Molecular Profiling. Molecular Pathology of Lung Cancer. Lung Cancer Biomarkers. Mutations in Lung Cancer 5/28/2011

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1 Molecular Pathology of Lung Cancer Molecular Profiling Emergence of personalized treatment HER2 receptor-directed therapy in breast cancer with HER2 amplification Recent discovery of genetic alterations in lung cancer that may be acted upon Kirk D. Jones, MD UCSF Dept. of Pathology Lung Cancer Biomarkers Mutations in Lung Cancer New drugs being developed (or already developed) which target specific molecules in susceptible tumors. Epidermal Growth Factor Receptor KRAS EML-4/ALK fusion Eur J Cancer Jul;46(10):

2 Overview EGFR Mutations Predicts response to EGFR TKI KRAS Mutations Negative predictor of response to EGFR TKI EML4/ALK Fusion Protein Possible targeted therapy Chemotherapy responsiveness assays? 2

3 Epidermal Growth Factor Receptor Member of the ErbB family of receptor tyrosine kinases. Targeted by tyrosine kinase inhibitors Tarceva erlotinib Iressa - gefitinib An unexpected cohort IDEAL study Gefitinib for treatment of NSCLC in previously treated patients. Better response in adenocarcinomas and women. Journal of Clinical Oncology 2003; 21: Increased Progression-Free Survival in EGFR mutated patients Identification of activating mutations within the kinase domain of the EGFR gene. NEJM 2004; 350:

4 I-PASS Study EGFR Testing Immunohistochemistry? FISH? Mutation analysis How much tissue do I need? NEJM 2009; 361: Immunohistochemistry Positive staining correlates with survival benefit. Not as significant as other tests. Marked variability between antibodies. Mutation-Specific IHC Development of mutation-specific immunohistochemical stains may help screen cases prior to molecular testing. Clin Cancer Res Mar 1;13(5): Clin Cancer Res May 1;15(9):

5 FISH shows correlation with response to TKI s. >40% of cells with 4 or more gene copies. FISH Mutation Analysis Activating mutations Exon 21 L858R Leucine to Arginine 85-90% Exon 19 microdeletions Several others Mutations which confer resistance to TKI therapy Mostly exon 20 Methods include direct sequencing of exons 18-21, and directed amplification of common mutations How much tissue? In order to perform these tests, it is generally advisable to have greater than 400 cells. 4 good FNA passes 4-5 transbronchial biopsies 2-3 CT-guided core needle biopsies Acquired Resistance The effect of EGFR-TKI s is not permanent. Acquired resistance often from additional mutations. 50% new EGFR mutations (esp. exon 20) 20% MET mutations 30% unknown 5

6 KRAS GTP-ase active in many signal transduction pathways. Downstream location from EGFR results in the finding that the mutations are almost always mutually exclusive. KRAS Mutations Suggest Lack of Response to EGFR TKI s J Clin Oncol Nov 1;28(31): KRAS Testing KRAS expression Not useful, but offered. KRAS mutation analysis PCR amplification of exon 2 Sequence the amplicon Examine for substitution mutations KRAS Importance Con: Not as important a positive predictive marker. Mutants may behave similarly to wild-type. Pro: If KRAS is positive, some oncologists will not try EGFR-TKI s. Whereas if EGFR is negative, they might still use as second or third line. 6

7 EML4/ALK Fusion Fusion of anaplastic lymphoma kinase (ALK) with echinoderm microtubuleassociated protein-like 4. First identified in Soda M, et al. Nature 2007; 448 (7153): Oral ALK inhibitor, crizotinib under clinical trials. Kwak EL, et al. NEJM 2010; 363: EML4/ALK Variants While the breakpoint to the ALK gene is uniform (2p23), the breakpoint in the EML4 gene varies. Eur J Cancer Jul;46(10):

8 EML4/ALK Testing 6 month progression free survival was 72% - didn t get a median before publishing FISH is often used and shows an increased distance in positive cases. IHC using typical markers shows some false negatives. RT-PCR can be used, but the primers are specific to the different variants. NEJM 2010; 363: KRAS Flow Chart for Testing (possible) - + EGFR No further molecular testing. - + EML4/ALK No further molecular testing. - + Whatever they find next. No further molecular testing. Biomarkers of Chemotherapy Treatment Responsiveness ERCC1: Increased levels may decrease lung tumor cell response to cisplatin. RRM1: Molecular target of gemcitabine increased levels decreases effectiveness of gemcitabine. Thymidylate synthase: Target of folate analogue therapies (methotrexate and pemetrexed). Increased levels decreases response to these therapies. n.b. I send them all at once. 8

9 Who to Test? Difficult issue Base on histology? But may miss a small fraction of mutations in cases classified as squamous cell carcinoma. Mucinous tumors often KRAS positive. Send all cases? Pro No cases slip through the cracks. Con MANY cases do not need testing. Clinical indication Patients with advanced disease and desire to treat. System set up for rapid TAT after requested. Take Home Points Biomarkers such as EGFR mutations and EML4/ALK translocations are being increasingly used to determine treatment options, including first line chemotherapy. 9