A phase 2 trial of single low doses of rasburicase for treatment of hyperuricemia in adult patients with acute leukemia

BACKGROUND

Rasburicase can markedly and rapidly decrease uric acid (UA) levels, thereby preventing and treating tumor lysis syndrome. However, rasburicase is expensive, especially when used as per the manufacturer's recommended dosage of 0.2 mg/kg/day for up to 5 days. Numerous reports have shown that lower, and even single doses are effective in lowering UA levels but prospective randomized studies comparing low doses have not been performed.

OBJECTIVES

To prospectively determine the efficacy and safety of two single low doses of rasburicase in adult patients (pts) with acute leukemia and elevated plasma UA.

METHODS

Eligible pts aged ≥ 18 years old with acute leukemia and UA ≥ 7.5 mg/dL were randomized to receive an initial single dose of rasburicase 1.5 mg (Arm A) or 3 mg (Arm B) on day 1 in an unblinded fashion. All pts received allopurinol 300 mg daily on days 1-6.

RESULTS

Twenty-four pts (median age 69 years; 14 males and 10 females) were enrolled in this phase 2 study (12 on each arm). Twenty pts had acute myeloid leukemia while 3 had acute lymphoblastic leukemia, and 1 had acute promyelocytic leukemia. Median initial UA level was 9.8 mg/dL. Eighty-three percent of pts in both arms achieved UA < 7.5 mg/dL by 24 h after therapy. Five pts (21 %; 2 from Arm A and 3 from Arm B) required additional doses of rasburicase. The majority (23/24) of pts achieved UA goals after 1-2 doses of rasburicase. None had worsening renal function. Both doses were well tolerated, and no treatment related adverse events were reported.

CONCLUSIONS

Single doses of rasburicase (as low as 1.5-3 mg) used in addition to allopurinol were well tolerated and highly efficacious (83 % response rate) in decreasing UA levels within 24 h of administration in adult acute leukemia pts with hyperuricemia.

Tumor lysis syndrome in an extraskeletal osteosarcoma: a case report and review of the literature

BACKGROUND

This case report describes a spontaneous tumor lysis syndrome due to a rare solid tumor.

CASE PRESENTATION

A 65-year-old white woman had tumor lysis syndrome, which represent a dangerous oncological emergency. This syndrome occurs usually with a hematological tumor, but in this case our patient had a solid tumor, which was a rare extraskeletal osteosarcoma, localized in her pelvic region. She also had lung metastases and bilateral hydronephrosis. After spontaneous tumor lysis syndrome, she had acute renal insufficiency, which was treated with hemodialysis and successively with rasburicase, Kayexalate (sodium polystyrene sulfonate), and febuxostat.

CONCLUSION

Tumor lysis syndrome represents an oncological emergency, which must be suspected and treated as soon as possible.

Spontaneous Tumor Lysis Syndrome: A Case Report and Critical Evaluation of Current Diagnostic Criteria and Optimal Treatment Regimens

Tumor lysis syndrome (TLS) is a known complication of malignancy and its treatment. The incidence varies on malignancy type, but is most common with hematologic neoplasms during cytotoxic treatment. Spontaneous TLS is thought to be rare. This case study is of a 62-year-old female admitted with multisystem organ failure, with subsequent diagnosis of aggressive B cell lymphoma. On admission, laboratory abnormalities included renal failure, elevated uric acid (20.7 mg/dL), and 3+ amorphous urates on urinalysis. Oliguric renal failure persisted despite aggressive hydration and diuretic use, requiring initiation of hemodialysis prior to chemotherapy. Antihyperuricemic therapy and hemodialysis were used to resolve hyperuricemia. However, due to multisystem organ dysfunction syndrome with extremely poor prognosis, the patient ultimately expired in the setting of a terminal ventilator wean. Although our patient did not meet current TLS criteria, she required hemodialysis due to uric acid nephropathy, a complication of TLS. This poses the clinical question of whether adequate diagnostic criteria exist for spontaneous TLS and if the lack of currently accepted guidelines has resulted in the underestimation of its incidence. Allopurinol and rasburicase are commonly used for prevention and treatment of TLS. Although both drugs decrease uric acid levels, allopurinol mechanistically prevents formation of the substrate rasburicase acts to solubilize. These drugs were administered together in our patient, although no established guidelines recommend combined use. This raises the clinical question of whether combined therapy is truly beneficial or, conversely, detrimental to patient outcomes.

Rasburicase in the management of tumor lysis: an evidence-based review of its place in therapy

Tumor lysis syndrome (TLS) is a potentially life-threatening complication of cancer therapy characterized by two or more of the following laboratory abnormalities: hyperuricemia, hyperkalemia, hypocalcemia, and hyperphosphatemia, with resultant end-organ damage, eg, renal failure, seizures, or cardiac arrhythmias. High-risk patients include those with highly proliferative cancers and/or large tumor burdens, particularly in the setting of highly effective chemotherapy, among other risk factors. Before 2002, antihyperuricemic drug therapy was limited to allopurinol, a xanthine oxidase inhibitor. Rasburicase, a recombinant urate oxidase, was approved by the US Food and Drug Administration for children in 2002 and adults in 2009, ushering in a new era in TLS therapy. We attempted to critically appraise the available evidence supporting the perceived benefits of rasburicase in the management of TLS. A Medline search yielded 98 relevant articles, including 26 retrospective and 22 prospective studies of rasburicase for the treatment of TLS, which were then evaluated to determine the best available evidence for the effectiveness of rasburicase in terms of disease-oriented, patient-oriented, and economic outcomes. Rasburicase is now a standard of care for patients at high risk of TLS despite continuing debate on the correlation between its profound and rapid lowering of plasma uric acid levels with hard patient outcomes, eg, need for renal replacement therapy and mortality. Rasburicase is dramatically effective in lowering plasma uric acid levels. The mortality and cost-effectiveness benefits of this expensive drug remain to be conclusively proven, and well designed, randomized controlled trials are needed to answer these fundamentally important questions.

SIRT5 deacetylates and activates urate oxidase in liver mitochondria of mice

We identified urate oxidase (UOX) as a target of SIRT5 by comparing mitochondrial proteins in livers of SIRT5-overexpressing transgenic (SIRT5 Tg) and wild-type mice by using two-dimensional electrophoresis. Acetylation levels of UOX in liver of SIRT5 Tg mice were approximately half of those in wild-type mice, and UOX activity was significantly increased. Invitro-synthesized UOX protein was acetylated when incubated with mitochondria from wild-type mice liver but the levels were less when incubated with those from SIRT5 Tg mice liver. These results suggest that SIRT5 activates UOX through deacetylation in mouse liver mitochondria.

Renal management in the critically ill patient

Acute kidney injury is common in the hospital setting and morbidity and mortality outcomes depend on early recognition and early intervention. Identifying patients at risk of acute kidney injury is critical in prevention, early identification, and appropriate treatment.

Diagnosis and management of acute myeloid leukemia in children and adolescents: recommendations from an international expert panel

Despite major improvements in outcome over the past decades, acute myeloid leukemia (AML) remains a life-threatening malignancy in children, with current survival rates of ∼70%. State-of-the-art recommendations in adult AML have recently been published in this journal by Döhner et al. The primary goal of an international expert panel of the International BFM Study Group AML Committee was to set standards for the management, diagnosis, response assessment, and treatment in childhood AML. This paper aims to discuss differences between childhood and adult AML, and to highlight recommendations that are specific to children. The particular relevance of new diagnostic and prognostic molecular markers in pediatric AML is presented. The general management of pediatric AML, the management of specific pediatric AML cohorts (such as infants) or subtypes of the disease occurring in children (such as Down syndrome related AML), as well as new therapeutic approaches, and the role of supportive care are discussed.