Oral Sirolimus Therapy for Patients with Complex Low-flow Vascular Malformations.

The evidence on the efficacy and safety of sirolimus therapy in patients with low-flow vascular malformations (LFVM) has indicated its potential benefit in extensive and complicated lesions. This study aimed to assess the efficacy and safety of oral sirolimus therapy on complex LFVM patients when standard treatment alone was inadequate.

Methods: This was a retrospective study of all adult patients with diagnosed LFVMs who were treated with oral sirolimus where standard therapy was inadequate in a single specialist centre from 1^st May 2016 until 30^th April 2023. Demographic and clinical data including patient reported responses, visual analogue scores for pain and adverse effects, and quality-of-life (QoL) scores (SF-36) were reviewed.

Results: 55 LFVM patients (14 with syndromic disease and 41 with non-syndromic) with a median age of 41 (range 23 to 72) years were included. 32 patients (58.2%) experienced some improvement whilst on sirolimus with a non-significant higher percentage of non-syndromic patients experiencing some improvements (p=0.6478). There was a non-significant improvement in the QoL scores for physical problems, energy/fatigue and pain. There was also a non-significant increase in anxiety and depression scores. There was a significant decrease in the lesion size (p=0.0004). Two patients reported a cessation of cellulitis episodes, and eight patients reported a partial or complete reduction in bleeding from their malformation or rectal bleeding. The most common side effects reported were mouth ulcers (54.5%), fatigue (29.1%), headache (25.5%), gastrointestinal problems (25.5%), rash (12.7%) and only five (9.1%) did not report any side effects. No significant difference was found between the side effects reported by syndromic and non-syndromic patients.

Conclusion: Oral sirolimus therapy was clinically effective and safe in patients with complex LFVM when standard therapy alone was inadequate. Further studies with longer follow-up are needed to evaluate oral sirolimus therapy in LFVM patients.