New treatment offers hope for multiple myeloma and lymphoma

Cancer is a devious adversary. It figures out all kinds of ways to hide from the body’s detection systems and grow unchecked until it’s too late to stop them. One of cancer’s most cunning methods of evading the immune system is to increase the frequency of a kind of cellular “train” – a protein called XPO1 – that makes regular back-and-forth trips in and out of the nucleus of a cell. The XPO1 protein’s job is to shuttle other proteins to the right stops on the line.

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One passenger on the XPO1 shuttle is a tumor-suppressing protein

One passenger on the XPO1 shuttle is a tumor-suppressing protein. Its job is to conduct regular “audits” of a cell to ensure the DNA is not damaged. If it is, the protein instructs the cell to enter“programmed cell death,” whereby the cell essentially commits suicide. Cancer cells, by their very nature, have damaged DNA – that’s what causes them to divide uncontrollably, creating tumors. In a healthy immune system, the tumor-suppressor proteins would catch the DNA mistakes in the nucleus and stop the cells from proliferating. But cancer outwits the tumor-suppressing proteins by increasing XPO1 activity. More frequent trains take the suppressor proteins out of the nucleus of the cell – where they should be stopping the cancer – and deposit them far away. “They can’t do their job because they’re geographically removed from where they’re supposed to be,” says Sharon Shacham, CEO of Karyopharm Therapeutics, an Israel- and Massachusetts-based company that has developed a new drug that inhibits XPO1 activity in a cell. “We stop the train from taking the passengers.”-- More...