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New Analysis Reveals Immune Composition of Some Pituitary Tumors

April 23, 2020
by Jennifer Chen

Pituitary tumors are the third most common type of primary brain tumor in adults. They can affect the production of hormones that are responsible for many bodily functions, such as growth, stress response, and more. Currently, pituitary tumors are treated with medication, surgery, or radiation, all of which can have side effects. There is currently no effective treatment available for aggressive cases. This is why Yale neurosurgery chief resident Jacky Yeung, MD is hoping that the newest cancer treatment on the block, immunotherapy, could be used on pituitary tumors as well.

Immunotherapies, popularized in the last decade, are drugs that potentiates the immune system to help the body fight cancer. There are several types of immunotherapies, ranging from immune checkpoint inhibitors, which take the “brakes” off your immune system to allow It to respond more strongly to cancer, to monoclonal antibodies, which are lab-created proteins that bind to cancer cells and help your immune system identify them as targets. While immunotherapies seem a promising alternative to the heavy-handed treatment options we have now, one of the biggest hurdles to making them the new standard of care is knowing which therapy is most effective for each cancer.

In a paper published on April 1, 2020, in the Journal of Neuro-Oncology titled, “In silico analysis of the immunological landscape of pituitary adenomas,” Dr. Yeung attempts to help us get closer to answering that question. He and Yale MD/PhD student Danielle Miyagishima analyzed the genetic data of 134 pituitary adenomas (benign pituitary tumors) from a previously published gene expression dataset to begin categorizing how various adenomas are infiltrated by different kinds of immune cells. He found that the majority of adenomas contained immunosuppressive macrophages, while Cushing tumors, which over-secrete steroidal hormones, had higher CD8+ T cells fractions than others, which suggest that immune checkpoint inhibitor type drugs could be a useful treatment.

“The basic thought is that to beat the enemy you have to know enemy,” says Dr. Yeung, noting that the main obstacle in using immunotherapies on pituitary tumors has been a lack of understanding about which therapies to use, based on the immune compositions in these tumors.

While the analysis in this paper was digital and may not capture all the complexities of a real-life tumor, it provides significant understanding to the treatment of pituitary tumors using immunotherapies.

“My impetus for this study is because immunotherapy is a hot topic and has gained traction over last decade, but in order to properly implement immunotherapy we have to understand what makes up the tumor,” says Dr. Yeung. “The next steps would be to confirm these findings using other assays and design immunotherapy trials based on those results.”

Submitted by Jennifer Chen on April 23, 2020