Chronic lymphedema in patients with kaposiform hemangioendothelioma: incidence, clinical features, risk factors and management

Sirolimus for kaposiform hemangioendothelioma: Potential mechanisms of action and resistance

Kaposiform hemangioendotheliomas (KHEs) are vascular tumors that are considered borderline or locally aggressive and may lead to lethal outcomes. Traditional therapies, such as surgery and embolization, may be insufficient or technically impossible for patients with KHE. Sirolimus (or rapamycin), a specific inhibitor of mechanistic target of rapamycin, has recently been demonstrated to be very useful in the treatment of KHEs. Here, we highlight recent substantial progress regarding the effects of sirolimus on KHEs and discuss the potential mechanisms of action of sirolimus in treating this disease. The prevention of platelet activation and inflammation, along with antiangiogenic effects, the inhibition of lymphangiogenesis, the attenuation of fibrosis, or a combination of all these effects, may be responsible for the therapeutic effects of sirolimus. In addition, the mechanism of sirolimus resistance in some KHE patients is discussed. Finally, we review the somatic mutations that have recently been identified in KEH lesions, and discuss the potential of novel therapeutic targets based on these further understandings of the cellular and molecular pathogenesis of KHE.

Consensus statement for the diagnosis, treatment, and prognosis of kaposiform hemangioendothelioma

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor that typically presents in infancy or early childhood. As awareness of KHE increases, it is imperative that the management of KHE be updated to reflect the latest evidence-based guidelines. The aim of this study was to integrate the literature and Chinese expert opinions to provide updated recommendations that will guide the diagnosis, treatment, and prognosis of patients with KHE. According to this consensus statement, 28 nationally peer-recognized experts in vascular anomalies and an expert in evidence-based medicine were assembled and formed three consensus subgroups. A series of key themes and questions were developed for each group, including recommendations for diagnosis, treatment, and prognosis. A systematic search was conducted for English-language articles published in PubMed and other relevant studies identified by the expert panel. A diagnosis of KHE necessitates the integration of clinical, imaging, and histologic features. The treatment of KHE should be tailored to the specific characteristics of each patient, including the size of the lesion, the presence of symptoms, the location, and the overall condition of the patient. In addition to focusing on the disease itself, it is also important to consider the complications of KHE and their impact on prognosis. The recommendations presented herein are intended to assist in the guidance of clinical practice and decision-making in patients with KHE, with the objective of improving patient outcomes.

Sirolimus for vascular anomalies in the first year of life: a systematic review

Evidence on effectiveness and safety of sirolimus in congenital vascular anomalies in infancy is lacking. We aim to systematically review the efficacy and safety of sirolimus in treating congenital VA in infancy. We searched for and included all studies evaluating sirolimus for VA in the first year of life. The primary outcome was effectiveness. The secondary outcome was safety. We included 84 case series and reports (172 participants). Sirolimus decreased the size of the VA in >50% of participants, most of whom had minor transient side effects, and 27% had no adverse effects at all. When categorized by age (<1 month, 1-5 months and 6-12 months), the effectiveness was similar in all age groups. Available evidence suggests that sirolimus is effective and well tolerated. The effectiveness of sirolimus should be evaluated in a well-designed randomized controlled or observational studies.

Kaposiform Hemangioendothelioma with Bone Destruction: A 16-Year Follow-Up Cohort Study of the Clinical Characteristics and Prognosis

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that often occurs in infants and young children. The goal of this study was to analyze the clinical characteristics of KHE patients with bone destruction and provide clinical guidance for diagnosis and treatment.

METHODS

We conducted a descriptive cohort study with follow-up from January 2007 to January 2023 to collect demographic information and tumor-related clinical information from KHE patients with bone destruction.

RESULTS

A total of 269 KHE patients were included in the study, of whom 70 (26.0%) patients had tumors with bone destruction. The median age at diagnosis of patients with bone destruction was 19.0 months, which was much later than that of patients without bone destruction (P < 0.001). Patients with bone destruction were more likely to have a decreased range of motion (ROM) (P < 0.001). Metaphysis involvement was more likely to occur in the lower limb bones (P = 0.039), and the lower limb bones were more likely to be associated with decreased ROM (P = 0.001). Tumors involving extracompartmental bone were more likely to have decreased ROM (P = 0.003) and exhibit the Kasabach-Merritt phenomenon (P = 0.006).

CONCLUSIONS

Based on the rarity and significant heterogeneity of KHE patients with bone destruction, we should give full play to the role of multidisciplinary teams in addressing disease to reduce the long-term complications of KHE with bone destruction and improve the quality of life of patients.

TYPE OF STUDY

Prognostic Study.

LEVEL OF EVIDENCE

Level II.

Long-term outcomes of sirolimus treatment for kaposiform hemangioendothelioma: Continuing successes and ongoing challenges

Treatment with sirolimus, an inhibitor of the mammalian target of rapamycin pathway, has improved the prognosis of patients with kaposiform hemangioendothelioma (KHE). However, the efficacy, durability and tolerability of long-term sirolimus treatment in patients with KHE have not been well elucidated. We performed efficacy and safety assessments based on more than 4.5 years of follow-up in patients receiving sirolimus therapy for KHE. One hundred sixty-seven patients were analyzed, including 102 (61.1%) patients with the Kasabach-Merritt phenomenon (KMP). Follow-up was conducted after a median of 56.0 months. A total of 154 (92.2%) patients had a durable response to sirolimus treatment. No difference in durable response was found between patients without KMP and patients with KMP (95.4% vs 90.2%; difference, 5.2%; 95% confidence interval [CI], -4.0% to 13.1%). Rebound growth occurred in 17.3% of patients upon sirolimus discontinuation. Early treatment discontinuation (odds ratio [OR]: 3.103; 95% CI: 1.529-6.299; P = .002) and mixed lesion type (OR: 2.271; 95% CI: 0.901-5.727; P = .047) were associated with tumor rebound growth. No KHE-related deaths occurred in this cohort. At the last follow-up, approximately 17.4% of patients had active disease and/or changes in body structures to a variable extent. Serious adverse events occurred most commonly during the first year of sirolimus therapy. Follow-up of almost 4.5 years demonstrated that the efficacy of sirolimus persisted over time and that long-term treatment with sirolimus was not associated with unacceptable cumulative toxicities. However, nonresponse, tumor relapse and long-term sequelae remained challenges despite intensified and prolonged sirolimus therapy.

How we approach lymphedema in the pediatric population

Lymphedema in children is rare; however, it is usually a progressive and chronic condition. Accurate diagnosis of lymphedema in the pediatric population often takes several months and sometimes is delayed for years. Lymphedema can be isolated or associated with genetic syndromes, thus it is very important to identify the correct diagnosis, to select carefully which patients to refer for genetic testing, and to initiate appropriate treatment in a timely fashion. In this article, we review key information about diagnosis of lymphedema, associated conditions and syndromes, and current treatment modalities.

How we approach lymphedema in the pediatric population

Lymphedema in children is rare; however, it is usually a progressive and chronic condition. Accurate diagnosis of lymphedema in the pediatric population often takes several months and sometimes is delayed for years. Lymphedema can be isolated or associated with genetic syndromes, thus it is very important to identify the correct diagnosis, to select carefully which patients to refer for genetic testing, and to initiate appropriate treatment in a timely fashion. In this article, we review key information about diagnosis of lymphedema, associated conditions and syndromes, and current treatment modalities.

Effective low-dose sirolimus regimen for kaposiform haemangioendothelioma with Kasabach-Merritt phenomenon in young infants

AIMS

Management of kaposiform haemangioendotheliomas (KHE) with Kasabach-Merritt phenomenon is challenging in young infants who are subjected to developmental pharmacokinetic changes. Sirolimus, sometimes combined with corticosteroids, can be used as an effective treatment of KHE. Simultaneously, toxicities such as interstitial pneumonitis related to the use of sirolimus may be fatal. As infants have a very low CYP3-enzyme expression at birth, which rises during ageing, we hypothesize that a reduced metabolization of sirolimus might lead to high sirolimus serum levels and low dose may be sufficient without the side effects.

METHODS

A case series of 5 infants with kaposiform haemangioendothelioma with Kasabach-Merritt phenomenon was analysed retrospectively. All infants were treated with sirolimus 0.2 mg/m2 every 24 or 48 hours according to their age. Prednisone was added to the therapy for additional effect in 4 patients.

RESULTS

In all patients, low dose of sirolimus led to therapeutic sirolimus levels (4-6 ng/mL). All infants (aged 4 days-7 months) had a complete haematological response, without serious adverse events. In all patients, the Kasabach-Merritt phenomenon resolved, the coagulation profile normalized and tumour size reduction was seen.

CONCLUSION

Low-dose sirolimus treatment is safe for infants with kaposiform haemangioendothelioma and Kasabach-Merritt phenomenon. It is essential to realize that during the first months of life, metabolism is still developing and enzymes necessary to metabolise drugs like sirolimus still have to mature. To avoid toxic levels, the sirolimus dosage should be based on age and the associated pharmacological developments.

Sirolimus plus prednisolone vs sirolimus monotherapy for kaposiform hemangioendothelioma: a randomized clinical trial

The Kasabach-Merritt phenomenon (KMP) in kaposiform hemangioendothelioma (KHE) is characterized by life-threatening thrombocytopenia and consumptive coagulopathy. This study compared the efficacy and safety of sirolimus plus prednisolone vs sirolimus monotherapy as treatment strategies for KHE with KMP in the largest cohort to date. Participants were randomized to receive either sirolimus in combination with a short course of prednisolone or sirolimus monotherapy for at least 12 months. The primary outcome was defined as achievement of a durable platelet response (platelet count >100 × 109/L) at week 4. Participants completed efficacy assessments 2 years after the initial treatment. At week 4, a durable platelet response was achieved by 35 of 37 patients given sirolimus and prednisolone compared with 24 of 36 patients given sirolimus monotherapy (difference 27.9%; 95% confidence interval, 10.0-44.7). Compared with the sirolimus monotherapy group, the combination treatment group showed improvements in terms of measures of durable platelet responses at all points during the initial 3-week treatment period, median platelet counts during weeks 1 to 4, increased numbers of patients achieving fibrinogen stabilization at week 4, and objective lesion responses at month 12. Patients receiving combination therapy had fewer blood transfusions and a lower total incidence of disease sequelae than patients receiving sirolimus alone. The frequencies of total adverse events and grade 3-4 adverse events during treatment were similar in both groups. The responses seen in patients with KHE with KMP were profound and encouraging, suggesting that sirolimus plus prednisolone should be considered a valid treatment of KHE with KMP. This trial was registered at www.clinicaltrials.gov as #NCT03188068.

Antiproliferative therapy with sirolimus and propranolol for congenital vascular anomalies in newborns (Case reports)

We present a series of four newborns diagnosed with complicated congenital vascular anomalies, with different localization: Congenital lymphatic malformation (CLM) on the left hemithorax extending on the left upper limb; congenital hepatic hemangioma (CHH) with important complications in the first 7 weeks of life; Kaposiform hemangioendothelioma (KHE) of the left lower limb complicated with Kasabach Merritt phenomenon (KMM) and most probable diffuse capillary malformation with overgrowth (DCMO). All patients were treated with combined antiproliferative therapy with sirolimus and propranolol. The initial dose of sirolimus was 0.45-0.5 mg/m² with doses adjusted according to plasmatic levels. Therapeutic intervals of sirolimus were considered at plasmatic levels of 7-12 ng/ml. Our aim was to use the lowest therapeutic dose in order to avoid possible side effects. Propranolol was initiated in doses of 0.5-1.0 mg/kg/day and was increased up to 3.0 mg/kg/day depending on tolerability. Following two months, every patient showed a marked reduction in the size of the mass, improvement in overall appearance or even calcification in the liver vascular tumor. No patient showed life threatening side effects to the treatment. Hypertriglyceridemia was the only side effect noted in all patients. This is in accordance with several international studies, which try to demonstrate the importance of sirolimus in neonatal vascular malformations in monotherapy or combined with different drugs.