1. L-Asparagine depletion in plasma and cerebro-spinal fluid of children with acute lymphoblastic leukemia during subsequent exposures to Erwinia L-asparaginase
D Gentili, V Conter, C Rizzari, B Tschuemperlin, M Zucchetti, D Orlandoni, M D'Incalci, G Masera Ann Oncol. 1996 Sep;7(7):725-30. doi: 10.1093/oxfordjournals.annonc.a010722.
Background: Monitoring L-asparagine (L-ASN) plasma levels could provide information useful for determining whether the dosage or schedule of L-asparaginase (L-ASE) administration is adequate. Very few data are available on depletion caused by the Erwinia chrysanthemi (E. chrysanthemi) product. Since it has been suggested that L-ASN depletion may have been overestimated in the past due to residual L-ASE activity, samples in this study have been analyzed after deproteinization with sulphosalicylic acid. Patients undergoing subsequent exposures to L-ASE derived from E. chrysanthemi have been investigated. Patients and methods: Fifty-four children with newly diagnosed acute lymphoblastic leukemia (ALL) at our institution entered this study. L-ASE was given at conventional doses (10,000 IU/sqm) every three days during the induction phase (8 doses, first exposure) or twice a week (4 doses, second exposure) during the reinduction phase. High-dose L-ASE (i.e., HD-L-ASE 25,000 IU/sqm) was given weekly, for a total of 20 doses, as a second or third exposure during the reinduction and/or maintenance phases. To determine the plasma levels of L-ASN, samples were deproteinized with sulphosalicylic acid, stored at -80 degrees C and then analyzed by HPLC after precolumn derivatization with o-phthaldialdehyde. The CSF samples were analyzed by the same procedure. An experiment was carried out to detect in vitro L-ASE deactivation in patients' plasma. Results: L-ASN plasma depletion was observed in 80% of the cases during the first exposure to conventional doses of L-ASE and only in 25% of the cases during the second or third exposures to either conventional or high doses of L-ASE. A correlation was found between plasma and CSF L-ASN levels. Activity inhibitory to L-ASE was found in the plasma of patients not depleted during L-ASE treatment and was not found in the plasma of those in whom L-ASN plasma depletion was obtained. Conclusions: L-ASN plasma depletion is regularly obtained in the majority of patients during the first exposure to conventional doses of E. chrysanthemi L-ASE. Conversely, in most cases depletion does not occur during subsequent exposures. Studies should be performed to evaluate whether L-ASE derived from different species or conjugated with polyethylene-glycole are effective in obtaining L-ASN plasma depletion in patients previously treated with Erwinia C. L-ASE. The clinical impact of L-ASN depletion should also be investigated in large cohorts of patients.
2. Rituximab in B-Lineage Adult Acute Lymphoblastic Leukemia
Sébastien Maury, et al. N Engl J Med. 2016 Sep 15;375(11):1044-53. doi: 10.1056/NEJMoa1605085.
Background: Treatment with rituximab has improved the outcome for patients with non-Hodgkin's lymphoma. Patients with B-lineage acute lymphoblastic leukemia (ALL) may also have the CD20 antigen, which is targeted by rituximab. Although single-group studies suggest that adding rituximab to chemotherapy could improve the outcome in such patients, this hypothesis has not been tested in a randomized trial. Methods: We randomly assigned adults (18 to 59 years of age) with CD20-positive, Philadelphia chromosome (Ph)-negative ALL to receive chemotherapy with or without rituximab, with event-free survival as the primary end point. Rituximab was given during all treatment phases, for a total of 16 to 18 infusions. Results: From May 2006 through April 2014, a total of 209 patients were enrolled: 105 in the rituximab group and 104 in the control group. After a median follow-up of 30 months, event-free survival was longer in the rituximab group than in the control group (hazard ratio, 0.66; 95% confidence interval [CI], 0.45 to 0.98; P=0.04); the estimated 2-year event-free survival rates were 65% (95% CI, 56 to 75) and 52% (95% CI, 43 to 63), respectively. Treatment with rituximab remained associated with longer event-free survival in a multivariate analysis. The overall incidence rate of severe adverse events did not differ significantly between the two groups, but fewer allergic reactions to asparaginase were observed in the rituximab group. Conclusions: Adding rituximab to the ALL chemotherapy protocol improved the outcome for younger adults with CD20-positive, Ph-negative ALL. (Funded by the Regional Clinical Research Office, Paris, and others; ClinicalTrials.gov number, NCT00327678 .).
3. Paenidase, a novel D-aspartyl endopeptidase from Paenibacillus sp. B38: purification and substrate specificity
Saori Takahashi, Hironobu Ogasawara, Kazuyuki Hiwatashi, Kazuyuki Hori, Keishi Hata, Tadanori Tachibana, Yoshifumi Itoh, Toshihiro Sugiyama J Biochem. 2006 Feb;139(2):197-202. doi: 10.1093/jb/mvj016.
We discovered and characterized a novel type D-aspartyl endopeptidase (DAEP) produced extracellularly by Paenibacillus sp. B38. This bacterial DAEP of M(r) 34,798 (named paenidase) appeared to be converted into a smaller form of M(r) 34,169 by the proteolytic removal of 5 amino acid residues from the N-terminal. The intact and modified forms of the enzyme displayed essentially the same enzymatic properties. The enzyme specifically hydrolyzed succinyl-D-aspartic acid alpha-(p-nitroanilide) and succinyl-D-aspartic acid alpha-(4-methylcoumaryl-7-amide) to generate p-nitroaniline and 7-amino-4-methylcoumarin, and internally cleaved a synthetic peptide (D-A-E-F-R-H-[D-Asp]-G-S-Y) of the [D-Asp](7) amyloid beta (Abeta) protein between [D-Asp](7)-G(8). Either was totally inert to the normal Abeta peptide sequence containing L-Asp, instead of D-Asp at the 7th position. Thus, paenidase is the first DAEP from a microorganism that specifically recognizes an internal D-Asp residue to cleave [D-Asp]-X peptide bonds.
