Acute lymphoblastic leukaemia patients treated with PEGasparaginase develop antibodies to PEG and the succinate linker.

Polyethylene glycol (PEG) conjugated asparaginase (PEGasparaginase) is essential for treatment of paediatric acute lymphoblastic leukaemia. We developed an assay identifying antibodies against the PEG-moiety, the linker and the drug itself in patients experiencing hypersensitivity reactions to PEGasparaginase. Eighteen patients treated according to the DCOG ALL-11 protocol, with a neutralizing hypersensitivity reaction to PEGasparaginase to the first PEGasparaginase doses in induction (12 patients) or during intensification after interruption of several months (6 patients) were included. ELISA was used to measure antibodies, coating with the succinimidyl succinate linker conjugated to BSA, PEGfilgrastim and Escherichia coli asparaginase, and using hydrolysed PEGasparaginase and mPEG5,000 for competition. Anti-PEG antibodies were detected in all patients (IgG 100%; IgM 67%) of whom 39% had anti-PEG antibodies exclusively. Pre-existing anti-PEG antibodies were also detected in patients who not previously received a PEGylated therapeutic (58% IgG; 21% IgM). Antibodies against the SS-linker were predominantly detected during induction (50% IgG; 42% IgM). Anti-asparaginase antibodies were detected in only 11% during induction but 94% during intensification. In conclusion, anti-PEG and anti-SS-linker antibodies predominantly play a role in the immunogenic response to PEGasparaginase during induction. Thus, switching to native E. coli asparaginase would be an option for adequate asparaginase treatment.

Differences in the reporting rates of serious allergic adverse events from intravenous iron by country and population.

BACKGROUND: Previous studies have compared rates of adverse events between intravenous (IV) iron preparations; however, there has been no comparison of adverse event rates by country and population. OBJECTIVES: To compare rates of adverse events to IV iron products by country and population. METHODS: All adverse events reported from 18 countries from January 1, 2003 to June 30, 2009 were obtained for iron dextran (ID), iron sucrose (IS), IS similars (ISS), and sodium ferric gluconate (FG). Rates of all adverse events and serious adverse events (anaphylaxis plus other serious allergic reactions) were calculated as number of events per gram of iron sold (gFe) per million inhabitants (mil) × 10-3. Odds ratios (ORs) were calculated for the risks of adverse events between products. RESULTS: Iron use ranged from 1 gFe/mil (Poland) to 48,674 gFe/mil (Italy). Rates of all adverse events (reports/gFe/mil × 10-3) varied: for IS, it ranged from 0 (Poland, Austria, Czech Republic) to 1,222 (Ireland); for FG, from 3.3 (Czech Republic) to 183.6 (United States); for ID, from 0.9 (Turkey) to 46,875 (Switzerland). There were no reports of adverse events in ISS. In a subset of countries that used 2 or more iron products and had more than 1 serious adverse event, rates (reports/gFe/mil × 10-3) of all adverse events and serious adverse events were lowest for IS (39.8 and 1.7), intermediate for FG (54.8 and 4.5), and greatest for ID (337.7 and 20.5). IS had lower risks for all adverse events (OR, 0.63; P<.0001) and serious adverse events (OR, 0.31; P=.001) versus FG, and for all adverse events (OR, 0.13; P<.0001) and serious adverse events (OR, 0.07; P<.0001) versus ID. FG had lower risks for all adverse events (OR, 0.20; P<.0001) and serious adverse events (OR, 0.24; P<.0001) versus ID. CONCLUSIONS: Considerable international variation existed in the extent and choice of iron product and adverse event reporting, suggesting under-reporting in some instances. Clinicians should appreciate the differential risks between available products, and should critically review local reporting practices.

Differences in spontaneously reported hypersensitivity and serious adverse events for intravenous iron preparations: comparison of Europe and North America.

Spontaneously-reported rates of adverse events (AEs) of intravenous (i.v.) iron products have not been compared since 2007. AEs in Europe (Eur) and North America (NA) have never been compared. New products have been marketed and many changes in prescribing habits have occurred since then, and the effect on AEs reporting is unclear. It was hypothesized that changing practices for i.v. iron products has caused changes in the rates of serious AEs and large differences exist between Eur and NA. Rates of AEs for three i.v. iron preparations (iron sucrose [IS], ferric gluconate [FG] and high and low MW iron dextran [HMWID, LMWID]) were compared by product and continent from January 1, 2003 to June 30, 2009 for selected countries in Eur and NA, using the Uppsala Monitoring Center's database. Rates of total, anaphylaxis and other serious allergic AEs were calculated as number of AEs divided by i.v. iron sales standardized to 100 mg dose equivalents (DEq) of iron. Quarterly sales (millions of 100 mg DEq of iron) increased from the first quarter 2003 to the end of the second quarter of 2009 by 1% for FG, 16% for IS and 2% for ID. Total AEs for NA plus Eur were similar for FG and IS, but total AEs were 6- to 7-fold higher for ID. Rates of anaphylaxis were 6- to 11-fold higher in Eur plus NA combined for ID than for IS or FG. In NA, there were substantially higher reports for total, anaphylaxis and other serious allergic AEs with FG compared to IS, whereas the reverse was the case in Eur. Odds ratios (OR) showed higher risks of anaphylaxis with FG in NA vs. Eur (OR = 4.40, P < 0.0001) and lower risks with IS (OR = 0.24, P < 0.0001). Odds of anaphylaxis with LMWID in Eur vs. FG and IS were 42.08 and 16.92 (both P < 0.0001), respectively. In NA, odds of anaphylaxis with ID vs. FG and IS were 2.36 and 17.73 (both P < 0.0001), respectively. Differences between NA and Eur may be related to varied treatment practices. ID had the highest rates of all types of AEs, and IS and FG had a continued trend for lowest rates of AEs.