Modern chemotherapeutic compounds are distinguished by the fact that they bind to very specific molecules on or inside cells and thus block the function of these molecules. Of course, before using them in patients, it must first be checked, if these molecules are present in the tumor cells of the patient in question. This concept is sold under the title “personalized cancer therapy” as a great hope of the future.
Modern chemotherapeutic compounds are distinguished by the fact that they bind to very specific molecules on or inside cells and thus block the function of this molecule. This can be, for example, a molecule which stimulates growth of cancer cells or cell division, inhibits cell death of a cancer cell, or is responsible for the formation of new vital blood vessels for the tumor. Accordingly, these are almost invariably antibodies. They are used either alone or in combination with other chemotherapeutic agents.
One of the newer antibodies is pembrolizumab. It is an antibody against the PD-L1 molecule, a molecule that inhibits cell death of immune cells, and PD-L1 stands for “programmed death-ligand 1”. We block this ligand with an antibody, so the immune cells do not die so quickly. Rapid death can be desirable in the event of an infection or autoimmune disease, because otherwise the inflammation would be continued endlessly. In the case of cancer, it could be an advantage if the cell death of the immune cells is inhibited, so goes the highly simplified concept.
Like all chemotherapeutic agents, pembrolizumab may only be used by trained oncologists in certain forms of lung cancer and is not intended for prescription in a general medical practice. However, as a general practitioner, I have received a mail which is intended to inform physicians about the possible side effects of this medication in order to be able to recognize them quickly and, if necessary, to direct the patient correctly.
The drug is usually administered every 3 weeks. It takes two vials. One vial costs Euro 4.921.90 (in words: four thousand nine hundred twenty-one euros and ninety cents). The progression free interval of lung cancer was 6 months in the chemotherapy group, and 10.3 months in the group receiving pembrolizumab. The survival rate after 6 months was 72.4% in the chemotherapy group, 80.2% in the pembrolizumab group. Irritating here is that the study mentions an “estimated rate of survival;” there are (still) no figures for the general survival rate.
Thus, the effect can be summarized as follows: Pembrolizumab produces better results than chemotherapy in the short term, although the study group as a whole had apparently favorable conditions (still more than 70% survivors in the chemotherapy group after 6 months). But long-term data is still missing.
Now to the side effects, which were the reason for the mailing from the pharmacist. Possible side effects are:
- Immuno-mediated pneumonitis (in simplified terms: non-bacterial pneumonia)
- Colitis (inflammation of the gut)
- Hepatitis (liver inflammation)
- Nephritis (renal inflammation)
- Endocrinopathies including hypohysitis, type I diabetes mellitus, diabetic ketoacidosis, hypothyroidism, hyperthyroidism (metabolic and hormonal disorders including inflammation of the pituitary gland in the brain, diabetes type I, diabetic metabolic dermatitis with menacing acidification of the blood, hypothyroidism and hyperthyroidism)
- Uveitis (eye inflammation)
- Arthritis (joint inflammation)
- Myositis (muscle inflammation)
- Severe skin reactions (this was not further specified)
- Guillain-Barré syndrome (a nerve inflammation)
- Myasthenia syndrome (muscle weakness due to antibodies against muscles)
- Haemolytic anemia (anemia due to increased decomposition of the blood corpuscles)
- Focal seizures (epilepsy)
Adverse effects occurred in 73.4% of the patients in the pembrolizumab group, and in 90.0% of the ones in the chemotherapy group.
Dear Oncologist, dear health politician, my intention is not to diminish your efforts. But the improvement achieved here is moderate and extremely expensive – not only in the literal sense of the word. I do not reject research in new chemotherapeutics. It is, however, incomprehensible, in view of these data, why, at least a small part of the research funding, is not devoted to research into a suitable diet or to the many plant-derived remedies, that have been shown to produce the same results in laboratories.
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