Hi AA, I think the rationale for the hormonal receptor reversing is so the cancer cells can survive via of the estrogen pathway once the her2 pathway is shut down. It just doesn't seem like a cancer cells would want to shut off an alternate good growth pathway by becoming estrogen negative. Ney, they would want to keep the estrogen pathway upregulated or positive so they could grow so I don't see how Herceptin would increase the chances of evolving from a estrogen positive to negative state.
It would be interesting to know why cancers become estrogen negative. I've read that once cancer cells are really growing fast, the estrogen receptor gets downregulated and pathways like her2 take over to drive the cancer. Seemingly, new research seems to indicate all this can be reversed with Herceptin, interesting.
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Robin
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