Taxanes

To the group of Taxanes include the active ingredients paclitaxel, docetaxel and cabazitaxel. Their effect is due to the disruption of cell division (mitosis), which medicine makes use of for the treatment of various cancers.

What are taxanes?

Taxanes form a group of active substances that belong to the cytostatics and also as Taxoids are known. They are used in the treatment of various types of cancer and are used there as chemotherapeutic agents. In this context, they can often be found in combinations with other active ingredients.

The taxane that was first discovered is paclitaxel. In 1962, medical professionals first extracted it from the bark of the Pacific yew tree, and in subsequent studies determined its effect on cancer cells. In 1993, Paclitaxel was approved as a drug against ovarian cancer in Germany.

The later developed docetaxel is a derivative of paclitaxel and also a taxane. Its pharmaceutical production is based on a substance that comes from the European yew tree and is found there in the bark. Since the tree grows faster than the Pacific yew, this production offers practical advantages.

Improved active ingredients in the form of second-generation taxanes have not yet been approved, but are still being developed.

Pharmacological effect

The exact mechanism of action of taxanes can vary slightly depending on the active ingredient. What they all have in common is that they inhibit the natural process of cell division. The process known as mitosis is just as relevant for healthy cells as it is for cancer cells. In tumors, however, the increased formation of new cells leads to the development of the ulcer.

During the first phase of mitosis, the prophase, the centriole doubles and one of them moves to a pole of the cell. From there, the cell organelle forms the spindle fibers, which consist of microtubules and form the spindle apparatus.

In undisturbed mitosis, the spindle fibers attach to the chromosomes in the metaphase and separate them in the middle into two parts during the anaphase, so that each of the two cell halves receives a chromatid. The spindle apparatus dissolves again in the final telophase and the cell finally divides.

Taxanes intervene in mitosis by preventing the breakdown of the spindle apparatus in the telophase. For this reason, taxanes are also considered spindle poisons. The cell is then no longer able to double and the body initiates programmed cell death instead. This process is also known as apoptosis and leads to the destruction of the cell.

Since tumor cells have a particularly high division rate, the effects of the taxanes affect them more strongly than healthy cells, which for the most part multiply more slowly.

Medical application & use

Taxanes are used in cancer therapy. Since they represent a group of active ingredients, the indication of a taxane depends not only on the type of substance, but also on the preparation of the respective preparation. The use also depends on individual factors and can only be decided on a case-by-case basis. Combinations with other cytostatics and drugs from other groups of active ingredients are also common in practice after careful coordination.

Paclitaxel is used for bronchial carcinoma in the lungs and breast cancer in the breast. Breast cancer is the most common cancer in women. Paclitaxel can also be used in chemotherapy for ovarian cancer in the ovaries of women or for prostate cancer in the prostate gland of men.

In addition, medicine uses the taxane paclitaxel to some extent in drug-eluting stents. These are stents that are coated with a pharmacological substance and release their drug over several weeks.

Cabazitaxel is particularly indicated for mHRPC. The abbreviation stands for “metastatic hormone refractory prostate cancer” and describes a more severe course of the cancer in which the tumor spreads. Cabazitaxel is used after previous treatment with docetaxel. Medicine uses it in combination with prednisone or prednisolone.

Prednisone and prednisolone belong to the group of glucocorticoids and generally have an antiallergic and anti-inflammatory effect. In addition to prostate cancer, ovarian, breast, gastric and non-small cell lung cancer are also possible reasons for using docetaxel.

Risks & side effects

The risks and side effects of taxanes differ depending on the specific active ingredient and preparation. What these substances have in common, however, is that they mainly affect cells that divide quickly. Allergic and hypersensitive reactions are possible with all taxanes. The respective contraindications that apply to a corresponding preparation must also be observed.

In general, taxanes can affect blood cells and decrease the number of platelets (thrombocytopenia), decrease the number of neutrophils (neutropenia), or lower the concentration of hemoglobin (anemia).

Common side effects of the taxane paclitaxel are hair loss (alopecia) and gastrointestinal symptoms such as diarrhea, nausea and vomiting. Neuropathy and muscle pain (myalgia) are other potential side effects. Docetaxel use has also been linked to neuropathy. Liver dysfunction is also possible.

Known side effects of Cabazitaxel include, in addition to the blood count disorders mentioned, which can also occur with the other two taxanes, a reduction in leukocytes (leukocytopenia). Diarrhea, constipation, vomiting, poor appetite, and taste disorders may also manifest themselves.

Cabazitaxel side effects may also include irregular heartbeat, general pain and joint pain, fever, and fatigue.