Polygenic Pharmacogenomic Markers as Predictors of Toxicity Phenotypes in the Treatment of Acute Lymphoblastic Leukemia: A Single-Center Study.

PURPOSE: Acute lymphoblastic leukemia (ALL) is the most prevalent cause of childhood cancer and requires a long course of therapy consisting of three primary phases with interval intensification blocks. Although these phases are necessary to achieve remission, the primary chemotherapeutic agents have potentially serious toxicities, which may lead to delays or discontinuations of therapy. The purpose of this study was to perform a comprehensive pharmacogenomic evaluation of common antileukemic agents and develop a polygenic toxicity risk score predictive of the most common toxicities observed during ALL treatment. METHODS: This cross-sectional study included 75 patients with pediatric ALL treated between 2012 and 2020 at the University of Florida. Toxicity data were collected within 100 days of initiation of therapy using CTCAE v4.0 for toxicity grading. For pharmacogenomic evaluation, single-nucleotide polymorphisms (SNPs) and genes were selected from previous reports or PharmGKB database. 116 unique SNPs were evaluated for incidence of various toxicities. A multivariable multi-SNP modeling for up to 3-SNP combination was performed to develop a polygenic toxicity risk score of prognostic value. RESULTS: We identified several SNPs predictive of toxicity phenotypes in univariate analysis. Further multivariable SNP-SNP combination analysis suggest that susceptibility to chemotherapy-induced toxicities is likely multigenic in nature. For 3-SNPscore models, patients with high scores experienced increased risk of GI (P = 2.07E-05, 3 SNPs: TYMS-rs151264360/FPGS-rs1544105/GSTM1-GSTM5-rs3754446), neurologic (P = .0005, 3 SNPs: DCTD-rs6829021/SLC28A3-rs17343066/CTPS1-rs12067645), endocrine (P = 4.77E-08, 3 SNPs: AKR1C3-rs1937840/TYMS-rs2853539/CTH-rs648743), and heme toxicities (P = .053, 3 SNPs: CYP3A5-rs776746/ABCB1-rs4148737/CTPS1-rs12067645). CONCLUSION: Our results imply that instead of a single-SNP approach, SNP-SNP combinations in multiple genes in drug pathways increases the robustness of prediction of toxicity. These results further provide promising SNP models that can help establish clinically relevant biomarkers allowing for greater individualization of cancer therapy to maximize efficacy and minimize toxicity for each patient.

Romiplostim as a Therapeutic Intervention for Tacrolimus-induced Immune Thrombocytopenia in a Pediatric Cardiac Transplant Patient.

Tacrolimus-induced immune thrombocytopenia (ITP) is a rare entity that can occur years after initiation of tacrolimus therapy following solid organ transplantation, and platelet recovery can be substantially delayed following discontinuation of tacrolimus. Romiplostim, a thrombopoietin receptor agonist approved by the FDA in 2018 for the treatment of chronic ITP in children, may be a useful therapy to hasten platelet recovery in the acute ITP setting in place of immunomodulating agents. We present a case of tacrolimus-induced ITP successfully treated with romiplostim in a child following cardiac transplantation.

Parvovirus B19 infection masquerading as relapsed acute lymphoblastic leukaemia following haematopoietic stem cell transplantation.

A 7-year-old boy presented with a constellation of bone pain, a skeletal lesion, and pancytopenia after undergoing allogeneic haematopoietic stem cell transplantation for recurrent acute B-cell lymphoblastic leukaemia. Investigations to rule out leukaemia recurrence were unremarkable. Due to presence of maturation arrest in erythropoiesis with giant pronormoblasts and aberrant intranuclear inclusions on a bone marrow aspirate, parvovirus B19 (PVB-19) staining was completed and confirmed the diagnosis of disseminated PVB-19. Though PVB-19 infection after solid organ transplantation was reported in the literature as early as 1986, acquired PVB-19 viremia presenting with a solitary bone lesion is a novel presentation in paediatrics.

Chordoma of the Clivus and Acute Myeloid Leukemia: Is There a Connection?

Chordoma is a rare cancer in children and understanding the genesis of this tumor may contribute to treatment approaches. Evidence has proposed VDC/IE (vincristine, doxorubicin, cyclophosphamide/ifosfamide, etoposide) as a treatment option for young patients with chordoma to avoid the long-term effects of radiation therapy. We present a case of acute myeloid leukemia developing during treatment of localized chordoma of the clivus in a 20-month-old male. We propose a genomic relationship that may have contributed to the development of clival chordoma and acute myeloid leukemia without a latency period and advocate for genomic sequencing in children with chordoma before the initiation of systemic therapies.