Successful outcome with oral sirolimus treatment for complicated lymphatic malformations: a retrospective multicenter cohort study

ABSTRACT

Purpose@#Sirolimus has emerged as a safe and effective treatment for complicated lymphatic malformations (LMs). We aim to prove the effectiveness and safety of sirolimus as a therapeutic option for patients with complicated LMs. Methods: Fifty-eight patients with complicated LMs treated with sirolimus for at least 6 months at multicenter between July 2018 and January 2023 were enrolled. All patients were administered oral sirolimus starting at 0.8 mg/m 2 every 12 hours, with target serum concentration levels of 8–15 ng/mL. Evaluation for clinical symptoms and LMs volume on MRI were reviewed to assess treatment response and toxicities. Evaluation of disease response was divided into 3 valuescomplete response, partial response (significant, moderate, and modest), and progressive disease. @*Results@#The median age at the initiation of sirolimus treatment was 6.0 years (range, 1 month–26.7 years). The median duration of treatment was 2.0 years (range, 6 months–4.4 years). The most common lesions were head and neck (25 of 58, 43.1%). Forty-six patients (79.3%) demonstrated a reduction in LMs volume on MRI or improvement of clinical symptoms including 2 complete responses. The young age group and the patients who underwent few prior therapies showed better responses. None of the patients had toxicities attributable to sirolimus with a Common Terminology Criteria for Adverse Events grade of ≥3. @*Conclusion@#Oral sirolimus treatment brought a successful outcome without severe adverse effects. It could be the firstline therapy, especially for the young age group of complicated LMs, and an additional option for refractory lesions that did not respond to conventional treatment.