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Exelixis, Inc. Message Board

  • wildbiftek wildbiftek Jun 21, 2013 9:54 AM Flag


    1) If there's anything Ernie has taught me, it's to know the FDA prior decision record well as precedent for future approval decisions. Some light has recently been shed on Eliquis' troubled path to approval:

    "Roller Coaster Path To Approval For Eliquis Uncovered By FDA Documents"
    "Eliquis Approval Delayed By Fraud, Dispensing Errors In Pivotal Trial"

    The concerns here were fraud from conducting the trial in China and possible dispensing errors due to trial design. I'm guessing there were corners cut to save money on trials here. I'm not sure how much of this carries over to the FDA's decisions on oncology, but I think that the COMET trials take place in the US and western Europe and employs a simple control / experiment group design will reduce FDA misgivings about design. Any thoughts Ernie?

    2) There isn't much known about what happens on a cellular level when a patient develops cancer resistance. Ernie said that there's a core of cells that don't die which form the basis of tumor resurgence. It sounds like cells develop some level of heterogeneity under Cabo exposure.

    Anyway, there's tangentially related news from melanoma treatment about defeating certain types of heterogeneous cells:

    "Studies Demonstrate the Strategy to Kill Melanoma by Sensitizing Resistant Cells"

    It's not clear that what's being described is related to Cabo resistance since melanoma sounds much more heterogeneous than prostate cancer, but it would be very interesting to study those cells resistant to Cabo to see whether they exhibit similar behavior to the most resistant melanoma cells.

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    • "Ernie said that there's a core of cells that don't die which form the basis of tumor resurgence."

      That was a theory put forward by Dr. Legothetis based on unpublished work done at MD Anderson.

      "...will reduce FDA misgivings about design. Any thoughts Ernie?"

      I would assume that EXEL is using the same CRO that did the EXAM trial. As that priority review happened on time, I see no reason to think that there will be any future problems.

    • Advanced metastatic melanoma is a disease that has proven difficult to eradicate. Despite the success of melanoma-targeting drugs, tumors inevitably become drug resistant and return, more aggressive than before. In the current issue of the journal Cancer Cell, however, researchers at The Wistar Institute describe how they increase the effectiveness of anti-melanoma drugs by combining anticancer therapies with diabetes drugs. We have found that the individual cells within melanoma tumors are not all identical, and tumors contain a sub-population of cells that are inherently drug resistant, which accounts for the fact that advanced melanoma tumors return no matter how much the tumor is depleted, said Meenhard Herlyn, D.V.M., D.Sc., professor and director of Wistar’s Melanoma Research Center. We found that these slow-growing, drug-resistant cells are marked by a high rate of metabolism, which makes them susceptible to diabetes therapeutics.Our findings suggest a simple strategy to kill metastatic melanoma—regardless of cell type within the tumor—by combining anticancer drugs with diabetes drug,Herlyn said. The diabetes drug puts the brakes on the cells that would otherwise repopulate the tumor, thus allowing the anticancer drug to be more effective. In the Cancer Cell article, the researchers describe how various anticancer drugs, including cisplatin and the targeted therapy vemurafenib, which targets melanomas with the BRAF mutation, become more effective when co-delivered with phenformin. According to Herlyn, the researchers used the diabetes drug phenformin in their studies, but they are now working with colleagues to develop a clinical trial using a drug with less toxic side effects

      • 1 Reply to clemcaldwell
      • In 2010, Herlyn and his colleagues published findings that changed the way scientists look at tumor cells. Melanoma tumors were, as they described, heterogeneous. That is, they contained multiple populations of cells, including the so-called JARID1B cells, which their research suggested was responsible for allowing tumors to survive drug therapy. According to Herlyn, these slow-growing JARID1B cells represent only one to five percent of the cells in a tumor, yet readily divide into the fast-growing cells that are the hallmark of advanced melanoma.Amazingly, these cells were remarkably resistant to drug therapies. JARIRD1B cells shrug off chemotherapies and targeted drug inhibitors, regardless of their mode of action,Herlyn said.These are not dormant cells—they divide once every six or seven weeks as opposed to every other day like the rest of the melanoma cells, Herlyn explained. These slow-growing cells are apparently kept in check by the rest of the tumor, somehow--indeed, if you remove them from a tumor, they grow like crazy.
        Working with Wistar’s Proteomics Facility, the Herlyn laboratory surveyed JARID1B’s proteome (that is, the sum total of all the proteins these cells produce), and found that these cells were on metabolic overdrive. Despite the fact that they hardly seemed to grow and divide, they were continually synthesizing glucose, which is then used to produce chemical energy.
        Fortunately, an entire field of study has been created to combat cells that produce glucose—diabetes. Using phenformin, a drug first created nearly a half century ago, the researchers demonstrated it was possible to deprive melanoma tumors of the metabolic dynamos that allow melanoma to survive therapy.According to Herlyn, Wistar’s Melanoma Research Center is working with their clinical partners to develop a clinical trial to apply their research findings to patients with advanced melanoma.The research was funded by NIH grants CA25874, CA047159, and CA10815, a grant from the Dr. Miriam and Scheldon G. Adelson Medical Research Foundation, and grants from the German research foundation, Deutsche Forschungsgemeinschaft (DFG). The Wistar Institute is an international leader in biomedical research with special expertise in cancer research and vaccine development. Founded in 1892 as the first independent nonprofit biomedical research institute in the country, Wistar has long held the prestigious Cancer Center designation from the National Cancer Institute. The Institute works actively to ensure that research advances move from the laboratory to the clinic as quickly as possible. The Wistar Institute: Today’s Discoveries – Tomorrow’s Cures.

    • 3) Mole rats don't seem to get cancer and a paper theorizes that this is due to the high concentrations of Hyaluronan in their skin:

      "High-molecular-mass hyaluronan mediates the cancer resistance of the naked mole rat"
      "Cancer Cure Found In Naked Mole Rats? Chemical, Hyaluronan, May Contain Anti-Cancer Properties"

      Funnily enough, in human prostate cancer cells, Hyaluronan interaction with CD44v9 seems to be driving cancer resistance to AR pathway related inhibition:

      "Stromal hyaluronan interaction with epithelial CD44 variants promotes prostate cancer invasiveness by augmenting expression and function of hepatocyte growth factor and androgen receptor"

      In any case, there seems to be a rich relation between Hyaluronan and cancer.

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