holmium-166

Holmium‑166 is a radioactive isotope used as a radiopharmaceutical for cancer therapy, primarily in the form of microspheres or chitosan complexes. Its main mechanism involves emitting beta particles that directly kill tumor cells and gamma photons that enable nuclear imaging. Holmium‑166 is most commonly used in Selective Internal Radiation Therapy (SIRT) for primary liver cancer (hepatocellular carcinoma) and liver metastases, where it is delivered via intra‑arterial administration to target tumors locally while minimizing damage to healthy tissue. The paramagnetic properties of holmium also allow for MRI-based imaging, making it unique among radioisotopes. Other formulations, such as DOTMP HO‑166 and holmium‑chitosan (Milican), have been explored or approved for skeletal targeted radiotherapy and other cancers including prostate cancer, glioblastoma, and skin cancer. Development for rheumatoid arthritis was discontinued[1][2][3][4][5][6][7][8].

Brand names

QuiremSpheresQuiremScoutMilican

Other names

holmium Ho 166 poly(L-lactic acid) microspheresholmium 166 chitosanholmium166 chitosanholmium-166 chitosan