Lethal effect of a single dose of rasburicase in a preterm newborn infant

Tumor lysis syndrome in premature infant prompting early resection of a large sacrococcygeal teratoma: a case report

BACKGROUND

Sacrococcygeal teratomas (SCTs) are the most common congenital neoplasm and often require resection soon after birth. There are rare reports of cardiac arrest during surgery due to manipulation of the tumor triggering secondary necrosis and hyperkalemia.

CASE PRESENTATION

This case describes a very preterm infant with a SCT who develops spontaneous preoperative tumor lysis syndrome (TLS). The medical team utilized rasburicase and the patient underwent total gross resection at 40 h of life.

CONCLUSIONS

We emphasize the importance of the early recognition and management of tumor lysis syndrome in SCT with rasburicase, aggressive management of hyperkalemia and consideration of early resection of SCTs even in the case of a very premature infant.

Genetic variants causing G6PD deficiency: Clinical and biochemical data support new WHO classification

Glucose-6-phosphate dehydrogenase (G6PD) deficiency in erythrocytes causes acute haemolytic anaemia upon exposure to fava beans, drugs, or infection; and it predisposes to neonatal jaundice. The polymorphism of the X-linked G6PD gene has been studied extensively: allele frequencies of up to 25% of different G6PD deficient variants are known in many populations; variants that cause chronic non-spherocytic haemolytic anaemia (CNSHA) are instead all rare. WHO recommends G6PD testing to guide 8-aminoquinolines administration to prevent relapse of Plasmodium vivax infection. From a literature review focused on polymorphic G6PD variants we have retrieved G6PD activity values of 2291 males, and for the mean residual red cell G6PD activity of 16 common variants we have obtained reliable estimates, that range from 1.9% to 33%. There is variation in different datasets: for most variants most G6PD deficient males have a G6PD activity below 30% of normal. There is a direct relationship between residual G6PD activity and substrate affinity (Km G6P ), suggesting a mechanism whereby polymorphic G6PD deficient variants do not entail CNSHA. Extensive overlap in G6PD activity values of individuals with different variants, and no clustering of mean values above or below 10% support the merger of class II and class III variants.

Expanded Clinical Pharmacogenetics Implementation Consortium Guideline for Medication Use in the Context of G6PD Genotype

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is associated with development of acute hemolytic anemia in the setting of oxidative stress, which can be caused by medication exposure. Regulatory agencies worldwide warn against the use of certain medications in persons with G6PD deficiency, but in many cases, this information is conflicting, and the clinical evidence is sparse. This guideline provides information on using G6PD genotype as part of the diagnosis of G6PD deficiency and classifies medications that have been previously implicated as unsafe in individuals with G6PD deficiency by one or more sources. We classify these medications as high, medium, or low to no risk based on a systematic review of the published evidence of the gene-drug associations and regulatory warnings. In patients with G6PD deficiency, high-risk medications should be avoided, medium-risk medications should be used with caution, and low-to-no risk medications can be used with standard precautions, without regard to G6PD phenotype. This new document replaces the prior Clinical Pharmacogenetics Implementation Consortium guideline for rasburicase therapy in the context of G6PD genotype (updates at: www.cpicpgx.org).

Diagnosis and clinical management of enzymopathies

At least 16 genetically determined conditions qualify as red blood cell enzymopathies. They range in frequency from ultrarare to rare, with the exception of glucose-6-phosphate dehydrogenase deficiency, which is very common. Nearly all these enzymopathies manifest as chronic hemolytic anemias, with an onset often in the neonatal period. The diagnosis can be quite easy, such as when a child presents with dark urine after eating fava beans, or it can be quite difficult, such as when an adult presents with mild anemia and gallstones. In general, 4 steps are recommended: (1) recognizing chronic hemolytic anemia; (2) excluding acquired causes; (3) excluding hemoglobinopathies and membranopathies; (4) pinpointing which red blood cell enzyme is deficient. Step 4 requires 1 or many enzyme assays; alternatively, DNA testing against an appropriate gene panel can combine steps 3 and 4. Most patients with a red blood cell enzymopathy can be managed by good supportive care, including blood transfusion, iron chelation when necessary, and splenectomy in selected cases; however, some patients have serious extraerythrocytic manifestations that are difficult to manage. In the absence of these, red blood cell enzymopathies are in principle amenable to hematopoietic stem cell transplantation and gene therapy/gene editing.

Glucose-6-phosphate dehydrogenase deficiency

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is 1 of the commonest human enzymopathies, caused by inherited mutations of the X-linked gene G6PD. G6PD deficiency makes red cells highly vulnerable to oxidative damage, and therefore susceptible to hemolysis. Over 200 G6PD mutations are known: approximately one-half are polymorphic and therefore common in various populations. Some 500 million persons with any of these mutations are mostly asymptomatic throughout their lifetime; however, any of them may develop acute and sometimes very severe hemolytic anemia when triggered by ingestion of fava beans, by any of a number of drugs (for example, primaquine, rasburicase), or, more rarely, by infection. Approximately one-half of the G6PD mutations are instead sporadic: rare patients with these mutations present with chronic nonspherocytic hemolytic anemia. Almost all G6PD mutations are missense mutations, causing amino acid replacements that entail deficiency of G6PD enzyme activity: they compromise the stability of the protein, the catalytic activity is decreased, or a combination of both mechanisms occurs. Thus, genotype-phenotype correlations have been reasonably well clarified in many cases. G6PD deficiency correlates remarkably, in its geographic distribution, with past/present malaria endemicity: indeed, it is a unique example of an X-linked human polymorphism balanced through protection of heterozygotes from malaria mortality. Acute hemolytic anemia can be managed effectively provided it is promptly diagnosed. Reliable diagnostic procedures are available, with point-of-care tests becoming increasingly important where primaquine and its recently introduced analog tafenoquine are required for the elimination of malaria.

Glucose-6-Phosphate Dehydrogenase Deficiency

G6PD is a housekeeping gene expressed in all cells. Glucose-6-phosphate dehydrogenase (G6PD) is part of the pentose phosphate pathway, and its main physiologic role is to provide NADPH. G6PD deficiency, one of the commonest inherited enzyme abnormalities in humans, arises through one of many possible mutations, most of which reduce the stability of the enzyme and its level as red cells age. G6PD-deficient persons are mostly asymptomatic, but they can develop severe jaundice during the neonatal period and acute hemolytic anemia when they ingest fava beans or when they are exposed to certain infections or drugs. G6PD deficiency is a global health issue.

Hemolytic anemia following rasburicase administration: a review of published reports

Tumor lysis syndrome (TLS) is a potentially lethal complication of anticancer treatment. It is caused by the rapid death of malignant cells after initiation of cytotoxic therapy and is typically observed in patients with bulky or highly proliferative malignancies. Currently, rasburicase is one of the recommended therapies for this oncologic emergency. Although this drug is generally well tolerated among patients, there have been several reports of hemolytic anemia following rasburicase infusions. With drug-induced hemolytic anemia, the condition usually resolves shortly after the offending agent is discontinued. However, anemia that is prolonged or severe can lead to problems such as splenomegaly and rapid heart rate. This paper will review primary literature identified through PubMed, International Pharmaceutical Abstracts, and Embase concerning the incidence of hemolytic anemia with rasburicase use. From the available data, the occurrence of hemolytic anemia will be discussed.

Pharmacovigilance for children's sake

Child age-specific information on efficacy and risk of medicines can be limited for healthcare professionals and patients. It is therefore very important to make the best use of a risk planned approach to the pharmacological treatment of children. This means pharmacovigilance in the broadest sense of gaining the best data from the use of medicines in clinical practice. We consider issues that complicate safe medication use in paediatric care, as well as current progress and provide suggestions for building knowledge within paediatric pharmacovigilance to be used to minimise patient harm. The continuous development in children constitutes a challenge to prescribing and administering age-suitable doses for individual children. Children are not only different from adults but differ vastly within their own age group. Physical growth during childhood is apparent to the eye, but less obvious is the ongoing maturation of organ function important for drug disposition and action. Systematic issues such as medication errors, off-label use and the lack of age-suitable formulations are considerable obstacles for safe medication use in paediatrics. The recognition of emerging adverse drug reactions could be more challenging in developing children. Initiatives to improve the situation have been made by the WHO and regulators in the USA and EU. Age-specific changes in physiology, pharmacology and psychology, as well as systematic issues specific for children need to be considered in the work of assessing spontaneous reports in children. Pharmacovigilance needs to broaden its aims considerably beyond merely capturing new associations between drugs and events, and encompass careful collection on patient characteristics and circumstances around the reported adverse drug reaction to provide essential information that will give clues on how to prevent harm to children.

G6PD deficiency: a classic example of pharmacogenetics with on-going clinical implications

That primaquine and other drugs can trigger acute haemolytic anaemia in subjects who have an inherited mutation of the glucose 6-phosphate dehydrogenase (G6PD) gene has been known for over half a century: however, these events still occur, because when giving the drug either the G6PD status of a person is not known, or the risk of this potentially life-threatening complication is under-estimated. Here we review briefly the genetic basis of G6PD deficiency, and then the pathophysiology and the clinical features of drug-induced haemolysis; we also update the list of potentially haemolytic drugs (which includes rasburicase). It is now clear that it is not good practice to give one of these drugs before testing a person for his/her G6PD status, especially in populations in whom G6PD deficiency is common. We discuss therefore how G6PD testing can be done reconciling safety with cost; this is once again becoming of public health importance, as more countries are moving along the pathway of malaria elimination, that might require mass administration of primaquine. Finally, we sketch the triangular relationship between malaria, antimalarials such as primaquine, and G6PD deficiency: which is to some extent protective against malaria, but also a genetically determined hazard when taking primaquine.