The active ingredient paclitaxel is used for the therapy of different types of cancer. It has the property of inhibiting the division and proliferation of cancer cells.
What is paclitaxel?
The active ingredient paclitaxel is used to treat different types of cancer. Paclitaxel is a cytostatic drug. It belongs to the group of taxanes and is used to treat various types of cancer. These include ovarian and breast cancer. The drug comes from the bark of the Pacific yew tree (Taxus brevifolia). Research on paclitaxel began in the late 1960s by scientists M. C. Wani and Monroe E. Wall, who launched an extensive search for new anticancer agents. In 1971, the two researchers succeeded in isolating the compound paclitaxel for the first time by performing an extraction of Pacific yew. During this process, they noticed an anti-proliferative effect on cancer cells. In the present, paclitaxel is offered as an infusion concentrate. In Europe, the drug has been available since the early 1990s. Because the demand for natural Pacific yew cannot be met due to its limited distribution, partial synthetic extraction of the drug from baccatin III has taken place in recent years. This substance is contained in the needles of the European yew and is obtained by the Ojima-Holton process. Alternatively, biotechnological extraction of paclitaxel from yew cell cultures is also possible.
Pharmacological action
As mentioned above, paclitaxel originates from the yew tree, which belongs to the deciduous trees and has needle-shaped leaves. With the help of the drug, an anti-cancer effect is possible. Paclitaxel interferes with the division of cancer cells and belongs to the subgroup of mitosis inhibitors. During cell division, microtubules (bundles of filaments) are formed. At the crucial moment, these are able to attract duplicated chromosomes, which are part of the genetic material. Through this process they ensure the formation of an independent cell. Unlike the cytostatic drug vinblastine as well as the gout drug colchicine, which have a direct inhibitory effect on microtubule assembly, paclitaxel can prevent their degradation. In this way, an abnormal bundle structure of microtubules is formed during the cell cycle, which in turn leads to an obstruction of genetic division. Stabilizing the microtubules also affects the entire internal structure of the cells. Paclitaxel has the property of affecting all dividing cells. As a result, there is an increased risk of side effects. However, cancer cells are more affected because their division is particularly rapid.
Medical application and use
Paclitaxel can be used to treat various types of cancer. For example, it is presented together with the cytostatic drug cisplatin for the treatment of advanced ovarian cancer. The drug is also suitable if, following surgery, remnants of the tumor remain in the body that reach a size of more than one centimeter. Paclitaxel can also be used to treat metastases (daughter tumors) if platinum-containing substances do not lead to an improvement. Paclitaxel is also administered to breast cancer that has already metastasized to the neighboring lymph nodes. However, this requires pretreatment with cyclophosphamide and anthracyclines. Paclitaxel is also suitable for combination therapy with the monoclonal antibody trastuzumab if the patient has a specific growth receptor on the cancer cells and anthracycline treatment is not suitable. Paclitaxel is used alone in breast cancer treatment only if anthracycline therapy is unsuccessful. If radiation or surgery cannot be performed for non-small cell bronchial cancer, paclitaxel is administered together with cisplatin. Paclitaxel is also considered suitable for use in Kaposi’s sarcoma. This is a special type of cancer that primarily presents in AIDS patients. Paclitaxel is administered in the form of an intravenous infusion.
Risks and side effects
Taking paclitaxel can sometimes result in bothersome side effects. Upper respiratory tract infections are the most common. These include rhinitis, sore throat, oral thrush, and cold sores.In addition, urinary tract disorders, bleeding, anemia, white blood cell deficiency, mucosal inflammation, skin rashes, flushing, nerve dysfunction, diarrhea, nausea, vomiting, constipation, abdominal pain, muscle discomfort, joint pain, hair loss, and edema of the limbs may occur. Less common side effects include dizziness, nerve dysfunction, nervousness, flu-like symptoms, headache, taste changes, ringing in the ears, palpitations, fainting, itching, acne, calf cramps, bone pain, back pain, chest pain, depression, chills, and fever. During treatment, patients must apply sunscreen to their hands and feet. There are also some contraindications to paclitaxel. For example, the drug must not be administered if the patient has a pronounced hypersensitivity to the drug. Other contraindications include non-treatable infections in the case of Kaposi’s sarcoma, the presence of neutrophils, and severe liver dysfunction. In cases of cardiac dysfunction or mild hepatic dysfunction, the physician must carefully weigh the risks against the benefits. No information is available on the use of paclitaxel in pregnancy. However, it should not be administered during pregnancy because, as with other cytostatic drugs, it may cause harm to the pregnant woman. Paclitaxel should also be avoided during breastfeeding, as it is not known whether the drug passes into breast milk. Before using paclitaxel for ovarian cancer, it is important to always administer the drug before the cytostatic drug cisplatin. Otherwise, there is a risk of more severe impairment of bone marrow function if it is used in the opposite direction.
