Brachytherapy is an advanced cancer therapy involving implanting radioactive seeds directly in, or very close to, diseased tissue. The high dose of radiation has a very short travel length (“brachy” is Greek for short distance), blasting tumors while minimizing effect on nearby healthy cells.
IsoRay, Inc. (NYSE MKT:ISR) is developing Cesium-131 brachytherapy seeds as a new treatment for a variety of cancer types, with the most extensive research against prostate cancer. Cesium-131 is distinguished by having a higher average energy and shortest half-life compared to other prostate cancer brachytherapy isotopes.
IsoRay’s Cesium-131 therapy was detailed in a study recently published in The International Journal of Radiation Oncology, Biology, Physics. The study was conducted by Dr. Gabriella A. Wernicke and Dr. Theodore H. Schwartz of the Stich Radiation Oncology Center and Department of Neurosurgery, Brain and Spine Center, Weill Cornell Medical College/New York-Presbyterian Hospital.
The study evaluated permanent low-dose rate Cesium-131 brachytherapy on local control and radionecrosis (soft tissue death resulting from radiation exposure) in patients treated for large brain metastases. The study spanned from 2010 to 2015, during which 42 patients with a total of 46 tumors bigger than two centimeters underwent surgery to remove the tumors. During surgery, Cesium-131 seeds were implanted in the resection cavity.
Follow-up showed 100% efficacy in local progression, meaning that the tumor didn’t grow back in any of the patients. Importantly, there was zero radionecrosis reported, an impressive accomplishment given the propensity of radiation-induced cell death when treating large tumors.
The doctors concluded that IsoRay’s Cesium-131 brachytherapy is safe and effective as an adjuvant therapy alongside surgery for cancer patients with large brain metastases.
Surprisingly, shares of ISR have only moved modestly on the positive news, rather than soaring as most stocks due on positive study data.
Shares closed Monday at 56 cents and following printing as high as 62.5 cents shortly after Tuesday’s opening bell have melted a little lower than the intraday high to 60 cents for a gain of 7.1% early in the trading day.