Friday, May 14, 2010

Provenge, And Mylovenge

Several weeks ago, the FDA approved for certain types of refractory (i.e. unresponsive to standard treatment) cases of prostate cancer a new "vaccine", brand name Provenge. The reason I'm using the scare quotes here is that Provenge is not a vaccine in the conventional sense; no one who does not already have prostate cancer will be taking Provenge to avoid getting it. The mass media is using the term "vaccine" to characterize Provenge because it's a term that is much more familiar to the general public (not to mention more concise) than is "autologous cellular immunotherapy", and because it serves to convey an important fact about the drug: like an ordinary vaccine, it enables the patient's immune system to combat the cancer. A patient's white blood cells are extracted, are treated with the drug, and are then returned to the patient, having now been "taught" to recognize the cancer cells as things that should be attacked and destroyed. Provenge is the first therapy of this type approved by the FDA for the treatment of any type of cancer.

Therapeutically speaking, Provenge isn't notably impressive. It extends survival by only four or five months, and it doesn't seem to affect tumor progression at all, which is apparently one of the reasons why the FDA had such trouble granting approval for it, finally doing so about ten years after it was first presented. And it will of course be appallingly expensive, thus giving rise to yet another of those "health care rationing" conundrums that we seem to specialize in creating.

But in conceptual terms, one can visualize Provenge as being the prototype for an extremely effective class of future cancer therapies. The immune system's job is to attack and destroy bad guys; cancer cells are bad guys that diabolically pretend not to be; the obvious answer is to somehow make the immune system see through the cancer cells' disguises for what they are, and go git em. That's what Provenge, and its presumed successors, would seek to accomplish.

So what does this have to do with multiple myeloma? Nothing, except that at one time
-- ten years ago -- Dendreon, the company that developed Provenge, was working on a vaccine for multiple myeloma, called Mylovenge. Mylovenge was at some pointed granted "orphan drug" status by the FDA (thus qualifying it for certain types of research-related tax credits), and it reached Phase II clinical trials by 2002 or thereabouts. And then.... nothing. I was able to find traces of a clinical trial involving Mylovenge that completed in 2005, but not the results of the trial. There is nothing mentioning Mylovenge on Dendreon's web site, and calls to Dendreon's corporate offices proved fruitless. Intense Googling turned up a claim that Dendreon stopped working on Mylovenge when it became apparent that it would be difficult to manufacture, and that its therapeutic results compared poorly with those of other types of drugs that became available in the meantime -- drugs that didn't require the expensive and cumbersome pheresis process.

In fact, Mylovenge is the tip of a large iceberg of relative failure for cancer immunotherapies. This idea -- that the battle should be fought by the immune system -- as reasonable as it sounds, has proved difficult to implement in practice. Many types of immunotherapies have been developed and tested during the past couple of decades, to little practical effect so far. No doubt a tremendous amount has been learned in the process, but to date this knowledge has not been translated into longer lives for cancer patients. Reading the press around the Provenge approval is attended by deja vu: the potential of the immunotherapeutic approach is set forth in terms almost identical with researchers' promises made ten or fifteen years ago. That's not the researchers' fault, really; this stuff is hard, harder probably than anyone would have guessed at the beginning.

And now, suddenly, the President's Cancer Panel comes out of left field with a report declaring that the environmental causes of cancer have been "grossly underestimated", and recommending that maybe someone should look into this. So at this point, the larger problem of cancer -- where it comes from, and how to stop it -- is still generating many more questions than answers.

Tuesday, May 4, 2010

This Month's Tests

The monthly routine into which my medical life has settled goes something like this: A few days prior to visiting the oncologist, I have blood drawn for the battery of tests he wants to do. The office visit itself of course begins in the outermost waiting room; eventually I am called upon by a physician's assistant, who weighs me before ushering me into an examination room, where I await my audience with His Lordship. Upon entering, he gives me a glance up and down and pronounces his satisfaction with my appearance; then he jumps onto a computer, brings up my test results, mutters a bit about one number or another, but finally declares his general approval of the aggregate. He inquires about any pain I might be having, but am not. Then I'm up on the table while he listens to my lungs and heart, and gently probes my belly and squeezes my ankles. We talk about whether he needs to write any prescriptions for me. Finally, it's Q and A time, which these days usually is brief, although this month we chatted a bit about the new vaccine recently approved for prostate cancer, and whether there is anything like that being developed for multiple myeloma (but that's a subject that deserves a post of its own). Finally, on the way out, I schedule my next office visit, and a session for an Aredia IV, which ordinarily occurs a day or two later.

The blood tests that are being done fall into one of three broad categories, from my perspective. One category is that of blood cell counts: red, the various types of whites, and platelets. This month, these were all within their normal ranges, except that I am a bit low on red blood cells. This is a side effect of the Revlimid, and is a factor in my fatigue problem.

A second category of tests I think of as "levels of chemicals in the blood", stuff like calcium, sodium, potassium, creatinine, and glucose. Currently these are all in their normal ranges.

The third category is that of proteins and
immunoglobulins (a.k.a. antibodies). Oversimplifying greatly, we want to see adequate numbers of the types of antibodies expected to be produced by normal plasma cells, and we don't want to see any of the junk monoclonal proteins produced by defective, cancerous plasma cells. Again, currently the tests are showing more or less the right numbers of the former, and none of the latter. I will continue to take Revlimid as long as this state of affairs continues.

Meanwhile, the monthly Aredia treatments are supposed to be strengthening my bones; this, in concert with suppression of the disease that caused them, should be making some of the lytic lesions on my spine disappear. I haven't had a skeletal survey for awhile, so I will get one sometime in the next month or so, thus giving us a reading on how well I'm doing on this front.