Clinical utility of ammonia concentration as a diagnostic test in monitoring of the treatment with L-asparaginase in children with acute lymphoblastic leukemia

Correlation of ex vivo and in vivo ammonia production with L-asparaginase biological activity in adults with lymphoid malignancies

Silent inactivation of L-asparaginase (L-Asp) represents rapid clearance of L-Asp by anti-L-Asp IgG antibodies without clinical symptoms. Measurement of L-Asp activity is the gold standard for diagnosis of silent inactivation, but this test is not commercially available in Japan as of 2023. We evaluated ex vivo and in vivo ammonia production in relation to L-Asp activity. Blood samples from ten adult patients treated with L-Asp were collected to measure ammonia levels and L-Asp activity before the first dose and 24 h after the last dose of L-Asp, during each cycle of treatment. Plasma ammonia levels were analyzed immediately and 1 h after incubation at room temperature, and ex vivo ammonia production was defined as the increase in ammonia concentration. Ex vivo ammonia production correlated with L-Asp activity (R2 = 0.741), and ammonia levels measured immediately after blood collection were moderately correlated with L-Asp activity (R2 = 0.709). One patient with extranodal NK/T-cell lymphoma showed an increase in ammonia levels during the first cycle, but no increase in ammonia levels or L-Asp activity after L-Asp administration during the second cycle. Both ex vivo and in vivo ammonia production and surrogate markers are used for L-Asp biological activity.

Asparaginase therapy in patients with acute lymphoblastic leukemia: expert opinion on use and toxicity management

The addition of asparaginase to acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) treatment regimens provides significant patient benefits. Asparaginase therapies vary in origin (Escherichia coli- or Erwinia-derived) and preparation (native or pegylated), conferring distinct pharmacokinetic and immunogenic profiles. Clinical hypersensitivity reactions (HSRs) are commonly reported in patients and range from localized erythema to systemic anaphylaxis. Due to its favorable pharmacokinetic profile and reduced immunogenicity compared to native E. coli preparations, pegaspargase is the first-line asparaginase therapeutic option. Switching to an Erwinia-derived asparaginase is recommended for patients who experience HSRs or antibody-mediated inactivation to achieve the significant clinical benefit observed in patients who complete asparaginase treatment. Previous global shortages of asparaginase Erwinia chrysanthemi necessitated conversion mitigation strategies such as premedication protocols, desensitization, and asparaginase activity level monitoring. Here, we discuss the efficacy, safety, pharmacokinetics, current use, and administration of asparaginase therapies for pediatric and adolescent patients with ALL/LBL.

Multiple Asparaginase Infusions Cause Increasingly Severe Acute Hyperammonemia

Adverse reactions during and shortly after infusing asparaginase for the treatment of acute lymphoblastic leukemia can increase in severity with later doses, limiting further use and increasing relapse risk. Although asparaginase is associated with hyperammonemia, the magnitude of the increase in serum ammonia immediately after the infusion and in response to multiple infusions has not been examined. The concurrence of hyperammonemia and infusion reactions was studied using weaned juvenile pigs that received 12 infusions of Erwinia asparaginase (Erwinase; 1250 U/kg) over 28 days, with two 5-day recovery periods without asparaginase after the eighth and eleventh doses. Infusion reactions and prolonged hyperammonemia (>50 µM ammonia 48 h after the infusion) began after the fourth dose and increased with later doses. Dense sampling for 60 min revealed an acute phase of hyperammonemia that peaked within 20 min after starting the first infusion (298 + 62 µM) and lasted less than 1 h, without apparent symptoms. A pronounced acute hyperammonemia after the final infusion (1260 + 250 µM) coincided with severe symptoms and one mortality during the infusion. The previously unrecognized acute phase of hyperammonemia associated with asparaginase infusion coincides with infusion reactions. The juvenile pig is a translational animal model for understanding the causes of acute and chronic hyperammonemia, differentiating from hypersensitivity reactions, and for improving infusion protocols to reduce acute hyperammonemia and to allow the continued use of asparaginase.

Transient Hyperammonemic Encephalopathy in a Child with Relapsed Acute Lymphoblastic Leukemia and Severe Tumor Lysis Syndrome

Idiopathic hyperammonemia (IHA) is a severe condition, which has been reported in intensive chemotherapy and bone marrow transplantation. This case elucidates the diagnostic dilemma in children undergoing initiation of chemotherapy and developing severe disorders of qualitative and quantitative consciousness in the presence of hyperammonemia (HA) and lactic acidosis. The role of mitoxantrone as a causative agent for IHA in children is elusive. Children undergoing chemotherapy are often in a poor general condition, and the clinical presentation of HA is heterogeneous. This case should be a reminder for clinicians to check for HA in children with tumor lysis syndrome and acute neurological deterioration.

Ammonia level as a proxy of asparaginase inactivation in children: A strategy for classification of infusion reactions

INTRODUCTION

Allergic hypersensitivity reactions related to enzyme asparaginase may occur during intravenous infusion of drugs and other adverse reactions (non-allergic hypersensitivity and hyperammonemia), which do not require discontinuation of therapy as the first case. It makes differential diagnoses between infusion reactions essential to assure the team regarding the right decision to make after the adverse event. This study evaluated a pharmacovigilance strategy of differentiating infusion reactions to asparaginase in pediatric patients, based on the measurement of serum ammonia and the classification of the reactions by clinical symptoms and severity.

METHODOLOGY

We included children, diagnosed with ALL, and treated with native Escherichia coli asparaginase in a university hospital. The professional team monitored and evaluated all asparaginase infusions for continuity of treatment (rechallenge), seeing the measurement of serum ammonia and classification of reactions for type and severity grade. Data from this monitoring was collected retrospectively. Chi-square and Mann-Whitney tests were used to compare the ratios between serum ammonia concentration posterior and before asparaginase infusion.

RESULTS

245 infusions in 32 patients were monitored, and 19 reactions were observed in 17 children (53%). Three children have hyperammonemia and continue their treatment. The variation of the serum ammonia levels before and after the infusion was statistically significant, comparing the groups with no reaction or hyperammonemia versus the group with the hypersensitivity reaction.

CONCLUSION

The pharmacovigilance strategy applied in the hospital investigated was a useful and inexpensive tool that supported clinical decision-making and enabled the maintenance of asparaginase therapy for three (9,4%) patients followed up.

Reactions related to asparaginase infusion in a 10-year retrospective cohort

INTRODUCTION

Although it is an essential component of the treatment of acute lymphoid leukemia in children, asparaginase causes adverse reactions that sometimes make it impossible to use it fully. Hypersensitivity reactions are the most frequent and may lead to early discontinuation of treatment. The present study aimed to investigate suspicions of adverse reactions during the infusion of asparaginase in a pediatric cohort.

METHODS

A retrospective observational study was carried out at a university pediatric institute in the state of Rio de Janeiro. Information regarding clinical features and characteristics of adverse reactions was collected from hospital medical records. Suspicions of adverse reactions were classified regarding causality and severity.

RESULTS

Seventy-three suspicions of adverse reactions were recorded during asparaginase infusion in 72 children in the study period. Allergic hypersensitivity reactions were suspected in 60.5% of the cases. Of these, 25% of the reactions occurred during induction and 61.1% in concomitant use with vincristine, findings that diverge from other studies. High-risk classification and younger age were considered risk factors for these reactions. A total of 72.4% of the reactions were classified as grade 1 or 2, which suggest that not all are related to antibody formation; this highlights the importance of differential diagnosis with other reactions, such as non-allergic hypersensitivity and hyperammonemia.

CONCLUSION

The implementation of the differential diagnosis of reactions related to infusion of asparaginase with ammonia dosage and classification of the grade of reactions is crucial to facilitate the identification and proper management of each type of reaction.