Taxol (paclitaxel)
Page Medically Reviewed and Edited by Kyle J. Becker, PharmD, MBA, BCOPThis page has been fact checked by a Doctor of Pharmacy who specializes in Oncology. Sources of information are listed at the bottom of the article.
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Taxol® is a brand name for chemotherapy drug that has been in use since its U.S. Food and Drug Administration (FDA) approval in 1992. The history of this drug dates back decades earlier. It is a natural compound called paclitaxel and is derived from the Pacific yew, a type of tree. It took nearly 30 years to become an approved anti-cancer drug, though the first samples of the bark removed for testing for potential medicinal properties were harvested in 1962.
Under the generic name paclitaxel, this drug is now made and sold by a number of pharmaceutical companies and has been approved for use in the treatment of several types of cancer. Researchers are hopeful that this drug can prove useful in treating mesothelioma as part of a multimodal approach, but initial studies have had mixed and limited results.
What is Taxol?
Taxol is a brand name drug used to treat several types of cancer. Other names for this drug include the generic name, paclitaxel, as well as Praxel, Bristaxol, Onxol, Asotax, and the albumin-bound version called Abraxane. The drug was first approved by the FDA in 1992 and is currently approved to treat breast cancer, ovarian cancer, lung cancer, and AIDS-related Kaposi’s sarcoma. Common unapproved uses include the treatment of esophageal, endometrial, head and neck, bladder, and cervical cancers. Taxol is not commonly used to treat mesothelioma, but researchers continue to test this drug in combination with other treatments or medications for mesothelioma.
The History of Taxol
Today, Taxol is a very important drug, particularly for treating advanced ovarian cancer in patients who have not responded to other treatments. The discovery of this natural compound came as a result of National Cancer Institute (NCI)-funded research. The story began in the 1950s, when the NCI began a research project to screen synthetic and already known compounds for chemotherapeutic properties.
In the 1960s, the NCI partnered with the U.S. Department of Agriculture to begin screening natural compounds from plants. Over a couple of decades, more than 30,000 compounds were screened, and the compound that would become Taxol was discovered. Paclitaxel was isolated from the bark of the Pacific yew tree, and was studied for decades. Finally in 1977 it was noted to be effective at stopping tumor growth in mice and was then employed in clinical trials, eventually becoming approved by the FDA in 1992. The big breakthrough was a study showing that 30 percent of women with advanced ovarian cancer responded to the medication. Taxol quickly became the first blockbuster chemotherapy, and there is continued research into how it can help patients.
How it Works
Paclitaxel is a type of drug called an antimicrotubule agent. Like other chemotherapy drugs, it targets cells in the body that grow and divide rapidly and slow or stop their growth. The way antimicrotubule agents and other taxanes do this is by interfering with microtubules and how they arrange during cell division. These proteins have to line up in a certain way inside a cell for that cell to successfully reproduce and divide. When paclitaxel interferes with this process, the cancer cells can no longer thrive.
Side Effects
As with any type of chemotherapy, there are possible side effects when using Taxol. It is a cytotoxic drug and harms healthy cells along with cancer cells. The most common side effects seen with paclitaxel include pain and swelling at the injection site, nausea, vomiting, diarrhea, weakness, muscle and joint pain, stomach pains, mouth sores, and hair loss. These are largely not serious, but they can be painful or uncomfortable. The nausea and mouth sores can make healthy eating more challenging, so patients could also experience unintended weight loss due to this medication.
Black Box Warnings
In addition to the more common and less serious side effects that many patients experience with Taxol, there is a potential for more severe adverse events. The FDA has labeled Taxol with a black box, which it reserves for the most serious and potentially life-threatening side effects of drugs. One of these is the risk that Taxol will significantly reduce white blood cell count, which makes a patient susceptible to dangerous infections. Patients with already compromised immune systems are cautioned not to use this drug or to be carefully monitored while on it.
Another risk is the potential for infusion-related reactions, a reaction similar to anaphylaxis. Taxol contains polyoxyethylated castor oil to help the chemical stay as a liquid and some people may have a life-threatening allergic reaction to it. Notably, Abraxane does not have this same issue, as the drug is bound to small proteins in a more expensive manufacturing process.
Treating Mesothelioma
Researchers have been eager to find out what else this drug can do because Taxol proved to be so successful in advanced ovarian cancer. Despite the drug’s success in other challenging cancers, results in trials with mesothelioma have been disappointing. Early trials using Taxol for mesothelioma witnessed little or no improvement when it was used by itself. Patient survival in these studies was only five to nine months, not a great improvement over other treatments.
More recently, researchers have combined paclitaxel with other treatments and are hoping for better results. A published case study of a woman with peritoneal mesothelioma showed there could be hope for this drug. She was given intraperitoneal carboplatin with paclitaxel and achieved complete remission after six cycles. The doctors treating her concluded that combinations with paclitaxel, given aggressively, could possibly help other patients with mesothelioma. There is another case where Abraxane (nanoparticle albumin-bound paclitaxel) was administered in combination with carboplatin to a patient who didn’t respond well to first-line treatment. He responded so well to initial treatment that he was given a break. Then when the mesothelioma came back, they treated him with the same regimen and he saw benefit again.
While early studies of Taxol in mesothelioma patients were disappointing, more recent studies combining this drug with other medications and as part of a multimodal treatment approach are showing great promise. In the future, Taxol may be used more commonly for treating patients with all types of mesothelioma, but for now the medication is not often utilized.
Page Medically Reviewed and Edited by Kyle J. Becker, PharmD, MBA, BCOP
Kyle J. Becker, PharmD is certified by the Board of Pharmacy Specialties in Oncology Pharmacy. Dr. Becker earned his pharmacy degree from Shenandoah University and he currently serves as an oncology pharmacist at Parkview Cancer Institute.
