Genetic Test Highly Accurate in Differentiating Thymomas From Thymic Carcinoma Tumors

FRIENDSWOOD, Texas, Sept. 25, 2013 /PRNewswire/ -- Castle Biosciences Inc. today announced data from a study of a genetic test demonstrating high accuracy in differentiating thymomas from thymic carcinoma tumors. Thymomas and thymic carcinomas are both rare epithelial tumors of the thymus gland that can be challenging to differentiate, yet have very different metastatic behaviors. The study results were presented by researchers at the Indiana University School of Medicine at the Fourth International Thymic Malignancy Interest Group (ITMIG) Annual Meeting on September 7. Based on these study results, the genetic test now offers doctors an accurate and accessible method for making a precise diagnosis. This information can help choose the most effective and personalized treatment options for patients.

"This study shows that the gene signature can predictably differentiate thymomas from thymic carcinomas, two thymic cancers which can have a similar appearance but greatly varying behaviors," commented Sunil Badve, M.D., FRCPath, Professor of Pathology and Laboratory Medicine at the Indiana University School of Medicine. "Thymic cancers are typically much more aggressive and require immediate post-surgery treatment, while some thymomas are slow growing and patients may benefit from avoiding or delaying treatments associated with severe toxicities."

Study Details
Twenty-three genes were analyzed in formalin-fixed, paraffin-embedded archived tumor samples (111 primary thymomas, 35 thymic carcinomas). The test demonstrated very high overall accuracy, sensitivity and specificity (ROC 0.957), with an accuracy of 100% and 93% in the training (n=97) and confirmatory (n=47) data sets.

Commented Yesim Gokmen-Polar, PhD, Assistant Research Professor of Pathology and Laboratory Medicine at the Indiana University School of Medicine, "The availability of a tool that helps confirm an accurate diagnosis can help physicians move rapidly ahead with the most appropriate treatment plan, giving the patient the greatest chance for an extended, good quality life."

A gene expression profile signature is already in use for predicting whether a thymoma tumor will metastasize within 5 years¹, helping some patients avoid treatments associated with adverse events. This test, called DecisionDx-Thymoma, is available to physicians through Castle Biosciences Inc., which exclusively licensed the test from Indiana University. More information about the test, including how to order, can be found at www.thymiccancer.com.

About Thymic Cancer
The thymus is a small organ that is part of the lymph system and located just beneath the breastbone. There are two main types of thymic cancers: thymic carcinoma and thymoma. Both are extremely rare cancers; thymoma accounts for 90% of cases and is diagnosed in approximately 500 people in the United States each year. Thymic carcinoma and thymoma have very different metastatic behaviors and can be challenging to differentiate. Thymic carcinoma is considered to be more aggressive than thymoma, yet not all of these patients experience rapid recurrence or metastasis. In comparison, thymoma usually does not spread outside of the thymus. It can occasionally spread to the lining of the lung (or pleura), but rarely spreads to other internal organs. While only 10% of thymomas are metastatic at the time of diagnosis, some patients will experience recurrence at some point after treatment. The cause of cancer in the thymus is not well understood, but it appears to be most common in adults between the ages of 40 and 70. Thymic cancer symptoms can include chest pain, shortness of breath, or a choking sensation, but often the tumor shows no signs at all and is discovered incidentally during a doctor's visit.

About Castle Biosciences
Castle Biosciences is a molecular diagnostics and prognostics company dedicated to helping patients and their physicians make the best possible decisions about their treatment and follow-up care based on the individual molecular signature of their tumor. The Company currently offers tests for patients with skin melanoma and other rare cancers including uveal melanoma, thymoma, esophageal and brain cancers. More information can be found at www.castlebiosciences.com.

^1. "A Gene Signature to Determine Metastatic Behavior in Thymomas" was published in the July 24, 2013 issue of PLOS One and authored by Dr. Badve, Yesim Gokmen-Polar, Ph.D. and Patrick J. Loehrer Sr., M.D., all of Indiana University School of Medicine. The full article can be found at: http://dx.plos.org/10.1371/journal.pone.0066047

SOURCE Castle Biosciences Inc.