A label for a brain tumor
Specialists from the University of Pennsylvania, working under the guidance of Associate Professor John Y.K. Lee, have developed an experimental imaging tool that uses a fluorescent dye to label benign brain tumors directly during surgery to remove them. Such tumors, known as pituitary adenomas, are the third most common among brain tumors and are rarely malignant, but they compress brain tissue, which can lead to the development of blindness, hormonal disorders and, in some cases, gigantism.
Complete removal of such a tumor using traditional endoscopic methods is quite a difficult task, and in about 20% of patients, the surviving fragments of tumor tissue form new tumors. The approach proposed by the authors makes it possible to identify the molecular characteristics of tumor tissue during surgery and effectively remove it.
Non-specific tags have previously been used to visualize and accurately remove brain tumors. In contrast, the OTL38 dye used by the authors is considered the first selective label in neurosurgical practice. Its molecule consists of two components: vitamin B9 (folic acid), a compound necessary for cell growth, and a fluorescent protein that emits a glow in the near infrared region of the spectrum. As the tumor grows and proliferates, its cells express an increasing number of folic acid receptors. The expression levels of these receptors on pituitary tumor cells in some cases may be more than 20 times higher than normal values. The OTL38 dye binds to these receptors, allowing the selective identification of tumor cells.
During the pilot clinical trial involving 15 patients, the scientists used VisionSense IridiumTM 4-millimeter endoscopes and a unique camera system suitable for use in a very limited space of the nasal sinuses. Magnetic resonance imaging (MRI) performed after surgery confirmed complete removal of the tumor in 73% of the study participants. Residual tumors were detected only in patients with the most severe tumors, including those that had grown into the cavernous sinus.
At the same time, for three patients with the highest levels of folic acid expression, the new technology made it possible to accurately predict the results of postoperative MRI.
To increase the effectiveness of pituitary adenoma removal, some surgical centers resort to the use of MRI directly during surgery. However, placing the massive equipment necessary for this inside the operating room requires a lot of financial costs. In addition, this approach often gives false positive results. The authors believe that the use of fluorescent dye is a very promising alternative, however, for further confirmation of the clinical effectiveness of the method, it is necessary to conduct larger-scale clinical studies.
Article by John Y. K. Lee et al. Folate receptor overexpression can be visualized in real time during pituitary adenoma endoscopic transsphenoidal surgery with near-infrared imaging published in the Journal of Neurosurgery.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the Perelman School of Medicine at the University of Pennsylvania: Penn's Glowing Cancer Tool Illuminates Benign, but Dangerous, Brain Tumors during Pituitary Surgery.
08.09.2017