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Exelixis, Inc. Message Board

  • erniewerner erniewerner Nov 6, 2013 9:19 AM Flag

    Question for Oncodocs

    It's no secret that a handful of oncologists read and occasionally post on this mb. Let me provide some contest and then ask a question. This is related to the recent inclusion of Cabo by the NCCN as a recommended treatment for RET positive NSCLC.
    I've alluded in the past that now that a regulatory barrier has come down with NCCN inclusion, the remaining roadblock to widespread use of Cabo for RET positive NSCLC is identification of patients with this particular genetic variation. Genetic testing of NSCLC patients is the norm, but the process is hardly uniform or standardized. I suspect the most common approach is for the physician to collect the required tumor sample and submit it to a lab for testing. The current identified markers tested for in order of frequency are KRAS (common for smokers), EGFR, ALK, and ROS1. From what I can gather, the lab test for this profile runs about $1500. The testing done is with FISH (fluorescence in situ hybridization). Each FISH kit costs about $250 and the testing is done sequentially for each mutation. Since the mutations generally come one per customer, I think the lab tech probably stops with the first positive. A FISH test for RET exists, but is not yet in general use. Patient enrichment for EGFR, ALK, ROS1 and RET mutations can be increased by screening for younger nonsmokers.
    I believe the MSKCC trial is using a variety of genetic testing procedures, including FISH tests, Sequenom HotSpot testing, and FoundationOne NGS (Next Generation Sequencing) testing. The list price for the FoundationOne test is $5800, but it is a comprehensive parallel test that will detect mutations missed by the standard tests and will show multiple mutations if they exist. A subtle disadvantage is that treatment has not kept pace with the diagnostic capability of this test and it may display a combination of mutations for which there is no standard treatment.
    My question, What is the actual standard for NSCLC dianostics? more....

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    • Do any of you use mass array or NGS testing that are more accurate and comprehensive or are these options still largely limited to research use? The targeted drugs are tied to specific proprietary tests. If you were to use something like the FoundationOne test to say, for instance, identify an ALK positive tumor, would you then feel obligated to backtrack and confirm that finding with the FDA approved FISH test? Do the standard cheaper panel tests look for the ROS1 mutation? I ask because it occurs with the same relative frequency as RET and is NCCN approved for Xalkori treatment. If labs are testing for ROS1, the same economics would apply to test for RET. Thx.

      • 1 Reply to erniewerner
      • Standard testing is only EGFR and ALK along with KRAS which doesn't help much.. I order ROS only in special patients (non-smokers, Asian, ets) ROS is only 1% overall and even rarer in smokers. I think most approved labs are only using FISH. Sloan does gene analysis on most or all of their lung cancers but useful results are pending. Certainly no one has approached me to push RET testing in any form. Will await developments.

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