Skip Ribbon Commands
Skip to main content

Hepar 1

166Ho radioembolization is feasible and safe1 for the treatment of patients with unresectable and chemorefractory liver metastases and enables image-guided treatment.

21/08/2017 -  

​Main Findings HEPAR 1 study:

  • 166Ho radioembolization is considered feasible and safe1.
  • Toxicity after 166Ho-radioembolization was mainly confined to symptoms associated with post-embolization syndrome; including fatigue, nausea, vomiting, abdominal pain, fever, and anorexia.
  • The Maximum Tolerated Radiation Dose was identified to be an aimed whole liver average absorbed dose of 60 Gy.
  • The distribution of 166Ho microspheres can be visualised in vivo by both single-photon-emission CT (SPECT) and MRI, possibly enabling individualized and improved2 patient treatment in the future. 

Patient population

15 Patients with unresectable, chemo refractory liver metastases were treated in cohorts of 3 patients. The primary tumour types were ocular melanoma (6/15), colorectal carcinoma (6/15), cholangiocarcinoma involvement (2/15), and breast carcinoma (1/15).


Single radioembolization with 166Ho polylactic microspheres, administered by infusion in the liver artery using an arterial catheter in the femoral artery. Aimed whole-liver absorbed doses for consecutive dose cohorts were 20 Gy (n=6), 40 Gy (n=3), 60 Gy (n=3), and 80 Gy (n=3). 


Abdominal pain and nausea were the most frequently experienced clinical toxicities, the most frequently encountered laboratory toxicities were lymphocytopenia, hypoalbuminaemia, raised ALP, AST, and GGT. According to the study protocol, the study was stopped after two patients in the 80 Gy cohort experienced dose-limiting toxicity (DLT); grade 3/4 haematological DLT in one patient, and grade 3 abdominal pain in another patient, and the Maximum Tolerated Radiation Dose was identified as 60 Gy. Stable disease or partial response regarding target lesions was achieved in 14/15 patients at 6 weeks and 9/14 patients at 12 weeks after radioembolization.


Smits et al, Journal of Experimental & Clinical Cancer Research 2010, 29:70

Smits et al, Lancet Oncol. 2012, Oct;13(10):1025-34 Identifier: NCT01031784

1. The recommended whole liver dose of 60Gy was identified as the maximum tolerated radiation dose in a phase I trial (no dose-limiting toxicity occured in the 60Gy cohort) Smits et al, Lancet Oncol.
2012, Oct;13(10):1025-34. Identifier: NCT01031784

2. Compared to radioembolization without post-treatment imaging.