TY - JOUR
T1 - Imatinib mesylate efficiently achieves therapeutic intratumor concentrations in vivo but has limited activity in a xenograft model of small cell lung cancer
AU - Wolff, Nicholas C.
AU - Randle, Dwight E.
AU - Egorin, Merrill J.
AU - Minna, John D.
AU - Ilaria, Robert L.
PY - 2004/5/15
Y1 - 2004/5/15
N2 - Purpose: Despite recent advances in cancer therapy, long-term survival in small cell lung cancer (SCLC) remains uncommon, underscoring the need for novel therapeutic approaches. Previous studies have identified constitutive expression of the receptor tyrosine kinase, c-Kit, and its ligand, stem cell factor, in a substantial proportion of SCLC specimens. The purpose of this study was to determine whether imatinib mesylate, an inhibitor of c-Kit, could achieve therapeutic concentrations in tumors and in brain (a frequent site of SCLC metastasis) and interfere with SCLC tumor growth in vivo. Experimental Design: Human SCLC tumor cell lines with constitutive c-kit expression and tyrosine phosphorylation (NCI-H209, NCI-H526, and NCI-HI607) were used to establish SCLC tumor xenografts in NCr nude (nu/nu)-immunodeficient mice. SCLC tumor-bearing mice were randomly assigned to imatinib or control (water) administered twice a day by oral gavage. Imatinib concentrations in plasma, brain, and tumor were quantitated and correlated with tumor response. Results: Therapeutic concentrations of imatinib were achieved in plasma and tumor xenografts but not in the brain. Imatinib blocked the constitutive activation of c-kit in SCLC tumor cell lines in vitro but had a negligible effect on SCLC xenograft growth in vivo. Conclusions: Orally administered imatinib rapidly reaches therapeutic concentrations in SCLC xenografts, suggesting the feasibility of combining imatinib with other novel or traditional chemotherapeutic agents in SCLC or other solid tumors. The c-Kit signaling pathway does not appear to play a critical role in SCLC proliferation and viability in vivo, however, suggesting that imatinib is unlikely to be effective as monotherapy for SCLC.
AB - Purpose: Despite recent advances in cancer therapy, long-term survival in small cell lung cancer (SCLC) remains uncommon, underscoring the need for novel therapeutic approaches. Previous studies have identified constitutive expression of the receptor tyrosine kinase, c-Kit, and its ligand, stem cell factor, in a substantial proportion of SCLC specimens. The purpose of this study was to determine whether imatinib mesylate, an inhibitor of c-Kit, could achieve therapeutic concentrations in tumors and in brain (a frequent site of SCLC metastasis) and interfere with SCLC tumor growth in vivo. Experimental Design: Human SCLC tumor cell lines with constitutive c-kit expression and tyrosine phosphorylation (NCI-H209, NCI-H526, and NCI-HI607) were used to establish SCLC tumor xenografts in NCr nude (nu/nu)-immunodeficient mice. SCLC tumor-bearing mice were randomly assigned to imatinib or control (water) administered twice a day by oral gavage. Imatinib concentrations in plasma, brain, and tumor were quantitated and correlated with tumor response. Results: Therapeutic concentrations of imatinib were achieved in plasma and tumor xenografts but not in the brain. Imatinib blocked the constitutive activation of c-kit in SCLC tumor cell lines in vitro but had a negligible effect on SCLC xenograft growth in vivo. Conclusions: Orally administered imatinib rapidly reaches therapeutic concentrations in SCLC xenografts, suggesting the feasibility of combining imatinib with other novel or traditional chemotherapeutic agents in SCLC or other solid tumors. The c-Kit signaling pathway does not appear to play a critical role in SCLC proliferation and viability in vivo, however, suggesting that imatinib is unlikely to be effective as monotherapy for SCLC.
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U2 - 10.1158/1078-0432.CCR-0957-03
DO - 10.1158/1078-0432.CCR-0957-03
M3 - Article
C2 - 15161712
AN - SCOPUS:2542466775
SN - 1078-0432
VL - 10
SP - 3528
EP - 3534
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 10
ER -