While some promising new treatments for breast cancer are years away from regular treatment regimens, others are on the market or just around the corner.
Still on the horizon for treating breast cancer are anti-angiogenesis drugs. They block the formation of new blood vessels that feed tumors and help them grow. These drugs have shown promise in treating colon cancer and are now being studied in patients with advanced breast cancer. But it may be some time before these drugs have been studied enough to make the leap to treating early-stage breast cancer.
About two-thirds of women with breast cancer have tumors that contain estrogen receptors (called ER-positive). This type of cancer depends on the female hormone to grow. Hormone therapy is given to block the body's naturally occurring estrogen and fight the cancer's growth. Women who are ER-positive are more likely to respond to hormone treatment than women who are ER-negative.
Even so, new breast cancer treatments are available now. Over the past year, doctors have learned a lot more about many targeted therapies that very soon may be helping millions of women live longer and healthier lives after learning they have breast cancer.
Abraxane and Albumin-Bound Nanoparticle Drugs
In January, headlines trumpeted the release of a new chemotherapy drug for breast cancer called Abraxane. Technically, Abraxane isn't a new drug -- it's an exciting new way of delivering an existing drug.
Paclitaxel, commonly marketed as Taxol or Taxotere, is part of many chemotherapy drug regimens, but it has one big problem, says Clifford Hudis, chief of the Breast Cancer Medicine Service at New York's Memorial Sloan-Kettering Cancer Center. "It doesn't dissolve in water, which means we have to put the drugs in solvents to deliver them to patients." Those solvents can cause a number of side effects, including severe allergic reactions. Patients taking paclitaxel have to receive heavy doses of other medications first, such as steroids and antihistamines, before getting their chemotherapy.
Abraxane does a neat end run around that problem. A process called protein-bound nanoparticle technology creates tiny particles that bind the paclitaxel to a naturally occurring protein called albumin. "The binding makes little packets of paclitaxel -- think of them as little bubbles -- that can be dissolved in water," says Hudis. This means no more solvent, which in turn means no more medications before chemotherapy, and no more of the side effects that go along with them. It's also shortened the chemotherapy's infusion time from more than three hours to around half an hour.
These practical pluses would be enough to make anyone receiving chemotherapy rejoice. But there may also be a bonus in terms of the drug's effectiveness. In one of the major clinical trials that led to Abraxane's FDA approval, women who got this drug had almost twice the response rate to chemotherapy compared with women who received regular Taxol. This may be in part because without the need for solvents, higher doses of paclitaxel could be delivered to the women getting Abraxane.
Or another factor could be involved. Because albumin, which normally transports nutrients to cells, accumulates in rapidly growing tumors, it's possible that the bundles of Abraxane in their albumin "envelopes" are sent by express delivery directly to cancer cells. "There are signs indicating that albumin receptors in breast cancer and other cancer cells would preferentially pick up these albumin-bound packets," says Hudis.