Have you ever heard of immunotherapy?
You may not be familiar with the term.
It is a method of cancer treatment that is now attracting the most attention.
Surgery, radiotherapy, and chemotherapy have been the three major treatment methods in Japan up to now, but immunotherapy is now attracting a great deal of attention as the fourth major treatment method to be added to them.
Although it is still rarely broadcast in the media, if you are undergoing cancer treatment or have a family member with cancer, you may be familiar with it.
In this issue, we summarize the “immunotherapy” that is now attracting a great deal of attention.
Breakthrough cancer drug (1)
Immune checkpoint inhibitors are a revolutionary cancer treatment that has recently attracted much attention. Unlike conventional anticancer agents and radiotherapy, they are a fundamental treatment method that attacks and eliminates cancer cells by activating the patient’s own immune system.
1) Mechanism of immune checkpoint inhibitors
Our body has an immune system that originally monitors and eliminates cancer cells. However, cancer cells evade the immune system in ingenious ways and continue to proliferate.
Immune checkpoint inhibitors inhibit the mechanism called “immune checkpoint” that cancer cells use to escape from the immune system, thereby enabling the immune system to attack cancer cells that were originally suppressed.
Immune checkpoints include PD-1, PD-L1, and CTLA-4.
PD-1/PD-L1 pathway: PD-L1 on the surface of cancer cells binds to PD-1 on the surface of T cells, thereby inhibiting T cell activation. Immune checkpoint inhibitors block this binding and promote T cell activation.
CTLA-4 pathway: CTLA-4 on the surface of T cells binds to CD80/CD86 on the surface of antigen-presenting cells, thereby inhibiting T cell activation. Immune checkpoint inhibitors block this binding and promote T cell activation.
representative immune checkpoint inhibitors
PD-1 inhibitors: nivolumab, pembrolizumab, tesitlimab
PD-L1 inhibitors: atesolizumab, dovicilimumab, durvalcitab
CTLA-4 inhibitors: ipilimumab
types of cancer for which they are indicated
Immune checkpoint inhibitors are expected to be effective against various types of cancer.
The main types of cancer for which they are indicated
Malignant melanoma
Bladder cancer
Hodgkin’s lymphoma
Gastric cancer
Esophageal cancer
Hepatobiliary cancer
Lung cancer
Kidney cancer
Head and neck cancer
We provide treatment for a wide range of cancers, including
efficacy and side effects
Immune checkpoint inhibitors are said to be highly effective in treating advanced and metastatic cancers that have been difficult to treat with conventional therapies.
Main effects
Tumor shrinkage
Inhibition of disease progression
Long-term survival
Main side effects
Immune-related adverse events (irAE): skin disorders, gastrointestinal symptoms, lung dysfunction, etc.
May be severe and require caution
challenges and future prospects
Immune checkpoint inhibitors are a breakthrough therapy, but they are not a panacea. They are not effective for all patients and have many side effects.
Major Challenges
Not effective for all patients
High cost of treatment
Potential for serious side effects
Groundbreaking Cancer Treatment Method (2)
CAR-T cell therapy is a revolutionary cancer treatment that has recently been attracting attention. The patient’s own T cells are removed from the body and genetically engineered to introduce a gene called “CAR (Chimeric Antigen Receptor),” which can specifically recognize and attack cancer cells. The introduced CAR-T cells are then administered to the patient, where they proliferate in the body and attack cancer cells.
Mechanism of CAR-T cell therapy
1) Collection of T cells
T cells are harvested from the patient’s own blood.
2) Gene manipulation
The CAR gene is designed to recognize specific antigens on the surface of cancer cells and activate the T cells.
3) Expansion of CAR-T cells
The genetically engineered T cells are cultured and proliferated.
4) Administration
Cultured and proliferated CAR-T cells are administered to the patient.
Targeted cancer types
CAR-T cell therapy has been shown to be effective mainly for cancers of the blood (leukemia, malignant lymphoma, etc.).
Main target cancer types
Acute lymphocytic leukemia (ALL)
Multiple myeloma
Malignant lymphoma
efficacy and side effects
CAR-T cell therapy is expected to be highly effective in treating advanced and recurrent cancers that have been difficult to treat with conventional therapies.
Main Effects
Induction of remission
Prolongation of survival
Main side effects
Cytokine release syndrome (CRS): fever, chills, headache, myalgia, hypotension, etc.
Neurotoxicity: impaired consciousness, seizures, aphasia, etc.
challenges and future prospects
CAR-T cell therapy is a revolutionary treatment, but it is not a panacea. It is not effective for all patients, and there are challenges such as the high cost of treatment.
Major Challenges
Not effective for all patients
High cost of treatment
Potential for serious side effects
A groundbreaking treatment method (iii)
Tumor vaccine is a type of revolutionary cancer immunotherapy, this method has also recently attracted much attention. Unlike conventional anticancer agents and radiotherapy, this is a fundamental treatment method that attacks and eliminates cancer cells by activating the patient’s own immune system.
How tumor vaccines work
There are two major types of tumor vaccines.
1) Systemic tumor vaccine
By administering the patient’s own tumor cells or cancer antigens as a vaccine, the immune system’s ability to recognize and attack cancer cells is strengthened.
Unlike conventional vaccines, they are used for therapeutic rather than prophylactic purposes.
Target cancer: Applicable to various types of cancer, but with limited efficacy
2) Dendritic cell vaccine
The patient’s own dendritic cells (a type of immune cell) are removed from the body, processed to present cancer antigens, and then returned to the body.
Dendritic cells activate immune cells such as T cells and encourage them to attack cancer cells.
Target cancers: melanoma, kidney cancer, colon cancer, lung cancer, head and neck cancer
effects and expected actions of tumor vaccines
Although the effects of tumor vaccines are not yet fully understood, the following actions are expected
Enhance the immune system’s ability to recognize and attack cancer cells
Tumor shrinkage and suppression of tumor progression
Improvement of long-term survival rate
However, it is not a universal treatment.
challenges and future prospects of tumor vaccines
Tumor vaccines are a breakthrough therapy, but there are still many challenges.
Major challenges
Limited efficacy
It takes time for the effect to appear.
Possible side effects
High cost of treatment
SUMMARY
The immunotherapies listed above are only some of them. Several other immunotherapies have been developed.
Since immunotherapy is still in the development stage, there is a strong possibility that several types of immunotherapy will be developed in the future, some of which are highly effective and some of which can be cured radically.
I could not summarize them all in this article, so I would like to continue with immunotherapy in the next article.
