Currently, researchers are working hard to develop analogs or “cousins” of suramin—to make it more powerful, with fewer side effects. And scientists are investigating whether suramin given in combination with another drug— EMCYT, perhaps—might be more effective.
“We’re talking about the very end of a lifetime of a tumor here,” says the Johns Hopkins oncologist. “By this point, tumors become resistant to drugs in many ways; they express different pathways of resistance. If you treat with Drug A, for instance, this may be effective against a certain portion of the tumor, but probably not all of it—some part of that tumor is probably going to be resistant to that treatment. Therefore, because we’re dealing with a heterogeneous disease, it’s unlikely that any one drug is going to make a significant impact.”
Timing of treatment also may make drugs such as suramin more effective. Some doctors are letting PSA be the guide to beginning additional treatment. “In following men on hormonal therapy,” says the oncologist, “if we see that the PSA is rising—even before patients develop problems—that is probably a better time to start (with other drugs) because the disease is not as extensive as it becomes if you wait until pain, weight loss and other cancer-related symptoms begin.”
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