Immunotherapy, or biological therapy, uses compounds that boost or suppress the immune system. Doctors currently use certain types of immunotherapy to treat several conditions, including small cell lung cancer (SCLC).
Immunotherapy works by using natural or synthetic compounds — similar to those that are present naturally in the body — to increase or reduce immune responses. Immunotherapy medications treat SCLC by increasing the ability of the immune system to recognize and destroy cancer cells.
Keep reading to learn more about immunotherapy, including its effectiveness, the types for SCLC, and the potential side effects and risks.
Many immune cells have special proteins on their surface, which turn on and off to initiate an immune response. These proteins, or checkpoints, help prevent the body from accidentally attacking and destroying healthy, normal cells.
However, cancer cells can also act on these checkpoints to avoid destruction by the immune system. In some cases, tumor cells may also suppress or reduce the immune response to cancer. Checkpoint inhibitors essentially stop cancer cells from acting on these checkpoints. By doing this, they allow T cells, which play an essential role in the immune system, to destroy the cancer cells.
The seven approved checkpoint inhibitors for treating SCLC fall into two groups that target different checkpoints. The two groups are:
Compounds that block PD-1
These are medications that target programmed cell death protein 1 (PD-1), a protein present on the outside of some immune and tumor cells, or its ligand, PD-L1. Blocking the PD-1 checkpoint should boost the immune system’s response to cancer cells, helping it recognize and destroy them.
The FDA has approved
Compounds that block CTLA-4
These medications target cytotoxic T-lymphocyte antigen-4 (CTLA-4), a checkpoint that helps control the action of cytotoxic T lymphocytes (CTLs). These specialized immune cells are primarily responsible for destroying and removing harmful substances, such as cancer cells, from the body.
The only CTLA-4 checkpoint inhibitor that the FDA has currently approved to treat SCLC is ipilimumab.
Current research shows that immunotherapy may help people with advanced stages of SCLC live longer.
In a recent clinical trial, 201 people with advanced SCLC took the immunotherapy medication atezolizumab in combination with standard chemotherapy treatment. The results show that this treatment increased the chances of surviving to some degree compared with chemotherapy and placebo.
Some research also suggests that immunotherapy medications may be effective against SCLC when people take them on their own. In a 2019 study, pembrolizumab allowed 15.5% of people in the trial with advanced SCLC to live at least 5 years longer. When the trial began in 2012, the average 5-year survival rate for people with advanced SCLC was only 5.5%.
Most people who receive immunotherapy to treat SCLC have advanced stage SCLC. However, a team of doctors will consider various factors — including age, underlying conditions, and cancer stage — when recommending exactly which treatment, or combination of treatments, someone should receive.
Although research suggests that adding immunotherapy to a standard treatment regimen can make it more effective, it is important to remember that not all types of immunotherapy work for everyone. The current treatments can only be effective if the person with SCLC has PD-L1 proteins or CTLA-4 checkpoints on their cells. According to one review,
Immunotherapy drugs may not be safe for people with autoimmune conditions or other conditions that can weaken the immune system, such as severe or chronic diseases.
Immunotherapy can be a first-line treatment for advanced SCLC, often in combination with the medication etoposide and platinum-based chemotherapy medications, such as cisplatin or carboplatin. In some cases, someone may keep taking atezolizumab or durvalumab as a type of maintenance therapy to keep cancer in remission.
Most people taking immunotherapy for SCLC receive a dose of medication through a vein in their arm at 2-, 3-, or 4-week intervals. How long or much treatment someone receives depends largely on their stage of cancer and their overall health, among other factors.
Someone may experience several side effects while undergoing immunotherapy for SCLC.
Common side effects include:
Serious side effects can occur from taking immunotherapy for SCLC, but they are less common.
However, a person might have a negative reaction to receiving the drugs intravenously. Infusion reactions can cause similar symptoms to allergic reactions, such as:
- skin rash and itchy skin
- wheezing and trouble breathing
- face flushing
- fever and chills
It is important to tell a nurse or doctor immediately if any symptoms of an infusion reaction occur during or after the treatment.
Autoimmune reactions can also develop when someone is taking immunotherapy for SCLC. Immunotherapy reduces or removes the built-in safeguards that prevent the immune system from attacking normal, healthy cells.
When someone has an autoimmune reaction to immunotherapy, the immune system attacks healthy cells in other areas of the body. Autoimmune reactions can cause serious and even deadly side effects, including organ damage.
Aside from the risk of organ damage associated with autoimmune reactions, a few other complications are possible when taking immunotherapy for SCLC, including:
Certain types of immunotherapy may help some people with SCLC survive longer, especially those with advanced stage SCLC.
Currently, checkpoint-inhibiting medications are the only approved immunotherapy for the treatment of SCLC, and doctors often use them in combination with other, more standard medications or treatments, such as chemotherapy.
A person with SCLC can speak with their healthcare team about the available immunotherapy options to determine whether they may be a suitable candidate for this type of treatment.