PURPOSE Pegaspargase (PEG-ASP) has largely replaced native Escherichia coli asparaginase (L-ASP) in the treatment of acute lymphoblastic leukemia because of its longer half-life and lower immunogenicity. Risk factors for allergic reactions to PEG-ASP remain unclear. Here, we identify risk factors for reactions in a front-line acute lymphoblastic leukemia trial and assess the usefulness of serum antibodies for diagnosing allergy and predicting rechallenge outcome. PATIENTS AND METHODS PEG-ASP was administered to 598 patients in St Jude’s Total XVI study. Results were compared with Total XV study ( ClinicalTrials.gov identifiers: NCT00549848 and NCT00137111 ), which used native L-ASP. Serum samples (n = 5,369) were analyzed for anti–PEG-ASP immunoglobulin G by enzyme-linked immunosorbent assay. Positive samples were tested for anti–polyethylene glycol (PEG) and anti–L-ASP. We analyzed potential risk factors for reactions and associations between antibodies and reactions, rechallenge outcomes, and PEG-ASP pharmacokinetics. RESULTS Grade 2 to 4 reactions were less common in the Total XVI study with PEG-ASP (81 [13.5%] of 598) than in the Total XV study with L-ASP (169 [41.2%] of 410; P = 1.4 × 10−23). For Total XVI, anti-PEG, not anti–L-ASP, was the predominant component of anti–PEG-ASP antibodies (96%). In a multivariable analysis, more intrathecal therapy (IT) predicted fewer reactions ( P = 2.4 × 10−5), which is consistent with an immunosuppressant contribution of IT. Anti–PEG-ASP was associated with accelerated drug clearance ( P = 5.0 × 10−6). Failure of rechallenge after initial reactions was associated with anti–PEG-ASP ( P = .0078) and was predicted by the occurrence of angioedema with first reaction ( P = .01). CONCLUSION Less IT therapy was the only independent clinical risk factor for reactions to PEG-ASP. PEG, and not L-ASP, is the major antigen that causes allergic reactions. Anti–PEG-ASP has utility in predicting and confirming clinical reactions to PEG-ASP as well as in identifying patients who are most likely to experience failure with rechallenge.

Background Glucarpidase rapidly reduces methotrexate plasma concentrations in patients experiencing methotrexate-induced renal dysfunction. Debate exists regarding the role of glucarpidase in therapy given its high cost. The use of reduced-dose glucarpidase has been reported, and may allow more institutions to supply this drug to their patients. This report explores the relationship between glucarpidase dosage and patient outcomes in pediatric oncology patients. Methods The authors evaluated data from 26 patients who received glucarpidase after high-dose methotrexate. Decrease in plasma methotrexate concentrations and time to renal recovery were evaluated for an association with glucarpidase dosage, which ranged from 13 to 90 units/kg. Results No significant relationship was found between glucarpidase dosage (units/kg) and percent decrease in methotrexate plasma concentrations measured by TDx (P >0.1) or HPLC (P >0.5). Patients who received glucarpidase dosages <50 units/kg had a median percent reduction in methotrexate plasma concentration of 99.4% (range, 98–100) measured by HPLC compared to a median percent reduction of 99.4% (range, 77.2–100) in patients who received ≥50 units/kg. Time to SCr recovery was not related to glucarpidase dosage (P >0.8). Conclusions The efficacy of glucarpidase in the treatment of HDMTX-induced kidney injury was not dosage-dependent in this retrospective analysis of pediatric oncology patients. Pediatr Blood Cancer 2015;62:1518–1522.

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pneumonia is a life-threatening opportunistic infection in children receiving immunosuppressive chemotherapy. Without prophylaxis, up to 25% of pediatric oncology patients receiving chemotherapy will develop pneumonia. Trimethoprim-sulfamethoxazole is the preferred agent for prophylaxis against pneumonia. Pentamidine may be an acceptable alternative for pediatric patients unable to tolerate trimethoprim-sulfamethoxazole. A retrospective review was conducted of pediatric oncology patients who received ≥1 dose of pentamidine for pneumonia prophylaxis between January 2007 and August 2014. Electronic medical records were reviewed to determine the incidence of breakthrough pneumonia or discontinuation of pentamidine associated with adverse events. A total of 754 patients received pentamidine prophylaxis during the period. There were no cases of probable or proven pneumonia, and 4 cases (0.5%) of possible pneumonia. The incidence of possible breakthrough pneumonia was not significantly different between subgroups based on age (<12 months [1.7%] versus ≥12 months [0.4%], = 0.3), route of administration (aerosolized [0%] versus intravenous [1.0%], = 0.2), or hematopoietic stem cell transplant status (transplant [0.4%] versus no transplant [0.8%], = 0.6). Pentamidine was discontinued due to an adverse drug event in 23 children (3.1%), more frequently for aerosolized than for intravenous administration (7.6% versus 2.2%, respectively, = 0.004). Intravenous or inhaled pentamidine may be a safe and effective second-line alternative for prophylaxis against pneumonia in children with cancer receiving immunosuppressive chemotherapy or hematopoietic stem cell transplantation.

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