Gefitinib is effective against juvenile pilocytic astrocytoma in vitro.
BACKGROUND
Juvenile pilocytic astrocytomas (JPAs) are the most common central nervous system tumors in children. If completely resected, JPAs are associated with an excellent outcome. However, there is need for additional therapeutic approaches for those JPAs which are incompletely resected and fail subsequent standard chemotherapy/radiation. To explore the possibility for a novel therapeutic approach we measured the effect of the epidermal growth factor receptor (EGFR) small molecule tyrosine kinase inhibitor gefitinib on five JPA primary cell-cultures.


METHODS
Due to a lack of established cell-lines of JPA very few in vitro drug sensitivity assays have been performed. In this study we have succeeded in propagating short-term primary cell-cultures established from surgical specimens. The effect of gefitinib on proliferation in JPA derived primary cell-cultures was measured by a standard tritiated thymidine incorporation assay. The level of expression of EGFR, the intended target of gefitinib, was measured by immunohistochemistry, flow cytometry and RT-PCR.


RESULTS
Gefitinib was shown to inhibit proliferation in all five JPA cell-cultures tested, with IC-50's between 1.6 and 9.6 microM. However, EGFR protein and mRNA expression was undetectable. Further studies with cetuximab, an EGFR-specific inhibitory monoclonal antibody, showed no effect on proliferation in JPA.


CONCLUSIONS
Based on these preclinical data, gefitinib may be a suitable salvage chemotherapy drug to explore further in those patients with JPA who have recurred after primary chemotherapy. Of interest, it appears that the anti-tumor effect of gefitinib in JPA cell-cultures may be mediated through a pathway other than EGFR inhibition.
Foreman
Nicholas K
NK
University of Colorado at Denver and Health Sciences Center (UCDHSC) and The Children's Hospital, Denver, Colorado. foreman.nicholas@tchden.org
Gore
Lia
L
Wells
Daniel
D
Straessle
Jennifer
J
Heideman
Richard
R
Donson
Andrew M
AM
D001254:Astrocytoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D016543:Central Nervous System Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D000077156:Gefitinib; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D020411:Oligonucleotide Array Sequence Analysis; D011799:Quinazolines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
D011799:Quinazolines; D012333:RNA, Messenger; D066246:ErbB Receptors; D000077156:Gefitinib; D013936:Thymidine