ABSTRACT
To develop effective interleukin-2 (IL-2) protocols for pediatric malignancies, it is important to define IL-2 pharmacokinetics in children. In a phase I trial, we studied IL-2 pharmacokinetics in seven children, aged 6-18, five with leukemia, one with neuroblastoma, and one with rhabdomyosarcoma. IL-2 was administered as a 15-min i.v. infusion of either 1 X 10(6) CU/m2/dose or 3 X 10(6) CU/m2/dose (every Monday, Wednesday, and Friday for 3 weeks). IL-2 levels were determined using an IL-2-dependent murine T lymphocyte cell line bioassay. Peak IL-2 levels of 120-426 and 330-740 CU/ml were achieved after the lower and higher doses, respectively. Pediatric IL-2 kinetics resembled data reported for adults, fitting a two-compartment model (least-squares-regression technique), with an alpha half-life of 14.0 +/- 5.6 min (range, 6.3-23.1) and a beta half-life of 51.4 +/- 10.7 min (range, 33.0-66.0). The volume of distribution approximated total extracellular fluid (mean, 0.18 L/kg). Further clinical trials are needed to identify which pediatric malignancies are sensitive to immunotherapy and to establish the optimal treatment regimens.
Subject(s)
Interleukin-2/pharmacokinetics , Neuroblastoma/metabolism , Precursor Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Rhabdomyosarcoma/metabolism , Adolescent , Child , Drug Evaluation , Humans , Interleukin-2/therapeutic use , Neuroblastoma/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Recombinant Proteins/pharmacokinetics , Recombinant Proteins/therapeutic use , Rhabdomyosarcoma/drug therapyABSTRACT
Natural killer (NK) cells and NK cell activity were determined in three groups (newly diagnosed [n = 21], on therapy [n = 21], and off therapy [n = 18]) of children with various types of malignant solid tumors and in a control group (n = 26) by means of Leu-7 and Leu-11b monoclonal antibodies and a 4-hour 51Cr-release assay, respectively. The erythroleukemia cell line K562 was used as a target cell. The newly diagnosed group included eight patients with localized disease (Stage I-II), ten with bulky but nonmetastatic disease (Stage III), and three with metastases (Stage IV). The mean percent of NK cell activity in the newly diagnosed group was significantly higher than that of the control group. Children with Stage III tumors at diagnosis had higher mean NK cell function than those with Stage I-II and Stage IV. On therapy patients had significantly fewer NK cells and lower NK cell cytotoxicity than those in the other groups studied. We also studied the following: (1) the in vitro effect of recombinant interferon-alpha (rIFN-alpha) and recombinant interleukin-2 (rIL-2) on NK cell function of peripheral blood lymphocytes (PBL) from children with solid malignancies; and (2) the susceptibility of neuroblastoma-derived (CHP-126 and SKNSH) and rhabdomyosarcoma-derived (A-204) cell lines to NK cell lysis. Both rIFN-alpha and rIL-2 enhanced NK cell activity of PBL from children with malignancies and healthy children against K562 and solid tumor cell lines. The enhancing effect or rIL-2 was greater than that of rIFN-alpha. CHP-126 and SKNSH cell lines were susceptible to NK cell lysis mediated by the PBL of children with neuroblastoma and the control group. The A-204 cell line was less sensitive than K562 to NK cell cytotoxicity. Our results suggest a potential therapeutic role for both cytokines in the treatment of malignant solid tumors of childhood.