Interferon-αnl in Children with Recurrent Acute Lymphocytic Leukemia: A Phase I Study of Pharmacokinetics and Tolerance

Twelve children ages 3-15 years with relapsed acute lymphocyte leukemia (ALL) were treated over 25 days by intravenous or intramuscular administration of interferon-αnl (IFN-αnl). Single doses ranged from 2.5 to 15 MU/m², total doses from 60 to 200 MU/ m². Serum pharmacokinetics were determined following administration of two different doses. Calculation of area under serum concentration curve (AUC) values showed increased AUC with increased dose. Mean AUC (h x U/ml) ranged from 735 to 3986 at doses of 2.5 and 15 MU/m², respectively, when given intramuscularly. AUC for i.v. and i.m. administration were similar. Side effects reported most commonly were fever and chills in 11 of 12 patients, nausea/vomiting in 7, mild lethargy in 3, and injection site pain in 4 of 9 treated i.m. Reversible hepatotoxicity occurred in the 3 patients receiving the highest doses, 10 then 15 MU/m². Three patients had clinically significant bleeding associated with mildly increased coagulation studies and an additional three patients had increased coagulation parameters without bleeding. Four patients were considered to have stable disease; one treated at the highest dose level had clearance of peripheral blasts but remained in bone marrow relapse. IFN-αnl as used in this study produced detectable blood levels with associated side effects. A Phase II intramuscular trial is recommended.