90Y-microspheres are resin- (SIRspheres) or glass- (TheraSpheres) based microspheres with embedded 90Y. Both products were filed as a brachytherapy drug and as such still to be considered as a medical device.
90Y-microspheres are approved for a larger number of indications (depending upon the territories). These indications, described with the acronym SIRT for Selective Internal Radio-Therapy, include all metastasized tumors that spread to the liver. Data are available for use in hepatocellular carcinoma (HCC) and liver metastases of colorectal, neuroendocrine tumors, breast, and ocular melanoma tumors, as well as liver metastases of cholangiocarcinoma and a series of different primary cancers for which no large, specific clinical trials have been performed. In all these indications, this product has shown significant increase in overall survival (up to several years), but not full cure.
As this product is generic, several companies are developing analogues while others are exploring microspheres labeled with different radionuclides such as 166Ho.