Glowing cancer tool illuminates benign, but dangerous, brain tumors during pituitary surgery

University of Pennsylvania School of Medicine

PHILADELPHIA – An experimental imaging tool that uses a targeted fluorescent dye successfully lit up the benign brain tumors of patients during removal surgery, allowing surgeons to identify tumor tissue, a new study from researchers at the Perelman School of Medicine at the University of Pennsylvania shows. The tumors, known as pituitary adenomas, are the third most common brain tumor, and very rarely turn cancerous, but can cause blindness, hormonal disorders, and in some cases, gigantism.

Findings from the pilot study of 15 patients, published this week in the Journal of Neurosurgery, build upon previous clinical studies showing intraoperative molecular imaging developed by researchers at Penn’s Center for Precision Surgery can improve tumor surgeries. According to first author John Y.K. Lee, MD, MSCE, an associate professor of Neurosurgery in the Perelman School of Medicine at the University of Pennsylvania and co-director of the Center for Precision Surgery, this study describes the first targeted, near infrared dye to be employed in brain tumor surgery. Other dyes are limited either by their fluorescent range being in the busy visible spectrum or by lack of specificity.

“This study heralds a new era in personalized tumor surgery. Surgeons are now able to see molecular characteristics of patient’s tumors; not just light absorption or reflectance,” Lee said. “In real time in the operating room, we are seeing the unique cell surface properties of the tumor and not just color. This is the start of a revolution.”

Non-specific dyes have been used to visualize and precisely cut out brain tumors during resection surgery, but this dye is believed to be the first targeted, near infrared dye to be used in neurosurgery. The fluorescent dye, known as OTL38, consists of two parts: vitamin B9 (a necessary ingredient for cell growth), and a near infrared glowing dye. As tumors try to grow and proliferate, they overexpress folate receptors. Pituitary tumors can overexpress folate receptors more than 20 times above the level of the normal pituitary gland in some cases. This dye binds to these receptors and thus allows us to identify tumors.

“Pituitary adenomas are rarely cancerous, but they can cause other serious problems for patients by pushing up against parts of their brain, which can lead to Cushing’s disease, gigantism, blindness and death,” Lee explained. “The study shows that this novel, targeted, near infrared fluorescent dye technique is safe, and we believe this technique will improve surgery.”

Lee says larger studies are warranted to further demonstrate its clinical effectiveness, especially in nonfunctioning pituitary adenomas.

A big challenge with this type of brain surgery is ensuring the entire tumor is removed. Parts of the tumor issue are often missed by conventional endoscopy approaches during removal, leading to a recurrence in 20 percent of patients. The researchers showed that the technique was safe and effective at illuminating the molecular features of the tumors in the subset of patients with nonfunctioning pituitary adenomas.

The technique uses near-infrared, or NIR, imaging and OTL38 fluoresces brightly when excited by NIR light. The VisionSense IridiumTM 4mm endoscope is a unique camera system which can be employed in the narrow confines of the nasal cavity to illuminate the pituitary adenoma. Both the dye and the camera system are needed in order to perform the surgery successfully.

The rate of gross-total resection (GTR) for the 15 patients, based on postoperative MRI, was 73 percent. The GTR with conventional approaches ranges from 50 to 70 percent. Residual tumor was identified on MRI only in patients with more severe tumors, including cavernous sinus invasion or a significant extrasellar tumor.

In addition, for the three patients with the highest overexpression of folate, the technique predicted post-operative MRI results with perfect concordance.

Some centers have resorted to implementing MRI in the operating room to maximize the extent of resection. However, bringing a massive MRI into the operating room theater remains expensive and has been shown to produce a high number of false-positives in pituitary adenoma surgery. The fluorescent dye imaging tool, Lee said, may serve as a replacement for MRIs in the operating room.

Co-authors on the study include M. Sean Grady, MD, chair of Neurosurgery at Penn, and Sunil Singhal, MD, an associate professor of Surgery, and co-director the Center for Precision Surgery.

Over the past four years, Singhal, Lee, and their colleagues have performed more than 400 surgeries using both nonspecific and targeted near infrared dyes. The breadth of tumor types include lung, brain, bladder and breast.

Most recently, in July, Penn researchers reported results from a lung cancer trial using the OTL38 dye. Surgeons were able to identify and remove a greater number of cancerous nodules from lung cancer patients with the dye using preoperative positron emission tomography, or PET, scans. Penn’s imaging tool identified 60 of the 66 previously known lung nodules, or 91 percent. In addition, doctors used the tool to identify nine additional nodules that were undetected by the PET scan or by traditional intraoperative monitoring.

Researchers at Penn are also exploring the effectiveness of additional contrast agents, some of which they expect to be available in the clinic within a few months.

“This is the beginning of a whole wave of new dyes coming out that may improve surgeries using the fluorescent dye technique,” Lee said. “And we’re leading the charge here at Penn.”

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This study was supported in part by the National Institutes of Health (R01 CA193556), the Institute for Translational Medicine and Therapeutics of the Perelman School of Medicine at the University of Pennsylvania, and the National Center for Advancing Translational Sciences of the National Institutes of Health (UL1TR000003).

Editor’s Note: Dr. Singhal holds patent rights over the technologies presented in this article.

Penn Medicine is one of the world’s leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation’s first medical school) and the University of Pennsylvania Health System, which together form a $6.7 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 20 years, according to U.S. News & World Report’s survey of research-oriented medical schools. The School is consistently among the nation’s top recipients of funding from the National Institutes of Health, with $392 million awarded in the 2016 fiscal year.

The University of Pennsylvania Health System’s patient care facilities include: The Hospital of the University of Pennsylvania and Penn Presbyterian Medical Center — which are recognized as one of the nation’s top “Honor Roll” hospitals by U.S. News & World Report — Chester County Hospital; Lancaster General Health; Penn Wissahickon Hospice; and Pennsylvania Hospital — the nation’s first hospital, founded in 1751. Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Good Shepherd Penn Partners, a partnership between Good Shepherd Rehabilitation Network and Penn Medicine.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2016, Penn Medicine provided $393 million to benefit our community.

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From https://eurekalert.org/pub_releases/2017-09/uops-gct090517.php

Familial isolated pituitary adenoma (AIP study)

Professor Márta Korbonits is the Chief Investigator for the NIHR Clinical Research Network supported familial pituitary adenomas study (AIP) which is investigating the cause, the clinical characteristics and family screening of this relatively recently established disease group.

Please tell us about the condition in layman’s terms?
Pituitary adenomas are benign tumours of the master gland of the body, the pituitary gland. It is found at the base of the brain. The most commonly identified adenoma type causing familial disease makes excess amounts of growth hormone, and if this starts in childhood the patient have accelerated growth leading them to become much taller than their peers. This condition is known as gigantism.

How rare is this condition?
Pituitary adenomas cause disease in 1 in a 1000 person of the general population. About five to seven percent of these cases are familial pituitary adenomas.

How it is normally diagnosed?
There are different types of pituitary adenomas causing quite varied diseases. Gigantism and its adult counterpart acromegaly is usually diagnosed due to rapid growth, headaches, joint pains, sweating, high blood pressure and visual problems. Pituitary adenomas grow slowly and it usually takes 2-10 years before they get diagnosed. The diagnosis finally is made by blood tests measuring hormones, such as growth hormone, and doing an MRI scan of the pituitary area.

What is the study aiming to find out?
The fact that pituitary adenomas can occur in families relatively commonly was not recognised until recently. Our study introduced testing for gene alterations in the AIP (Aryl Hydrocarbon Receptor Interacting Protein) gene in the UK, and identified until now 38 families with 160 gene carriers via screening. We also aim to identify the disease-causing genes in our other families as well.

How will it benefit patients?
The screening and early treatment of patients can have a huge benefit to patients as earlier treatment will lead to less complications and better chance to recovery. We hope we can stop the abnormal growth spurts therefore avoiding gigantism. Patients that are screened will find out if they carry the AIP gene and whether they are likely to pass on the gene to their families. For most patients, knowing they have a gene abnormality also helps them to understand and accept their condition.

How will it change practice?
As knowledge of the condition becomes more understood, genetic testing of patients to screen for AIP changes should be more commonplace. Patients can be treated knowing they have this condition, and family members who are carriers of the gene can benefit from MRI scans to monitor their pituitary gland and annual hormone tests.

How did the NIHR CRN support the study?
The familial pituitary adenoma study is on the NIHR CRN Portfolio. The study’s association with NIHR has allowed the widespread assessment of the patients, has incentivised referrals from clinicians and raised awareness of both our study and the familial pituitary adenoma condition itself.

For more information contact NIHR CRN Communications Officer, Damian Wilcock on 020 3328 6705  or email damian.wilcock@nihr.ac.uk

From https://www.crn.nihr.ac.uk/blog/case_study/national-rare-disease-day-2016-familial-isolated-pituitary-adenoma-aip-study/

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