Where There’s A Pill, There’s A Way Leukemia Drug Gleevec Continues To Show Promise In Patients And Clinical Trials

Ten years ago, the idea of taking a pill once a day to fight cancer seemed like a far away notion to most people.

Now, although a cure is still far off, a so-called ‘wonder drug’ is changing the face of cancer treatment one dose at a time, and heralding the arrival of a new era in cancer treatment.

Gleevec, the brand name for imatinib mesylate, was the first cancer drug if its kind to be put on the market. The FDA approved the drug in 2001 for use in treating one specific type of leukemia – chronic myeloid leukemia (CML), which affects about 10,000 people worldwide each year. It has also proven effective in fighting other disorders such as gastrointestinal stromal cell tumors, and research into Gleevec’s effects on other cancers continues, as well as the promise of similar drugs.

“It was the first drug of its kind to be marketed, but a lot were being researched and tested at the same time, and continue to be,” said Dr. Richard Steingart, a hematologist with Baystate Health Systems.

Steingart said of all cancers, CML and GI stromal cell tumors are relatively uncommon, and most types of cancer do not respond to Gleevec. But he said the drug represents something larger than a treatment for rare, specific disorders – it epitomizes an entirely new, and remarkably effective, way of treating cancer.
Chemistry 101

The intrinsic difference between Gleevec and other cancer drugs, according to Steingart, is that it targets the root of the problem, searching out the cancer-causing abnormality in a patient’s body and correcting it at the molecular level.

Most people with CML, for instance, have an abnormal chromosome called the Philadelphia Chromosome, which Steingart explained is formed when small portions of chromosomes 9 and 22 break off and fuse together. The protein this chromosome creates is the cause of the disease; Gleevec works by binding with the protein and halting the overactive production of white blood cells.

Because of how it works, Steingart refers to Gleevec as a “designer molecule” rather than a miracle drug, but admits the drug’s first few years on the market have made a marked difference in treatment of CML and in the lives of CML patients.

“About 98{06cf2b9696b159f874511d23dbc893eb1ac83014175ed30550cfff22781411e5} of people that go on Gleevec go into hematologic remission – they no longer show symptoms,” he said. “Gleevec essentially shuts off disease-making proteins, and it works regardless of the phase the disease is in, although the activity of the drug is lower at more progressed stages.

“It also works really, really fast,” Steingart added. “After just a week, you already see measurable differences in patients.”

“These drugs are not a cure. And they are still only being applied to very specific cancers. But what we have here is a very tight Band Aid.”

The drug is a culture change for patients that have been on regimens of chemotherapy drugs like interferon. Cancer treatments such as chemotherapy and radiation, said Steingart, work by eradicating cancer cells, but healthy cells are damaged in the process. Instead of launching into an often debilitating drug treatment meant to eradicate as many cancer cells as possible during a limited treatment time, patients taking Gleevec instead remain on the drug indefinitely – presumably, for the rest of their lives, not unlike diabetics taking insulin or treating other chronic disorders.

In addition, side effects of Gleevec are markedly less destructive than chemo-therapy. Patients may experience nausea, weight gain, muscle cramps, diarrhea, and edema – a swelling around the ankles and sometimes the eyes, according to Steingart – but most of those symptoms abate after a few months or be either controlled with mild medications or by splitting the daily dose of Gleevec into two smaller doses – one in the morning and one in the evening.

And because Gleevec is a pill, splitting doses is as easy as breaking one small, orange capsule in half each day.

“The fact that it’s a pill is very nice to say the least. People would much rather swallow a pill once a day than have an injection or some other treatment.”

Gleevec can also be combined with other treatments to create the best possible regimen for a patient, Steingart said. In short, the drug is an attractive option for some cancer patients, as well as the first of what he hopes will be many molecular cancer drugs.

Run of the Pill

And with Gleevec’s fledgling years on the market behind it, both research and use of the drug continue to surge ahead. New findings have been published as recently as last month examining Gleevec’s effects on other cancers, such as the AIDS-related Kaposi’s Sarcoma. (The Journal of Clinical Oncology reported that of 10 KS patients, cancerous tumors regressed in five people, and the tumors in the remaining five patients stabilized.)

Novartis, Gleevec’s manufacturer, has also unveiled a new drug the functions on the same premise as its predecessor. Still being tested under its research name – AMN107 – the drug has been shown to work in patients who had an initial or developed resistance to the original compound. The pharmaceutical company Bristol-Meyers-Squibb is also testing a similar drug.

“These drugs are not a cure,” Steingart cautioned, “And they are still only being applied to very specific cancers. But what we have here is a very tight Band Aid.”