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Abstract Repurposing anticancer drugs to vascular malformations has significantly improved patient outcomes. Complex Lymphatic Anomalies (CLA) are part of the spectrum of lymphatic malformations (LMs) that share similar oncogenic mutations to cancer. We report the case of a young patient with highly symptomatic CLA who was initially treated with sirolimus, due to the frequent involvement of the PI3K-AKT-mTOR pathway in CLA pathogenesis. Despite an initial reduction in symptoms, sirolimus progressively lost its effectiveness. After an unsuccessful attempt with trametinib alone, sirolimus was added to trametinib and resulted in a significant, rapid and sustained improvement in symptoms. This suggests that, contrary to current dogmas, combination therapy using sub-therapeutic doses targeting both the PI3K and RAS pathways retains efficacy without generating the toxicity known for combination therapies, and is beneficial in the management of CLAs and potentially other vascular anomalies.

Abstract Background Theragnostic management, treatment according to precise pathological molecular targets, requests to unravel patients’ genotypes. We used targeted next-generation sequencing (NGS) or digital droplet polymerase chain reaction (ddPCR) to screen for somatic PIK3CA mutations on DNA extracted from resected lesional tissue or lymphatic endothelial cells (LECs) isolated from lesions. Our cohort (n = 143) was composed of unrelated patients suffering from a common lymphatic malformation (LM), a combined lymphatic malformation [lymphatico-venous malformation (LVM), capillaro-lymphatic malformation (CLM), capillaro-lymphatico-venous malformation (CLVM)], or a syndrome [CLVM with hypertrophy (Klippel-Trenaunay-Weber syndrome, KTS), congenital lipomatous overgrowth-vascular malformations-epidermal nevi -syndrome (CLOVES), unclassified PIK3CA-related overgrowth syndrome (PROS) or unclassified vascular (lymphatic) anomaly syndrome (UVA)]. Results We identified a somatic PIK3CA mutation in resected lesions of 108 out of 143 patients (75.5%). The frequency of the variant allele ranged from 0.54 to 25.33% in tissues, and up to 47% in isolated endothelial cells. We detected a statistically significant difference in the distribution of mutations between patients with common and combined LM compared to the syndromes, but not with KTS. Moreover, the variant allele frequency was higher in the syndromes. Conclusions Most patients with an common or combined lymphatic malformation with or without overgrowth harbour a somatic PIK3CA mutation. However, in about a quarter of patients, no such mutation was detected, suggesting the existence of (an)other cause(s). We detected a hotspot mutation more frequently in common and combined LMs compared to syndromic cases (CLOVES and PROS). Diagnostic genotyping should thus not be limited to PIK3CA hotspot mutations. Moreover, the higher mutant allele frequency in syndromes suggests a wider distribution in patients’ tissues, facilitating detection. Clinical trials have demonstrated efficacy of Sirolimus and Alpelisib in treating patients with an LM or PROS. Genotyping might lead to an increase in efficacy, as treatments could be more targeted, and responses could vary depending on presence and type of PIK3CA-mutation.

Abstract Background Extensive and complex vascular malformations often cause chronic pain and severe functional restraint. Conventional treatments, such as surgery and/or sclerotherapy, are rarely curative, underscoring the great need for new therapeutic modalities. Recent preclinical and clinical data demonstrated that sirolimus could offset the progression of vascular malformations and significantly improve quality of life of patients through inhibition of the Phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian Target of Rapamycin (mTOR) pathway. The purpose of this prospective study was to assess the efficacy and safety of this treatment in patients with extensive or complex slow-flow vascular malformations. Methods Sirolimus was administered orally on a continuous dosing schedule with pharmacokinetic-guided target serum concentration level of 10 to 15 ng/ml. Patients were seen every month for the first three months and subsequently every three months. The primary endpoints were safety and efficacy, based on clinical, biological and radiological evaluations, as well as a quality of life questionnaire. Results Nineteen patients, from 3 to 64 years old, with lymphatic (LM), venous (VM) or complex slow-flow malformations, refractory to standard care, were enrolled and received sirolimus continuously. After 12 months of follow-up, 16 patients were available for assessment of efficacy and safety: all had a significant and rapid improvement of their symptoms and quality of life. In two patients, sirolimus treatment permitted sclerotherapy and surgery, initially evaluated unfeasible. Sirolimus was well tolerated, with mucositis as the most common (10% of patients) grade 3 adverse event. Conclusions Sirolimus was efficient in extensive LM, VM and/or complex malformations that were refractory to conventional treatments and was well tolerated.