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L. Diao
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Best of Posters - IASLC Selection - Part 2 (ID 263)
- Event: WCLC 2013
- Type: Exhibit Showcase Session
- Track:
- Presentations: 1
- Moderators:
- Coordinates: 10/30/2013, 09:55 - 10:25, Exhibit Hall, Ground Level
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P2.06-032 - SMO mutations occur in non-small cell lung cancer (NSCLC) and may respond to hedgehog inhibitors (ID 2483)
09:55 - 10:25 | Author(s): L. Diao
- Abstract
Background
Smoothened (SMO) is a 7-membrane spanning receptor involved in the hedgehog signaling pathway. In the absence of Patched inhibition, SMO accumulates and inhibits proteolytic cleavage of transcription factors. We previously identified a lung cancer patient with SMO mutation (Patient A, Table 1) and successfully treated him with erivedge, a hedgehog inhibitor. We therefore sought to determine the incidence of SMO mutations in The Cancer Genome Atlas (TCGA) lung cohorts, identify additional NSCLC patients with SMO mutations, and initiate therapy with hedgehog inhibition as proof-of-concept.Methods
TCGA databases for lung adenocarcinoma (n=230) and squamous cell carcinoma (n=178) were interrogated for SMO mutations and hedgehog pathway dyregulation. Mutations were determined by whole exome sequencing. Copy number was assessed by GISTIC 2.0 (scores of 2 considered high level amplification). The lung SMO mutation patients were undergoing treatment at M.D. Anderson Cancer Center Thoracic Clinic for metastatic/refractory disease. Mutations in hotspot regions of 46 cancer-related genes including SMO was performed as part of their clinical diagnostic evaluation (Ion AmpliSeq Cancer Panel; Life Technologies, CA).Results
In TCGA lung adenocarcinomas, alterations in SMO (mutation, amplification, mRNA overexpression) were observed in 12.2% of tumors. The incidence of SMO mutations was 2.6% and SMO gene amplifications 5%. SMO mutations and amplifications strongly correlated with sonic hedgehog gene dysregulation (p<0.0001). In TCGA squamous cell, SMO was altered in 10.1% of tumors, primarily via mRNA upregulation. Only 1 SMO missense mutation was identified in the Lung SCC cohort (D209Y). We identified 3 NSCLC patients with SMO mutations (Table 1) by the 46-gene panel. Patient A was treated with erivedge as he had a concomitant localized basal cell carcinoma (BCC) with a significant reduction in tumor burden. He continues to respond to therapy after 14 weeks. It is possible that Patient A’s NSCLC-SCC was misidentified and that this was metastatic BCC or that this is a germline variant. Germ-line mutation analysis is underway. However, the precise SMO mutation in Patient A was also identified in a lung adenocarcinoma Patient C (Table 1). Two additional SMO-mutated patients have just initiated erivedge and updates on their status will be provided at WLCC.Table 1
Patient Biopsy site SMO mutation Reported Histology Duration of Erivedge Therapy Response to Erivedge A Lung Codon 641, exon 11 (CCT to GCT) p. Pro641Ala NSCLC SCC 14 weeks PR A Skin lesion Codon 641, exon 11 (CCT to GCT) p. Pro641Ala BCC 14 weeks CR B AP window lymph node Codon 525, exon 9 (ATG to TTG) p.Met525Leu NSCLC Adenoca pending pending C Axillary lymph node Codon 641, exon 11 (CCT to GCT) p.Pro241Ala NSCLC Adenoca pending pending Conclusion
SMO mutations and pathway alterations occur in NSCLC and may be an actionable target with hedgehog inhibitors; a clinical trial is under development. Screening lung SCC tumors for SMO mutations is recommended to prevent misdiagnosis of metastatic BCC. Additional analysis of hedgehog signaling pathway alterations is underway and will subsequently be reported.
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MO15 - Novel Genes and Pathways (ID 89)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Biology
- Presentations: 2
- Moderators:Y. Ohe, G. Reid
- Coordinates: 10/29/2013, 16:15 - 17:45, Parkside Ballroom A, Level 1
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MO15.02 - Impact of co-occurring genetic events on the signaling landscape of KRAS-mutant lung adenocarcinoma. (ID 2936)
16:15 - 17:45 | Author(s): L. Diao
- Abstract
- Presentation
Background
Personalized medicine frameworks centered on identification and therapeutic targeting of dominant oncogenic driver mutations are rapidly becoming a standard of care in the clinical management of patients with lung adenocarcinoma. However, little is currently known about the nature and impact of co-occurring genetic events on signaling output downstream of initiating oncogenes. This lacuna in our understanding is particularly pertinent for the subgroup of KRAS-driven tumors, where mounting data point towards considerable heterogeneity in pathway activation and clinical response to targeted therapies. Here, we report a comprehensive analysis of genetic events that co-occur with or are mutually exclusive of mutant KRAS in a cohort of 230 lung adenocarcinomas and assess the impact of individual co-mutations on signaling streams using data derived from state of the art transcriptomic and (phospho)proteomic profiling of primary tumors.Methods
An integrated analysis of 230 lung adenocarcinomas from The Cancer Genome Atlas (TCGA) consortium was performed using mutation (whole exome sequencing), transcriptomic (RNASeq), and proteomic (reverse phase protein array) datasets. Fischer’s exact test was applied to identify secondary mutations that occurred more frequently in either KRAS-mutant (n=68) or KRAS-wild-type (n=162) tumors and (phospho)protein markers that associated with each co-mutation. Genes with a mutation rate of ≥3% in the overall cohort were included in the analysis.Results
Mutations in 18 genes were associated with KRAS mutational status in patient tumors (p≤0.01). Mutations in EGFR (p=0.0001), NF1 (p=0.001), and TP53 (p=0.001) were negatively correlated with the KRAS mutation. On the other hand, mutations in STK11 were significantly more frequent in the KRAS-mutant cohort (p=0.004), as were mutations in ATM (p=0.023) and MTOR (p=0.045). The most significant positive association involved mutations in ARHGEF11, a gene that encodes a Rho guanine nucleotide exchange factor (p=0.0004). Mutations in STK11 (29.4%) and TP53 (29.4%), the two most highly prevalent genetic events within the KRAS-mutant cohort were mutually exclusive. Unsupervised hierarchical clustering of transcriptomic and quantitative (phospho)proteomic profiles revealed separation of STK11-mutant tumors at the first branch of the cluster dendrogram, indicating activation of distinct signaling pathways downstream of this key tumor suppressor gene. Several less frequent genetic events had prominent and consistent effects on signaling output. We focused our attention on signaling via the MAPK pathway which may impact clinical sensitivity to MEK inhibitors, one of the most promising classes of targeted agents currently in clinical development for KRAS-mutant tumors. Preliminary analysis suggests that mutations in 3 individual genes can identify a subgroup of tumors (19% of the cohort) with profoundly suppressed MAPK signaling flux.Conclusion
Analysis of recurrent secondary genetic events may define distinct and clinically relevant subsets of KRAS-mutant lung adenocarcinoma. Efforts to refine the sub-classification further and assess the impact of co-mutations on sensitivity to molecularly targeted agents are underway and updated results will be presented at the meeting.Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.
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MO15.08 - KDR (VEGFR-2) copy number gains and mutations are targetable alterations in non-small cell lung cancer (ID 1466)
16:15 - 17:45 | Author(s): L. Diao
- Abstract
- Presentation
Background
Therapeutic regimens targeting the vascular endothelial growth factor (VEGF) pathway have been extensively tested in the treatment of malignancies including non-small cell lung cancer (NSCLC). VEGF pathway inhibitors including bevacizumab or VEGF receptor (VEGFR) tyrosine kinase inhibitors (TKIs) have been shown to prolong progression-free survival (PFS) and/or overall survival (OS). These benefits, however, have been modest, occurring only in subsets of patients. Therefore, predictive markers to identify patients likely to derive benefit are critically needed. Although expression of VEGFR-2, also known as KDR, was initially thought to localize primarily on endothelial cells, VEGFR-2 has been detected on malignant cells. We recently observed that KDR copy number gains (CNGs) were detectable by FISH in ~30% of both adenocarcinoma and squamous cell carcinoma and were associated with poor clinical outcome in early stage NSCLC patients treated with adjuvant chemotherapy. In addition to CNGs, mutations and polymorphisms within the KDR gene were also observed. The impact of these alterations is unknown. Here, we investigated KDR CNGs, polymorphisms, and mutations in NSCLC and their effects on sensitivity to VEGFR targeting agents in preclinical models and in NSCLC patients.Methods
Cell migration was evaluated by Boyden chamber assay. NSCLC cell lines were treated with VEGF pathway inhibitors for 24 hours, and protein lysates where collected. HIF-1α levels were evaluated by ELISA assay. VEGFR, p38, and p70s6K were evaluated by Western blotting. Tumor DNA and peripheral blood DNA, were analyzed in duplicate using Affymetrix Genome-Wide SNP Array 6.0. Transformation of Ba/F3 cells was evaluated by an IL-3-independent growth assay.Results
In tumor cells with KDR CNG, VEGF stimulation induced activation of p38 and p70S6K, and VEGFR TKIs including sorafenib and vandetanib effectively inhibited VEGF-mediated signal transduction. In tumor cell lines with KDR CNG, exogenous VEGF ligand increased cell motility and this was inhibited by VEGFR blockade with TKIs including sunitinib, sorafenib, and axitinib. Various receptor tyrosine kinases have been shown to drive HIF-1α levels, and NSCLC cells with KDR CNG express elevated levels of HIF-1α in normoxia compared to NSCLC cell lines without KDR CNG. In NSCLC cell lines with KDR CNG, VEGFR TKIs decreased protein levels of HIF-1α and HIF-1α regulated proteins. Furthermore, we report a clinical case in which a NSCLC patient with KDR CNG had a partial response to the VEGFR inhibitor, sorafenib. In addition to gene amplification, mutations and polymorphisms within the KDR gene were also observed. KDR mutation 1586A>T and polymorphism 1416A>T effectively transformed Ba/F3 cells. Finally, we report two clinical cases in which NSCLC patients with the 1416A>T polymorphism had a partial response the VEGF pathway inhibitor, bevacizumab.Conclusion
Collectively, our data indicate that KDR amplification promotes downstream signaling events including activation of the p38, mTOR, and HIF pathways and are targetable by VEGF pathway inhibitors. KDR gene alterations may be predictive markers for VEGF pathway inhibitors.Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.
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MO20 - Preclinical Therapeutic Models II (ID 93)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Biology
- Presentations: 1
- Moderators:P. Waring, M. Kohonen-Corish
- Coordinates: 10/30/2013, 10:30 - 12:00, Bayside Gallery B, Level 1
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MO20.02 - Proteomic analysis identifies baseline PI3K/Akt pathway activation and treatment-induced supppression of mTOR signaling as determinants of response to MEK inhibition (ID 2845)
10:30 - 12:00 | Author(s): L. Diao
- Abstract
- Presentation
Background
Inhibition of MEK is a promising treatment strategy for non-small cell lung cancer (NSCLC). MEK inhibitors are being investigated for KRAS mutant disease, but KRAS alone is not predictive of efficacy, and other predictors of response and resistance are not known. The downstream effects of MEK inhibition have not been fully described. Here, we report broad proteomic analysis of NSCLC cell lines before and after treatment with MEK inhibitor BAY86-9766.Methods
We treated 109 NSCLC cell lines with BAY86-9766. Drug sensitivity was determined by CellTiter-Glo assay and cell lines were classified as sensitive or resistant based on whether their IC50 values were in the highest or lowest 1/3[rd] of those tested. Proteomic analysis for regular and phospho-proteins was performed by reverse phase protein array. Using paired t-tests, we compared pre- versus post-treatment protein levels in the overall group and between the sensitive vs. resistant cell lines.Results
Increased activation of the PI3 kinase pathway at baseline correlated with resistance to MEK inhibition, with resistant cell lines showing higher baseline levels of pAkt (S437), pAkt (T308), pPDK1, and p4E-BP1 (S65), and lower baseline levels of PTEN (all p<0.05). Cell lines with increased MEK phosphorylation at baseline were more sensitive to MEK inhibition (p=0.048). BAY86-9766 was very effective at reducing pERK (p=1.65x10[-35]) but this modulation was not significantly different between sensitive and resistant cell lines (p=0.64). Increased phosphorylation of MEK was seen with treatment (1.66x10[-16]). mTOR signaling was suppressed by MEK inhibition, with decreased phospho-p70S6K, pS6 (S235/236), and pS6 (S240/S244) and increased eIF4E following treatment (all p<0.02). These effects were significantly more pronounced in sensitive vs resistant cell lines (all p<0.01). Higher levels of LKB1 total protein, pAMPK, and pTSC2 were also seen following treatment (all p<0.02).Conclusion
We have performed broad proteomic analysis of NSCLC cell lines treated with MEK inhibitor BAY86-9766. Baseline activation of the PI3K/Akt pathway predicts for resistance to MEK inhibition. Sensitive cell lines, but not resistant cell lines, show suppression of mTOR activity with treatment with BAY86-9766. The effects of MEK inhibition of mTOR may be modulated by p90RSK through an LKB1 dependent pathway. This suggests a basis for combining targeted agents to overcome resistance, such as combinations of MEK inhibitors with PI3K inhibitors or mTOR inhibitors.Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.
