Two pediatric oncologic cases of hypereosinophilic syndrome and review of the literature.

BACKGROUND: Persistent peripheral blood hypereosinophilia may cause tissue damage, leading to hypereosinophilic syndrome (HES) with end-organ dysfunction. Here we discuss two unique pediatric cases of primary hypereosinophilic syndrome with oncologic etiologies to highlight the importance of early recognition, workup and treatment of HES. CASE 1: A previously healthy 7-year-old male presented with acute myocardial infarction and transient ischemic attack and found to have significant hyperleukocytosis with a total white blood count of 131 000 and hypereosinophilia with an absolute eosinophil count of 99 560. He was ultimately diagnosed with precursor B-cell acute lymphoblastic leukemia with immunoglobulin heavy chain gene rearrangement. He completed standard treatment without significant complications and remains in remission at about 2 years off therapy. He is in overall good health and has normal cardiac function. CASE 2: A 13-year-old female was referred for iron deficiency and reported a history of severe anxiety, shortness of breath and anorexia. She had experienced fatigue and dizziness associated with frequent panic attacks and shortness of breath with strenuous activity since the age of five. Serial laboratory investigations revealed persistent hypereosinophilia (AEC 4000-6000/µl). Additional workup revealed elevated vitamin B12 (>2000 pg/ml; normal range: 243-894) and tryptase (16.4 ng/ml; normal range: ≤10.9). The FIP1L1-PDGFRA gene fusion was detected by fluorescence in situ hybridization (FISH) on peripheral blood, diagnostic for myeloid/lymphoid neoplasm with eosinophilia. Evaluation for end-organ damage associated with persistent hypereosinophilia included an echocardiogram which revealed severe restrictive cardiomyopathy with pulmonary hypertension. Monotherapy with imatinib was initiated, after which she achieved a rapid hematologic response and remains in molecular remission, though she continues to have persistent asymptomatic severe pulmonary hypertension in the setting of severe diastolic dysfunction. CONCLUSION: Persistent hyperosinophilia can be a silent cause of significant and often irreversible tissue damage and should therefore always prompt workup for both primary and secondary causes.

Clinical impact of selumetinib on pediatric elephantiasis neuromatosa.

Elephantiasis neuromatosa (EN) is a rare and extreme form of plexiform neurofibroma in patients with neurofibromatosis type 1 (NF1). EN is often associated with significant morbidity and remains difficult to treat. We present a case of an 11-year-old female with NF1 whose thoracolumbar plexiform neurofibroma and lower extremity EN exhibited clinical improvement from treatment with selumetinib, a selective MEK inhibitor.

Bloom syndrome in a Mexican American family with rhabdomyosarcoma: evidence of a Mexican founder mutation.

Bloom syndrome is a rare autosomal recessive disorder with less than 300 cases reported in the literature. Bloom syndrome is characterized by chromosome instability, physical stigmata, growth deficiency, immunodeficiency, and a predisposition to cancer, most commonly leukemias, although solid tumors are reported as well. Bloom syndrome occurs in multiple ethnic groups with a higher incidence in persons of Ashkenazi Jewish origin. Few patients of Hispanic ethnicity have been reported. We report here a Mexican American family with a BLM pathogenic variant, c.2506_2507delAG, previously reported in a single patient from Mexico. In this family of four siblings, three have phenotypic features of Bloom syndrome, and BLM gene mutation was homozygous in these affected individuals. Our proband developed a rhabdomyosarcoma. Analysis of surrounding markers in the germline DNA revealed a common haplotype, suggesting a previously unrecognized founder mutation in the Hispanic population of Mexican origin.

Isobaric Labeling Strategy Utilizing 4-Plex N,N-Dimethyl Leucine (DiLeu) Tags Reveals Proteomic Changes Induced by Chemotherapy in Cerebrospinal Fluid of Children with B-Cell Acute Lymphoblastic Leukemia.

The use of mass spectrometry for protein identification and quantification in cerebrospinal fluid (CSF) is at the forefront of research efforts to identify and explore biomarkers for the early diagnosis and prognosis of neurologic disorders. Here we implemented a 4-plex N,N-dimethyl leucine (DiLeu) isobaric labeling strategy in a longitudinal study aiming to investigate protein dynamics in children with B-cell acute lymphoblastic leukemia (B-cell ALL) undergoing chemotherapy. The temporal profile of CSF proteome during chemotherapy treatment at weeks 5, 10-14, and 24-28 highlighted many differentially expressed proteins, such as neural cell adhesion molecule, neuronal growth regulator 1, and secretogranin-3, all of which play important roles in neurodegenerative diseases. A total of 63 proteins were significantly altered across all of the time points investigated. The most over-represented biological processes from gene ontology analysis included platelet degranulation, complement activation, cell adhesion, fibrinolysis, neuron projection, regeneration, and regulation of neuron death. We expect that results from this and future studies will provide a means to monitor neurotoxicity and develop strategies to prevent central nervous system injury in response to chemotherapy in children.

Combined innate and adaptive immunotherapy overcomes resistance of immunologically cold syngeneic murine neuroblastoma to checkpoint inhibition.

BACKGROUND: Unlike some adult cancers, most pediatric cancers are considered immunologically cold and generally less responsive to immunotherapy. While immunotherapy has already been incorporated into standard of care treatment for pediatric patients with high-risk neuroblastoma, overall survival remains poor. In a mouse melanoma model, we found that radiation and tumor-specific immunocytokine generate an in situ vaccination response in syngeneic mice bearing large tumors. Here, we tested whether a novel immunotherapeutic approach utilizing radiation and immunocytokine together with innate immune stimulation could generate a potent antitumor response with immunologic memory against syngeneic murine neuroblastoma. METHODS: Mice bearing disialoganglioside (GD2)-expressing neuroblastoma tumors (either NXS2 or 9464D-GD2) were treated with radiation and immunotherapy (including anti-GD2 immunocytokine with or without anti-CTLA-4, CpG and anti-CD40 monoclonal antibody). Tumor growth, animal survival and immune cell infiltrate were analyzed in the tumor microenvironment in response to various treatment regimens. RESULTS: NXS2 had a moderate tumor mutation burden (TMB) while N-MYC driven 9464D-GD2 had a low TMB, therefore the latter served as a better model for high-risk neuroblastoma (an immunologically cold tumor). Radiation and immunocytokine induced a potent in situ vaccination response against NXS2 tumors, but not in the 9464D-GD2 tumor model. Addition of checkpoint blockade with anti-CTLA-4 was not effective alone against 9464D-GD2 tumors; inclusion of CpG and anti-CD40 achieved a potent antitumor response with decreased T regulatory cells within the tumors and induction of immunologic memory. CONCLUSIONS: These data suggest that a combined innate and adaptive immunotherapeutic approach can be effective against immunologically cold syngeneic murine neuroblastoma. Further testing is needed to determine how these concepts might translate into development of more effective immunotherapeutic approaches for the treatment of clinically high-risk neuroblastoma.

Advances in Anti-GD2 Immunotherapy for Treatment of High-risk Neuroblastoma.

Neuroblastoma (NBL) is the most common extracranial solid tumor in pediatrics, yet overall survival is poor for high-risk cases. Immunotherapy regimens using a tumor-selective antidisialoganglioside (anti-GD2) monoclonal antibody (mAb) have been studied for several decades now, but have only recently been incorporated into standard of care treatment for patients with high-risk NBL with clear benefit. Here we review a brief history of anti-GD2-based immunotherapy, current areas of neuroblastoma research targeting GD2, and potential diagnostic and therapeutic uses targeting GD2.

Autoimmune Ataxia During Maintenance Therapy for Acute Lymphoblastic Leukemia.

Neurologic dysfunction during acute lymphoblastic leukemia treatment is commonly associated with chemotherapy. Nonchemotherapy contributions should be considered for persistent atypical symptoms. We describe a boy with acute lymphoblastic leukemia who developed recurrent fevers, diarrhea, progressive ataxia, and neuropsychiatric impairment during maintenance chemotherapy. He was found to have cytomegalovirus in his serum and colon, but not in his cerebrospinal fluid. Instead, his cerebrospinal fluid revealed oligoclonal bands not present in the serum, suggesting an autoimmune process. Prompt treatment with ganciclovir and immunotherapy resulted in marked clinical improvement. Early recognition and treatment of an autoimmune encephalitis is paramount for optimal clinical outcome.