Holmium-166 Transarterial Radioembolization for the Treatment of Intrahepatic Cholangiocarcinoma: A Case Series

SIMPLE SUMMARY: Intrahepatic cholangiocarcinoma (ICC) is a liver cancer with a poor prognosis, which is often not resectable at diagnosis. The search for novel effective treatments for ICC continues, but without much progress. One of the options is treatment with small particles carrying radionuclides yttrium-90 or holmium-166, which are delivered to the tumor through the artery to irradiate it locally. This allows for fewer side effects than systemic treatments while achieving good tumor control. While substantial evidence has accumulated for yttrium-90 radiotherapy, much less evidence is available for the more recent holmium-166. This work describes a series of seven patients with ICC treated with holmium-166 transarterial radiotherapy. Most of the patients achieved good tumor control after treatment and had no severe adverse events, highlighting the tolerability of the therapy. In cases of palliative intent of the treatment, this approach can help improve the quality of life and prolong the remaining years of life. ABSTRACT: Background: Transarterial radioembolization (TARE) is used to treat primary and secondary malignancies in the liver that are not amenable to curative resection. Accumulating evidence demonstrates the efficacy and safety of TARE with yttrium-90 ((90)Y), which is the most widely used radionuclide for TARE, and later with holmium-166 ((166)Ho) for various indications. However, the safety and efficacy of (166)Ho TARE in patients with intrahepatic cholangiocarcinoma (ICC) remains to be studied. Methods: This was a retrospective case series study of seven consecutive patients with ICC who were treated with (166-)Ho-TARE in our center. We recorded the clinical parameters and outcomes of the TARE procedures, the tumor response according to mRECIST, subsequent treatments, and adverse events. Results: Three out of the seven patients had a partial or complete response. Two patients had stable disease after the first TARE procedure, and two of the patients (one with a complete response, and one with stable disease) were alive at the time of analysis. No serious adverse events related to the procedure were recorded. Conclusions: This is the first case series reporting the safety and tumor response outcomes of (166)Ho-TARE for ICC. The treatment demonstrated its versatility, allowing for reaching a high tumor dose, which is important for improving tumor response and treating patients in a palliative setting, where safety and the preservation of quality of life are paramount.