Hepatic sinusoidal obstruction syndrome during maintenance therapy of childhood acute lymphoblastic leukemia is associated with continuous asparaginase therapy and mercaptopurine metabolites

DNA polymerase gamma variants and hepatotoxicity during maintenance therapy of childhood acute lymphoblastic leukemia: is there a causal relationship?

Hepatotoxicity is a frequent complication during maintenance therapy of acute lymphoblastic leukemia (ALL) with 6-mercaptopurine and methotrexate. Elevated levels of methylated 6-mercaptopurine metabolites (MeMP) are associated with hepatotoxicity. However, not all mechanisms are known that lead to liver failure in patients with ALL. Variants in the POLG gene, which encodes the catalytic subunit of mitochondrial DNA polymerase gamma (POLG1), have been related to drug-induced hepatotoxicity, for example, by sodium valproate. The association of common POLG variants with hepatotoxicity during maintenance therapy was studied in 34 patients with childhood ALL. Of the screened POLG variants, four different variants were detected in 12 patients. One patient developed severe hepatotoxicity without elevated MeMP levels and harbored a heterozygous POLG p.G517V variant, which was not found in the other patients.

Sinusoidal Obstruction Syndrome of the Liver Associated With 6-Mercaptopurine During Maintenance in a Child With T-cell Acute Lymphoblastic Leukemia

Sinusoidal obstruction syndrome (SOS) of the liver is a complication of chemotherapy most often encountered with hematopoietic stem cell transplant due to high-dose conditioning regimens, but it can also occur with regimens outside of the transplant setting. Mild-to-moderate SOS is a well-described 6-thioguanine toxicity; however, it has rarely been reported as secondary to 6-mercaptopurine, a related thiopurine. This report details a case of a 10-year-old male with T-cell acute lymphoblastic leukemia who developed severe SOS during maintenance therapy with 6-mercaptopurine, and a review of the related literature.

Abdominal Complications During Treatment for Pediatric Acute Myeloid Leukemia

Acute myeloid leukemia (AML) accounts for 15% to 20% of childhood leukemias. Because of high-intensive therapy, up to 5% of patients suffer from treatment-related mortality (TRM). Abdominal complications are frequent, however, literature on this subject is sparse. We aimed to characterize severe abdominal pain (AP) and hyperbilirubinemia experienced by pediatric AML patients treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO)-AML 2004 protocol (n=313). Patients were censored at hematopoietic stem cell transplantation and relapse. Toxicity information was collected prospectively. Additional information was requested retrospectively from the treating centers. Sixteen episodes of hyperbilirubinemia and 107 episodes of AP were reported. The treating centers deemed infection (30%) and typhlitis (18%) as the most frequent causes of AP. Six patients developed appendicitis (2%). Patients experiencing concurrent AP and sepsis had a high risk of TRM (36%, n=4). Eighty percent of episodes with hyperbilirubinemia fulfilled the European Society for Bone and Marrow Transplantation criteria for sinusoidal obstruction syndrome. In conclusion, abdominal complications were frequent with infection considered the predominate cause. Most patients with hyperbilirubinemia fulfilled the criteria for sinusoidal obstruction syndrome. AML treatment might be associated with appendicitis. Patients suffering from concurrent AP and sepsis had a high risk of TRM indicating that high awareness of abdominal complications is essential to reduce mortality, especially during sepsis.

Hepatic sinusoidal obstruction syndrome and short-term application of 6-thioguanine in pediatric acute lymphoblastic leukemia

Long-term treatment with 6-thioguanine (6-TG) for pediatric acute lymphoblastic leukemia (ALL) is associated with high rates of hepatic sinusoidal obstruction syndrome (SOS). Nevertheless, current treatment continues to use short-term applications of 6-TG with only sparse information on toxicity. 6-TG is metabolized by thiopurine methyltransferase (TPMT) which underlies clinically relevant genetic polymorphism. We analyzed the association between hepatic SOS reported as a serious adverse event (SAE) and short-term 6-TG application in 3983 pediatric ALL patients treated on trial AIEOP-BFM ALL 2000 (derivation cohort) and defined the role of TPMT genotype in this relationship. We identified 17 patients (0.43%) with hepatic SOS, 13 of which with short-term exposure to 6-TG (P < 0.0001). Eight of the 13 patients were heterozygous for low-activity TPMT variants, resulting in a 22.4-fold (95% confidence interval 7.1-70.7; P ≤ 0.0001) increased risk of hepatic SOS for heterozygotes in comparison to TPMT wild-type patients. Results were supported by independent replication analysis. All patients with hepatic SOS after short-term 6-TG recovered and did not demonstrate residual symptoms. Thus, hepatic SOS is associated with short-term exposure to 6-TG during treatment of pediatric ALL and SOS risk is increased for patients with low-activity TPMT genotypes.

Clinical Utility of Pegaspargase in Children, Adolescents and Young Adult Patients with Acute Lymphoblastic Leukemia: A Review

Acute lymphoblastic leukemia (ALL) is a heterogenous hematological malignancy representing 25% of all cancers in children less than 15 years of age. Significant improvements in survival and cure rates have been made over the past four decades in pediatric ALL treatment. Asparaginases, derived from Escherichia coli and Erwinia chrysanthemi, have become a critical component of ALL therapy since the 1960s. Asparaginases cause depletion of serum asparagine, leading to deprivation of this critical amino acid for protein synthesis, and hence limit survival of lymphoblasts. Pegaspargase, a conjugate of monomethoxypolyethylene glycol (mPEG) and L-asparaginase, has become an integral component of pediatric upfront and relapsed ALL protocols due to its longer half-life and improved immunogenicity profile compared to native asparaginase preparations. Over the past two decades great strides have been made in outcomes for pediatric ALL due to risk stratification, incorporation of multiagent chemotherapy protocols, and central nervous system prophylaxis with pegaspargase having played an important role in this success. However, adolescents and young adults (AYA) with ALL when treated on contemporaneous trials using adult ALL regimens, continue to have poor outcomes. There is increasing realization of adapting pediatric trial regimens for treating AYAs, especially those incorporating higher intensity of chemotherapeutic agents with pegaspargase being one such agent. Dose or treatment-limiting toxicity is observed in 25-30% of patients, most notable being hypersensitivity reactions. Other toxicities include asparaginase-associated pancreatitis, thrombosis, liver dysfunction, osteonecrosis, and dyslipidemia. Discontinuation or subtherapeutic levels of asparaginase are associated with inferior disease-free survival leading to higher risk of relapse, and in cases of relapse, a higher risk for remission failure. This article provides an overview of available evidence for use of pegaspargase in pediatric acute lymphoblastic leukemia.

Allopurinol to Prevent Mercaptopurine Adverse Effects in Children and Young Adults With Acute Lymphoblastic Leukemia

Mercaptopurine (6MP) is used to treat acute lymphoblastic leukemia (ALL) and is metabolized by hypoxanthine guanine phosphoribosal transferase to form 6-thioguanine nucleotide (6TGN). It is also metabolized by thiopurine methyl-transferase to produce 6-methylmercaptopurine (6MMP). Elevated levels of 6MMP have been associated with toxic effects that may interfere with therapy. Allopurinol is known to inhibit thiopurine methyl-transferase which reduces red cell 6MMP and increases 6TGN. Allopurinol has been utilized successfully in adult and pediatric patients with inflammatory bowel disease who have experienced 6MMP related gastrointestinal toxicity. Between August 2015 and August 2018 we started 25 patients with ALL in maintenance on allopurinol in combination with a reduced dose of 6MP. They all had unacceptable side-effects from elevated 6MMP, including abdominal pain, nausea, vomiting, decreased appetite, hypoglycemia, fatigue, and liver toxicity. In addition many had a facial rash. All patients showed resolution of symptoms within a few weeks after starting allopurinol. The red cell levels of 6MMP rapidly declined in the first month. The red cell levels of 6TGN transiently increased in spite of the lower 6MP dose. There was no decrease in absolute neutrophil count or hemoglobin. Platelets decreased slightly not requiring therapy modification. Elevated bilirubin normalized, and alanine aminotransferase decreased significantly with most normalizing. All patients continued on allopurinol with reduced dose 6MP until completing therapy. Allopurinol, in conjunction with a reduced dose of 6MP, effectively resolves 6MMP related side-effects in ALL patients on maintenance chemotherapy. This approach may lead to increased adherence to oral 6MP during ALL maintenance in patients with 6MMP induced side-effects.

TPMT polymorphisms and minimal residual disease after 6-mercaptopurine post-remission consolidation therapy of childhood acute lymphoblastic leukaemia

Bone marrow minimal residual disease (MRD) is the strongest predictor of relapse in children with acute lymphoblastic leukemia (ALL). 6-mercaptopurine (6MP) in ALL therapy has wide inter-individual variation in disposition and is strongly influenced by polymorphisms in the thiopurine methyltransferase (TPMT) gene. In 952 patients treated according to the NOPHO ALL2008 protocol, we explored the association between thiopurine disposition, TPMT genotypes and MRD levels after consolidation therapy with 6MP, high-dose methotrexate (HD-MTX), asparaginase, and vincristine. The levels of the cytotoxic DNA-incorporated thioguanine were significantly higher on day 70-79 in G460A/A719G TPMT heterozygous (TPMT_HZ) compared to TPMT wild type (TPMT_WT) patients (mean: 230.7 vs. 149.7 fmol/µg DNA, p = 0.002). In contrast, TPMT genotype did not associate with the end of consolidation MRD levels irrespective of randomization of the patients to fixed dose (25 mg/m²/day) or 6MP escalation (up to 50 or 75 mg/m²/day) during consolidation therapy.

Dynamics of leucocyte DNA thioguanine nucleotide levels during maintenance therapy of childhood acute lymphoblastic leukemia

PURPOSE

Methotrexate (MTX)/6-Mercaptopurine (6MP)-based maintenance therapy is crucial to cure childhood acute lymphoblastic leukemia (ALL). Cytotoxicity is mediated by incorporation of thioguanine nucleotides (TGN) into DNA (DNA-TG) with higher levels in leucocytes being associated with reduced relapse risk. To further understand the dynamics of DNA-TG formation, we measured DNA-TG levels in leucocyte subsets during maintenance therapy and in the months following its discontinuation.

METHODS

DNA-TG levels were measured in leucocytes (DNA-TG_Total), polymorph nucleated granulocytes (neutrophils, eosinophils, basophils [DNA-TG_PMN]) and mononucleated cells (lymphocytes, monocytes [DNA-TG_MNC]) in 1013 samples from 52 patients on ALL maintenance therapy (951 samples during therapy and 62 samples after therapy discontinuation, respectively).

RESULTS

Median DNA-TG_Total, DNA-TG_PMN and DNA-TG_MNC during maintenance therapy were 539, 563 and 384 fmol/µg DNA, respectively. DNA-TG_PMN displayed more pronounced fluctuation than DNA-TG_MNC (range 0-3084 [interquartile range IQR 271-881] versus 30-1411 [IQR 270-509] fmol/µg DNA). DNA-TG_Total was more strongly correlated with DNA-TG_PMN (r_S = 0.95, p < 0.0001) than DNA-TG_MNC (r_S = 0.73, p < 0.0001). DNA-TG_PMN correlated less with DNA-TG_MNC (r_S = 0.64, p < 0.0001) and to a much lesser extent with absolute neutrophil count (r_S = 0.35, p < 0.0001). Following discontinuation of therapy, DNA-TG_PMN was rapidly eliminated, and not measurable beyond day 22 after discontinuation, whereas DNA-TG_MNC was slowly eliminated, and five patients demonstrated a measurable DNA-TG_MNC more than 365 days after therapy discontinuation.

CONCLUSION

Fluctuations in DNA-TG_Total are predominantly caused by corresponding fluctuations in DNA-TG_PMN, thus DNA-TG_Total measures recent TGN incorporation in these short-lived cells. Measurement of DNA-TG_Total at 2-4 weeks intervals provides a reliable profile of DNA-TG levels.

Transjugular Intrahepatic Portosystemic Shunt for Very Severe Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome (VOD/SOS) after Unmanipulated Haploidentical Hematopoietic Stem Cell Transplantation with Post-transplantation Cyclophosphamide

Hepatic veno-occlusive disease or sinusoidal obstruction syndrome (VOD/SOS) is a threatening complication after both autologous and allogeneic hematopoietic stem cell transplantation (HSCT), with high mortality rates despite early medical treatment, including the use of defibrotide (DF). We retrospectively analyzed 185 unmanipulated haploidentical (haplo-) HSCT with post-transplantation cyclophosphamide as graft-versus-host disease prophylaxis performed consecutively between 2011 and June 2019 in a single center. Seventeen patients (9.2%) were diagnosed with VOD/SOS. Based on revised European Society for Blood and Marrow Transplantation severity criteria, the VOD/SOS cases were classified as mild in 2 patients (11.7%), moderate in 2 (11.7%), severe in 2 (11.7%), and very severe in 11 (64.9%). Thirteen patients (76%) were treated with DF, including all patients with severe or very severe VOD/SOS, except 1 patient with CNS hemorrhage. Sixteen patients (94%) were alive at day +100 after HSCT. Seven patients (41%) with very severe VOD/SOS were treated with transjugular intrahepatic portosystemic shunt (TIPS) owing to rapid clinical or analytical deterioration or refractory hepatorenal syndrome despite medical treatment, including DF. TIPS insertion was performed at a median time since VOD/SOS diagnosis of 4 days (range, 1 to 28 days) without technical complications in any case. The median hepatic venous pressure gradient before and after TIPS treatment was 24 mmHg (range, 14 to 29 mmHg) and 7 mmHg (range, 2 to 11 mmHg), respectively, with a median drop of 16 mmHg (range, 9 to 19 mmHg). Following TIPS insertion, all patients showed clinical improvement with hepatomegaly, ascites, and renal failure resolution, and all showed analytical improvement with reduced alanine aminotransferase (ALT), creatinine, and international normalized ratio values, except for patient 2, whose indication for TIPS was refractory hepatorenal syndrome with a normal ALT level. The 6 patients who had initiated DF before TIPS insertion completed 21 days of treatment. All patients met the criteria for complete remission (CR) at a median of 8 days after TIPS insertion (range, 2 to 82 days). The 100-day overall survival was 100%. For patients with rapid progressive VOD/SOS, early TIPS insertion allowed completion of DF therapy. The use of TIPS together with DF resulted in CR and no associated complications with no VOD/SOS-associated mortality despite high severity. In our experience, timely and individualized use of TIPS significantly improves outcomes of very severe VOD/SOS after haplo-HSCT. Therefore, TIPS should be promptly considered in rapidly progressive cases.

Prophylactic, preemptive, and curative treatment for sinusoidal obstruction syndrome/veno-occlusive disease in adult patients: a position statement from an international expert group

Sinusoidal obstruction syndrome, also known as veno-occlusive disease (SOS/VOD), is a potentially life-threatening complication that can develop after hematopoietic cell transplantation (HCT). While SOS/VOD may resolve within a few weeks in the majority of patients with mild-to-moderate disease, the most severe forms result in multiorgan dysfunction and are associated with a high mortality rate (>80%). Therefore, careful surveillance may allow early detection of SOS/VOD, particularly as the licensed available drug is proven to be effective and reduce mortality. The aim of this work is to propose an international consensus guideline for the treatment and prevention of SOS/VOD in adult patients, on behalf of an international expert group.

Intermittent Versus Continuous PEG-Asparaginase to Reduce Asparaginase-Associated Toxicities: A NOPHO ALL2008 Randomized Study

PURPOSE

Asparaginase is an essential drug in childhood acute lymphoblastic leukemia (ALL) therapy and is frequently given for months to obtain continuous asparagine depletion. We randomly assigned patients to continuous versus intermittent pegylated-asparaginase (PEG-asp) treatment, hypothesizing there would be decreased toxicity with unchanged efficacy.

METHODS

Children (median age, 4.2 years) treated for non–high-risk ALL according to the Nordic Society for Pediatric Hematology and Oncology ALL2008 protocol received five intramuscular PEG-asp injections (1,000 IU/m2) every two weeks and were then randomly assigned to additional three doses (6-week intervals [experimental arm], n = 309) versus 10 doses (2-week intervals [standard arm], n = 316). The primary end point was noninferior (6% margin) disease-free survival. Toxicity reduction was a secondary end point. Occurrence of asparaginase-associated hypersensitivity, pancreatitis, osteonecrosis, and thromboembolism were prospectively registered.

RESULTS

After a median follow-up of 4.1 years, the 5-year disease-free survival was 92.2% (95% CI, 88.6 to 95.8) and 90.8% (95% CI, 87.0 to 94.6) in the experimental and standard arms, respectively. The 3-year cumulative incidence of any first asparaginase-associated toxicity (hypersensitivity [n = 13]; osteonecrosis [n = 29]; pancreatitis [n = 24]; thromboembolism [n = 17]) was 9.3% in the experimental arm and 18.1% in the standard arm ( P = .001). Asparaginase-associated toxicity reduction was confirmed in sex- and risk-group–adjusted Cox regression analysis stratified by age (≥ 10 and < 10 years; hazard ratio, 0.48; P = .001). The experimental arm had the lowest incidences of all four toxicities, reaching significance for pancreatitis (6-month risk, 5.8% v 1.3%; P = .002).

CONCLUSION

The excellent cure rates and reduced toxicity risk support the use of intermittent PEG-asp therapy after the first 10 weeks in future childhood ALL trials that apply prolonged PEG-asp therapy.

PAI-1 and protein C as early markers of veno-occlusive disease in patients treated for Wilms tumor

BACKGROUND

Hepatic veno-occlusive (VOD) disease has been described in hematopoietic stem cell transplantation (HSCT), solid tumors, and acute lymphoblastic leukemia. The incidence of VOD in Wilms tumor (WT) ranges from 1.2% to 8%. The diagnosis of VOD is clinical, and there are no validated laboratory biomarkers.

PROCEDURE

We prospectively evaluated the specificity and sensitivity of plasminogen-activator inhibitor-1 (PAI-1) and protein C as diagnostic markers of VOD in WT patients. Fifty patients treated from 2008 to 2016 for WT were eligible. VOD was diagnosed according to modified Seattle criteria and retrospectively reclassified according to the recently published criteria for VOD in pediatric HSCT patients.

RESULTS

VOD occurred in 6 of 50 patients (12%) after 20 to 97 days from starting chemotherapy. The average duration of VOD was 10 days (range, 4-13 days). PAI-1 levels were elevated in all VOD patients, while a decrease in protein C levels was observed in 33% of patients with VOD. PAI-1 antigen (Ag) values ≥ 26.4 ng/mL demonstrated high sensitivity and specificity for the clinical diagnosis of VOD with sensitivity 100%, specificity 93%; whereas protein C levels below 34.5% had sensitivity 67%, specificity 100%. Both PAI-1 and protein C had an high negative predictive value: PAI-1 Ag 100%; protein C 95%.

CONCLUSIONS

PAI-1 Ag and protein C have good sensitivity and specificity for the diagnosis of VOD in WT patients. Their high negative predictive value can be used in the differential diagnosis of liver toxicity, especially in VOD episodes with absent or delayed hyperbilirubinemia.

Hepatotoxicity during 6-thioguanine treatment in inflammatory bowel disease and childhood acute lymphoblastic leukaemia: A systematic review

Background

The recently established association between higher levels of DNA-incorporated thioguanine nucleotides and lower relapse risk in childhood acute lymphoblastic leukaemia (ALL) calls for reassessment of prolonged 6-thioguanine (6TG) treatment, while avoiding the risk of hepatotoxicity.

Objectives

To assess the incidence of hepatotoxicity in patients treated with 6TG, and to explore if a safe dose of continuous 6TG can be established.

Data sources

Databases, conference proceedings, and reference lists of included studies were systematically searched for 6TG and synonyms from 1998–2018.

Methods

We included studies of patients with ALL or inflammatory bowel disorder (IBD) treated with 6TG, excluding studies with 6TG as part of an intensive chemotherapy regimen. We uploaded a protocol to PROSPERO (registration number CRD42018089424). Database and manual searches yielded 1823 unique records. Of these, 395 full-texts were screened for eligibility. Finally, 134 reports representing 42 studies were included.

Results and conclusions

We included data from 42 studies of ALL and IBD patients; four randomised controlled trials (RCTs) including 3,993 patients, 20 observational studies including 796 patients, and 18 case reports including 60 patients. Hepatotoxicity in the form of sinusoidal obstruction syndrome (SOS) occurred in 9–25% of the ALL patients in two of the four included RCTs using 6TG doses of 40–60 mg/m²/day, and long-term hepatotoxicity in the form of nodular regenerative hyperplasia (NRH) was reported in 2.5%. In IBD patients treated with 6TG doses of approximately 23 mg/m²/day, NRH occurred in 14% of patients. At a 6TG dose of approximately 12 mg/m²/day, NRH was reported in 6% of IBD patients, which is similar to the background incidence. According to this review, doses at or below 12 mg/m²/day are rarely associated with notable hepatotoxicity and can probably be considered safe.

Venoocclusive disease due to chemotherapy for pediatric acute lymphoblastic leukemia is associated with increased levels of plasminogen-activator inhibitor-1

We describe three cases of sinusoidal obstruction syndrome/venoocclusive disease (SOS) in pediatric patients with acute lymphoblastic leukemia (ALL). All three episodes occurred during or just after the induction or reinduction phase of treatment based on prednisone/dexamethasone, vincristine, daunorubicin, and pegylated-l-asparaginase. SOS episodes were categorized as mild/moderate and resolved in 7, 10, and 16 days using supportive measures or defibrotide therapy. In all three episodes, the clinical diagnosis of SOS was associated with a significant increase in plasminogen-activator inhibitor-1 (PAI-1) that reduced with patient clinical improvement. PAI-1 warrants study as a diagnostic marker for SOS in ALL.

Treatment-related sinusoidal obstruction syndrome in children with de novo acute lymphoblastic leukemia during intensification

PURPOSE

Sinusoidal obstruction syndrome (SOS), also known as veno-occlusive disease, has been described following treatment of acute lymphoblastic leukemia (ALL) with the anti-metabolite 6-thioguanine (6-TG). Previous studies incorporating daily 6-TG into maintenance chemotherapy demonstrated a high incidence of SOS, typically presenting after prolonged exposures to 6-TG. 6-TG continues to be used as a single, 14-day burst during intensification; however, SOS associated with brief courses of 6-TG is poorly described. We aim to describe this rare though clinically significant phenomenon.

METHODS

Children with 6-TG-related SOS were retrospectively identified from 680 de novo patients with ALL at Texas Children's Cancer Center over 8 years. Clinical characteristics and outcomes are described.

RESULTS

Ten (1.5%) patients were identified with SOS. No predominant sex, ethnicity, or race was noted. SOS was diagnosed 16.5 (6-42) days from starting 6-TG. Isolated thrombocytopenia (IT) was noted in 9/10 patients and presented a median of 5 days prior to SOS. Refractoriness to platelet transfusions was noted in 8/10 patients, presenting a median of 2 days prior to SOS. Most patients were otherwise clinically stable outpatients upon presenting with IT or transfusion refractoriness. Fever was noted in 7/10 patients at diagnosis and 6/10 had documented or suspected infection within 14 days of SOS. Two patients died, while eight fully recovered. Intermediate thiopurine methyltransferase genotype was noted in 5/8 patients with data available.

CONCLUSION

SOS following short courses of 6-TG in DI is clinically distinct from SOS following prolonged courses of 6-TG in maintenance, particularly in its early presentation and outcomes.

Non-infectious chemotherapy-associated acute toxicities during childhood acute lymphoblastic leukemia therapy

During chemotherapy for childhood acute lymphoblastic leukemia, all organs can be affected by severe acute side effects, the most common being opportunistic infections, mucositis, central or peripheral neuropathy (or both), bone toxicities (including osteonecrosis), thromboembolism, sinusoidal obstruction syndrome, endocrinopathies (especially steroid-induced adrenal insufficiency and hyperglycemia), high-dose methotrexate-induced nephrotoxicity, asparaginase-associated hypersensitivity, pancreatitis, and hyperlipidemia. Few of the non-infectious acute toxicities are associated with clinically useful risk factors, and across study groups there has been wide diversity in toxicity definitions, capture strategies, and reporting, thus hampering meaningful comparisons of toxicity incidences for different leukemia protocols. Since treatment of acute lymphoblastic leukemia now yields 5-year overall survival rates above 90%, there is a need for strategies for assessing the burden of toxicities in the overall evaluation of anti-leukemic therapy programs.