Indications and Limitations of Sirolimus in the Treatment of Vascular Anomalies-Insights From a Retrospective Case Series

BACKGROUND

Despite recent developments, the role of sirolimus in the heterogeneous spectrum of vascular anomalies is yet to be defined, in terms of indication, dosage, and therapy duration, recognizing both its potential and limitations.

METHODS

We retrospectively analyzed 16 children with vascular anomalies treated with sirolimus in two pediatric centers between 2014 and 2020 [male: n = 7, the median age at diagnosis: 4.6 months (range, 0-281.4)]. In addition, repetitive volumetric analyses of the vascular anomalies were performed when possible (11 cases).

RESULTS

Ten patients were diagnosed with vascular malformations and 6 with vascular tumors. The mean therapy duration was 27.2 months (range, 3.5-65). The mean sirolimus level was 8.52 ng/ml (range, 5.38-12.88). All patients except one with central conducting lymphatic anomaly responded to sirolimus, with the most noticeable volume reduction in the first 4-6 months. Additional administration of vincristine was needed in five patients with kaposiform hemangioendothelioma and yielded a response, even in cases, refractory to sirolimus monotherapy. As a single agent, sirolimus led to impressive improvement in a patient with another vascular tumor-advanced epithelioid hemangioendothelioma. Complicated vascular malformations required long-term sirolimus therapy. Side effects of sirolimus included mucositis and laboratory abnormalities. No major infectious episodes were recorded. An infant with COVID-19, diagnosed while on sirolimus therapy, presented with a mild course.

CONCLUSION

In the current series, we reported limitations of sirolimus as monotherapy, addressing the need to redefine its indications, and explore combination regimens and multimodal treatment strategies. Tools for objective evaluation of response trends over time could serve as a basis for the establishment of future therapeutic algorithms.

The Phenotype and Treatment of WIP Deficiency: Literature Synopsis and Review of a Patient With Pre-transplant Serial Donor Lymphocyte Infusions to Eliminate CMV

Early diagnosis of primary immunodeficiency disorders (PID) is vital and allows directed treatment, especially in syndromes with severe or profound combined immunodeficiency. In PID patients with perinatal CMV or other opportunistic, invasive infections (e.g., Pneumocystis or Aspergillus), multi-organ morbidity may already arise within the first months of life, before hematopoietic stem cell transplantation (HSCT) or gene therapy can be undertaken, compromising the definitive treatment and outcome. Deficiency of Wiskott-Aldrich syndrome (WAS) protein-interacting protein (WIP deficiency) causes an autosomal recessive, WAS-like syndrome with early-onset combined immunodeficiency that has been described in three pedigrees to date. While WAS typically includes combined immunodeficiency, microthrombocytopenia, and eczema, the clinical and laboratory phenotypes of WIP-deficient patients-including lymphocyte subsets, platelets, lymphocyte proliferation in vitro, and IgE-varied widely and did not entirely recapitulate WAS, impeding early diagnosis in the reported patients. To elucidate the phenotype of WIP deficiency, we provide a comprehensive synopsis of clinical and laboratory features of all hitherto-described patients (n = 6) and WIP negative mice. Furthermore, we summarize the treatment modalities and outcomes of these patients and review in detail the course of one of them who was successfully treated with serial, unconditioned, maternal, HLA-identical donor lymphocyte infusions (DLI) against life-threatening, invasive CMV infection, followed by a TCRαβ/CD19-depleted, treosulfan/melphalan-conditioned, peripheral blood HSCT and repetitive, secondary-prophylactic, CMV-specific DLI with 1-year post-HSCT follow-up. This strategy could be useful in other patients with substantial premorbidity, considered "too bad to transplant," who have an HLA-identical family donor, to eliminate infections and bridge until definitive treatment.

Bone marrow necrosis in a girl with Hodgkin's disease

Bone marrow necrosis (BMN) is a rare finding in children with malignancy occurring most commonly in children with acute lymphoblastic leukemia. This article describes the first case of a girl who developed BMN during treatment for Hodgkin's disease. During the second cycle of chemotherapy, she experienced sudden profound bone pain in the lumbosacral region associated with elevated levels of lactate dehydrogenase (LDH), fibrin degradation products (D-Dimer), and alkaline phosphatase as well as pancytopenia and leukoerythroblastosis. MRI studies showed multiple confluent areas with low signal intensity and rim contrast enhancement in all vertebral bodies. Bone marrow biopsy revealed focal necrosis within hypocellular bone marrow. The patient responded quickly to symptomatic treatment with analgetics and heparin; however, elevations of LDH and D-Dimer persisted for 1.5 and 8 months, respectively. Clinicians should be aware of this rare condition to establish the diagnosis and to continue oncologic treatment as early as possible.