Gefitinib is effective against juvenile pilocytic astrocytoma in vitro
Nicholas K Foreman1, Lia Gore, Daniel Wells
1University of Colorado at Denver and Health Sciences Center (UCDHSC) and The Children's Hospital, Denver, Colorado. foreman.nicholas@tchden.org
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.
Procedure:
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.
Insights
Gefitinib inhibited growth in pediatric brain tumors called juvenile pilocytic astrocytomas (JPAs). This suggests gefitinib could be a new treatment option, even though it doesn't seem to work by targeting the epidermal growth factor receptor (EGFR).
Area of Science:
- Pediatric neuro-oncology
- Molecular targeted therapy
- Cancer cell biology
Background:
- Juvenile pilocytic astrocytomas (JPAs) are the most common pediatric central nervous system tumors.
- Complete resection offers excellent outcomes, but treatment options are limited for incompletely resected or recurrent JPAs.
- Novel therapeutic strategies are needed for refractory JPA cases.
Purpose of the Study:
- To investigate the efficacy of gefitinib, a small molecule tyrosine kinase inhibitor targeting the epidermal growth factor receptor (EGFR).
- To evaluate gefitinib's effect on proliferation in primary cell cultures derived from JPA surgical specimens.
- To determine EGFR expression levels in JPA cells to understand the drug's mechanism of action.
Main Methods:
- Established and utilized short-term primary cell cultures from JPA surgical specimens for in vitro drug sensitivity assays.
- Quantified gefitinib's impact on JPA cell proliferation using a tritiated thymidine incorporation assay.
- Assessed EGFR expression via immunohistochemistry, flow cytometry, and RT-PCR.
Main Results:
- Gefitinib demonstrated significant inhibition of proliferation across all five tested JPA cell cultures, with IC50 values ranging from 1.6 to 9.6 microM.
- Epidermal growth factor receptor (EGFR) protein and mRNA expression were undetectable in the JPA cell cultures.
- Cetuximab, an EGFR-specific monoclonal antibody, did not affect proliferation in JPA cell cultures, further questioning the role of EGFR.
Conclusions:
- Preclinical data suggest gefitinib holds potential as a salvage chemotherapy agent for patients with recurrent JPA after initial treatment.
- The anti-tumor effects of gefitinib in JPA cell cultures appear to be mediated via a pathway independent of EGFR inhibition.
- Further clinical investigation is warranted to explore gefitinib's therapeutic utility in refractory pediatric pilocytic astrocytomas.
