Pediatric phase I trial and pharmacokinetic study of the platelet-derived growth factor (PDGF) receptor pathway inhibitor SU101.
OBJECTIVE
To determine the maximum tolerated dose and the toxicity profile of the PDGF receptor pathway inhibitor SU101 in pediatric patients with refractory solid tumors, and to define the plasma pharmacokinetics of SU101 and its active metabolite SU0020 in children.


METHODS
Patients between 3 and 21 years of age with CNS malignancy, neuroblastoma, or sarcoma refractory to standard therapy were eligible. The starting dose of SU101 was 230 mg/m(2) per day administered as a 96-h continuous infusion every 21 days. Blood for pharmacokinetic analysis was obtained during the first cycle.


RESULTS
Entered into the trial were 27 patients, and 24 were fully evaluable for toxicity. Dose-limiting central nervous system toxicity was observed in two patients at the 440 mg/m(2) per day dose level. Non-dose-limiting toxicities included nausea, vomiting, headache, fatigue, abdominal discomfort, diarrhea, pruritus, anorexia, constipation, and paresthesias. There were no complete or partial responses. One patient with rapidly progressive desmoplastic small round-cell tumor experienced symptomatic improvement and prolonged stable disease. Steady-state concentrations of SU101 were rapidly achieved and proportional to dose. The concentration of SU0020 was 100- to 1000-fold greater than that of SU101. The median clearance of SU0020 was 0.19 l/day per m(2) and its terminal elimination half-life was 14 days.


CONCLUSIONS
SU101 administered on this schedule was generally well tolerated. The maximum tolerated dose of SU101 is 390 mg/m(2) per day for 4 days repeated every 3 weeks. The neurotoxicity observed at the 440 mg/m(2) per day dose level suggests that patients receiving repetitive cycles must be monitored closely, as SU0020 may accumulate over time.
Adamson
P C
PC
Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD, USA. adamsonp@mail.med.upenn.edu
Blaney
S M
SM
Widemann
B C
BC
Kitchen
B
B
Murphy
R F
RF
Hannah
A L
AL
Cropp
G F
GF
Patel
M
M
Gillespie
A F
AF
Whitcomb
P G
PG
Balis
F M
FM
D000293:Adolescent; D000328:Adult; D000814:Aniline Compounds / Q000097:blood; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016543:Central Nervous System Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D005260:Female; D006207:Half-Life; D006801:Humans; D007555:Isoxazoles / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000077339:Leflunomide; D008279:Magnetic Resonance Imaging; D008297:Male; D009570:Nitriles / Q000097:blood; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D000814:Aniline Compounds; D000970:Antineoplastic Agents; D007555:Isoxazoles; D009570:Nitriles; C460097:SU 0020; D000077339:Leflunomide