Cancer Treatments - Biologic Therapy and Immunotherapy
22 Nov 2019
What is biologic therapy? How can it help treat cancer? What does it mean when a doctor talks about immunotherapy? At what point during treatment and under what conditions should a patient be given access to a biologic therapy? Find out more!
Care for cancer patients is turning more and more towards personalised medicine and targeted therapies. Over the past 15 years, the use of biologic therapies has exploded in the oncology field and have overturned many long-standing practices in patient care, notably the integration of monoclonal antibodies into therapeutic strategies. The results are promising and have attracted the attention of researchers, with many projects currently under evaluation.
Biologic therapy, immunotherapy, target therapy: what's the difference?
What is biologic therapy?
Biologic therapies are medications and/or treatment regimes based on the functions of living organisms and the laws of biology. They are derived from molecules produced by living organisms (yeasts, microbial fermentation, genes, cells, tissues...) or from substances taken directly from living organisms (hormones, antibodies, interleukins…). Though biologic therapies may be used in cancer treatments, they are also seen in treatments for a number of other conditions, including inflammatory diseases.
Within oncology (a branch of medicine that deals with the prevention, diagnosis, and treatment of cancer) biologic therapies may be called on to hinder or reduce different elements that contribute to a tumour’s spread.
- Stopping, controlling or reversing the tumour growth cycle
- “Marking” cancerous cells to allow them to be more easily identified and killed by the patient’s immune system
- Increasing the “killing power” of the patient’s immune cells so they can attack tumour cells more efficiently (immunotherapy)
- Preventing cancerous cells from spreading (metastasis)
One form of biologic therapy used to treat cancer is target therapy, where each molecule targets a specific characteristic of the tumour. The idea is to destroy only the cancerous cells while living the maximum amount of healthy cells unharmed, unlike chemotherapy. In this way, the patient enjoys a better quality of life.
In order to target cancer cells, the tumour’s specific characteristics or “tumour heterogeneity” are closely scrutinised to determine which of those characteristics should be targeted and by what treatment.
The term “biologic therapy” is wide and includes immunotherapy treatments. Immunotherapy is a kind of biologic therapy, but not all biologic therapies are immunotherapies. The purpose of immunotherapy is to stimulate the patient’s own immune system to attack cancerous cells.
Biologic therapies for cancer treatment
Biologic therapies, whether target therapy or immunotherapy, can be classified by the way they work and the characteristics they target in the tumour cells. The physician will choose one or a combination of molecules after examining factors such as what kind of cancer it is, how far advanced it is and the patient’s profile
Monoclonal antibodies target the exterior or the surface of cancerous cells, acting similarly to the antibodies naturally produced by our bodies. They act to halt tumour growth. They can also be attached to a chemotherapy molecule, a toxin or a radioactive substance in order to guide them specifically to the cancerous cells, while sparing the surrounding healthy cells. Their names usually end in “mab” and they are always administered intravenously. Among them, we find ERBITUX for the treatment of metastatic colorectal cancer or HERCEPTIN for treating HER2 positive breast cancer.
Another type of monoclonal antibody attacks intracellular targets, burrowing into the cancerous cells. They inhibit signalling cascades and thus stop tumour growth. Their names generally end with “nib” and they are taken orally. Among them, we find IRESSA or TARCEVA used for treating metastatic mutated EGFR non-small cell bronchial cancer.
A class that’s largely made up of inhibitors of tyrosine kinases – key enzymes that facilitate tumour cell growth and division. In this category, we find LYNPARZA for the treatment of mutated BRCA ovarian cancer or ZELBORAF for treating mutated BRAF melanoma.
Other molecule types
Certain biologic therapies target membrane receptors, others inhibit the formulation of new blood vessels (angiogenesis) which tumours depend upon for survival, and still others block cellular replication mechanisms or even provoke cell death and/or cell protein degradation. The choice of therapy depends on a large number of important factors and can only be decided by a physician, who will follow the patient during treatment to assure its effectiveness.
Where are biologic therapies useful for cancer treatment?
A separate treatment altogether?
Biologic therapies are not a replacement for conventional cancer treatments like surgery, radiation therapy, or chemotherapy. They complete an anti-cancer arsenal and are usually prescribed in combination with conventional treatments.
What’s the ideal patient profile for biologic therapy?
Targeted treatments are prescribed for patients with advanced-stage cancers or those who have relapsed after finishing another treatment
However, there are some treatments available for early stage cancers like TRASTUZUMAB a “HER2 positive” breast cancer treatment administered in combination with chemotherapy and following surgery, and IMATINIB for the treatment of gastrointestinal stromal tumours (GIST) following surgery.
How effective are they?
With their specific and targeted nature, biologic therapies have proven to be quite effective at treating cancer. They allow the patient's health, in most cases, to improve on both a biological and clinical level and are much better at sparing a patient’s healthy cells, unlike radiation and chemotherapies, greatly increasing patient quality of life while reducing the risk of after effects over the long term.
WARNING: Biologic therapies are not a replacement for conventional treatments and are not suitable for every patient. Talk to your doctor!
What are the main side effects?
Biologic therapy treatments main cause occasional side-effects which usually disappear as soon as the treatment is stopped. Side-effects can often be reduced, or eliminated altogether, by paying close attention to hygiene, getting recommended vaccinations, etc. However, as these treatments are relatively new, some of their side effects are still little known in the medical community. You should talk to your physician about any side effects that you were not already warned about!
· Anaphylaxis: a violent and often serious allergic reaction
· Moderate allergic reactions during injection (the patient’s body may develop antibodies against the molecule)
· Soreness at the injection site
Risks of infection
· Immunodeficiency: Since biologic therapies slow down the immune system, the body cannot protect itself adequately against bacteria and viruses which can lead to sometimes severe infections.
· Inflammation: immunotherapy may cause inflammation in the internal organs and even provoke an auto-immune reaction.
· There are factors which increase the risk of infection such as a medical history of stubborn infections, being at or over the age of 65, chronic illnesses, a history of respiratory illnesses, or taking a corticotherapy at the same time.
Tumour cell resistance to biologic therapies
A tumour is usually composed of many types of cells in constant evolution rather than a mass of uniform ones. Within a single tumour, different cells might present various molecular anomalies – this referred to as “tumour heterogeneity”.
Tumour heterogeneity can in certain cases cause the appearance of resistance to biologic therapies. Since the target has moved, the treatment loses its effectiveness. The resistance may be “primary”, meaning the treatment will be ineffective from the start, or “secondary” where resistance appears a few weeks, months or even years after the treatment is begun.
To keep the risk of resistance to a minimum and attack the tumour on all fronts, a variety of different treatments may be prescribed at the same time.
Warning: This article is a general overview of biologic therapies and is not meant as medical advice. Each patient is different and the article cannot cover every individual case. Always talk to your doctor before beginning any treatment!
Article written by Louise-B with Camille Dauvergne, 4th-year pharmacy student.