Photodynamic Diagnosis of Kidney Cancer Using Fluorescence Endoscopy and Oral 5-ALA

5-Aminolevulinic Acid (5-ALA), Gleolan, Kidney Cancer, Renal Cell Carcinoma, Partial Nephrectomy, Photodynamic Diagnosis (PDD), Fluorescence-Guided Surgery, Blue Light Imaging, Tumor Detection, Surgical Margins, Safety Profile, Adverse Events, Clinical Trial, Robotic Surgery, Pathology, Fluorescence Imaging, Renal Tumors, Pilot Study, Diagnostic Accuracy, Phase III Trial

This pilot clinical study aims to evaluate the safety and efficacy of 5-aminolevulinic acid (5-ALA; Gleolan) as a fluorescence-guided imaging agent for patients undergoing partial nephrectomy for suspected kidney cancer. Although 5-ALA is currently FDA-approved for visualization of high-grade gliomas during neurosurgery, emerging evidence suggests that it may also improve the detection of renal tumors through photodynamic diagnosis (PDD). The investigators hypothesize that oral administration of 5-ALA will cause kidney tumors to fluoresce under blue light, allowing surgeons to more easily identify tumors and assess resection margins while maintaining a favorable safety profile with minimal adverse events.

The study plans to enroll 10 adult patients aged 18 to 75 years who have kidney tumors amenable to standard-of-care partial nephrectomy. Eligible participants must have good performance status (ECOG 0-1) and adequate renal, hepatic, and hematologic function. Patients with significant cardiovascular disease, active liver disease, poorly controlled infections, pregnancy, porphyria-related hypersensitivity, or other major comorbidities will be excluded.

After informed consent is obtained, patients will undergo baseline laboratory testing including a comprehensive metabolic panel (CMP), liver function tests, lactate dehydrogenase (LDH), and γ-glutamyl transferase (GGT). On the day of surgery, participants will receive 20 mg/kg of oral 5-ALA dissolved in water approximately 2-4 hours before the procedure. Patients will be monitored preoperatively for known side effects such as nausea, vomiting, hypotension, and photosensitivity.

The surgical procedure will follow standard robotic partial nephrectomy techniques, with the addition of fluorescence imaging. Surgeons will first visualize the exposed tumor under white light and capture images. The operative field will then be examined using a specially modified blue-light imaging system to determine whether the tumor exhibits fluorescence. Following tumor excision under standard white light, the resection bed will again be examined with blue light to identify any residual fluorescent tissue that may indicate remaining tumor. If concerning fluorescence is observed, additional tissue margins may be resected and sent separately for pathological examination.

The primary outcomes include the ability of blue-light fluorescence imaging to detect kidney tumors and assist in evaluating residual disease. Investigators will compare tumor detection under white light versus blue light and calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) using final surgical pathology as the gold standard. Receiver operating characteristic (ROC) curve analysis will be used to compare diagnostic performance between imaging modalities.

This proof-of-concept study seeks to determine whether 5-ALA fluorescence-guided surgery can improve intraoperative visualization of kidney tumors while maintaining an acceptable safety profile. Positive findings could support larger studies and potentially justify advancement to a Phase III clinical trial investigating fluorescence-guided kidney cancer surgery.