Efficacy and safety of ethanolamine oleate in sclerotherapy in patients with difficult-to-resect venous malformations: A multicenter, open-label, single-arm study

Objective To evaluate the efficacy and safety of sclerotherapy in patients with difficult-to-resect venous malformations treated with ethanolamine oleate. Design and setting This investigator-initiated clinical trial employed a multicenter, single-arm, open-label design and was conducted in Japan. Patients Overall, 44 patients with difficult-to-resect venous malformations were categorized into two cohorts: 22 patients with cystic-type malformations and 22 patients with diffuse-type malformations. Interventions Patients received injections of 5% ethanolamine oleate solution, double diluted with contrast or normal saline, with a maximum dose of 0.4 mL/kg. The same method of administration was used for children (<15 years old). The maximum volume of the prepared solution in one treatment was 30 mL. Evaluation methods Treatment efficacy was assessed by evaluating changes in lesion volume using magnetic resonance imaging and changes in pain using a visual analog scale. Results Among the 45 patients who consented, one was excluded owing to potential intracranial involvement of venous malformations during screening. Regarding the primary outcome, 26 of 44 patients (59.1%, 95% confidence interval: 44.41–72.31%) achieved ≥ 20% reduction in malformation volume, with 16 patients having cystic lesions (72.7%, 51.85–86.85%) and 10 patients having diffuse lesions (45.5%, 26.92–65.34%). Both cohorts showed significant improvement in self-reported pain scores associated with lesions 3 months post-sclerotherapy. No death or serious adverse events occurred. Hemoglobinuria was observed in 23 patients (52%), a known drug-related adverse event. Prompt initiation of haptoglobin therapy led to full recovery within a month for these patients. Conclusions Ethanolamine oleate shows potential as a therapeutic sclerosing agent for patients with difficult-to-resect venous malformations.