Cancer survival rates are rising in part because of advances in treatments. According to the American Cancer Society, the five-year survival rate for all cancers between 2001-2007 is 67 percent, a rise from 49 percent in 1975-77. One area of research that has exploded since 2000 is personalized cancer medicine, which uses genetics to individualize patients’ treatments.
“Personalized cancer medicine is in its infancy,” says Dr. Rajiv Datta, medical director of the cancer program and chairman of the department of surgery at South Nassau Communities Hospital in Oceanside, New York. “But I can envision 40 to 60 years from now that we will take a blood sample, run a genetic code and predict the type of cancer someone is likely to get. We would be fixing the disease before it happened.”
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Although personalized cancer medicine is not there yet, these advances exemplify ways that the study of the genetic and molecular is advancing personalized cancer medicine and improving cancer survival rates.
- Kinase inhibitors. The first of these, imatinib mesylate (Gleevec), was approved by the U.S. Food and Drug Administration (FDA) in 2001 to treat myelogenous leukemia (CML), a once-deadly bone marrow cancer. Kinase inhibitors work by blocking the breakdown of proteins involved in uncontrolled cancer cell growth. “Gleevec, for instance, stops growth and causes cell death,” says Datta. There are 14 FDA-approved kinase inhibitors treating a variety of cancers, including non-small cell lung cancer and some breast and thyroid cancers.
- Therapeutic antibodies. “Therapeutic antibodies are drugs directed toward a particular protein manufactured by a cancer,” says Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society. “The most common is Avastin. It attaches to a protein called VEGF to prevent the creation of blood vessels that feed the cancer.” Some combination therapies such use therapeutic antibodies attached to radioactive particles, explains Lichtenfeld: ”The antibodies direct the radiation to a particular marker on a cancer cell.” The therapy then attacks the cancer without damaging normal cells. A dozen therapeutic antibodies have been approved by the FDA for certain cancers including some lymphomas and leukemias, colon, head and neck, and breast cancer, and melanoma.
- Drugs targeting cancer cell’s environment. Five FDA-approved drugs work by blocking the growth of blood vessels and lymphatic vessels that a cancer needs to grow. “These drugs are effective, but they can cause harm because they affect all the blood vessels,” says Datta. They are used to treat renal cell carcinoma, medullary thyroid cancer, gastrointestinal stromal tumors, non-small cell lung cancer, some colorectal and pancreatic cancer.
- Immune system drugs. “One reason tumors grow is that the body does not recognize them as foreign,” says Datta. “So we’re looking for ways to alert the body that the cancer is foreign so the immune system will kill it.” The prostate cancer vaccine Provenge works in this way. Other such therapies are in development.
- Targeting tumor subpopulations. Researchers have discovered that different cancer cells can be in the same tumor. So some cells may respond to treatment while others do not. “Also, chemo may only attack cancer cells that are still multiplying,” says Datta. “Sometimes cancer cells have completely matured, but they are still dangerous. So we are trying to find drugs that recognize mature cells.” To target such diversity, researchers combine chemotherapies, or traditional drugs with newer, more targeted drugs. They are also testing for multiple biomarkers so that they can predict which drugs the tumor may resist.