^18F-FDG PET/CT, estimation of diagnostic sensitivity, specificity, and accuracy, evaluation of tracer uptake across different tumor types, assessment of the association between Sortilin expression and imaging parameters, and exploration of the potential clinical value of ^68Ga-SorB PET/CT in tumor diagnosis and staging.

Study Significance This exploratory clinical study is expected to generate preliminary evidence regarding the safety, feasibility, and diagnostic performance of ^68Ga-SorB PET/CT in patients with solid tumors. The results may support further multicenter validation studies and facilitate the clinical development of Sortilin-targeted molecular imaging and future theranostic strategies.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Meixin Zhao; Phone Number: 86-10-82264936; Email: zhaomeixin.student@sina.com

Study Locations

• China
  • Beijing Municipality
    • Beijing, Beijing Municipality, China, 100191
      • Recruiting
      • Peking University Third Hospital
      • Contact: Meixin Zhao; Phone Number: 86-10-82264936; Email: zhaomeixin.student@sina.com

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• - Adults aged 18 to 75 years.
• Histologically confirmed or clinically suspected melanoma, hepatocellular carcinoma, lung cancer, breast cancer, pancreatic cancer, or ovarian cancer.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Adequate hematologic, hepatic, renal, and coagulation function:
• White blood cell count ≥ 4.0 × 10^9/L or absolute neutrophil count ≥ 1.5 × 10^9/L;
• Platelet count ≥ 100 × 10^9/L;
• Hemoglobin ≥ 90 g/L;
• PT or APTT ≤ 1.5 × upper limit of normal (ULN);
• Total bilirubin ≤ 1.5 × ULN;
• ALT and AST ≤ 2.5 × ULN (or ≤ 5 × ULN for participants with liver metastases);
• ALP ≤ 2.5 × ULN (or ≤ 4.5 × ULN for participants with bone or liver metastases);
• Blood urea nitrogen and serum creatinine ≤ 1.5 × ULN.
• Normal cardiac function.
• Estimated life expectancy of at least 12 weeks.
• Willing and able to comply with study procedures and follow-up.
• At least one measurable target lesion according to RECIST version 1.1.
• Participants of childbearing potential agree to use effective contraception during the study and for 3 months after PET/CT imaging.
• Clinically indicated to undergo 18F-FDG PET/CT for tumor evaluation.
• Able to understand the study procedures and provide written informed consent.

Exclusion Criteria:

• Pregnant or breastfeeding women.
• Severe dysfunction of major organs (including heart, liver, or kidney) that, in the investigator's judgment, would make participation inappropriate.
• Inability to tolerate PET/CT imaging or complete study follow-up.
• Any other condition that, in the investigator's judgment, makes the participant unsuitable for the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: 68Ga-SorB PET/CT Imaging; Participants with suspected or confirmed malignant tumors will receive a single intravenous administration of 68Ga-SorB followed by PET/CT imaging. Imaging findings will be compared with clinically indicated 18F-FDG PET/CT performed within the predefined time window. No therapeutic intervention will be administered as part of this study.

Diagnostic test: 68Ga-SorB PET/CT; Participants will receive a single intravenous administration of 68Ga-SorB (approximately 3.7 MBq/kg), followed by whole-body PET/CT imaging approximately 60 minutes after injection. The imaging findings will be compared with clinically indicated 18F-FDG PET/CT and reference standard findings to evaluate the safety, feasibility, biodistribution, tumor uptake, and exploratory diagnostic performance of 68Ga-SorB PET/CT.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of adverse events related to 68Ga-SorB PET/CT	Incidence and severity of adverse events (AEs) and serious adverse events (SAEs) related to administration of 68Ga-SorB, graded according to CTCAE.	From tracer administration until completion of the imaging visit (approximately 24 hours).
Successful completion of 68Ga-SorB PET/CT imaging	Proportion of participants completing 68Ga-SorB PET/CT with evaluable image quality.	At completion of PET/CT imaging (approximately 60 minutes after tracer injection)
Tumor uptake of 68Ga-SorB measured by SUVmax	Maximum standardized uptake value (SUVmax) of target lesions measured on 68Ga-SorB PET/CT.	At PET/CT imaging (approximately 60 minutes after tracer injection)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Lesion detection rate on 68Ga-SorB PET/CT	Detection rate of reference standard-confirmed primary and metastatic tumor lesions visually identified on 68Ga-SorB PET/CT. Lesion detection will be assessed by lesion-based visual interpretation of 68Ga-SorB PET/CT images by nuclear medicine physicians. The detection rate will be calculated as the percentage of reference standard-confirmed lesions detected on 68Ga-SorB PET/CT. The reference standard will include pathology, clinical diagnosis, and/or imaging follow-up, as applicable.	At completion of 68Ga-SorB PET/CT imaging, with reference-standard adjudication up to approximately 3 months after imaging.
Cohen's kappa coefficient for lesion detection agreement between 68Ga-SorB PET/CT and 18F-FDG PET/CT	Agreement in lesion detection between 68Ga-SorB PET/CT and clinically indicated 18F-FDG PET/CT. For each evaluable lesion, detection status will be recorded as detected or not detected on each PET/CT modality based on lesion-based visual image interpretation by nuclear medicine physicians. Agreement between the two PET/CT modalities will be assessed using Cohen's kappa coefficient with 95% confidence interval. Unit of Measure: Cohen's kappa coefficient, unitless.	Within 2 weeks after completion of both PET/CT examinations.
Diagnostic sensitivity of 68Ga-SorB PET/CT for lesion detection	Diagnostic sensitivity of 68Ga-SorB PET/CT for lesion detection will be calculated using pathology, clinical diagnosis, and/or imaging follow-up as the reference standard. Lesion detection will be assessed by lesion-based visual interpretation of 68Ga-SorB PET/CT images by nuclear medicine physicians. Unit of Measure: Percentage.	Within approximately 3 months after PET/CT imaging, following completion of pathology assessment, clinical diagnosis, and/or imaging follow-up.
Tumor SUVmax on 68Ga-SorB PET/CT by tumor type	Maximum standardized uptake value of tumor lesions on 68Ga-SorB PET/CT across different tumor types, including malignant melanoma, hepatocellular carcinoma, lung cancer, breast cancer, pancreatic cancer, and ovarian cancer, as applicable. SUVmax will be measured on fused PET/CT images using ROI/VOI delineation. Unit of Measure: Unitless standardized uptake value.	At completion of 68Ga-SorB PET/CT imaging, approximately 60 minutes after tracer administration.
Correlation between Sortilin expression H-score and 68Ga-SorB PET/CT uptake parameters	Correlation between Sortilin expression in pathological tumor specimens and quantitative 68Ga-SorB PET/CT uptake parameters, including SUVmax and tumor-to-background ratio. For participants with available tissue samples, Sortilin expression will be measured by immunohistochemistry and reported as an H-score. SUVmax and tumor-to-background ratio will be measured on fused PET/CT images using ROI/VOI delineation. Correlation will be assessed using Pearson correlation analysis or Spearman rank correlation analysis, as appropriate. Unit of Measure: Correlation coefficient, unitless. Underlying Variable Units: Sortilin H-score, score range 0-300; SUVmax, unitless standardized uptake value; tumor-to-background ratio, unitless ratio.	Within approximately 3 months after PET/CT imaging, following completion of pathological assessment.
Percentage of participants with a change in clinical diagnosis or tumor staging after 68Ga-SorB PET/CT	Percentage of participants whose clinical diagnosis or tumor staging changes after review of 68Ga-SorB PET/CT findings compared with the pre-PET/CT assessment based on standard imaging and clinical information. Changes in clinical diagnosis or tumor stage will be determined by investigator review of available clinical, imaging, pathological, and follow-up information. Unit of Measure: Percentage of participants.	Within approximately 3 months after 68Ga-SorB PET/CT imaging.
Diagnostic specificity of 68Ga-SorB PET/CT for lesion detection	Diagnostic specificity of 68Ga-SorB PET/CT for lesion detection will be calculated using pathology, clinical diagnosis, and/or imaging follow-up as the reference standard. Lesion detection will be assessed by lesion-based visual interpretation of 68Ga-SorB PET/CT images by nuclear medicine physicians. Unit of Measure: Percentage.	Within approximately 3 months after PET/CT imaging, following completion of pathology assessment, clinical diagnosis, and/or imaging follow-up.
Diagnostic accuracy of 68Ga-SorB PET/CT for lesion detection	Diagnostic accuracy of 68Ga-SorB PET/CT for lesion detection will be calculated using pathology, clinical diagnosis, and/or imaging follow-up as the reference standard. Lesion detection will be assessed by lesion-based visual interpretation of 68Ga-SorB PET/CT images by nuclear medicine physicians. Unit of Measure: Percentage.	Within approximately 3 months after PET/CT imaging, following completion of pathology assessment, clinical diagnosis, and/or imaging follow-up.
Positive predictive value of 68Ga-SorB PET/CT for lesion detection	Positive predictive value of 68Ga-SorB PET/CT for lesion detection will be calculated using pathology, clinical diagnosis, and/or imaging follow-up as the reference standard. Lesion detection will be assessed by lesion-based visual interpretation of 68Ga-SorB PET/CT images by nuclear medicine physicians. Unit of Measure: Percentage.	Within approximately 3 months after PET/CT imaging, following completion of pathology assessment, clinical diagnosis, and/or imaging follow-up.
Negative predictive value of 68Ga-SorB PET/CT for lesion detection	Negative predictive value of 68Ga-SorB PET/CT for lesion detection will be calculated using pathology, clinical diagnosis, and/or imaging follow-up as the reference standard. Lesion detection will be assessed by lesion-based visual interpretation of 68Ga-SorB PET/CT images by nuclear medicine physicians. Unit of Measure: Percentage.	Within approximately 3 months after PET/CT imaging, following completion of pathology assessment, clinical diagnosis, and/or imaging follow-up.

Collaborators and Investigators

• Sponsor: Peking University Third Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): July 24, 2026
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: July 29, 2026
• First Submitted That Met QC Criteria: August 9, 2026
• First Posted (Actual): August 12, 2026

Study Record Updates

• Last Update Posted (Actual): August 12, 2026
• Last Update Submitted That Met QC Criteria: August 9, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: PET/CT; Positron Emission Tomography; Oncology; Radiotracer; Diagnostic Imaging; Molecular Imaging; Sortilin; 68Ga-SorB
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Endocrine System Diseases; Urogenital Neoplasms; Neoplasms by Site; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Respiratory Tract Diseases; Neoplasms by Histologic Type; Digestive System Neoplasms; Digestive System Diseases; Genital Diseases, Female; Lung Diseases; Endocrine Gland Neoplasms; Pancreatic Diseases; Liver Diseases; Neoplasms, Glandular and Epithelial; Adenocarcinoma; Liver Neoplasms; Respiratory Tract Neoplasms; Thoracic Neoplasms; Ovarian Diseases; Adnexal Diseases; Genital Neoplasms, Female; Gonadal Disorders; Skin Diseases; Breast Diseases; Carcinoma; Neuroectodermal Tumors; Neoplasms, Germ Cell and Embryonal; Neoplasms, Nerve Tissue; Neuroendocrine Tumors; Nevi and Melanomas; Skin Neoplasms; Skin and Connective Tissue Diseases; Neoplasms; Carcinoma, Hepatocellular; Lung Neoplasms; Ovarian Neoplasms; Breast Neoplasms; Pancreatic Neoplasms; Melanoma
• Other Study ID Numbers: IRB00006761-M20260651

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be made publicly available because of participant privacy considerations and institutional data-sharing policies.

Drug and device information, study documents

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