Stomach cancer and gastronintestinal stromal tumors (GIST) can be an expensive disease to treat, but for approximately $5,000 a month Novartis AG’s cancer pill Gleevec (imatinib) seems to extend the lives of patients with this type of gastrointestinal cancer over the long-term when taking the drug for three years after surgery. When FDA approved in May 2001, Gleevec made the cover of TIME magazine as the “magic bullet” to cure cancer.
What the drug does is turn off certain proteins within cancer cells that cause them to grow and spread. Imatinib is the first member of a new class of agents that act by specifically inhibiting a certain enzyme that is characteristic of a particular cancer cell, rather than non-specifically inhibiting and killing all rapidly dividing cells, and served as a model for other targeted therapy modalities through tyrosine kinase inhibition.
After five years, two-thirds of patients that took Gleevec for three years remained cancer-free, compared with 48% in patients that took the drug for a single year. Also, 92% of patients in the three-year group were alive after five years, compared with 82% in the one-year group according to information presented at the annual meeting of the American Society of Clinical Oncology.
Heikki Joensuu, M.D., Ph.D., Professor, Oncology, University of Helsinki and principal investigator of the study states:
“This study confirms the hypothesis that extending the duration of Gleevec treatment for patients following surgery improves recurrence-free survival. For the first time, an effect on overall survival was found. Results from this trial may positively impact clinical practice by helping physicians create the optimal treatment plan for patients with operable GIST.”
It was also reported that prior to Gleevec, which was approved by the Food and Drug Administration in 2001, less than 50% of such patients survived five years with the disease making this a real breakthrough.
Gastrointestinal stromal tumors (GISTs) belong to a group of cancers called soft tissue sarcomas. Sarcomas are a rare type of cancer that can occur in connective tissues, bones, muscles, fat, nerves, blood vessels, and cartilage. Sarcomas are derived from the general class of cells known as “mesenchymal cells”. In contrast, most of the “common” cancers, such as lung cancer, skin cancer, and prostate cancer, are derived from a different type of cell, known as “epithelial cells”, the cells which line the body’s many surfaces.
Why does this distinction matter? Because carcinomas and sarcomas behave very differently and are treated differently. Sarcomas are much less common than carcinomas. As a result, there are relatively few oncologists who specialize in treating sarcomas.
Although the exact incidence is still somewhat unclear, it is now estimated that, in the United States, between 3,000 and 5,000 people each year develop GISTs.
About 40-70% of GISTs arise from the stomach, 20-40% arise from the small intestine, and 5-15% from the colon and rectum. GISTs can also be found in the esophagus. Sometimes GISTs develop outside the intestinal tract in the abdominal cavity. These are called eGISTs.
However, patients should not use the drug forever. The reason that patients shouldn’t be left on the drug indefinitely is because about half of patients that have surgery are cured by the surgery alone, but there is no way to tell which patients should get the drug.
Despite the findings in the study, Dr. Joensuu said that patients still need to be monitored closely because early detection of the disease’s resumption is important. Such patients could still have treatment options, including Gleevec itself again, he said.
It is Novartis’ second-best selling drug with sales of more than $4 billion last year.
Written by Sy Kraft