Pre-existing antibodies against polyethylene glycol reduce asparaginase activities on first administration of pegylated E. coli asparaginase in children with acute lymphocytic leukemia.

Antibodies against polyethylene glycol (PEG) in healthy subjects raise concerns about the efficacy of pegylated drugs. We evaluated the prevalence of antibodies against PEG among patients with acute lymphoblastic leukemia (ALL) prior to and/or immediately after their first dose of pegylated E.coli asparaginase (PEG-ASNase). Serum samples of 701 children, 673 with primary ALL, 28 with relapsed ALL, and 188 adults with primary ALL were analyzed for anti-PEG IgG and IgM. Measurements in 58 healthy infants served as reference to define cut-points for antibody-positive and -negative samples. Anti-PEG antibodies were detected in ALL patients prior the first PEG-ASNase with a prevalence of 13.9% (anti-PEG IgG) and 29.1% (anti-PEG IgM). After administration of PEG-ASNase the prevalence of anti-PEG antibodies decreased to 4.2% for anti-PEG IgG and to 4.5% for anti-PEG IgM. Pre-existing anti-PEG antibodies did not inhibit PEG-ASNase activity but significantly reduced PEGASNase activity levels in a concentration dependent manner. Although pre-existing anti-PEG antibodies did not boost, pre-existing anti-PEG IgG were significantly associated with firstexposure hypersensitivity reactions (CTCAE grade 2) (p.

Asparagine levels in the cerebrospinal fluid of children with acute lymphoblastic leukemia treated with pegylated-asparaginase in the induction phase of the AIEOP-BFM ALL 2009 study.

Asparagine levels in cerebrospinal fluid and serum asparaginase activity were monitored in children with acute lymphoblastic leukemia treated with pegylated-asparaginase. The drug was given intravenously at a dose of 2,500 IU/m2 on days 12 and 26. Serum and cerebrospinal fluid samples obtained on days 33 and 45 were analyzed centrally. Since physiological levels of asparagine in the cerebrospinal fluid of children and adolescents are 4-10 µmol/L, in this study asparagine depletion was considered complete when the concentration of asparagine was ≤0.2 µmol/L, i.e. below the lower limit of quantification of the assay used. Over 24 months 736 patients (AIEOP n=245, BFM n=491) and 903 cerebrospinal fluid samples (n=686 on day 33 and n=217 on day 45) were available for analysis. Data were analyzed separately for the AIEOP and BFM cohorts and yielded superimposable results. Independently of serum asparaginase activity levels, cerebrospinal fluid asparagine levels were significantly reduced during the investigated study phase but only 28% of analyzed samples showed complete asparagine depletion while relevant levels, ≥1 µmol/L, were still detectable in around 23% of them. Complete cerebrospinal fluid asparagine depletion was found in around 5-6% and 33-37% of samples at serum asparaginase activity levels <100 and ≥ 1,500 IU/L, respectively. In this study cerebrospinal fluid asparagine levels were reduced during pegylated-asparaginase treatment, but complete depletion was only observed in a minority of patients. No clear threshold of serum pegylated-asparaginase activity level resulting in complete cerebrospinal fluid asparagine depletion was identified. The consistency of the results found in the two independent data sets strengthen the observations of this study. Details of the treatment are available in the European Clinical Trials Database at https://www.clin-icaltrialsregister.eu/ctr-search/trial/2007-004270-43/IT.

Four Additional Doses of PEG-L-Asparaginase During the Consolidation Phase in the AIEOP-BFM ALL 2009 Protocol Do Not Improve Outcome and Increase Toxicity in High-Risk ALL: Results of a Randomized Study.

PURPOSE: The AIEOP-BFM ALL 2009 protocol included, at the end of the induction phase, a randomized study of patients with high-risk (HR) ALL to investigate if an intensive exposure to pegylated L-asparaginase (PEG-ASNASE, 2,500 IU/sqm once a week × 4) on top of BFM consolidation phase IB allowed us to decrease minimal residual disease (MRD) and improve outcome. PATIENTS AND METHODS: A total of 1,097 patients presented, from June 2010 to February 2017, with one or more of the following HR criteria: KMT2A::AFF1 rearrangement, hypodiploidy, prednisone poor response, poor bone marrow response at day 15 (Flow MRD ≥10%), or no complete remission (CR) at the end of induction. Of them, 809 (85.1%) were randomly assigned to receive (404) or not receive (405) four weekly doses of PEG-ASNASE. RESULTS: By intention to treat (ITT) analysis, there was no significant difference in the proportion of patients with polimerase chain reaction MRD ≥5 × 10-4 at the end of phase IB in the experimental versus control arm (13.9% v 17.0%, P = .25). The 5-year event-free survival (median follow-up 6.3 years) by ITT in the experimental and control arms was 70.4% (2.3) versus 75.0% (2.2; P = .18), and the 5-year overall survival was 81.5% (2.0) versus 84.0% (1.9; P = .25), respectively. The corresponding 5-year cumulative incidence of death in CR was 9.5% (1.5) versus 5.7% (1.2; P = .08), and that of relapse was 17.7% (1.9) versus 17.2% (1.9), respectively (P = .94). Adverse reactions in phase IB occurred in 22.2% and 8.9% of patients in the experimental and control arm, respectively (P < .001). CONCLUSION: Additional PEG-ASNASE in phase IB did not translate into a benefit for decreasing relapse incidence but was associated with higher toxicity. Further improvements with conventional chemotherapy might be difficult in the context of intensive treatment protocols.

Pharmacodynamic effects in the cerebrospinal fluid of rats after intravenous administration of different asparaginase formulations.

PURPOSE: Asparaginase (ASNase) is used to treat various hematological malignancies for its capacity to deplete asparagine (ASN) in serum and cerebrospinal fluid (CSF). Since the biological mechanisms underlying CSF asparagine depletion in humans are not yet fully elucidated, this study compared, for the first time, the pharmacological properties of three clinically used ASNase formulations in a rodent model. METHODS: Male Wistar rats were treated with E.coli-ASNase, PEG-ASNase, or ERW-ASNase at different doses. Serum and CSF amino-acid levels and ASNase activities were evaluated at 1 and 24 h after the intravenous administration of different ASNase doses. RESULTS: All the ASNase formulations showed higher activities in serum after 1 h than 24 h and completely deplete ASN. Mean ASNase activity in the CSF at 1 h was higher with ERW-ASNase compared to PEG-ASNase (36 ± 29 vs 8 ± 7 U/L, p < 0.037) and similar to E.coli-ASNase (21 ± 9 U/L, ns). ERW-ASNase and E.coli-ASNase at the highest doses were able to deplete ASN in the CSF after 1 h. This effect was transient and not evident at 24 h after treatment. CONCLUSIONS: Together with the ASN depletion in serum and CSF, a never before demonstrated transient penetration of ASNases into the CSF, more evident for non-pegylated formulations, was detected when the ASNases were administered at high dose.

A pharmacological study on pegylated asparaginase used in front-line treatment of children with acute lymphoblastic leukemia.

BACKGROUND AND OBJECTIVES: Pegylated-asparaginase (PEG-ASP) has been traditionally used as a second-line preparation in children with acute lymphoblastic leukemia (ALL) presenting with clinical allergy to native asparaginase (ASP) products. The main goal of the present study was to investigate the pharmacological effects of the administration of PEG-ASP given as a first-line product in children with ALL. DESIGN AND METHODS: PEG-ASP serum enzymatic activity and serum and cerebrospinal fluid (CSF) levels of asparagine were investigated in 20 children with newly diagnosed ALL enrolled in the ongoing AIEOP ALL 2000 protocol and treated with PEG-ASP as a first-line ASP preparation. During induction the drug was administered at the dosage of 1,000 U/m2 i.v. on days 12 and 27. During reinduction the drug was administered only once at the same dosage. RESULTS: Among the 20 patients treated in induction serum PEG-ASP activity equalled or exceeded 100 U/L in 18/18, 11/11 and 15/18 of the samples available on days 22, 25 and 27, respectively, and in 16/16, 12/15 and 5/8 samples available on days 36, 39 and 45, respectively. In the 15 patients treated during reinduction serum PEG-ASP activity > or =100 U/L was observed in 14/15, 11/14, 6/10, and 0/12 samples available on days 11, 15, 18 and 23, respectively, after the administration of the drug. Serum asparagine levels were below the detection limit (< or =0.2 microM) in all patients/samples and at all time points evaluated during induction; during reinduction only one patient had detectable asparagine levels from day 11. CSF asparagine levels were below the detection limit of the method only in a few patients during both induction and reinduction. INTERPRETATION AND CONCLUSIONS: PEG-ASP given as a first-line ASP product in the context of an intensive chemotherapy protocol for pediatric ALL allowed adequate plasma enzymatic activity and asparagine depletion during both exposures to the drug. However, CSF asparagine depletion was inadequate.