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Deoxycytidine therapy in two patients with adenosine deaminase deficiency and severe immunodeficiency disease
Insights
Parenteral deoxycytidine showed transient T-cell improvement in children with adenosine deaminase (ADA) deficiency. However, clinical benefits were limited, suggesting a potential but constrained role for deoxycytidine therapy in ADA deficiency.
Area of Science:
- Immunology
- Biochemistry
- Pharmacology
Background:
- Adenosine deaminase (ADA) deficiency causes severe combined immunodeficiency disease, characterized by profound T-cell dysfunction.
- Parenteral deoxycytidine administration was explored as a therapeutic strategy to restore T-cell immunity in ADA-deficient patients.
Observation:
- Two children with ADA deficiency received deoxycytidine therapy via intravenous and subcutaneous routes.
- The co-administration of tetrahydrouridine (THU) increased plasma deoxycytidine levels and intracellular dCTP/dATP ratios.
- Immunologic assessments revealed transient improvements in T-cell immunity following intravenous deoxycytidine infusions.
Findings:
- Intravenous deoxycytidine infusions led to temporary enhancements in T-cell function in one patient.
- Subcutaneous deoxycytidine administration and a single intravenous course in the second patient showed minimal immunologic and no clinical improvement.
- Pharmacologic parameters of human deoxycytidine metabolism were elucidated, including the impact of THU.
Implications:
- Deoxycytidine therapy may offer a limited potential for improving T-cell-mediated immunity in some ADA-deficient patients.
- The clinical efficacy of deoxycytidine appears constrained, necessitating further research into optimizing treatment strategies.
- This study contributes to understanding deoxycytidine's pharmacologic profile and its therapeutic possibilities in primary immunodeficiencies.
Abstract:
Two children with adenosine deaminase (ADA) deficiency and combined immunodeficiency disease were given parenteral deoxycytidine in order to reverse the severe T-cell immunodeficiency associated with this disease. One patient received a total of three courses of parenteral deoxycytidine. On two occasions deoxycytidine (50 mg/kg/day) was infused intravenously continuously for 2 weeks. During one of the infusions she received the deoxycytidine deaminase inhibitor tetrahydrouridine (THU). Steady-state levels of plasma deoxycytidine increased 4-fold with THU. RBC dCTP/dATP increased more than 10-fold after 48 hr of deoxycytidine infusion. Immunologic studies following the intravenous infusion of deoxycytidine showed transient improvement in T-cell immunity. The third course of deoxycytidine (50 mg/kg/day) was administered subcutaneously during a 10-hr night-time infusion. After 6 and 12 weeks of nightly subcutaneous infusions, there was minimal improvement in the in vitro immunologic studies and no clinical improvement. The second patient received a single 2-week course of continuous intravenous deoxycytidine (50 mg/kg/day) following which there was no significant change in T-cell immunity. This study defines some of the pharmacologic parameters of human deoxycytidine metabolism and suggests that some patients with ADA deficiency may respond to deoxycytidine therapy with improvement in T-cell-mediated immunity, although the changes are small and the effect on clinical status appears to be limited.