Trop2-Targeted Near-Infrared Fluorescence Imaging-Guided Precise Resection of Non-Muscle Invasive Bladder Cancer

• Research Background Bladder cancer ranks the fifth most common human malignancy, with an incidence rate of 81.2 per 100,000 individuals. Approximately 70% of patients present with non-muscle invasive bladder cancer (NMIBC) at initial diagnosis, wherein tumors are superficial (carcinoma in situ) or confined to the mucosa (Ta) and submucosa (T1). Up to 90% of NMIBC cases are pathologically confirmed as urothelial neoplasms. Urothelial tumors exhibit heterogeneous morphological features, which may be solitary, multiple, flat or exophytic, and can arise anywhere on the urothelial lining of the bladder. Bladder cancer generally confers a favorable prognosis, especially when detected at early Ta or T1 stages.

Although white-light cystoscopy, recommended by cancer prevention guidelines, serves as a convenient and noninvasive modality for bladder cancer detection, up to 30% of tumors may be missed-particularly small satellite lesions and flat carcinoma in situ. This oversight contributes to a recurrence rate as high as 70%, and recurrent lesions may progress to invasive carcinoma, severely impairing patients' quality of life. Therefore, improving the detection performance of bladder cancer, especially for lesions frequently overlooked by conventional approaches, will optimize the prognosis of patients with NMIBC.

Novel imaging modalities have recently been developed to enhance tumor detection rates. Endoscopic techniques including narrow-band imaging and blue-light cystoscopy have been introduced to boost tumor identification and guide endoscopic resection. Nevertheless, these approaches are limited by high false-positive rates due to insufficient specificity. Microscopic imaging technologies, such as confocal laser endomicroscopy and optical coherence tomography, can visualize tissue microarchitecture and cellular morphology; however, their narrow field of view renders them unsuitable for full bladder survey.

Near-infrared (NIR) fluorescence imaging has emerged as a promising precision imaging technique widely adopted in precision surgery. Accurate intraoperative tumor recognition relies not only on the high signal-to-noise ratio of NIR imaging but also on specific enrichment of targeted fluorescent dyes at tumor sites. Researchers have developed a variety of fluorescent probes that actively target tumors at the molecular and cellular levels for surgical navigation. Most such strategies target mutated or overexpressed tumor-specific biomarkers in solid tumors, such as folate receptor α, epidermal growth factor receptor, and tumor-associated antigens (e.g., prostate-specific membrane antigen, carcinoembryonic antigen), or exploit enzymes overexpressed in tumor tissues, including cathepsins and matrix metalloproteinases.

Human trophoblast cell surface antigen 2 (Trop2), a single-pass transmembrane cell-surface glycoprotein, belongs to the tumor-associated calcium signal transducer (TACSTD) family. Trop2 is overexpressed in multiple solid malignancies including breast cancer and bladder urothelial carcinoma, and plays critical roles in cell self-renewal, proliferation and invasion. Encouragingly, sacituzumab govitecan (SG), an antibody-drug conjugate (ADC) targeting Trop2, has been approved by the U.S. Food and Drug Administration for the treatment of locally advanced or metastatic urothelial carcinoma, further validating Trop2 as a reliable therapeutic target for bladder urothelial carcinoma. Accordingly, construction of an NIR fluorescent probe targeting Trop2 is expected to enable precise intraoperative navigation for NMIBC and improve patient prognosis.

• Research Objective Based on Trop2, a specific target of bladder urothelial carcinoma, this study employs a Trop2-targeted NIR fluorescent probe combined with a rapid intravesical incubation imaging system to investigate the safety profile of this imaging system and whether it can improve the intraoperative detection accuracy of NMIBC (to assist surgeons in localizing NMIBC lesions during surgery).
• Study Procedures If you volunteer to participate in this study and sign the informed consent form, study investigators will conduct pre-enrollment screening. You will be enrolled only if you meet all eligibility criteria.

The study consists of three phases: Screening Phase, Treatment Phase, and Follow-up Phase.

• Screening Phase You will receive clinical consultations and examinations administered by study physicians as follows: medical history collection and physical examination; collection of blood and urine specimens for laboratory tests including complete blood count, serum biochemistry, coagulation function assay, routine urinalysis, etc.; electrocardiography and B-mode ultrasonography of the liver, gallbladder, pancreas, spleen and bilateral kidneys. Study physicians will assess your eligibility for this trial based on all above examination results.

Eligibility Criteria Inclusion Criteria 1.Aged between 18 and 80 years old; 2.Suspected or confirmed bladder tumor patients scheduled for transurethral partial bladder resection; 3.Able to sign informed consent and comply with study protocols. Exclusion Criteria 1.Suffering from other invasive malignant tumors; 2.Severe concomitant diseases: congenital malformations, acute inflammation, cachexia, myocardial infarction or stroke within the past 6 months, severe hepatic or renal dysfunction, etc.; 3.Pregnant or lactating women; 4.Patients with gross hematuria or history of allergies (including drug and food allergies); 5.Complicated with cystitis, urinary tract malformations or urethral stricture; 6.Participation in other clinical trials within the preceding 30 days. Discontinuation Criteria 1.Intraoperative conversion to alternative surgical procedures (e.g., radical cystectomy); 2.Occurrence of severe adverse reactions; 3.Subject-initiated withdrawal from the clinical trial; 4.Investigators' judgment that continued participation is inappropriate for the subject.

Subjects passing screening will receive standardized treatment and follow-up in accordance with the trial protocol.

• Treatment Phase After intraoperative bladder emptying, 50 mL of TTP-ICG solution (20 μg/mL) will be instilled into the bladder for a 3-minute full incubation over the entire bladder mucosal surface. Upon incubation completion, the TTP-ICG solution will be drained, followed by three cycles of bladder irrigation with 50 mL normal saline per cycle.

A dual-modal white-light and near-infrared fluorescence endoscopic imaging system will then be utilized to image the whole bladder lumen. The number and anatomical location of lesions detected under white light and NIR fluorescence will be recorded and compared; images and video recordings will be archived for subsequent analysis. All lesions highlighted under NIR fluorescence and suspected lesions identified under white light endoscopy will be resected and submitted for pathological examination.

• Follow-up Phase The follow-up period commences immediately after surgery and lasts until postoperative Day 30. Subjects' vital signs (blood pressure, heart rate, body temperature, etc.) and symptomatic changes will be closely monitored intraoperatively and postoperatively. Blood and urine samples will be collected postoperatively for laboratory tests including complete blood count, serum biochemistry, coagulation function assay and routine urinalysis. All adverse reactions observed in subjects will be documented in detail.

Inclusion criteria

• Age between 18 and 80 years old
• Patients with suspected or confirmed bladder tumor who are scheduled for transurethral partial bladder resection
• Capable of providing written informed consent and adhering to the study protocol

Exclusion criteria

• Diagnosis of other invasive malignant tumors
• Severe comorbidities, including congenital malformations, acute inflammatory disease, cachexia, myocardial infarction or cerebrovascular stroke within the previous 6 months, severe liver or renal insufficiency
• Pregnant or breastfeeding female patients
• Patients with gross hematuria or a history of allergic reactions to drugs or food
• Concurrent cystitis, urinary tract malformation or urethral stricture
• Enrollment in another interventional clinical trial within 30 days prior to screening