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PDF file - 92K, Effects of HER2 overexpression on the sensitivity of HCC827 cells to EGFR TKIs

PDF file - 91K, Levels of HER2 affect the sensitivity of EGFR-mutant NSCLC cells to EGFR TKIs

PDF file - 36K, Increased murine Her2 expression in erlotinib-resistant mutant EGFR-induced transgenic mouse tumors

PDF file, 80K, Level of EML4-ALK mRNA in NSCLC cells. Total RNA extracted from the indicated cell lines was subjected to RT and real-time PCR analysis for determination of the abundance of EML4-ALK mRNA. Data were normalized by the amount of GAPDH mRNA and then expressed relative to the corresponding value for H3122 cells, and they are means from three independent experiments.

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Supplementary Data from Enhanced Anticancer Effect of the Combination of BIBW2992 and Thymidylate Synthase–Targeted Agents in Non–Small Cell Lung Cancer with the T790M Mutation of Epidermal Growth Factor Receptor

Therapeutic strategies that target c-Src hold promise for a wide variety of cancers. We have now investigated both the effects of dasatinib, which inhibits the activity of c-Src and several other kinases, on cell growth as well as the mechanism of dasatinib resistance in human gastric cancer cell lines. Immunoblot analysis revealed the activation of c-Src at various levels in most gastric cancer cell lines examined. Dasatinib inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) and induced G1 arrest, as revealed by flow cytometry, in a subset of responsive cell lines. In other responsive cell lines, dasatinib inhibited both ERK and AKT phosphorylation and induced apoptosis, as revealed by an increase in caspase-3 activity and cleavage of poly(ADP-ribose) polymerase. Depletion of c-Src by RNA interference also induced G1 arrest or apoptosis in dasatinib-responsive cell lines, indicating that the antiproliferative effect of dasatinib is attributable to c-Src inhibition. Gastric cancer cell lines positive for the activation of MET were resistant to dasatinib. Dasatinib had no effect on ERK or AKT signaling, whereas the MET inhibitor PHA-665752 induced apoptosis in these cells. The subsets of gastric cancer cells defined by a response to c-Src or MET inhibitors were distinct and nonoverlapping. Our results suggest that c-Src is a promising target for the treatment of gastric cancer and that analysis of MET amplification might optimize patient selection for treatment with c-Src inhibitors. Mol Cancer Ther; 9(5); 1188–97. ©2010 AACR.

Supplementary Figure S1.

Purpose: Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKI) such as crizotinib show marked efficacy in patients with non–small cell lung cancer positive for the echinoderm microtubule-associated protein–like 4 (EML4)–ALK fusion protein. However, acquired resistance to these agents has already been described in treated patients, and the mechanisms of such resistance remain largely unknown.Experimental Design: We established lines of EML4-ALK–positive H3122 lung cancer cells that are resistant to the ALK inhibitor TAE684 (H3122/TR cells) and investigated their resistance mechanism with the use of immunoblot analysis, ELISA, reverse transcription and real-time PCR analysis, and an annexin V binding assay. We isolated EML4-ALK–positive lung cancer cells (K-3) from a patient who developed resistance to crizotinib and investigated their characteristics.Results: The expression of EML4-ALK was reduced at the transcriptional level, whereas phosphorylation of epidermal growth factor receptor (EGFR), HER2, and HER3 was upregulated, in H3122/TR cells compared with those in H3122 cells. This activation of HER family proteins was accompanied by increased secretion of EGF. Treatment with an EGFR-TKI induced apoptosis in H3122/TR cells, but not in H3122 cells. The TAE684-induced inhibition of extracellular signal–regulated kinase (ERK) and STAT3 phosphorylation observed in parental cells was prevented by exposure of these cells to exogenous EGF, resulting in a reduced sensitivity of cell growth to TAE684. K-3 cells also manifested HER family activation accompanied by increased EGF secretion.Conclusions: EGF-mediated activation of HER family signaling is associated with ALK-TKI resistance in lung cancer positive for EML4-ALK. Clin Cancer Res; 18(22); 6219–26. ©2012 AACR.

Most non–small cell lung cancer (NSCLC) tumors with activating mutations of the epidermal growth factor receptor (EGFR) are initially responsive to first-generation, reversible EGFR tyrosine kinase inhibitors (TKI) such as gefitinib, but they subsequently develop resistance to these drugs through either acquisition of an additional T790M mutation of EGFR or amplification of the proto-oncogene MET. We have now investigated the effects of combination treatment with thymidylate synthase (TS)–targeting drugs and the second-generation, irreversible EGFR-TKI BIBW2992 on the growth of NSCLC cells with the T790M mutation. The effects of BIBW2992 on EGFR signaling and TS expression in gefitinib-resistant NSCLC cells were examined by immunoblot analysis. The effects of BIBW2992 and the TS-targeting agents S-1 (or 5-fluorouracil) or pemetrexed on the growth of gefitinib-resistant NSCLC cells were examined both in vitro and in vivo. The combination of BIBW2992 with 5-fluorouracil or pemetrexed synergistically inhibited the proliferation of NSCLC cells with the T790M mutation in vitro, whereas an antagonistic interaction was apparent in this regard between gefitinib and either of these TS-targeting agents. BIBW2992 induced downregulation of TS in the gefitinib-resistant NSCLC cells, implicating depletion of TS in the enhanced antitumor effect of the combination therapy. The combination of BIBW2992 and either the oral fluoropyrimidine S-1 or pemetrexed also inhibited the growth of NSCLC xenografts with the T790M mutation to an extent greater than that apparent with either agent alone. The addition of TS-targeting drugs to BIBW2992 is a promising strategy to overcome EGFR-TKI resistance in NSCLC with the T790M mutation of EGFR. Mol Cancer Ther; 9(6); 1647–56. ©2010 AACR.

Supplementary Data from Identification of c-Src as a Potential Therapeutic Target for Gastric Cancer and of MET Activation as a Cause of Resistance to c-Src Inhibition

Purpose:EML4-ALK (echinoderm microtubule-associated protein–like 4 anaplastic lymphoma kinase) was recently identified as a transforming fusion gene in non–small cell lung cancer. The purpose of the present study was to characterize the mechanism of malignant transformation by EML4-ALK.Experimental Design: We established NIH 3T3 cells that stably express variant 1 or 3 of EML4-ALK and examined the signaling molecules that function downstream of EML4-ALK.Results: Forced expression of EML4-ALK induced marked activation of extracellular signal–regulated kinase (ERK) and STAT3, but not that of AKT. Inhibition of ERK or STAT3 signaling resulted in substantial attenuation of the proliferation of cells expressing either variant of EML4-ALK, suggesting that these signaling pathways function downstream of EML4-ALK in lung cancer cells. The specific ALK inhibitor TAE684 induced apoptosis that was accompanied both by upregulation of BIM, a proapoptotic member of the Bcl-2 family, and by downregulation of survivin, a member of the inhibitor of apoptosis protein (IAP) family, in EML4-ALK–expressing NIH 3T3 cells as well as in H3122 human lung cancer cells harboring endogenous EML4-ALK. Depletion of BIM and overexpression of survivin each inhibited TAE684-induced apoptosis, suggesting that both upregulation of BIM and downregulation of survivin contribute to TAE684-induced apoptosis in EML4-ALK–positive lung cancer cells. Furthermore, BIM and survivin expression was found to be independently regulated by ERK and STAT3 signaling pathways, respectively.Conclusions: ALK inhibitor–induced apoptosis is mediated both by BIM upregulation resulting from inhibition of ERK signaling as well as by survivin downregulation resulting from inhibition of STAT3 signaling in EML4-ALK–positive lung cancer cells. Clin Cancer Res; 17(8); 2140–8. ©2011 AACR.

Supplementary Figure 1 from Role of Survivin in EGFR Inhibitor–Induced Apoptosis in Non–Small Cell Lung Cancers Positive for EGFR Mutations

Supplementary Figure 2 from Role of Survivin in EGFR Inhibitor–Induced Apoptosis in Non–Small Cell Lung Cancers Positive for EGFR Mutations

Supplementary Figure Legends 1-3 from Role of Survivin in EGFR Inhibitor–Induced Apoptosis in Non–Small Cell Lung Cancers Positive for EGFR Mutations

Supplementary Figure 3 from Role of Survivin in EGFR Inhibitor–Induced Apoptosis in Non–Small Cell Lung Cancers Positive for EGFR Mutations

Purpose: Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKI) such as crizotinib show marked efficacy in patients with non–small cell lung cancer positive for the echinoderm microtubule-associated protein–like 4 (EML4)–ALK fusion protein. However, acquired resistance to these agents has already been described in treated patients, and the mechanisms of such resistance remain largely unknown. Experimental Design: We established lines of EML4-ALK–positive H3122 lung cancer cells that are resistant to the ALK inhibitor TAE684 (H3122/TR cells) and investigated their resistance mechanism with the use of immunoblot analysis, ELISA, reverse transcription and real-time PCR analysis, and an annexin V binding assay. We isolated EML4-ALK–positive lung cancer cells (K-3) from a patient who developed resistance to crizotinib and investigated their characteristics. Results: The expression of EML4-ALK was reduced at the transcriptional level, whereas phosphorylation of epidermal growth factor receptor (EGFR), HER2, and HER3 was upregulated, in H3122/TR cells compared with those in H3122 cells. This activation of HER family proteins was accompanied by increased secretion of EGF. Treatment with an EGFR-TKI induced apoptosis in H3122/TR cells, but not in H3122 cells. The TAE684-induced inhibition of extracellular signal–regulated kinase (ERK) and STAT3 phosphorylation observed in parental cells was prevented by exposure of these cells to exogenous EGF, resulting in a reduced sensitivity of cell growth to TAE684. K-3 cells also manifested HER family activation accompanied by increased EGF secretion. Conclusions: EGF-mediated activation of HER family signaling is associated with ALK-TKI resistance in lung cancer positive for EML4-ALK. Clin Cancer Res; 18(22); 6219–26. ©2012 AACR.

Introduction: The presence of the transforming fusion gene echinoderm microtubule-associated protein–like 4 (EML4)–anaplastic lymphoma kinase (ALK) in non–small-cell lung cancer (NSCLC) is a predictive marker for the efficacy of anaplastic lymphoma kinase inhibitors. However, the currently available assays for the detection of the different variants of EML4-ALK have limitations. Methods: We developed an assay system for the detection of EML4-ALK variants 1, 2, 3a, 3b, 4, 5a, 5b, 6, or 7 transcripts in total RNA obtained from formalin-fixed, paraffin-embedded (FFPE) specimens of NSCLC tissue. The assay is based on region-specific polymerase chain reaction amplification of EML4-ALK complementary DNA followed by specific single-base primer extension and analysis of the extension products by matrix-assisted laser desorption/ionization–time of flight mass spectrometry. The assay was validated by fluorescence in situ hybridization and the results confirmed by subcloning and sequencing of polymerase chain reaction products. Results: Evaluation of the analytic sensitivity of the assay with serial dilutions of plasmids containing EML4-ALK complementary DNA sequences revealed it to be capable of the reliable detection of one copy of each plasmid per reaction. The assay also detected EML4-ALK variants 1 or 3 in three FFPE samples of surgically resected NSCLC shown to be positive for anaplastic lymphoma kinase rearrangement by fluorescence in situ hybridization. Furthermore, the assay identified variant 1 of EML4-ALK in 3 of 20 FFPE biopsy samples from patients with advanced NSCLC. All positive samples were confirmed by subcloning and sequencing. Conclusions: Our novel assay is highly sensitive and effective for the detection of EML4-ALK in FFPE specimens.

Background: Thymidylate synthase (TS), a key enzyme in the de novo synthesis of thymidine, is an important chemotherapeutic target for malignant tumours including lung cancer. Although inhibition of TS has an antiproliferative effect in cancer cells, the precise mechanism of this effect has remained unclear. Methods: We examined the effects of TS inhibition with an RNA interference-based approach. The effect of TS depletion on the growth of lung cancer cells was examined using colorimetric assay and flow cytometry. Results: Measurement of the enzymatic activity of TS in 30 human lung cancer cell lines revealed that such activity differs among tumour histotypes. Almost complete elimination of TS activity by RNA interference resulted in inhibition of cell proliferation in all tested cell lines, suggestive of a pivotal role for TS in cell proliferation independent of the original level of enzyme activity. The antiproliferative effect of TS depletion was accompanied by arrest of cells in S phase of the cell cycle and the induction of caspase-dependent apoptosis as well as by changes in the expression levels of cyclin E and c-Myc. Moreover, TS depletion induced downregulation of the antiapoptotic protein X-linked inhibitor of apoptosis (XIAP), and it seemed to activate the mitochondrial pathway of apoptosis. Conclusion: Our data provide insight into the biological relevance of TS as well as a basis for clinical development of TS-targeted therapy for lung cancer.

Background: Survivin, a member of the inhibitor of apoptosis protein family, is an attractive target for cancer therapy. We have now investigated the effects of the combination of YM155, a novel small-molecule inhibitor of survivin expression, and platinum compounds (cisplatin and carboplatin) on human non-small cell lung cancer (NSCLC) cell lines. Methods: The anti-cancer efficacy of YM155 in combination with platinum compounds was evaluated on the basis of cell death and progression of tumour xenografts. Platinum compound-induced DNA damage was evaluated by immunofluorescence analysis of histone γ-H2AX. Results: Immunofluorescence analysis of histone γ-H2AX showed that YM155 delayed the repair of double-strand breaks induced in nuclear DNA by platinum compounds. The combination of YM155 and platinum compounds also induced synergistic increases both in the number of apoptotic cells and in the activity of caspase-3. Finally, combination therapy with YM155 and platinum compounds delayed the growth of NSCLC tumour xenografts in nude mice to an extent greater than that apparent with either treatment modality alone. Conclusion: These results suggest that YM155 sensitises tumour cells to platinum compounds both in vitro and in vivo, and that this effect is likely attributable to the inhibition of DNA repair and consequent enhancement of apoptosis.

Therapeutic strategies that target c-Src hold promise for a wide variety of cancers. We have now investigated both the effects of dasatinib, which inhibits the activity of c-Src and several other kinases, on cell growth as well as the mechanism of dasatinib resistance in human gastric cancer cell lines. Immunoblot analysis revealed the activation of c-Src at various levels in most gastric cancer cell lines examined. Dasatinib inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) and induced G1 arrest, as revealed by flow cytometry, in a subset of responsive cell lines. In other responsive cell lines, dasatinib inhibited both ERK and AKT phosphorylation and induced apoptosis, as revealed by an increase in caspase-3 activity and cleavage of poly(ADP-ribose) polymerase. Depletion of c-Src by RNA interference also induced G1 arrest or apoptosis in dasatinib-responsive cell lines, indicating that the antiproliferative effect of dasatinib is attributable to c-Src inhibition. Gastric cancer cell lines positive for the activation of MET were resistant to dasatinib. Dasatinib had no effect on ERK or AKT signaling, whereas the MET inhibitor PHA-665752 induced apoptosis in these cells. The subsets of gastric cancer cells defined by a response to c-Src or MET inhibitors were distinct and nonoverlapping. Our results suggest that c-Src is a promising target for the treatment of gastric cancer and that analysis of MET amplification might optimize patient selection for treatment with c-Src inhibitors. Mol Cancer Ther; 9(5); 1188–97. ©2010 AACR.

Objective: The optimal management of elderly patients with limited-disease small cell lung cancer (LD-SCLC) has not been established. Methods: The records of elderly (� 70 years of age) patients with LD-SCLC who had been treated with etoposide and cisplatin chemotherapy with early concurrent twice-daily thoracic radiotherapy (TRT) were reviewed retrospectively. Results: Of the 25 elderly patients with LD-SCLC identified, 12 (48%) individuals received etoposide‐cisplatin chemotherapy with early concurrent twice-daily TRT. The main toxicities of this treatment regimen were hematologic, with neutropenia of Grade 4 being observed in all patients and febrile neutropenia of Grade 3 in eight patients during the first cycle of chemoradiotherapy. The toxicity of TRT was acceptable, with all patients completing the planned radiotherapy within a median of 29 days (range, 19‐33). No treatment-related deaths were observed. The median progression-free survival and overall survival times were 14.2 months (95% confidence interval, 4.3‐18.2) and 24.1 months (95% confidence interval, 11.3‐27.2), respectively. Conclusions: Etoposide‐cisplatin chemotherapy with early concurrent twice-daily TRT was highly myelotoxic in elderly patients with LD-SCLC, although no treatment-related deaths were observed in our cohort. Prospective studies are required to establish the optimal schedule and dose of chemotherapy and TRT in such patients.

Sorafenib is a multikinase inhibitor whose targets include B-RAF and C-RAF, both of which function in the extracellular signal-regulated kinase (ERK) signaling pathway but which also have distinct downstream targets. The relative effects of sorafenib on B-RAF and C-RAF signaling in tumor cells remain unclear, however. We have now examined the effects of sorafenib as well as of B-RAF or C-RAF depletion by RNA interference on cell growth and ERK signaling in non–small cell lung cancer (NSCLC) cell lines with or without KRAS mutations. Sorafenib inhibited ERK phosphorylation in cells with wild-type KRAS but not in those with mutant KRAS. Despite this difference, sorafenib inhibited cell growth and induced G1 arrest in both cell types. Depletion of B-RAF, but not that of C-RAF, inhibited ERK phosphorylation as well as suppressed cell growth and induced G1 arrest in cells with wild-type KRAS. In contrast, depletion of C-RAF inhibited cell growth and induced G1 arrest, without affecting ERK phosphorylation, in cells with mutant KRAS; depletion of B-RAF did not induce G1 arrest in these cells. These data suggest that B-RAF-ERK signaling and C-RAF signaling play the dominant roles in regulation of cell growth in NSCLC cells with wild-type or mutant KRAS, respectively. The G1 arrest induced by either C-RAF depletion or sorafenib in cells with mutant KRAS was associated with down-regulation of cyclin E. Our results thus suggest that sorafenib inhibits NSCLC cell growth by targeting B-RAF in cells with wild-type KRAS and C-RAF in those with mutant KRAS. [Cancer Res 2009;69(16):6515–21]

Cancer chemotherapy is not well established for patients on hemodialysis (HD). A 77-year-old man on HD presented with small cell lung cancer. He was treated with the combination of carboplatin and etoposide while the pharmacokinetics of the drugs were monitored. The patient showed a response with manageable toxicity and remained progression free for at least 8 months. The area under the concentration-time curve for each antitumor agent in the patient was within the therapeutic range achieved in individuals with normal renal function. Carboplatin and etoposide chemotherapy combined with HD thus allowed the drugs to achieve an appropriate area under the concentration-time curve and sufficient efficacy in a small cell lung cancer patient with chronic renal failure.

EGF receptor (EGFR)–mutant lung cancers eventually become resistant to treatment with EGFR tyrosine kinase inhibitors (TKI). The combination of EGFR-TKI afatinib and anti-EGFR antibody cetuximab can overcome acquired resistance in mouse models and human patients. Because afatinib is also a potent HER2 inhibitor, we investigated the role of HER2 in EGFR-mutant tumor cells. We show in vitro and in vivo that afatinib plus cetuximab significantly inhibits HER2 phosphorylation. HER2 overexpression or knockdown confers resistance or sensitivity, respectively, in all studied cell line models. FISH analysis revealed that HER2 was amplified in 12% of tumors with acquired resistance versus only 1% of untreated lung adenocarcinomas. Notably, HER2 amplification and EGFRT790M were mutually exclusive. Collectively, these results reveal a previously unrecognized mechanism of resistance to EGFR-TKIs and provide a rationale to assess the status and possibly target HER2 in EGFR-mutant tumors with acquired resistance to EGFR-TKIs. Significance: Because all EGFR-mutant lung adenocarcinomas eventually develop resistance to TKI therapy, understanding mechanisms of acquired resistance may improve clinical outcomes. These results implicate HER2 as a novel protein involved in the sensitivity or resistance of EGFR-mutant lung cancer and provide a rationale to assess the status of and possibly target HER2 in such tumors. Cancer Discov; 2(10); 922–33. ©2012 AACR. Read the Commentary on this article by Blakely and Bivona, p. 872. This article is highlighted in the In This Issue feature, p. 857.

Background A phase I study was performed to evaluate dose-limiting toxicity and the recommended dose for the oral fluoropyrimidine S-1 administered concurrently with thoracic radiotherapy (TRT) in elderly (≥70 years of age) patients with locally advanced non-small cell lung cancer. Methods S-1 was administered on days 1 to 14 and 22 to 35 at oral doses of 65 or 80 mg m−2 day−1. TRT was administered in 2-Gy fractions five times weekly for a total dose of 60 Gy. Twelve previously untreated patients were treated with S-1 at 65 (n = 6) or 80 (n = 6) mg m−2 day−1. Results All patients completed the planned 60 Gy of TRT. Dose-limiting toxicity included pneumonitis (n = 2), infection (n = 1), and stomatitis (n = 1), each of grade 3, but each event was reversible. The recommended dose for S-1 was determined to be 80 mg m−2 day−1. No patient experienced toxicity of grade 4. The dose intensity of S-1 was well maintained and the combination of S-1 plus TRT was well tolerated overall. The overall response rate was 83.3 %, with a median survival time of 34.0 months. Conclusions Administration of S-1 at 80 mg m−2 day−1 on days 1 to 14 and 22 to 35 can be safely combined with concurrent TRT in elderly patients with locally advanced non-small cell lung cancer.

Background: Although a high level of thymidylate synthase (TS) expression in malignant tumours has been suggested to be related to a reduced sensitivity to the antifolate drug pemetrexed, no direct evidence for such an association has been demonstrated in non-small cell lung cancer (NSCLC). We have now investigated the effect of TS overexpression on pemetrexed sensitivity in NSCLC cells. Methods: We established NSCLC cell lines that stably overexpress TS and examined the effects of such overexpression on the cytotoxicity of pemetrexed both in vitro and in xenograft models. We further examined the relation between TS expression in tumour specimens from NSCLC patients and the tumour response to pemetrexed by immunohistochemical analysis. Results: The sensitivity of NSCLC cells overexpressing TS to the antiproliferative effect of pemetrexed was markedly reduced compared with that of control cells. The inhibition of DNA synthesis and induction of apoptosis by pemetrexed were also greatly attenuated by forced expression of TS. Furthermore, tumours formed by TS-overexpressing NSCLC cells in nude mice were resistant to the growth-inhibitory effect of pemetrexed observed with control tumours. Finally, the level of TS expression in tumours of non-responding patients was significantly higher than that in those of responders, suggestive of an inverse correlation between TS expression and tumour response to pemetrexed. Conclusion: A high level of TS expression confers a reduced sensitivity to pemetrexed. TS expression is thus a potential predictive marker for response to pemetrexed-based chemotherapy in NSCLC patients.

Purpose: EML4-ALK (echinoderm microtubule-associated protein–like 4 anaplastic lymphoma kinase) was recently identified as a transforming fusion gene in non–small cell lung cancer. The purpose of the present study was to characterize the mechanism of malignant transformation by EML4-ALK. Experimental Design: We established NIH 3T3 cells that stably express variant 1 or 3 of EML4-ALK and examined the signaling molecules that function downstream of EML4-ALK. Results: Forced expression of EML4-ALK induced marked activation of extracellular signal–regulated kinase (ERK) and STAT3, but not that of AKT. Inhibition of ERK or STAT3 signaling resulted in substantial attenuation of the proliferation of cells expressing either variant of EML4-ALK, suggesting that these signaling pathways function downstream of EML4-ALK in lung cancer cells. The specific ALK inhibitor TAE684 induced apoptosis that was accompanied both by upregulation of BIM, a proapoptotic member of the Bcl-2 family, and by downregulation of survivin, a member of the inhibitor of apoptosis protein (IAP) family, in EML4-ALK–expressing NIH 3T3 cells as well as in H3122 human lung cancer cells harboring endogenous EML4-ALK. Depletion of BIM and overexpression of survivin each inhibited TAE684-induced apoptosis, suggesting that both upregulation of BIM and downregulation of survivin contribute to TAE684-induced apoptosis in EML4-ALK–positive lung cancer cells. Furthermore, BIM and survivin expression was found to be independently regulated by ERK and STAT3 signaling pathways, respectively. Conclusions: ALK inhibitor–induced apoptosis is mediated both by BIM upregulation resulting from inhibition of ERK signaling as well as by survivin downregulation resulting from inhibition of STAT3 signaling in EML4-ALK–positive lung cancer cells. Clin Cancer Res; 17(8); 2140–8. ©2011 AACR.

The molecular mechanism by which epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR-TKI) induce apoptosis in non–small cell-lung cancer (NSCLC) cells that are positive for activating mutations of the EGFR remains unclear. In this study, we report the effects of the EGFR-TKI gefitinib on expression of the antiapoptotic protein survivin that have functional consequences in EGFR mutation–positive NSCLC cells. Immunoblot analysis revealed that gefitinib downregulated survivin expression, likely through inhibition of the PI3K-AKT signaling pathway, in NSCLC cells positive for EGFR mutation. Stable overexpression of survivin attenuated gefitinib-induced apoptosis and also inhibited the antitumor effect of gefitinib in human tumor xenografts. Furthermore, the combination of survivin overexpression with inhibition of the gefitinib-induced upregulation of the proapoptotic protein BIM attenuated gefitinib-induced apoptosis to a greater extent than either approach alone. Our results indicate that downregulation of survivin plays a pivotal role in gefitinib-induced apoptosis in EGFR mutation–positive NSCLC cells. Furthermore, they suggest that simultaneous interruption of the PI3K-AKT-survivin and MEK-ERK-BIM signaling pathways is responsible for EGFR-TKI–induced apoptotic death in these cells. Cancer Res; 70(24); 10402–10. ©2010 AACR.

Most non–small cell lung cancer (NSCLC) tumors with activating mutations of the epidermal growth factor receptor (EGFR) are initially responsive to first-generation, reversible EGFR tyrosine kinase inhibitors (TKI) such as gefitinib, but they subsequently develop resistance to these drugs through either acquisition of an additional T790M mutation of EGFR or amplification of the proto-oncogene MET. We have now investigated the effects of combination treatment with thymidylate synthase (TS)–targeting drugs and the second-generation, irreversible EGFR-TKI BIBW2992 on the growth of NSCLC cells with the T790M mutation. The effects of BIBW2992 on EGFR signaling and TS expression in gefitinib-resistant NSCLC cells were examined by immunoblot analysis. The effects of BIBW2992 and the TS-targeting agents S-1 (or 5-fluorouracil) or pemetrexed on the growth of gefitinib-resistant NSCLC cells were examined both in vitro and in vivo. The combination of BIBW2992 with 5-fluorouracil or pemetrexed synergistically inhibited the proliferation of NSCLC cells with the T790M mutation in vitro, whereas an antagonistic interaction was apparent in this regard between gefitinib and either of these TS-targeting agents. BIBW2992 induced downregulation of TS in the gefitinib-resistant NSCLC cells, implicating depletion of TS in the enhanced antitumor effect of the combination therapy. The combination of BIBW2992 and either the oral fluoropyrimidine S-1 or pemetrexed also inhibited the growth of NSCLC xenografts with the T790M mutation to an extent greater than that apparent with either agent alone. The addition of TS-targeting drugs to BIBW2992 is a promising strategy to overcome EGFR-TKI resistance in NSCLC with the T790M mutation of EGFR. Mol Cancer Ther; 9(6); 1647–56. ©2010 AACR.

Purpose: Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) such as crizotinib show marked efficacy in patients with non-small cell lung cancer positive for the echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion protein. However, acquired resistance to these agents has already been described in treated patients, and the mechanisms of such resistance remain largely unknown. Experimental Design: We established lines of EML4-ALK-positive H3122 lung cancer cells that are resistant to the ALK inhibitor TAE684 (H3122/TR cells) and investigated their resistance mechanism with the use of immunoblot analysis, ELISA, reverse transcription and real-time PCR analysis, and an annexin V binding assay. We isolated EML4-ALK-positive lung cancer cells (K-3) from a patient who developed resistance to crizotinib and investigated their characteristic. Results: The expression of EML4-ALK was reduced at the transcriptional level, whereas phosphorylation of the epidermal growth factor receptor (EGFR), HER2, and HER3 was up-regulated, in H3122/TR cells compared with those in H3122 cells. This activation of HER family proteins was accompanied by increased secretion of EGF. Treatment with an EGFR-TKI induced apoptosis in H3122/TR cells, but not in H3122 cells. The TAE684-induced inhibition of extracellular signal-regulated kinase (ERK) and STAT3 phosphorylation observed in parental cells was prevented by exposure of these cells to exogenous EGF, resulting in a reduced sensitivity of cell growth to TAE684. K-3 cells also manifested HER family activation accompanied by increased EGF secretion. Conclusions: EGF-mediated activation of HER family signaling is associated with ALK-TKI resistance in lung cancer positive for EML4-ALK. Citation Format: Junko Tanizaki, Isamu Okamoto, Takafumi Okabe, Kazuko Sakai, Kaoru Tanaka, Hidetoshi Hayashi, Hiroyasu Kaneda, Ken Takezawa, Kazuto Nishio, Kazuhiko Nakagawa. Activation of HER Family signaling as a mechanism of acquired resistance to ALK Inhibitors in EML4-ALK-positive Non-Small Cell Lung Cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4446. doi:10.1158/1538-7445.AM2013-4446

Introduction The presence of the transforming fusion gene EML4-ALK in non-small-cell lung cancer (NSCLC) is a predictive marker for the efficacy of ALK kinase inhibitors. Currently available assays for detection of the different variants of EML4-ALK have limitations, however. Methods We developed an assay system for the detection of EML4-ALK variant 1, 2, 3a, 3b, 4, 5a, 5b, 6, or 7 transcripts in total RNA obtained from formalin-fixed, paraffin-embedded (FFPE) specimens of NSCLC tissue. The assay is based on region-specific polymerase chain reaction (PCR) amplification of EML4-ALK cDNA followed by specific single-base primer extension and analysis of the extension products by MALDI-TOF mass spectrometry. The assay was validated by fluorescence in situ hybridization (FISH) and the results confirmed by subcloning and sequencing of PCR products. Results Evaluation of the analytic sensitivity of the assay with serial dilutions of plasmids containing EML4-ALK cDNA sequences revealed it to be capable of the reliable detection of one copy of each plasmid per reaction. The assay also detected EML4-ALK variants 1 or 3 in three FFPE samples of surgically resected NSCLC shown to be positive for ALK rearrangement by FISH. Furthermore, the assay identified variant 1 of EML4-ALK in 3 of 20 FFPE biopsy samples from patients with advanced NSCLC. All positive samples were confirmed by subcloning and sequencing. Conclusions Our novel assay is highly sensitive and effective for the detection of EML4-ALK in FFPE specimens.

The epidermal growth factor receptor (EGFR) T790M mutation confers acquired resistance to tyrosine kinase inhibitors (TKIs) in approximately 50% of drug-resistant EGFR mutant lung adenocarcinomas. Experiments using genetically engineered mouse models of EGFR mutant lung cancer have revealed that T790M-mediated resistance can be overcome by a second-generation TKI, afatinib, in combination with the anti-EGFR antibody, cetuximab. This drug combination is currently in clinical trials in patients with TKI-resistant tumors and is showing a promising ∼40% response rate. Nevertheless, cases of afatinib+cetuximab resistance are beginning to emerge. To identify the molecular mechanisms that play a role in afatinib+cetuximab resistance and test new therapies to overcome resistance to these drugs, we have developed mouse models of afatinib+cetuximab resistance in mice with inducible expression of the EGFRL858R+T790M mutant in type II pneumocytes. Mice harboring lung tumors were treated five days a week with afatinib and twice a week with cetuximab for four weeks. After the first round of treatment, drug-treatments were interrupted for one month. This on/off drug treatment was repeated until lung tumors no longer responded to treatment, as evidenced by imaging as well as clinical symptoms. Resistance to afatinib+cetuximab treatment was also studied in xenografts. Eight-week-old nu/nu athymic nude mice were injected subcutaneously with human lung adenocarcinoma cells, expressing the erlotinib-resistant EGFRDel19+T790M mutant. Notably, both transgenic and xenografts models harboring EGFRT790M-induced tumors developed resistance to EGFR-dual targeting and preliminary molecular studies on the resistant tumors show the absence of additional mutations in EGFR and in the ERBB2 tyrosine kinase domain in resistant tumors. These findings suggest that an alternative pathway or mechanism is involved in mediating resistance to the afatinib and cetuximab combination. We are further exploring mechanisms of resistance by performing genome-wide and signaling pathway analyses of drug-resistant tumors from these models. Findings from mouse models will be validated in repeat biopsy specimens from patients who have developed resistance to the drug combination. An improved understanding of the molecular mechanisms responsible for acquired resistance to EGFR inhibition will provide new insight into the biology of this subset of lung cancers with immediate therapeutic implications for patients.

EGFR mutant lung cancers eventually become resistant to treatment with EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib. The combination of an irreversible EGFR TKI, afatinib, and the anti-EGFR monoclonal antibody, cetuximab, depletes both phosphorylated and total EGFR and can overcome resistance in mouse lung tumor models and human patients with acquired resistance. Since afatinib is also a potent HER2 inhibitor, here we investigated the role of HER2 in EGFR mutant tumor cells. We show in vitro and in vivo that afatinib plus cetuximab or the related antibody, panitumumab, significantly inhibits HER2 phosphorylation. HER2 overexpression or knockdown confers resistance or sensitivity, respectively, in all studied cell line models. Fluorescent in situ hybridization analysis revealed that HER2 was amplified in 3 of 26 (12%) tumors with acquired resistance versus only 1 of 99 (1%) untreated lung adenocarcinomas (p=0.03 Fisher's exact test). Notably, HER2 amplification and EGFR T790M were mutually exclusive (0 of 17 T790M-positive versus 3 of 9 T790M-negative cases (p=0.02 Fisher's exact test)). Collectively, these results reveal a previously unrecognized mechanism of resistance to EGFR TKIs and provide a rationale to assess the status and possibly target HER2 in EGFR mutant tumors with acquired resistance to EGFR TKIs.

Sorafenib is a multikinase inhibitor whose targets include B-RAF and C-RAF, both of which function in the extracellular signal-regulated kinase (ERK) signaling pathway but which also have distinct downstream targets. The relative effects of sorafenib on B-RAF and C-RAF signaling in tumor cells remain unclear, however. We have now examined the effects of sorafenib as well as of B-RAF or C-RAF depletion by RNA interference on cell growth and ERK signaling in non-small cell lung cancer (NSCLC) cell lines with or without KRAS mutations. Sorafenib inhibited ERK phosphorylation in cells with wild-type KRAS but not in those with mutant KRAS. Despite this difference, sorafenib inhibited cell growth and induced G1 arrest in both cell types. Depletion of B-RAF, but not that of C-RAF, inhibited ERK phosphorylation as well as suppressed cell growth and induced G1 arrest in cells with wild-type KRAS. In contrast, depletion of C-RAF inhibited cell growth and induced G1 arrest, without affecting ERK phosphorylation, in cells with mutant KRAS; depletion of B-RAF did not induce G1 arrest in these cells. These data suggest that B-RAF-ERK signaling and C-RAF signaling play the dominant roles in regulation of cell growth in NSCLC cells with wild-type or mutant KRAS, respectively. The G1 arrest induced by either C-RAF depletion or sorafenib in cells with mutant KRAS was associated with down-regulation of cyclin E. Our results thus suggest that sorafenib inhibits NSCLC cell growth by targeting B-RAF in cells with wild-type KRAS and C-RAF in those with mutant KRAS. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2505.

HER2 amplification is observed in 20-30% of gastric cancer and it has been correlated to poor outcomes and more aggressive disease. Combination therapies with HER2 targeting agents and cytotoxic agents are considered a therapeutic option for patients with HER2 amplified gastric cancer. We now investigated the effects of the combination treatment with S-1(or 5-fluorouracil (5FU)) and either lapatinib or trastuzumab on the growth of gastric cancer cells with or without HER2 amplification in vitro and in vivo. The combination of 5FU and either lapatinib or trastuzumab showed a synergistic antiproliferative effect in HER2 amplified gastric cancer cells. Combined treatment with 5FU and lapatinib or trastuzumab induced synergistic increases in the number of apoptotic cells and in the activity of caspase-3 in HER2 amplified cells, wheareas, such synergistic antiproliferative effect nor the enhancement of apoptosis was observed in cells without HER2 amplification. Thymidylate synthase (TS) is an important target enzyme for 5FU, with a reduced level of TS expression having been associated with a higher rate of response to 5FU-based chemotherapy. To elucidate the molecular mechanism of the synergistic effect by the combination of 5FU and lapatinib or trastuzumab, we examined the effects of lapatinib or trastuzumab on the expression and activity of TS in gastric cancer cells. Both lapatinib and trastuzumab induced down-regulation of TS expression and inhibition of TS activity in HER2 amplified cells, whereas neither lapatinib nor trastuzumab has such effects on TS expression and activity in cells without HER2 amplification. Similar to the effects of lapatinib or trastuzumab, TS depletion by siRNA resulted in the enhancement of 5FU-induced apoptosis, suggesting that TS down-regulation attributes, at least in part, to the synergistic proapoptotic interaction with 5FU. Furthermore, the combination of oral fluoropyrimidine S-1 and lapatinib or trastuzumab synergistically inhibited the growth of gastric cancer cell xenografts with HER2 amplification. Our results thus suggest that the combination of S-1 and lapatinib or trastuzumab has synergistic antitumor effects in HER2 amplified gastric cancer cells and that effect is likely attributable to the down-regulation of TS expression and inhibition of TS activity by lapatinib or trastuzumab. In conclusion, these observations provide a basis for clinical evaluation of combination chemotherapy with S-1 and HER2 targeting agents, lapatinib or trastuzumab, in gastric cancer patients with HER2 amplification. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3858.

Introduction Tyrosine kinase inhibitors (TKIs) targeted to MET are undergoing clinical trials in patients with solid tumors, but the precise mechanism of the antitumor activity of these drugs remains unclear. We examined the antitumor action of the MET-TKI crizotinib (PF-02341066) in lung cancer cells that are positive or negative for MET amplification or mutation. Methods The antitumor action of crizotinib was evaluated on the basis of signal transduction, cell proliferation, apoptosis, and progression of tumor xenografts. Results Inhibition of MET signaling by crizotinib or by RNA interference-mediated MET depletion resulted in the induction of apoptosis accompanied by inhibition of AKT and extracellular signal-regulated kinase phosphorylation in lung cancer cells with MET amplification but not in cells with a MET mutation or in those without amplification or mutation of MET. These results suggest that MET signaling is essential for the survival of cells with MET amplification but not for that of cells without this genetic change, including those with a MET mutation. Crizotinib up-regulated the expression of BIM, a proapoptotic member of the Bcl-2 family, and down-regulated that of survivin, a member of the inhibitor of apoptosis protein family, in cells with MET amplification. Forced depletion of BIM and expression of survivin each inhibited crizotinib-induced apoptosis, suggesting that both up-regulation of BIM and down-regulation of survivin contribute to the proapoptotic effect of crizotinib. Conclusions Crizotinib shows a marked antitumor action in MET amplification-positive lung cancer cells but not in cells without MET amplification, including those with a MET mutation.

Large cell neuroendocrine carcinoma (LCNEC) is a relatively new category of pulmonary neuroendocrine tumor. Although it was first detected in the lung, LCNEC has since been found in a variety of extrapulmonary sites. We now describe a patient who was diagnosed with LCNEC originating from the mediastinum, an extremely rare disorder. An increased serum concentration of alpha-fetoprotein (AFP) in the patient was reduced by chemotherapy in association with tumor shrinkage. Furthermore, the tumor was confirmed immunohistochemically to produce AFP. To our knowledge, this is the first report of a LCNEC that produces AFP.