Role of pharmacogenomics and pharmacodynamics in the treatment of acute lymphoblastic leukaemia

Pharmacodynamic studies have been used to establish the relationships between the administered dosage and the concentration of drugs and metabolites in the blood or tissues and that between these concentrations and pharmacological effects. Polymorphisms in the genes that encode drug-metabolizing enzymes, drug transporters and drug targets can affect a person's response to therapy and may affect the development of de novo or therapy-related leukaemias. The burgeoning field of pharmacogenomics elucidates inherited differences in drug metabolism and treatment response. Increasingly, pharmacodynamic and pharmacogenomic studies are being used to individualize therapy to enhance efficacy and reduce toxicity.     

Toxicity profile of repeated doses of PEG‐asparaginase incorporated into a pediatric‐type regimen for adult acute lymphoblastic leukemia

Despite having been long regarded as too toxic for adult patients, pediatric‐like regimens containing L‐asparaginase have resulted in improved outcomes for adults with acute lymphoblastic leukemia (ALL). To characterize the spectrum of toxicity of repeated doses of polyethylene glycolated‐asparaginase (PEG‐asp) in adults, we reviewed all doses (2000 IU/m²) administered as part of a pediatric‐inspired regimen in adult ALL at our center. Subjects aged 18–60 yr with ALL (n = 152, 69.1% male) contributed 522 dose cycles to the study. Hepatotoxicity was the most common adverse event: grades 3–4 transaminitis and hyperbilirubinemia occurred in 53.9% and 23.7% of subjects, respectively. Hepatotoxicity was reversible; no cases of fulminate hepatic failure were observed. Other toxicities affecting at least 5% of subjects were grades 3–4 triglyceridemia in 50.9%, hypofibrinogenemia (<100 mg/dL) in 47.9%, clinical pancreatitis in 12.6%, venous thromboembolism in 11.2%, allergic reaction in 7.2%, and any grade bleeding in 5.3%. PEG‐asp was always discontinued after grades 3–4 pancreatitis or allergic reaction. Otherwise, toxicities did not preclude administration of additional cycles of the drug. Our results suggest that repeated PEG‐asp dosing is safe in adults aged 18–60 yr, even after occurrence of a drug‐related toxicity.     

Outcomes of acute lymphoblastic leukaemia in adolescent and young adult Korean patients

This study used Korean national data to investigate the relationship between treatment patterns and outcomes in Korean adolescent and young-adult (AYA) acute lymphoblastic leukaemia (ALL) patients. Chemotherapy incorporating L-asparaginase was considered paediatric-inspired (PI), as opposed to adult protocols. In total, 65·3% of patients received PI therapy. Five-year overall survival (OS) of PI-treated patients outperformed adult protocols (63·1% vs. 40·4%; P < 0·0001); this trend was maintained within various age subgroups. Younger age, L-asparaginase therapy, and radiotherapy corresponded with superior OS by multivariable analysis. OS tends to improve with PI protocols that include L-asparaginase in AYA ALL, suggesting that therapy protocol is critical in the treatment performance of this group.     

Asparagine synthetase activity in paediatric acute leukaemias: AML-M5 subtype shows lowest activity

Lack of sufficient cellular activity of asparagine synthetase (AS) in blast cells compared with normal tissue is thought to be the basis of the antileukaemic effect of L-asparaginase in acute lymphoblastic leukaemia (ALL). Although L-asparaginase is routinely used in ALL, its role and value in the treatment of acute myelogenous leukaemia (AML) is still being discussed. To evaluate the pharmacological basis for L-asparaginase treatment, we established pretreatment monitoring of the intracellular AS activity in blast cells of patients with AML and ALL. There was no general difference in AS activity between ALL and AML samples. Significantly lower AS activity, however, was found in the B-lineage ALL subgroups as well as AML-M5.     

Pegylated asparaginase in combination with high-dose methotrexate for consolidation in adult acute lymphoblastic leukaemia in first remission: a pilot study

The German Multicentre acute lymphoblastic leukaemia (ALL) study group (GMALL) performed a pilot study using pegylated asparaginase (PEG-ASP) in combination with high-dose methotrexate as consolidation therapy in the 05/93 protocol. The aim of the study was an intra-individual comparison of two different doses of PEG-ASP in 26 patients, with regard to the depletion of asparagine in serum and toxicity. 'Pharmacokinetic' monitoring was performed to evaluate the effect of an intra-individual dose escalation of PEG-ASP from 500 to 1000 U/m2 intravenously in successive doses. Serum asparaginase activity was targeted at > or =100 U/l for 1 week and > or =50 U/l for 10 d. The second course of PEG-ASP was administered to 23 patients. Due to hypersensitivity reactions in five patients, only 18 patients were evaluable for pharmacokinetic monitoring. With respect to the PEG-ASP activity, an effective depletion of asparagine could be postulated in the majority of patients during 10 d after the first administration. The effect of an intraindividual dose escalation form 500 to 1000 U/m2 was evaluable in 17 of 22 patients. An increment in peak PEG-ASP activity >70% was observed in 65% of the patients. PEG-ASP was well tolerated. Despite the long half-life of PEG-ASP, neither pancreatic nor central nervous toxicities occurred among the 26 adult patients treated in this pilot study.     

Complete blood count using VCS (volume, conductivity, light scatter) technology is affected by hyperlipidemia in a child with acute leukemia

Asparaginase, an effective drug in the treatment of childhood acute lymphoblastic leukemia (ALL), has become an important component of most childhood ALL regimens during the remission induction or intensification phases of treatment. The incidence range of asparaginase‐associated lipid abnormalities that are seen in children is 67–72%. Lipemia causes erroneous results, which uses photometric methods to analyze blood samples. We describe a case of l ‐asparaginase‐associated severe hyperlipidemia with complete blood count abnormalities. Complete blood count analysis was performed with Beckman COULTER^® GEN·S? system, which uses the Coulter Volume, Conductivity, Scatter technology to probe hydrodynamically focused cells. Although an expected significant inaccuracy in hemoglobin determination occurred starting from a lipid value of 3450 mg/dl, we observed that triglyceride level was 1466 mg/dl. Complete blood count analysis revealed that exceptionally high hemoglobin, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration levels vs. discordant with red blood cell count, mean corpuscular volume, and hematocrit levels. Total leukocyte count altered spontaneously in a wide range, and was checked with blood smear. Platelet count was in expected range ( Table 1 ). Thus, we thought it was a laboratory error, and the patient’s follow‐up especially for red cell parameters was made by red blood cell and hematocrit values.

Table 1. Patient’s complete blood count analysis according to the days of induction

Cerebrospinal fluid asparagine depletion during pegylated asparaginase therapy in children with acute lymphoblastic leukaemia

L‐asparaginase is an important drug in the treatment of childhood acute lymphoblastic leukaemia (ALL). Cerebrospinal fluid (CSF) asparagine depletion is considered a marker of asparaginase effect in the central nervous system (CNS) and may play a role in CNS‐directed anti‐leukaemia therapy. The objective of this study was to describe CSF asparagine depletion during 30 weeks of pegylated asparaginase therapy, 1000 iu/m² i.m. every second week, and to correlate CSF asparagine concentration with serum L‐asparaginase enzyme activity. Danish children (1–17 years) with ALL, treated according to the Nordic Society of Paediatric Haematology and Oncology ALL2008 protocol, standard and intermediate risk, were included. CSF samples were obtained throughout L‐asparaginase treatment at every scheduled lumbar puncture. A total of 128 samples from 31 patients were available for analysis. Median CSF asparagine concentration decreased from a pre‐treatment level of 5·3 μmol/l to median levels ≤1·5 μmol/l. However, only 4/31 patients (five samples) had CSF asparagine concentrations below the limit of detection (0·1 μmol/l). In 11 patients, 24 paired same day serum and CSF samples were obtained. A decrease in CSF asparagine corresponded to serum enzyme activities above 50 iu/l. Higher serum enzyme activities were not followed by more extensive depletion. In conclusion, pegylated asparaginase 1000 iu/m² i.m. every second week effectively reduced CSF asparagine levels.     

Asparaginase‐associated pancreatitis in children with acute lymphoblastic leukaemia in the NOPHO ALL2008 protocol

L‐asparaginase is an important drug in the treatment of childhood acute lymphoblastic leukaemia (ALL). Treatment is associated with several toxicities, including acute pancreatitis. Clinical course, presentation, re‐exposure to L‐asparginase after pancreatitis and risk of recurrent pancreatitis within an asparaginase‐intensive protocol has been poorly reported. Children (1–17 years) on the ongoing Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol with asparaginase‐associated pancreatitis (AAP) diagnosed between 2008 and 2012 were identified through the online NOPHO ALL toxicity registry. NOPHO ALL2008 includes eight or 15 doses of intramuscular pegylated L‐asparginase (PEG‐asparaginase) 1000 iu/m²/dose at 2–6 weeks intervals, with a total of 30 weeks of exposure to PEG‐asparaginase (clinicaltrials.gov no: NCT00819351). Of 786 children, 45 were diagnosed with AAP with a cumulative risk of AAP of 5·9%. AAP occurred after a median of five doses (range 1–13), and 11 d (median) from the latest administration of PEG‐Asparaginase. Thirteen patients developed pseudocysts (30%) and 11 patients developed necrosis (25%). One patient died from pancreatitis. Twelve AAP patients were re‐exposed to L‐asparginase, two of whom developed mild AAP once more, after four and six doses respectively. In conclusion, re‐exposure to PEG‐asparaginase in ALL patients with mild AAP seems safe.     

Changes in coagulation and fibrinolysis in childhood ALL: a two-step dose reduction of one E. coli asparaginase preparation

The influence of two different E. coli asparaginase (ASP) preparations on fibrinolytic proteins in childhood ALL was recently reported, demonstrating a clearly significant association between ASP activity and haemostatic changes. Since the Bayer preparation is no longer available for treatment of large series of patients with ALL, the present study was designed to prospectively evaluate coagulation and fibrinolytic changes in leukaemic children receiving different doses of Medac ASP, which is now available for treatment of childhood ALL. Leukaemic children in whom ASP Medac was administered at 3 d intervals in a two-step dose reduction (5000 IU/m², n  = 10; 2500 IU/m², n  = 15) were compared with children who had received Bayer ASP 10 000 IU/m² in the same time schedule in a former randomized trial; at the same venipuncture, blood samples for coagulation studies were obtained before each ASP administration together with serum samples for pharmacoinetic monitoring. Compared with Bayer ASP 10 000 IU/m², patients receiving Medac ASP 5000 IU/m² showed significantly decreased values of fibrinogen, plasminogen, and α2-antiplasmin, along with significantly enhanced thrombin generation. Improvement occurred in children treated with 2500 IU/m² Medac ASP; α2-antiplasmin and D -dimer no longer differed from the Bayer group. Since both patient groups showed complete asparagine depletion during the course of ASP administration, the lower dosage of 2500 IU/m² administered at 3 d intervals should guarantee the specific metabolic therapy for ALL, leading to depletion of the circulating pool of asparagine.