Complying with the European Clinical Trials directive while surviving the administrative pressure – An alternative approach to toxicity registration in a cancer trial

Parents' perception of treatment-related toxicity in children treated according to the NOPHO ALL2008 protocol for acute lymphoblastic leukemia

This study aimed to assess how parents perceived treatment-related side effects during acute lymphoblastic leukemia (ALL) treatment. Parents of children 1-17.9 years at diagnosis in Sweden, Finland, and Denmark who were alive and in first remission ≥6 months after end of ALL treatment were asked to respond on specific items regarding how their child was affected by side effects related to vincristine (VCR), corticosteroids, peg-asparaginase (ASP), and maintenance therapy, as well as overall impact of these treatments, complications in general, and their perception of impact on their child in comparison with other children with ALL. Parents of 307 children responded. More than a third reported that their child had been affected to a high extent by VCR (39.7%) and corticosteroids (35.8%), with walking difficulties, muscular weakness, pain, changes in appetite, and mood swings as the most common and severe symptoms. Reporting of these toxicities was lacking from the NOPHO ALL2008 database, except for peripheral paralysis (12.1%). For distinct toxicities reported in the NOPHO ALL2008 database, for example, thrombosis and pancreatitis, parent reports were similar to the database. Although a high overall negative impact during treatment was reported, parents generally rated the impact on their child as less, or similar, to other children with ALL. Parents perceived VCR and corticosteroid therapy, in particular, to have a negative impact on their child during ALL treatment, which was not captured in the NOPHO ALL2008 toxicity reporting. Our results highlight the importance of including patient/parent-reported outcomes in toxicity reporting.

Chemotherapy-related toxicities follow a typical pattern in children treated for acute lymphoblastic leukaemia

AIM

Acute lymphoblastic leukaemia (ALL) therapy has been associated with a significant burden of toxicities. The aim of this study was to describe the full spectrum of toxic effects associated with childhood ALL.

METHODS

Toxicity-related data were collected from the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL-2008 toxicity registry, in which data on 19 clinically relevant toxicities were registered during ALL treatment, and from patient medical records. All patients treated according to the NOPHO ALL-2008 protocol in Oulu University Hospital between 2008 and 2020 were included in the study.

RESULTS

The cohort consisted of 73 patients, 38 of whom were male. Mean age at diagnosis was 6.6 ± 4.2 (range 1.4-16.0) years. All but one of the patients developed at least one treatment-related toxicity and more than half had multiple toxicities. Female sex and older age were associated with a higher tendency towards toxicity. The most common toxicity was vincristine-induced peripheral neuropathy, which was observed in 70 patients. Most toxicities were moderate or severe, but even mild toxicities often affected leukaemia treatment.

CONCLUSION

Moderate and severe treatment-related toxicities are common, and most toxicities occur in a typical pattern in relation to the treatment phases.

Impact of body mass index on outcome and treatment-related toxicity in young adults with acute lymphoblastic leukemia

BACKGROUND

Data on outcome for patients in different body mass index (BMI) categories in young adults with acute lymphoblastic leukemia (ALL) are scarce. We explored survival and toxicities in different BMI categories in young adults with ALL.

MATERIAL AND METHODS

Patients aged 18-45 years, diagnosed with ALL between July 2008 and June 2022 in the Nordic countries, Estonia, or Lithuania, and treated according to the NOPHO ALL2008 protocol, were retrospectively enrolled and classified into different BMI categories. Endpoints were overall survival (OS), event-free survival (EFS) and cumulative incidence of relapse as well as incidence rate ratio (IRR) of severe predefined toxic events, and treatment delays.

RESULTS

The group comprised 416 patients, of whom 234 (56%) were stratified to non-high-risk (non-HR) treatment. In the non-HR group, patients with severe obesity, BMI ≥35 kg/m2 had worse EFS due to relapses but there was no effect on toxicity or treatment delays compared with the healthy-weight patients. There was no association between BMI category and OS, overall toxicity, or treatment delays in the patients with high-risk treatment.

CONCLUSION

Severe obesity is associated with worse EFS in young adults treated according to the non-HR arms of the NOPHO ALL2008 protocol. Poorer outcome is explained with a higher risk of relapse, possibly due to under treatment, and not caused by excess therapy-related mortality.

Hyperlipidemia in children and adolescents with acute lymphoblastic leukemia: A systematic review and meta-analysis

BACKGROUND

The established association between acute lymphoblastic leukemia (ALL) and hyperlipidemia has, in some studies, been linked to toxicities such as pancreatitis, thrombosis, and osteonecrosis. However, a systematic review investigating the incidence, management, and clinical implications of hyperlipidemia during childhood ALL treatment is lacking.

OBJECTIVES

Systematically assess the incidence of hyperlipidemia during ALL treatment, explore associations with risk factors and severe toxicities (osteonecrosis, thrombosis, and pancreatitis), and review prevalent management strategies.

METHODS

A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Data synthesis was descriptive, and a meta-analysis of hypertriglyceridemia and risk of severe toxicities was performed.

RESULTS

We included 13 studies with 3,425 patients. Hyperlipidemia incidence varied widely (6.7%-85%) but with inconsistent definitions and screening strategies across studies. Evidence regarding risk factors was conflicting, but age (> 10 years) and treatment with asparaginase and glucocorticosteroids seem to be associated with hyperlipidemia. Hypertriglyceridemia (grade 3/4) increased the risk for osteonecrosis (odds ratio (OR): 4.27, 95% confidence interval (CI): 2.77-6.61). No association could be established for pancreatitis (OR: 1.60, 95% CI: 0.53-4.82) or thrombosis (OR: 2.45, 95% CI: 0.86-7.01), but larger studies are needed to confirm this.

CONCLUSION

The overall evidence of this systematic review is limited by the small number of studies and risk of bias. Our review suggests that hypertriglyceridemia increases the risk for osteonecrosis. However, larger studies are needed to explore the clinical implications of hyperlipidemia and randomized trials investigating hyperlipidemia management and its impact on severe toxicities.

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.

Prospective longitudinal evaluation of treatment-related toxicity and health-related quality of life during the first year of treatment for pediatric acute lymphoblastic leukemia

Background

Pediatric acute lymphoblastic leukemia (ALL) therapy is accompanied by treatment-related toxicities (TRTs) and impaired quality of life. In Australia and New Zealand, children with ALL are treated with either Children’s Oncology Group (COG) or international Berlin-Frankfurt-Munster (iBFM) Study Group-based therapy. We conducted a prospective registry study to document symptomatic TRTs (venous thrombosis, neurotoxicity, pancreatitis and bone toxicity), compare TRT outcomes to retrospective TRT data, and measure the impact of TRTs on children’s general and cancer-related health-related quality of life (HRQoL) and parents’ emotional well-being.

Methods

Parents of children with newly diagnosed ALL were invited to participate in the ASSET (Acute Lymphoblastic Leukaemia Subtypes and Side Effects from Treatment) study and a prospective, longitudinal HRQoL study. TRTs were reported prospectively and families completed questionnaires for general (Healthy Utility Index Mark 3) and cancer specific (Pediatric Quality of Life Inventory (PedsQL)-Cancer Module) health related quality of life as well the Emotion Thermometer to assess emotional well-being.

Results

Beginning in 2016, 260 pediatric patients with ALL were enrolled on the TRT registry with a median age at diagnosis of 59 months (range 1–213 months), 144 males (55.4%), majority with Pre-B cell immunophenotype, n = 226 (86.9%), 173 patients (66.5%) treated according to COG platform with relatively equal distribution across risk classification sub-groups. From 2018, 79 families participated in the HRQoL study through the first year of treatment. There were 74 TRT recorded, reflecting a 28.5% risk of developing a TRT. Individual TRT incidence was consistent with previous studies, being 7.7% for symptomatic VTE, 11.9% neurotoxicity, 5.4% bone toxicity and 5.0% pancreatitis. Children’s HRQoL was significantly lower than population norms throughout the first year of treatment. An improvement in general HRQoL, measured by the HUI3, contrasted with the lack of improvement in cancer-related HRQoL measured by the PedsQL Cancer Module over the first 12 months. There were no persisting differences in the HRQoL impact of COG compared to iBFM therapy.

Conclusions

It is feasible to prospectively monitor TRT incidence and longitudinal HRQoL impacts during ALL therapy. Early phases of ALL therapy, regardless of treatment platform, result in prolonged reductions in cancer-related HRQoL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10072-x.

Efficacy of ruxolitinib in acute lymphoblastic leukemia: A systematic review

Philadelphia-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk molecular subtype with a gene expression profile similar to Philadelphia-positive ALL, but not harboring the BCR-ABL1 gene fusion. We aimed to investigate the efficacy of target therapy with the Janus kinase inhibitor, ruxolitinib, in patients with Ph-like ALL and molecular signature of JAK-STAT signaling pathway. A systematic search of the literature was performed to identify reports concerning administration of ruxolitinib in Ph-like ALL patients. Additionally, Polish Pediatric ALL registries were searched for patients with Ph-like ALL treated with ruxolitinib. Extracted information included epidemiological background, somatic aberrations, treatment response, and patient outcome. After PubMed database search, twelve patients were identified, and one was identified in the Polish Pediatric ALL registry. In nine patients gene fusions affecting JAK2 (n = 7) and EPOR (n = 2) were detected. Surface overexpression of CRLF2 and IKZF1 deletions were observed in two and three patients, respectively. Induction failure occurred in all the patients. Therapy with ruxolitinib led to complete (n = 7) and partial (n = 2) remission, in three individuals no information was found. Based on the limited number of studies describing the efficacy of ruxolitinib as an additional compound administrated with standard ALL therapy, we conclude that this approach can be considered in patients with aberrations activating JAK-STAT pathway.

Cerebral sinovenous thrombosis and asparaginase re-exposure in patients aged 1-45 years with acute lymphoblastic leukaemia: A NOPHO ALL2008 study

Cerebral sinovenous thrombosis (CSVT) is a serious complication during asparaginase therapy in patients with acute lymphoblastic leukaemia (ALL). We identified 46 patients with CSVT among 2651 patients (1‒45 years) treated according to the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol between 2008 and 2018. CSVT cases were prospectively registered in the NOPHO database with retrospective updates. We examined the frequency of asparaginase re-exposure after CSVT, potential factors associated with asparaginase truncation, and sequelae after CSVT. This work was supported by the Danish Cancer Society and the Danish Childhood Cancer Foundation. The 2.5-year cumulative incidence of CSVT was 1.9% (95% confidence interval 1.4%-2.5%). The majority of patients (74%, n = 31) were re-exposed to asparaginase (with low-molecular-weight heparin coverage), one of whom had a second CSVT, without neurological sequelae. Patients re-exposed to asparaginase were earlier in ALL treatment and lacked more asparaginase doses than non-re-exposed patients at CSVT diagnosis (median 50 vs. 81 days, p = 0.03; mean 11.2 vs. 8.4 asparaginase doses, p = 0.04). No other examined factors had an impact on asparaginase re-exposure. At the last follow-up (median 4.5 years after CSVT), 61% of patients had normal neurological status, and 57% had complete recanalisation of CSVT, with no significant difference between patients re-exposed and non-re-exposed to asparaginase. Our results indicate that re-exposure to asparaginase is safe after CSVT during anticoagulation.

Whole blood long-chain n-3 fatty acids as a measure of fish oil compliance in children with acute lymphoblastic leukemia: a pilot study

Long-chain n-3 fatty acids (n-3 LCPUFA) may prevent chemotherapy-induced hyperlipidemia in children with acute lymphoblastic leukemia (ALL). However, compliance could be a problem and intake-biomarker correlations may be affected by bodyweight and blood transfusions. We assessed whole blood n-3 LCPUFA three times during the first 83 days of treatment in six 1-17-year-old children with ALL, who received 2.4-4.9 g/d n-3 LCPUFA depending on bodyweight. Mean compliance was 73%, which resulted in a 2.5-fold increase in blood n-3 LCPUFA irrespective of blood transfusions. The correlation between relative blood content of n-3 LCPUFA and intake in g/d across the study period was strong (r=0.76, p=0.001). When n-3 LCPUFA was expressed in absolute concentrations and intake per kg bodyweight the correlation decreased (r=0.39, p=0.164) and was driven by baseline values. Thus, relative content of n-3 LCPUFA in blood reflects fish oil compliance in children with ALL despite blood transfusions and differences in bodyweight.

The changing landscape of treatment options in childhood acute lymphoblastic leukaemia

New paediatric acute lymphoblastic leukaemia (ALL) treatments have been developed and innovative products are in the pipeline. However, despite many active clinical trials, bridging bench science to clinical development to authorised medicines remains challenging. Research in first-line treatment continues to focus on multidrug chemotherapy with the potential addition of new targeted molecules being studied. Research in second- and third-line treatment represents a shift from cytotoxic intensification to an area of precision medicine through emergent innovative and immuno-oncology products. The collaborative research model in ALL involving different stakeholders should intensify to facilitate bench-to-bedside clinical translation for the benefit of patients.

ICU Admission in Children With Acute Lymphoblastic Leukemia in Sweden: Prevalence, Outcome, and Risk Factors

OBJECTIVES

Despite progress in the treatment of childhood acute lymphoblastic leukemia, severe complications are common, and the need of supportive care is high. We explored the cumulative prevalence, clinical risk factors, and outcomes of children with acute lymphoblastic leukemia, on first-line leukemia treatment in the ICUs in Sweden.

DESIGN

A nationwide prospective register and retrospective chart review study.

SETTING

Children with acute lymphoblastic leukemia were identified, and demographic and clinical data were obtained from the Swedish Childhood Cancer Registry. Data on intensive care were collected from the Swedish Intensive Care Registry. Data on patients with registered ICU admission in the Swedish Childhood Cancer Registry were supplemented through questionnaires to the pediatric oncology centers.

PATIENTS

All 637 children 0-17.9 years old with acute lymphoblastic leukemia diagnosed between June 2008 and December 2016 in Sweden were included.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twenty-eight percent of the children (178/637) were admitted to an ICU at least once. The Swedish Intensive Care Registry data were available for 96% of admissions (241/252). An ICU admission was associated with poor overall survival (hazard ratio, 3.25; 95% CI, 1.97-5.36; p ≤ 0.0001). ICU admissions occurred often during early treatment; 48% (85/178) were admitted to the ICU before the end of the first month of acute lymphoblastic leukemia treatment (induction therapy). Children with T-cell acute lymphoblastic leukemia or CNS leukemia had a higher risk of being admitted to the ICU in multivariable analyses, both for early admissions before the end of induction therapy and for all admissions during the study period.

CONCLUSIONS

The need for intensive care in children with acute lymphoblastic leukemia, especially for children with T cell acute lymphoblastic leukemia and CNS leukemia, is high with most admissions occurring during early treatment.

Obesity as a predictor of treatment-related toxicity in children with acute lymphoblastic leukaemia

Obesity is associated with poor outcomes in childhood acute lymphoblastic leukaemia (ALL). We explored whether severe treatment-related toxicity and treatment delays could explain this observation. This study included 1 443 children aged 2·0-17·9 years with ALL treated with the Nordic Society of Pediatric Haematology and Oncology (NOPHO) ALL2008 non-high-risk protocol. Prospective treatment-related toxicities registered every three-month interval were used. Patients were classified according to sex- and age-adjusted international childhood cut-off values, corresponding to adult body mass index: underweight, <17 kg/m² ; healthy weight, 17 to <25 kg/m² ; overweight, 25 to <30 kg/m² ; and obese, ≥30 kg/m² . Obese children had a higher incidence rate ratio (IRR) for severe toxic events {IRR: 1·55 [95% confidence interval (CI) 1·07-2·50]}, liver and kidney failures, bleeding, abdominal complication, suspected unexpected severe adverse reactions and hyperlipidaemia compared with healthy-weight children. Obese children aged ≥10 years had increased IRRs for asparaginase-related toxicities compared with healthy-weight older children: thromboses [IRR 2·87 (95% CI 1·00-8·21)] and anaphylactic reactions [IRR 7·95 (95% CI 2·15-29·37)] as well as higher risk for truncation of asparaginase [IRR 3·54 (95% CI 1·67-7·50)]. The high prevalence of toxicity and a higher risk of truncation of asparaginase may play a role in the poor prognosis of obese children aged ≥10 years with ALL.

Asparaginase Enzyme Activity Levels and Toxicity in Childhood Acute Lymphoblastic Leukemia: a NOPHO ALL2008 study

Overall asparaginase-associated toxicity and relapse were not significantly associated with increased asparaginase enzyme activity levels.

The risk of pancreatitis and osteonecrosis were significantly associated with increasing asparaginase enzyme activity.

Asparaginase treatment is a mainstay in contemporary treatment of acute lymphoblastic leukemia (ALL), but substantial asparaginase-related toxicity may lead to jeopardized protocol compliance and compromises survival. We investigated the association between risk of asparaginase-associated toxicities (AspTox) and asparaginase enzyme activity (AEA) levels in 1155 children aged 1.0 to 17.9 years, diagnosed with ALL between July 2008 and March 2016, and treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol. Patients with ≥2 blood samples for AEA measurement drawn 14 ± 2 days after asparaginase administration were included (6944 trough values). AEA was measurable (or >0 IU/L) in 955 patients, whereas 200 patients (17.3%) had asparaginase inactivation and few AspTox recorded. A time-dependent multiple Cox model of time to any first asparaginase-associated toxicity adjusted for sex and age was used. For patients with measurable AEA, we found a hazard ratio (HR) of 1.17 per 100 IU/L increase in median AEA (95% confidence interval [CI], 0.98-1.41; P = .09). For pancreatitis, thromboembolism, and osteonecrosis, the HRs were 1.40 (95% CI, 1.12-1.75; P = .002), 0.99 (95% CI, 0.70-1.40; P = .96), and 1.36 (95% CI, 1.04-1.77; P = .02) per 100 IU/L increase in median AEA, respectively. No significant decrease in the risk of leukemic relapse was found: HR 0.88 per 100 IU/L increase in AEA (95% CI, 0.66-1.16; P = .35). In conclusion, these results emphasize that overall AspTox and relapse are not associated with AEA levels, yet the risk of pancreatitis and osteonecrosis increases with increasing AEA levels.

Endothelial dysfunction and thromboembolism in children, adolescents, and young adults with acute lymphoblastic leukemia

Endothelial dysfunction has not previously been investigated as a thrombogenic risk factor among patients with acute lymphoblastic leukemia (ALL), known to be at high risk of thromboembolism. We retrospectively explored the association between three circulating biomarkers of endothelial dysfunction (thrombomodulin, syndecan-1, VEGFR-1) measured in prospectively collected blood samples and risk of thromboembolism in 55 cases and 165 time-matched controls, treated according to the NOPHO ALL2008 protocol. In age-, sex-, and risk group-adjusted analysis, increasing levels of thrombomodulin and VEGFR-1 were independently associated with increased odds of developing thromboembolism (OR 1.37 per 1 ng/mL [95% CI 1.20‒1.56, P < 0.0001] and OR 1.21 per 100 pg/mL [95% CI 1.02‒1.21, P = 0.005], respectively). These associations remained significant when including only samples drawn >30 days before thromboembolic diagnosis. Thrombomodulin levels were on average 3.2 ng/mL (95% CI 2.6-8.2 ng/mL) higher in samples with measurable asparaginase activity (P < 0.0001). Among single nucleotide variants located in or neighboring coding genes for the three biomarkers, none were significantly associated with odds of thromboembolism. If results are validated in another cohort, thrombomodulin and VEGFR-1 could serve as predictive biomarkers, identifying patients in need of preemptive antithrombotic prophylaxis.

Maintenance therapy and risk of osteonecrosis in children and young adults with acute lymphoblastic leukemia: a NOPHO ALL2008 sub-study

PURPOSE

Osteonecrosis is a burdensome treatment-related toxicity that is mostly diagnosed during or soon after 6-mercaptopurine (6MP)/methotrexate (MTX) maintenance therapy for acute lymphoblastic leukemia (ALL), possibly indicating a pathogenic role of these drugs.

METHODS

We prospectively registered symptomatic osteonecrosis during treatment of 1234 patients aged 1.0-45.9 years treated according to the Nordic Society of Hematology and Oncology (NOPHO) ALL2008 protocol. MTX/6MP metabolites were measured as part of the NOPHO ALL2008 maintenance therapy study.

RESULTS

After a median follow-up of 5.6 years [interquartile range (IQR) 3.6-7.5], 68 patients had been diagnosed with symptomatic osteonecrosis. The cumulative incidence was 2.7% [95% confidence interval (CI) 1.6-3.8%] for patients aged < 10 years, 14.9% (95% CI 9.7-20.2%) for patients aged 10.0-17.9 years, and 14.4% (95% CI 8.0-20.8%) for patients aged ≥ 18 years. The median time from diagnosis of ALL to diagnosis of osteonecrosis in these age groups was 1.0 year (IQR 0.7-2.0), 2.0 years (IQR 1.1-2.4), and 2.2 years (IQR 1.8-2.8), respectively (p = 0.001). With 17,854 blood samples available for MTX and 6MP metabolite analysis, neither erythrocyte levels of 6-thioguanine (TG) nucleotides (p > 0.99), methylated 6MP metabolites (p = 0.37), MTX polyglutamates (p = 0.98) nor DNA-TG (p = 0.53) were significantly associated with the hazard of osteonecrosis in Cox models stratified by the three age groups and adjusted for sex.

CONCLUSION

Maintenance therapy intensity determined by 6MP and MTX metabolites was not associated with the risk of developing osteonecrosis in the NOPHO ALL2008 cohort.

Relapse risk following truncation of pegylated asparaginase in childhood acute lymphoblastic leukemia

Truncation of asparaginase treatment due to asparaginase-related toxicities or silent inactivation (SI) is common and may increase relapse risk in acute lymphoblastic leukemia (ALL). We investigated relapse risk following suboptimal asparaginase exposure among 1401 children aged 1 to 17 years, diagnosed with ALL between July 2008 and February 2016, treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol (including extended asparaginase exposure [1000 IU/m2 intramuscularly weeks 5-33]). Patients were included with delayed entry at their last administered asparaginase treatment, or detection of SI, and followed until relapse, death, secondary malignancy, or end of follow-up (median, 5.71 years; interquartile range, 4.02-7.64). In a multiple Cox model comparing patients with (n = 358) and without (n = 1043) truncated asparaginase treatment due to clinical toxicity, the adjusted relapse-specific hazard ratio (HR; aHR) was 1.33 (95% confidence interval [CI], 0.86-2.06; P = .20). In a substudy including only patients with information on enzyme activity (n = 1115), the 7-year cumulative incidence of relapse for the 301 patients with truncation of asparaginase treatment or SI (157 hypersensitivity, 53 pancreatitis, 14 thrombosis, 31 other, 46 SI) was 11.1% (95% CI, 6.9-15.4) vs 6.7% (95% CI, 4.7-8.6) for the 814 remaining patients. The relapse-specific aHR was 1.69 (95% CI, 1.05-2.74, P=.03). The unadjusted bone marrow relapse-specific HR was 1.83 (95% CI, 1.07-3.14, P=.03) and 1.86 (95% CI, 0.90- 3.87, P=.095) for any central nervous system relapse. These results emphasize the importance of therapeutic drug monitoring and appropriate adjustment of asparaginase therapy when feasible. This trial was registered at www.clinicaltrials.gov as #NCT03987542.

No association between relapse hazard and thiopurine methyltransferase geno- or phenotypes in non-high risk acute lymphoblastic leukemia: a NOPHO ALL2008 sub-study

PURPOSE

6-mercaptopurine(6MP)/methotrexate maintenance therapy is essential to reduce relapse of childhood acute lymphoblastic leukemia (ALL). Common germline variants in TPMT cause low activity of thiopurine methyltransferase (TPMT) and higher 6MP metabolite (TGN) levels. Higher levels of TGNs incorporated into DNA (DNA-TG) and low TPMT activity have previously been associated with a lower relapse risk. We explored if TPMT geno- or phenotype was associated with DNA-TG levels and relapse rate in NOPHO ALL2008.

METHODS

TPMT genotype, repeated phenotyping, and DNA-TG measurements were collected in 918 children with non-high risk ALL (NOPHO ALL2008 maintenance therapy study). Maintenance therapy started with 6MP at 50 and 75 mg/m² for TPMT heterozygous and wildtype patients and was adjusted to a target WBC of 1.5 - 3.0 × 10⁹/L.

RESULTS

Of 918 patients, 78 (8.5%) were TPMT heterozygous and 903 had at least one TPMT measurement (total 3063). Mean TPMT activities were higher with wildtype than heterozygous TPMT (N = 752, 16.6 versus 9.6 U/mL ery., p < 0.001). The 5-year cumulative incidence of relapse was 6.4% and 6.0% for TPMT heterozygous and wildtype patients, and there was no association between genotype and relapse rate (N = 918, hazard ratio = 1.01, 95% confidence interval [CI] 0.40 - 2.54, p = 0.98). Although TPMT heterozygous patients had higher DNA-TG (N = 548, median 760.9 [interquartile range (IQR) 568.7 - 890.3] versus 492.7 [IQR 382.1 - 634.6] fmol/µg, p < 0.001), TPMT activity was not associated with relapse rate (N = 813; hazard ratio = 0.98 per one U/mL ery. increase in TPMT activity, 95% CI 0.91 - 1.06, p = 0.67).

CONCLUSION

TPMT geno- and phenotype were not associated with relapse in non-high risk NOPHO ALL2008.

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.

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.

Effects of germline DHFR and FPGS variants on methotrexate metabolism and relapse of leukemia

Methotrexate (MTX) during maintenance therapy is essential for curing acute lymphoblastic leukemia (ALL), but dosing strategies aiming at adequate treatment intensity are challenged by interindividual differences in drug disposition. To evaluate genetic factors associated with MTX metabolism, we performed a genome-wide association study in 447 ALL cases from the Nordic Society for Pediatric Haematology and Oncology ALL2008 study, validating results in an independent set of 196 patients. The intergenic single-nucleotide polymorphism rs1382539, located in a regulatory element of DHFR, was associated with increased levels of short-chain MTX polyglutamates (P = 1.1 × 10-8) related to suppression of enhancer activity, whereas rs35789560 in FPGS (p.R466C, P = 5.6 × 10-9) was associated with decreased levels of long-chain MTX polyglutamates through reduced catalytic activity. Furthermore, the FPGS variant was linked with increased relapse risk (P = .044). These findings show a genetic basis for interpatient variability in MTX response and could be used to improve future dosing algorithms.

National, clinical cohort study of late effects among survivors of acute lymphoblastic leukaemia: the ALL-STAR study protocol

INTRODUCTION

More than 90% of patients diagnosed with childhood acute lymphoblastic leukaemia (ALL) today will survive. However, half of the survivors are expected to experience therapy-related chronic or late occurring adverse effects, reducing quality of life. Insight into underlying risk trajectories is warranted. The aim of this study is to establish a Nordic, national childhood ALL survivor cohort, to be investigated for the total somatic and psychosocial treatment-related burden as well as associated risk factors, allowing subsequent linkage to nation-wide public health registers.

METHODS AND ANALYSIS

This population-based observational cohort study includes clinical follow-up of a retrospective childhood ALL survivor cohort (n=475), treated according to a common Nordic ALL protocol during 2008-2018 in Denmark. The study includes matched controls. Primary endpoints are the cumulative incidence and cumulative burden of 197 health conditions, assessed through self-report and proxy-report questionnaires, medical chart validation, and clinical examinations. Secondary endpoints include organ-specific outcome, including cardiovascular and pulmonary function, physical performance, neuropathy, metabolic disturbances, hepatic and pancreatic function, bone health, oral and dental health, kidney function, puberty and fertility, fatigue, and psychosocial outcome. Therapy exposure, acute toxicities, and host genome variants are explored as risk factors.

ETHICS AND DISSEMINATION

The study is approved by the Regional Ethics Committee for the Capital Region in Denmark (H-18035090/H-20006359) and by the Danish Data Protection Agency (VD-2018-519). Results will be published in peer-reviewed journals and are expected to guide interventions that will ameliorate the burden of therapy without compromising the chance of cure.

Polygenic risk score-analysis of thromboembolism in patients with acute lymphoblastic leukemia

INTRODUCTION

Thromboembolism (TE) is a common and serious toxicity of acute lymphoblastic leukemia (ALL) treatment, but studies of genetic predisposition have been underpowered with conflicting results. We tested whether TE in ALL and TE in the general adult population have a shared genetic etiology.

MATERIALS AND METHODS

We prospectively registered TE events and collected germline DNA in patients 1.0-45.9 years in the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 study (7/2008-7/2016). Based on summary statistics from two large genome-wide association studies (GWAS) on venous TE in adults (the International Network of VENous Thromboembolism Clinical Research Networks (INVENT) consortium and the UK Biobank), we performed polygenic risk score (PRS) analysis on TE development in the NOPHO cohort, progressively expanding the PRS by increasing the p-value threshold of single nucleotide polymorphism (SNP) inclusion.

RESULTS AND CONCLUSION

Eighty-nine of 1252 patients with ALL developed TE, 2.5 year cumulative incidence 7.2%. PRS of genome-wide significant SNPs from the INVENT and UK Biobank data were not significantly associated with TE, HR 1.16 (p 0.14) and 1.02 (p 0.86), respectively. Expanding PRS by increasing p-value threshold did not reveal polygenic overlap. However, subgroup analysis of adolescents 10.0-17.9 years (n = 231), revealed significant polygenic overlap with the INVENT GWAS. The best fit PRS, including 16,144 SNPs, was associated with TE with HR 1.76 (95% CI 1.23-2.52, empirical p-value 0.02). Our results support an underlying genetic predisposition for TE in adolescents with ALL and should be explored further in future TE risk prediction models.

Seizures during treatment of childhood acute lymphoblastic leukemia: A population-based cohort study

BACKGROUND

Seizures are common in children with acute lymphoblastic leukemia (ALL). As ALL survival rates are improving, the challenge to minimize treatment related side effects and late sequelae rises. Here, we studied the frequency, timing, etiology and risk factors of seizures in ALL patients.

METHODS

The study included children aged 1-17.9 years at diagnosis of B-cell-precursor and T cell ALL who were treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol between 2008 and 2015. Detailed patient data were acquired from the NOPHO ALL2008 registry and by review of medical records.

RESULTS

Seizures occurred in 81/1464 (5.5%) patients. The cumulative incidence of seizures at one months was 1.7% (95% CI: 1.2-2.5) and at one year 5.3% (95% CI 4.2-6.5%). Patients aged 10-17.9 years, those with T cell immunophenotype, CNS involvement, or high-risk induction with dexamethasone had higher risk for seizures in univariable analyses. Only age remained a risk factor in multivariable analyses (the cumulative incidence of seizures for patients 10-17.9 years old at one year was 9.0% (95% CI: 6.2-12.9)). Of the 81 patients with seizures, 43 had posterior reversible encephalopathy syndrome (PRES), 15 had isolated seizures, nine had sinus venous thrombosis (SVT), three had stroke-like syndrome, and 11 had other neurotoxicities. Epilepsy diagnosis was reported in totally 11 ALL survivors at last follow up.

CONCLUSION

Seizures are relatively common in ALL patients and occur most often in patients with PRES, SVT, or as an isolated symptom. Older children have higher risk of seizures.

Pulmonary embolism in acute lymphoblastic leukemia - An observational study of 1685 patients treated according to the NOPHO ALL2008 protocol

BACKGROUND

Pulmonary embolism (PE) is a serious complication of acute lymphoblastic leukemia (ALL). We examined the cumulative incidence and clinical presentation of PE in a well-defined cohort of patients with ALL aged 1-45 years treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol.

METHODS

As part of the mandatory toxicity reporting of NOPHO ALL2008, thromboembolism including PE was reported consecutively. The cumulative incidence of first-time PE was calculated using the Aalen-Johansen estimator during a 2.5-year period from ALL diagnosis. We used Fisher's exact test to examine categorical variables and Cox logistic regression to estimate hazard ratios (HRs) for PE.

RESULTS

PE was diagnosed in 32 of 1685 patients. The 2.5-year cumulative incidence of first-time PE increased with age: 0.43% (95% CI, 0.18-1.03) in children aged 1-9 years, 3.28% (95% CI, 1.72-6.22) in children aged 10-17 years, and 7.22% (95% CI, 4.61-11.21) in adults aged 18-45 years. The majority of PEs, 78% (25/32), occurred during asparaginase treatment. HRs adjusted for age and sex were associated with male sex (HR, 2.4; 95% CI, 1.0-5.6) and older age (10-17 years: HR 7.5; 95% CI, 2.5-22.2), 18-45 years: HR, 16.5; 95% CI, 6.1-44.5). In two-thirds of the patients (63%; 17/27), PE and its treatment had no impact on the administered doses of asparaginase. PE-associated 30-day mortality was 9.4% (95% CI, 1.9-25.0).

CONCLUSIONS

Awareness of PE is warranted during ALL treatment. Larger multicenter studies are needed to examine predictors of PE in ALL.

Pharmacokinetics of tablet and liquid formulations of oral 6-mercaptopurine in children with acute lymphoblastic leukemia

PURPOSE

Mercaptopurine (6MP) is essential to cure childhood acute lymphoblastic leukemia (ALL). A liquid 6MP formulation was recently introduced to facilitate oral 6MP administration, especially to children. Its approval and bioequivalence with 6MP tablet were based on comparative pharmacokinetics in 60 healthy adults. Due to potential pharmacokinetic differences between healthy adults and children with ALL, we compared pharmacokinetics of tablet and liquid 6MP formulations in children with ALL.

METHODS

Pharmacokinetics of 50 mg 6MP tablet (Puri-Nethol^®) and 20 mg/ml 6MP liquid suspension (Xaluprine^®) were compared in a non-blinded, random order, single-dose, cross-over study in 16 children with ALL (eight males). 6MP was administered after a 12 h fast, and 6MP plasma concentrations measured consecutively over seven hours post-dose. Pharmacokinetic outcomes were as follows: Area under the curve (AUC), maximum plasma concentration (C_max), time to maximum plasma concentration (T_max), and terminal half-life (T_½).

RESULTS

Liquid 6MP formulation resulted in a 26% lower AUC (p = 0.02) compared with tablet (median 1215 vs. 1805 h × nmol/l). No significant differences were observed for C_max,T_max and T_½ (p = 0.28, p = 0.09, p = 0.41, respectively). Based on criteria declared by the World Health Organization the results did not establish non-inferiority of liquid 6MP formulation compared with 6MP tablet.

CONCLUSION

Non-inferiority of liquid 6MP formulation compared with 6MP tablet was not demonstrated. Yet, maintenance therapy doses are adjusted by degree of myelosuppression and not by 6MP dose. Thus, in spite of a lower bioavailability, a liquid 6MP formulation is still desirable in a clinical setting, especially for children. However, if shifting between 6MP formulation is indicated, dose adjustments should be anticipated to maintain equivalent treatment intensity in children with ALL. The study is registered on clinicaltrials.gov (NCT01906671). Date of registration: 24.07.13.

Asparaginase-Associated Pancreatitis in Acute Lymphoblastic Leukemia: Results From the NOPHO ALL2008 Treatment of Patients 1-45 Years of Age

PURPOSE

Asparaginase-associated pancreatitis (AAP) is common in patients with acute lymphoblastic leukemia (ALL), but risk differences across age groups both in relation to first-time AAP and after asparaginase re-exposure have not been explored.

PATIENTS AND METHODS

We prospectively registered AAP (n = 168) during treatment of 2,448 consecutive ALL patients aged 1.0-45.9 years diagnosed from July 2008 to October 2018 and treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol.

RESULTS

Compared with patients aged 1.0-9.9 years, adjusted AAP hazard ratios (HRa) were associated with higher age with almost identical HRa (1.6; 95% CI, 1.1 to 2.3; P = .02) for adolescents (10.0-17.9 years) and adults (18.0-45.9 years). The day 280 cumulative incidences of AAP were 7.0% for children (1.0-9.9 years: 95% CI, 5.4 to 8.6), 10.1% for adolescents (10.0 to 17.9 years: 95% CI, 7.0 to 13.3), and 11.0% for adults (18.0-45.9 years: 95% CI, 7.1 to 14.9; P = .03). Adolescents had increased odds of both acute (odds ratio [OR], 5.2; 95% CI, 2.1 to 13.2; P = .0005) and persisting complications (OR, 6.7; 95% CI, 2.4 to 18.4; P = .0002) compared with children (1.0-9.9 years), whereas adults had increased odds of only persisting complications (OR, 4.1; 95% CI, 1.4 to 11.8; P = .01). Fifteen of 34 asparaginase-rechallenged patients developed a second AAP. Asparaginase was truncated in 17/21 patients with AAP who subsequently developed leukemic relapse, but neither AAP nor the asparaginase truncation was associated with increased risk of relapse.

CONCLUSION

Older children and adults had similar AAP risk, whereas morbidity was most pronounced among adolescents. Asparaginase re-exposure should be considered only for patients with an anticipated high risk of leukemic relapse, because multiple studies strongly indicate that reduction of asparaginase treatment intensity increases the risk of relapse.

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.

Posterior reversible encephalopathy syndrome in children with acute lymphoblastic leukemia: Clinical characteristics, risk factors, course, and outcome of disease

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is a distinct entity with incompletely known predisposing factors. The aim of this study is to describe the incidence, risk factors, clinical course, and outcome of PRES in childhood acute lymphoblastic leukemia (ALL).

PROCEDURE

Patients aged 1.0 to 17.9 years diagnosed with ALL from July 2008 to December 2015 and treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol were included. Patients with PRES were identified in the prospective NOPHO leukemia toxicity registry, and clinical data were collected from the medical records.

RESULTS

The study group included 1378 patients, of whom 52 met the criteria for PRES. The cumulative incidence of PRES at one month was 1.7% (95% CI, 1.1-2.5) and at one year 3.7% (95% CI, 2.9-4.9). Older age (hazard ratios [HR] for each one-year increase in age 1.1; 95% CI, 1.0-1.2, P = 0.001) and T-cell immunophenotype (HR, 2.9; 95% CI, 1.6-5.3, P = 0.0005) were associated with PRES. Central nervous system (CNS) involvement (odds ratios [OR] = 2.8; 95% CI, 1.2-6.5, P = 0.015) was associated with early PRES and high-risk block treatment (HR = 2.63; 95% CI, 1.1-6.4, P = 0.033) with late PRES. At follow-up of the PRES patients, seven patients had epilepsy and seven had neurocognitive difficulties.

CONCLUSION

PRES is a neurotoxicity in the treatment of childhood ALL with both acute and long-term morbidity. Older age, T-cell leukemia, CNS involvement and high-risk block treatment are risk factors for PRES.

Genetic predisposition to PEG-asparaginase hypersensitivity in children treated according to NOPHO ALL2008

Asparaginase is essential in childhood acute lymphoblastic leukaemia (ALL) treatment, however hypersensitivity reactions to pegylated asparaginase (PEG-asparaginase) hampers anti-neoplastic efficacy. Patients with PEG-asparaginase hypersensitivity have been shown to possess zero asparaginase enzyme activity. Using this measurement to define the phenotype, we investigated genetic predisposition to PEG-asparaginase hypersensitivity in a genome-wide association study (GWAS). From July 2008 to March 2016, 1494 children were treated on the Nordic Society of Paediatric Haematology and Oncology ALL2008 protocol. Cases were defined by clinical hypersensitivity and no enzyme activity, controls had enzyme activity ≥ 100 iu/l and no hypersensitivity symptoms. PEG-asparaginase hypersensitivity was reported in 13·8% (206/1494) of patients. Fifty-nine cases and 772 controls fulfilled GWAS inclusion criteria. The CNOT3 variant rs73062673 on 19q13.42, was associated with PEG-asparaginase allergy (P = 4·68 × 10^-8 ). We further identified two signals on chromosome 6 in relation to HLA-DQA1 (P = 9·37 × 10^-6 ) and TAP2 (P = 1·59 × 10^-5 ). This study associated variants in CNOT3 and in the human leucocyte antigen (HLA) region with PEG-asparaginase hypersensitivity, suggesting that not only genetic variations in the HLA region, but also regulation of these genes are of importance in the biology of this toxicity. Furthermore, our study emphasizes the importance of using asparaginase enzyme activity measurements to identify PEG-asparaginase hypersensitivity.

Comparing osteonecrosis clinical phenotype, timing, and risk factors in children and young adults treated for acute lymphoblastic leukemia

BACKGROUND

Treatment-related osteonecrosis (ON) is a serious complication of treatment of acute lymphoblastic leukemia (ALL).

PROCEDURE

This study included 1,489 patients with ALL, aged 1-45 years, treated according to the Nordic Society of Paediatric Haematology and Oncology ALL2008 protocol, using alternate-week dexamethasone during delayed intensification, with prospective registration of symptomatic ON. We aimed at comparing risk factors, timing, and clinical characteristics of ON in children and young adults.

RESULTS

ON was diagnosed in 67 patients, yielding a 5-year cumulative incidence of 6.3%, but 28% in female adolescents. Median age at ALL diagnosis was 12.1 years and 14.9 years for females and males, respectively. At ON diagnosis, 59 patients had bone pain (91%) and 30 (46%) had multiple-joint involvement. The median interval between ALL and ON diagnosis was significantly shorter in children aged 1.0-9.9 years (0.7 years [range: 0.2-2.1]) compared with adolescents (1.8 years [range: 0.3-3.7, P < 0.001]) and adults (2.1 years [range: 0.4-5.3, P = 0.001]). Female sex was a risk factor in adolescent patients (hazard ratio [HR] = 2.1, 95% confidence interval [CI]: 1.1-4.2) but not in children aged 1.1-9.9 years (HR = 2.4, 95% CI: 0.9-6.2, P = 0.08) or adults aged 19-45 years (HR = 1.1, 95% CI: 0.3-4.0). Age above 10 years at ALL diagnosis (odds ratio [OR] = 3.7, P = 0.026) and multiple joints affected at ON diagnosis (OR = 3.4, P = 0.027) were risk factors for developing severe ON.

CONCLUSION

We provide a detailed phenotype of patients with ALL with symptomatic ON, including description of risk factors and timing of ON across age groups. This awareness is essential in exploring measures to prevent development of ON.

NT5C2 germline variants alter thiopurine metabolism and are associated with acquired NT5C2 relapse mutations in childhood acute lymphoblastic leukaemia

The antileukaemic drug 6-mercaptopurine is converted into thioguanine nucleotides (TGN) and incorporated into DNA (DNA-TG), the active end metabolite. In a series of genome-wide association studies, we analysed time-weighted means (_wm) of erythrocyte concentrations of TGN (Ery-TGN) and DNA-TG in 1009 patients undergoing maintenance therapy for acute lymphoblastic leukaemia (ALL). In discovery analyses (454 patients), the propensity for DNA-TG incorporation (_wmDNA-TG/_wmEry-TGN ratio) was significantly associated with three intronic SNPs in NT5C2 (top hit: rs72846714; P = 2.09 × 10^-10, minor allele frequency 15%). In validation analyses (555 patients), this association remained significant during both early and late maintenance therapy (P = 8.4 × 10^-6 and 1.3 × 10^-3, respectively). The association was mostly driven by differences in _wmEry-TGN, but in regression analyses adjusted for _wmEry-TGN (P < 0.0001), rs72846714-A genotype was also associated with a higher _wmDNA-TG (P = 0.029). Targeted sequencing of NT5C2 did not identify any missense variants associated with rs72846714 or _wmEry-TGN/_wmDNA-TG. rs72846714 was not associated with relapse risk, but in a separate cohort of 180 children with relapsed ALL, rs72846714-A genotype was associated with increased occurrence of relapse-specific NT5C2 gain-of-function mutations that reduce cytosol TGN levels (P = 0.03). These observations highlight the impact of both germline and acquired mutations in drug metabolism and disease trajectory.

Thromboembolism in acute lymphoblastic leukemia: results of NOPHO ALL2008 protocol treatment in patients aged 1 to 45 years

Thromboembolism frequently occurs during acute lymphoblastic leukemia (ALL) therapy. We prospectively registered thromboembolic events during the treatment of 1772 consecutive Nordic/Baltic patients with ALL aged 1 to 45 years who were treated according to the Nordic Society of Pediatric Hematology and Oncology ALL2008 protocol (July 2008-April 2017). The 2.5-year cumulative incidence of thromboembolism (N = 137) was 7.9% (95% confidence interval [CI], 6.6-9.1); it was higher in patients aged at least 10 years (P < .0001). Adjusted hazard ratios (HRas) were associated with greater age (range, 10.0-17.9 years: HRa, 4.9 [95% CI, 3.1-7.8; P < .0001]; 18.0-45.9 years: HRa, 6.06 [95% CI, 3.65-10.1; P < .0001]) and mediastinal mass at ALL diagnosis (HRa, 2.1; 95% CI, 1.0-4.3; P = .04). In a multiple absolute risk regression model addressing 3 thromboembolism risk factors, age at least 10 years had the largest absolute risk ratio (RR_age, 4.7 [95% CI, 3.1-7.1]; RR_{enlarged lymph nodes}, 2.0 [95% CI, 1.2-3.1]; RR_{mediastinal mass}, 1.6 [95% CI, 1.0-2.6]). Patients aged 18.0 to 45.9 years had an increased hazard of pulmonary embolism (HRa, 11.6; 95% CI, 4.02-33.7; P < .0001), and patients aged 10.0 to 17.9 years had an increased hazard of cerebral sinus venous thrombosis (HRa, 3.3; 95% CI, 1.5-7.3; P = .003) compared with children younger than 10.0 years. Asparaginase was truncated in 38/128 patients with thromboembolism, whereas thromboembolism diagnosis was unassociated with increased hazard of relapse (P = .6). Five deaths were attributable to thromboembolism, and patients younger than 18.0 years with thromboembolism had increased hazard of dying compared with same-aged patients without thromboembolism (both P ≤ .01). In conclusion, patients aged at least 10 years could be candidates for preemptive antithrombotic prophylaxis. However, the predictive value of age 10 years or older, enlarged lymph nodes, and mediastinal mass remain to be validated in another cohort.

Prolonged first-line PEG-asparaginase treatment in pediatric acute lymphoblastic leukemia in the NOPHO ALL2008 protocol-Pharmacokinetics and antibody formation

BACKGROUND

As pegylated asparaginase is becoming the preferred first-line asparaginase preparation in the chemotherapy regimens of childhood acute lymphoblastic leukemia (ALL), there is a need to evaluate this treatment.

METHODS

The aim of this study was to evaluate the pharmacokinetics of prolonged upfront biweekly PEG-asparaginase (where PEG is polyethylene glycol) treatment by measuring serum l-asparaginase activity and formation of anti-PEG-asparaginase antibodies. A total of 97 evaluable patients (1-17 years), diagnosed with ALL, and treated according to the NOPHO ALL2008 protocol (where NOPHO is Nordic Society of Paediatric Haematology and Oncology) were included. In the NOPHO ALL2008 protocol, patients are randomized to 8 or 15 doses of intramuscular PEG-asparaginase (Oncaspar^® ) 1,000 IU/m²/dose, at 2-week or 6-week intervals with a total of 30-week treatment (Clinical trials.gov. no.: NCT00819351).

RESULTS

The pharmacological target of treatment (l-asparaginase activity above 100 IU/l) was reached in 612 of 652 (94%) samples obtained 14 ± 2 days after PEG-asparaginase administration. Mean l-asparaginase activity was 338 IU/l. Six patients had l-asparaginase activity below 50 IU/l in all samples. A total of 25 patients (26%) developed Immunoglobulin G (IgG) anti-PEG-asparaginase antibodies, but there was no correlation between anti-PEG-asparaginase antibodies and low levels of asparaginase activity.

CONCLUSION

We conclude that prolonged first-line biweekly PEG-asparaginase therapy, 1,000 IU/m²/dose was above the pharmacological target in the vast majority of patients. Presence of anti-PEG-asparaginase antibodies was not a predictor of l-asparaginase activity.

Early presentation of osteonecrosis in acute lymphoblastic leukemia: Two children from the Nordic and Baltic cohort

Osteonecrosis (ON) is usually considered treatment related in patients with acute lymphoblastic leukemia (ALL). We report two patients with presentation of ON at the time of ALL diagnosis. Both were females and diagnosed with ALL at age 8 and 14 years. In the latter, some symptoms and radiologically verified ON in both knees were still present after the end of ALL therapy. No pediatric patients have previously been reported with ON presenting before initiation of ALL therapy.

Hypertriglyceridemia during asparaginase treatment in children with acute lymphoblastic leukemia correlates with antithrombin activity in adolescents

BACKGROUND

Asparaginase (ASP) is a cornerstone in the treatment of acute lymphoblastic leukemia (ALL). It is also known for its ability to cause side effects, such as allergy and pancreatitis, as well as lipid and coagulation disturbances. The most important laboratory abnormalities are hypertriglyceridemia (HTG) and low antithrombin (AT). HTG is usually considered to be transient and benign in children with ALL, whereas low AT activity predisposes to thrombosis. Studies on the incidence and significance of HTG in children with ALL are scarce, and their findings have not always been congruent. We investigated the incidence and significance of ASP-related HTG, defined as triglyceride values more than five times the upper normal limit, in children with ALL.

PROCEDURE

We analyzed the laboratory and clinical data of children diagnosed with ALL at the Karolinska Hospital, Stockholm, Sweden, from July 2008 to December 2014. Triglyceride and AT values were measured before each injection of pegylated ASP.

RESULTS

The study group comprised of 92 patients, aged 1-17.9 years at diagnosis (median 4.8 years), almost half (42/92, 46%) of whom had HTG. A significant negative correlation between triglyceride and AT values was observed in those aged over 10 years (P = 0.0002). No significant correlation was found between HTG and thrombosis, osteonecrosis, or pancreatitis.

CONCLUSIONS

Although common, ASP-associated HTG was not associated with other ASP-related toxicities. HTG correlated with decreased AT activity in older children, which may explain previous association between HTG and thrombosis. Larger studies are of interest with regard to establishing guidelines for HGT management.

Children with low-risk acute lymphoblastic leukemia are at highest risk of second cancers

BACKGROUND

The improved survival rates for childhood acute lymphoblastic leukemia (ALL) may be jeopardized by the development of a second cancer, which has been associated with thiopurine therapy.

PROCEDURE

We retrospectively analyzed three sequential Nordic Society of Paediatric Haematology and Oncology's protocols characterized by increasing intensity of thiopurine-based maintenance therapy. We explored the risk of second cancer in relation to protocols, risk group, thiopurine methyltransferase (TPMT) activity, ALL high hyperdiploidy (HeH), and t(12;21)[ETV6/RUNX1].

RESULTS

After median 9.5 years (interquartile range, 5.4-15.3 yrs) of follow-up, 40 of 3,591 patients had developed a second cancer, of whom 38 had non-high-risk B-cell precursor ALL. Patients with standard-risk ALL, who received the longest maintenance therapy, had the highest adjusted hazard of second cancer (hazard ratio [HR], intermediate vs. standard risk: 0.16, 95% CI: 0.06-0.43, P < 0.001; HR, high vs. standard risk: 0.09, 95% CI: 0.02-0.49, P = 0.006); no significant effects of protocol, age, or white blood cell count at diagnosis, ALL HeH, or t(12;21)[ETV6/RUNX1] were observed. A subset analysis on the patients with standard-risk ALL did not show an increased hazard of second cancer from either HeH or t(12;21) (adjusted HR 2.02, 95% CI: 0.69-5.96, P = 0.20). The effect of low TPMT low activity was explored in patients reaching maintenance therapy in clinical remission (n = 3,368); no association with second cancer was observed (adjusted HR 1.43, 95% CI: 0.54-3.76, P = 0.47).

CONCLUSIONS

The rate of second cancer was generally highest in patients with low-risk ALL, but we could not identify a subset at higher risk than others.

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

BACKGROUND

Hepatic sinusoidal obstruction syndrome (SOS) during treatment of childhood acute lymphoblastic leukemia (ALL) has mainly been associated with 6-thioguanine. The occurrence of several SOS cases after the introduction of extended pegylated asparaginase (PEG-asparaginase) therapy in the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol led us to hypothesize that PEG-asparaginase, combined with other drugs, may trigger SOS during 6-thioguanine-free maintenance therapy.

PROCEDURE

In children with ALL treated in Denmark according to the NOPHO ALL2008 protocol, we investigated the risk of SOS during methotrexate (MTX)/6-mercaptopurine (6MP) maintenance therapy that included PEG-asparaginase until week 33 (randomized to two- vs. six-week intervals), as well as alternating high-dose MTX or vincristine/dexamethasone pulses every four weeks.

RESULTS

Among 130 children receiving PEG-asparaginase biweekly, 29 developed SOS (≥2 criteria: hyperbilirubinemia, hepatomegaly, ascites, weight gain ≥2.5%, unexplained thrombocytopenia <75 × 10⁹ l^-1 ) at a median of 30 days (interquartile range [IQR]: 17-66) into maintenance (cumulative incidence: 27%). SOS cases fulfilling one, two, or three Ponte di Legno criteria were classified as possible (n = 2), probable (n = 8), or verified (n = 19) SOS, respectively. Twenty-six cases (90%) occurred during PEG-asparaginase treatment, including 21 (81%) within 14 days from the last chemotherapy pulse compared with the subsequent 14 days (P = 0.0025). Cytotoxic 6MP metabolites were significantly higher on PEG-asparaginase compared to after its discontinuation. Time-dependent Cox regression analysis showed increased SOS hazard ratio (HR) for erythrocyte levels of methylated 6MP metabolites (HR: 1.09 per 1,000 nmol/mmol hemoglobin increase, 95% confidence interval: 1.05-1.14). Six-week PEG-asparaginase intervals significantly reduced SOS-specific hazards (P < 0.01).

CONCLUSIONS

PEG-asparaginase increases cytotoxic 6MP metabolite levels and risk of SOS, potentially interacting with other chemotherapy pulses.

Results of NOPHO ALL2008 treatment for patients aged 1-45 years with acute lymphoblastic leukemia

Adults with acute lymphoblastic leukemia (ALL) do worse than children. From 7/2008 to 12/2014, Nordic and Baltic centers treated 1509 consecutive patients aged 1-45 years with Philadelphia chromosome-negative ALL according to the NOPHO ALL2008 without cranial irradiation. Overall, 1022 patients were of age 1-9 years (A), 266 were 10-17 years (B) and 221 were 18-45 years (C). Sixteen patients (three adults) died during induction. All others achieved remission after induction or 1-3 intensive blocks. Subsequently, 45 patients (12 adults) died, 122 patients relapsed (32 adults) with a median time to relapse of 1.6 years and 13 (no adult) developed a second malignancy. Median follow-up time was 4.6 years. Among the three age groups, older patients more often had higher risk ALL due to T-ALL (32%/25%/9%, P<0.001), KMT2A rearrangements (6%/5%/3%, P<0.001) and higher day 29 residual leukemia for B-lineage (P<0.001), but not T-ALL (P=0.53). Event-free survival rates (pEFS_5y) were 89±1% (A), 80±3% (B) and 74±4% (C) with significant differences only for non-high risk groups. Except for thrombosis, pancreatitis and osteonecrosis, the risk of 19 specified toxicities was not enhanced by age above 10 years. In conclusion, a pediatric-based protocol is tolerable and effective for young adults, despite their increased frequency of higher risk features.

Cerebellar mutism syndrome in children with brain tumours of the posterior fossa

Background

Central nervous system tumours constitute 25% of all childhood cancers; more than half are located in the posterior fossa and surgery is usually part of therapy. One of the most disabling late effects of posterior fossa tumour surgery is the cerebellar mutism syndrome (CMS) which has been reported in up to 39% of the patients but the exact incidence is uncertain since milder cases may be unrecognized. Recovery is usually incomplete. Reported risk factors are tumour type, midline location and brainstem involvement, but the exact aetiology, surgical and other risk factors, the clinical course and strategies for prevention and treatment are yet to be determined.

Methods

This observational, prospective, multicentre study will include 500 children with posterior fossa tumours. It opened late 2014 with participation from 20 Nordic and Baltic centres. From 2016, five British centres and four Dutch centres will join with a total annual accrual of 130 patients. Three other major European centres are invited to join from 2016/17. Follow-up will run for 12 months after inclusion of the last patient. All patients are treated according to local practice. Clinical data are collected through standardized online registration at pre-determined time points pre- and postoperatively. Neurological status and speech functions are examined pre-operatively and postoperatively at 1–4 weeks, 2 and 12 months. Pre- and postoperative speech samples are recorded and analysed. Imaging will be reviewed centrally. Pathology is classified according to the 2007 WHO system. Germline DNA will be collected from all patients for associations between CMS characteristics and host genome variants including pathway profiles.

Discussion

Through prospective and detailed collection of information on 1) differences in incidence and clinical course of CMS for different patient and tumour characteristics, 2) standardized surgical data and their association with CMS, 3) diversities and results of other therapeutic interventions, and 4) the role of host genome variants, we aim to achieve a better understanding of risk factors for and the clinical course of CMS - with the ultimate goal of defining strategies for prevention and treatment of this severely disabling condition.

Trial registration

Clinicaltrials.gov: NCT02300766, date of registration: November 21, 2014.

Consensus definitions of 14 severe acute toxic effects for childhood lymphoblastic leukaemia treatment: a Delphi consensus

Although there are high survival rates for children with acute lymphoblastic leukaemia, their outcome is often counterbalanced by the burden of toxic effects. This is because reported frequencies vary widely across studies, partly because of diverse definitions of toxic effects. Using the Delphi method, 15 international childhood acute lymphoblastic leukaemia study groups assessed acute lymphoblastic leukaemia protocols to address toxic effects that were to be considered by the Ponte di Legno working group. 14 acute toxic effects (hypersensitivity to asparaginase, hyperlipidaemia, osteonecrosis, asparaginase-associated pancreatitis, arterial hypertension, posterior reversible encephalopathy syndrome, seizures, depressed level of consciousness, methotrexate-related stroke-like syndrome, peripheral neuropathy, high-dose methotrexate-related nephrotoxicity, sinusoidal obstructive syndrome, thromboembolism, and Pneumocystis jirovecii pneumonia) that are serious but too rare to be addressed comprehensively within any single group, or are deemed to need consensus definitions for reliable incidence comparisons, were selected for assessment. Our results showed that none of the protocols addressed all 14 toxic effects, that no two protocols shared identical definitions of all toxic effects, and that no toxic effect definition was shared by all protocols. Using the Delphi method over three face-to-face plenary meetings, consensus definitions were obtained for all 14 toxic effects. In the overall assessment of outcome of acute lymphoblastic leukaemia treatment, these expert opinion-based definitions will allow reliable comparisons of frequencies and severities of acute toxic effects across treatment protocols, and facilitate international research on cause, guidelines for treatment adaptation, preventive strategies, and development of consensus algorithms for reporting on acute lymphoblastic leukaemia treatment.

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.

DNA-thioguanine nucleotide concentration and relapse-free survival during maintenance therapy of childhood acute lymphoblastic leukaemia (NOPHO ALL2008): a prospective substudy of a phase 3 trial

BACKGROUND

Adjustment of mercaptopurine and methotrexate maintenance therapy of acute lymphoblastic leukaemia by leucocyte count is confounded by natural variations. Cytotoxicity is primarily mediated by DNA-incorporated thioguanine nucleotides (DNA-TGN). The aim of this study was to establish whether DNA-TGN concentrations in blood leucocytes during maintenance therapy are associated with relapse-free survival.

METHODS

In this substudy of the NOPHO ALL2008 phase 3 trial done in 23 hospitals in seven European countries (Denmark, Estonia, Finland, Iceland, Lithuania, Norway, and Sweden), we analysed data from centralised and blinded analyses of 6-mercaptopurine and methotrexate metabolites in blood samples from patients with non-high-risk childhood acute lymphoblastic leukaemia. Eligible patients were aged 1·0-17·9 years; had been diagnosed with non-high-risk precursor B-cell or T-cell leukaemia; had been treated according to the Nordic Society of Pediatric Hematology and Oncology ALL2008 protocol; and had reached maintenance therapy in first remission. Maintenance therapy was (mercaptopurine 75 mg/m² once per day and methotrexate 20 mg/m² once per week, targeted to a leucocyte count of 1·5-3·0 × 10⁹ cells per L). We measured DNA-TGN and erythrocyte concentrations of TGN nucleotides, methylated mercaptopurine metabolites, and methotrexate polyglutamates. The primary objective was the association of DNA-TGN concentrations and 6-mercaptopurine and methotrexate metabolites with relapse-free survival. The secondary endpoint was the assessment of DNA-TGN concentration and 6-mercaptopurine and methotrexate metabolites during maintenance therapy phase 2.

FINDINGS

Between Nov 26, 2008 and June 14, 2016, 1509 patients from the NOPHO ALL2008 study were assessed for eligibility in the DNA-TGN substudy, of which 918 (89%) of 1026 eligible patients had at least one DNA-TGN measurement and were included in the analyses. Median follow-up was 4·6 years (IQR 3·1-6·1). Relapse-free survival was significantly associated with DNA-TGN concentration (adjusted hazard ratio 0·81 per 100 fmol/μg DNA increase, 95% CI 0·67-0·98; p=0·029). In patients with at least five blood samples, erythrocyte concentrations of TGN, methylated mercaptopurine metabolites, and methotrexate polyglutamates were associated with DNA-TGN concentration (all p<0·0001).

INTERPRETATION

Our results suggest the need for intervention trials to identify clinically applicable strategies for individualised drug dosing to increase DNA-TGN concentration, and randomised studies to investigate whether such strategies improve cure rates compared with current dose adjustments based on white blood cell counts.

FUNDING

Danish Cancer Society, Childhood Cancer Foundation (Denmark), Childhood Cancer Foundation (Sweden), Nordic Cancer Union, Otto Christensen Foundation, University Hospital Rigshospitalet, and Novo Nordic Foundation.

The effect of central nervous system involvement and irradiation in childhood acute lymphoblastic leukemia: Lessons from the NOPHO ALL-92 and ALL-2000 protocols

BACKGROUND

Central nervous system irradiation (CNS-RT) has played a central role in the cure of acute lymphoblastic leukemia (ALL), but due to the risk of long-term toxicity, it is now considered a less-favorable method of CNS-directed therapy.

PROCEDURES

Retrospectively, we estimated the effect of CNS involvement and CNS-RT on events and overall survival (OS) in 835 children treated for high-risk ALL in the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL-92 and ALL-2000 trials.

RESULTS

We did not observe a statistically significant difference in the OS or event-free survival (EFS) in patients with CNS involvement at diagnosis, but the risk of isolated CNS relapse was higher (hazard ratio [HR] 7.09, P < 0.001). CNS-RT was given to 169 of the 783 patients in first complete remission, of which 16 had CNS involvement at diagnosis. In general, CNS-RT improved EFS (HR 0.58, P < 0.05) but not OS (HR 0.69, P = n.s.). The adjusted HRs for all relapses, isolated bone marrow relapse, CNS-involving relapse, and isolated CNS relapse, were 0.47 (P < 0.01), 0.50 (P < 0.05), 0.34 (P < 0.01), and 0.12 (P < 0.01), respectively, in irradiated patients.

CONCLUSIONS

CNS-RT was associated with an advantage in EFS by decreasing the risk of relapse but without improving OS.

Asparaginase-associated pancreatitis is not predicted by hypertriglyceridemia or pancreatic enzyme levels in children with acute lymphoblastic leukemia

BACKGROUND

l-Asparaginase is an important drug for treatment of childhood acute lymphoblastic leukemia (ALL), but is associated with serious toxicities, including pancreatitis and hypertriglyceridemia (HTG). Asparaginase-associated pancreatitis (AAP) is a common reason for stopping asparaginase treatment. The aim of this study was to explore if HTG or early elevations in pancreatic enzymes were associated with the subsequent development of AAP.

METHOD

Children (1.0-17.9 years) diagnosed with ALL, treated with asparaginase for 30 weeks, according to the NOPHO ALL2008 protocol at the University Hospital Rigshospitalet, Copenhagen, Denmark, were eligible. Pancreatic enzymes, triglycerides, and cholesterol were measured regularly.

RESULTS

Thirty-one patients were included. Seven patients were diagnosed with AAP. HTG was most evident when PEG-asparaginase and dexamethasone were administered concomitantly. Overall, there was no significant difference in triglyceride levels in patients who experienced AAP and patients who did not. An increase in triglyceride levels during concomitant dexamethasone therapy in delayed intensification was significantly associated with an increase in pancreas-specific amylase levels two weeks later (P = 0.005).

CONCLUSIONS

AAP does not seem to be associated with HTG. Continuous monitoring of pancreas enzymes does not predict AAP.

Varicella Vaccination of Children With Leukemia Without Interruption of Maintenance Therapy: A Danish Experience

BACKGROUND

Varicella-zoster virus (VZV) can be fatal or cause severe complications in children with acute lymphoblastic leukemia (ALL). This analysis set out to investigate the morbidity and mortality of VZV vaccination without interruption of maintenance therapy in children with ALL.

METHODS

Files of 73 seronegative children with ALL were examined for data regarding VZV vaccination and infection, and long-term seroconversion was measured. Criteria before VZV vaccination were (1) seronegative, (2) in complete remission, (3) age ≥ 1.0 year, (4) lymphocyte count ≥ 0.6 × 10/L at time of vaccination and (5) receiving maintenance therapy.

RESULTS

Forty-five children were vaccinated. No child died or experienced serious adverse events due to VZV vaccination. Nine children developed late chickenpox despite vaccination. Long-term protection was found in 86% of children not receiving acyclovir and 78% of the entire population. Long-term seroconversion was found in 52% of the children. There were no severe cases of varicella infection. Acyclovir prophylaxis postvaccination was associated with an increased risk of late chickenpox [hazard ratio = 5.40 (1.43, 20.41), P = 0.01]. In contrast, a vaccine-induced rash reduced the risk of late chickenpox [hazard ratio = 0.08 (0.01, 0.66), P = 0.02]. No child had interruption of maintenance therapy at the time of vaccination, but 33% experienced discontinuation of therapy due to vaccine-induced rash. Dexamethasone was associated with an increased risk of vaccine-induced rash [hazard ratio = 2.9 (1.21, 6.90), P = 0.02].

CONCLUSIONS

This analysis indicates that VZV vaccination is feasible and justified in seronegative children with ALL, in countries where VZV vaccination is not part of the national vaccination program.