Internal Medicine

Chemotherapy substances

General

There are numerous different cytostatics that have their point of attack at different points in a tumor cell.
The cytostatics are divided into groups according to the respective mechanisms of action. The most important groups of cytostatics are named below.
However, given the abundance of terminology, brand names and possible combinations (so-called schemes), it is not possible to go into each of these details. The following examples of the substances are named by their active ingredient names.

The tyrosine kinase inhibitors are also chemotherapeutic agents. In contrast to the classic chemotherapeutic agents, the tyrosine kinase inhibitors work in a targeted manner and thus cause fewer side effects. Read more about the tyrosine kinase inhibitors at: Targeted chemotherapy with tyrosine kinase inhibitors

Alkylating agents

This Chemotherapy drugs disrupt tumor cell production at the level of DNA. They networked the molecules of the DNA (by Alkylation) in a manner that results in the normal readings required to produce Proteins are disturbed. Since a tumor cell on the proteins (Proteins) this leads to the death of the tumor cell. In addition, the alkylating agents prevent the formation of new DNA, which also causes the tumor cells to die.

This group is further divided into subgroups, all of which follow the above-mentioned mechanism of action:

Nitrogen mustard analogs: Bendamustine, cyclophosphamide, chlorambucil, melphalan, ifosfamide, trofosfamide
Alkyl sulfonates: Busulfan, treosulfan
Nirosoureas: Carmustine, Lomustine, Nimustine
Compounds containing platinum: Carboplatin, Cisplatin, Oxaliplatin (this group of substances is very effective and is often used in combination with other cytostatics)

Antimetabolites

Such Cytostatics are called "wrong“Building blocks built into the newly made DNA. This stops the formation of new DNA (the so-called DNA polymerase is inhibited). Since the DNA only doubles during cell division, the antimetabolites have a very specific effect on tumor cells. Here, too, 3 subgroups can be distinguished, which differ in their type as "wrong building blocks".

Folic acid analogs: Methotrexate (has been around for a long time, but is still one of the most important substances), pemetrexed
Purine analogs: Mercaptopurine, nelarabine, cladribine, fudarabine,
Pyrimidine analogs: Flouracil (5-FU), Capecitabine, Gemcitabine

Vinca alkaloids

This substance originally comes from the plant evergreen (Vinca). As already mentioned, the entire set of chromosomes (DNA) is doubled during cell division. In order to distribute this equally to 2 cells, the cell needs an "apparatus", the so-called mitotic (from Mitosis= Cell division) spindle, made up of subunits, the so-called. Microtubules. A cell cannot divide regularly without the mitotic spindle. The Vinca alkaloids disrupt the structure of this spindle and thus the ability of the tumor cells to divide.

Examples: Vinblastine, vincristine

Taxanes

These also have the so-called microtubules as their target structure. In contrast to the Vinca alkaloids, however, they do not disturb their structure, but on the contrary stabilize them Microtubules. For this you have to know that the mitotic spindle is subject to constant construction and dismantling. If you now inhibit the breakdown, which is just as important for the correct division of a cell, you again disturb the growth of the tumor cells.

Examples: Docetaxel, paclitaxel

Cytotoxic antibiotics

As well as bacteria Usually killed by antibiotics, some antibiotics can even target tumor cells. In principle, they proceed in the same way as with bacteria; Some bacteria, like us humans, have DNA in the form of a Double helix, a double strand wound around one another, is present. In order to untangle these coils we need a protein (an enzyme), the so-called topoisomerase. The information can only be read from the DNA when it is disentangled. The antibiotic, which in this case has a cytotoxic, i.e. cell-damaging effect, settles between the DNA strands in such a way that the topoisomerase is blocked.

Examples: Anthracyclines such as doxorubicin, mitoxantrone

antibody

This way of Fight against tumors is relatively new. First of all, an explanation of what an antibody actually is: It is a protein that is in the Immune defense plays a big role. An antibody specifically recognizes a foreign structure, an antigen, binds it and thus leads to its demise. The special thing about an antibody is that it only contains certain "sick“Recognizes structures, normally not healthy cells. Thus, in our case, it mainly acts on tumor cells. Some target structures are mentioned below:

Bevacizumab: binds to the vascular growth factor VEGF
Cetuximab : binds to the growth factor receptor EGFR
Rituximab: binds to the surface protein CD 20

Although this list at Cytostatics in most cases the base of everyone chemotherapy research into new substances never stands still. In many clinical studies, new substances are already being tested that may achieve significantly better results in the future!