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SkinCancerNet Article
Immunotherapy: What It is and How It Can Help Fight Cancer
The human body’s immune
system can protect itself from cancer by:
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Eliminating cancer before it becomes
established
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Attacking cancer cells after they
become established
-
In rare cases, completely eliminating
an established cancer to bring about spontaneous cure
Knowledge of how the immune system
works to destroy cancer is the basis for a form of cancer treatment
called immunotherapy. Also known as “biotherapy,” “biological
response modifier therapy,” and “biological therapy,” the purpose of
immunotherapy is to repair, stimulate or enhance the body’s immune
responses to fight established cancer.
Scientists have created several types of immunotherapy to treat
various forms of cancer, including skin cancer. These therapies are
classified as “active” when they stimulate the patient’s own immune
system to fight the cancer and “passive” when substances that the
body produces are synthetically created in a laboratory and do not
rely on the patient’s immune system to work.
Uses
Like chemotherapy, immunotherapy used to treat skin cancer can be
topical (applied to the skin) or systemic (taken by pill, injection,
or infusion).
Topical Immunotherapy
In mid-2004, a topical medication called imiquimod was
approved by the U.S. Food and Drug Administration (FDA) for patients
who have superficial basal cell carcinoma (one of the four types of
basal cell carcinoma) and a normal immune system.
Imiquimod comes in cream form and is approved for treating
superficial basal cell carcinoma (sBCC) tumors with a maximum
diameter of 2.0 centimeters. Use is limited to certain areas of the
body. Patients typically apply the cream once a day for
approximately 5 to 7 weeks. If imiquimod is an option, the
dermatologist will determine how often imiquimod should be applied.
As the medication works, local skin reactions, such as redness,
swelling, erosion, scabbing, scaling, and crusting occur. These are
a normal and expected part of treatment. In a recent research study,
a few patients with sBCC experienced headache, upper respiratory
tract infection, or back pain. Patients must be willing to apply the
medication as instructed and return for follow-up visits. The
dermatologist will need to examine the area to see if the tumor has
been destroyed. This determination should not be made by the
patient, patient’s family, or friends.
It is important to know that imiquimod does not work for every
patient, and another form of therapy may be necessary. The ability
of imiquimod to sustain long-term clearance is still not known, and
ongoing studies are evaluating the long-term effectiveness of this
medication.
Systemic Immunotherapy
In systemic form, immunotherapy may be used alone but most often is
part of a treatment plan that includes another cancer therapy, such
as surgery, radiation, or chemotherapy. Since immunotherapy helps
the body fight disease and infection, systemic immunotherapy is used
to treat skin cancers that are at risk of spreading, such as certain
melanomas and squamous cell carcinomas. Systemic immunotherapy also
can lessen the side effects from other cancer treatments, such as
chemotherapy. While systemic immunotherapy holds much promise for
the treatment of cancer, it is still in the experimental phases. The
hope is that systemic immunotherapy will eventually provide
effective treatment for metastatic melanoma.
Types of systemic immunotherapy used to treat skin cancer include:
Cytokine
Therapy
″Cytokines” are proteins released by cells in the immune system that
help boost immunity. Two cytokines have been approved by the FDA for
the treatment of metastatic melanoma:
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Interferon-alpha
-
Interleukin-2 (IL-2)
In clinical trials, these two cytokines
have helped shrink tumors in about 10% to 20% of patients with stage
III and stage IV melanoma. It is believed that cytokines hold
enormous potential for cancer therapy, and many cytokines are being
studied in clinical trials because of their ability to enhance the
body’s immune response to cancer cells.
Interferon. Interferons are substances within the immune
system that are produced in response to infection. They are
classified as alpha, beta, or gamma forms — depending on the
chemical structure, biologic activities, and other criteria.
Interferon-alpha is FDA-approved for treating melanoma in stage IIB
(primary tumor is 4 millimeters or more) and stage III (spread to
the lymph nodes) when used along with another therapy, such as
surgery. In these stages, interferon-alpha helps prevent recurrence
and increases the likelihood that all cancer is eliminated.
How interferon-alpha is administered. Following one month of
intravenous infusion, interferon-alpha is usually given as a shot 3
times a week and may be given for up to one year. Research shows
that this dosage proves more effective than giving the medication
once a week or intermittently.
Side effects from interferon-alpha. High doses must be given
for interferon-alpha to be effective; however, it is quite toxic in
high doses. The dropout rate is significant because many patients
cannot tolerate the side effects, which include flu-like symptoms,
such as fever, chills, aches, fatigue, and a general feeling of
illness. Interferon-alpha2b can also have adverse effects on the
heart and liver. Patients should be treated by a physician who is
experienced with this treatment and knows how to minimize the side
effects.
Interleukin: Interleukins activate the “killer” activities of
specific white blood cells in the immune system and are classified
by number as IL-1, IL-2, or IL-3, etc. IL-2, which is used to treat
metastatic melanoma, helps the immune cells reproduce more quickly.
It may be used as a single medication or in combination with other
medication to treat advanced melanoma. About 10% to 20% of patients
respond to IL-2. In a few cases, high doses of IL-2 have produced
long-term remissions.
How IL-2 is administered. IL-2 may be injected into the skin
or a vein over a 15-minute period. It also may be given by infusion
over 24 hours.
Side effects from IL-2. Accumulation of fluid in the body
that causes the person to swell and feel quite ill is a possible
side effect. For this reason, IL-2 therapy should be administered in
a medical center experienced in its use. Other side effects include
flu-like symptoms, confusion, and weight gain. Some people develop
low blood pressure, which can be treated. A small percentage of
patients develop an irregular heartbeat, chest pain, or serious
heart problems.
Monoclonal Antibody Therapy
This type of therapy is showing much promise in treating many types
of cancer, including melanoma; however, its effectiveness in
treating melanoma is still being investigated in clinical trials.
Monoclonal antibody therapy is proving effective when the patient’s
immune system is weak since the immune system need not play an
active role in fighting the cancer. It also is proving effective
when other forms of treatment no longer work.
Monoclonal antibody therapy is known as "passive" immunotherapy
because the antibodies (protein on the surface of B cells that work
to attack foreign cells) are produced in the laboratory and then
infused into the patient’s body. The antibodies are called
"monoclonal" because they are identical clones produced from a
single (mono) cell. Side effects are milder than those experienced
with chemotherapy.
Vaccine Therapy
After years of research, melanoma vaccines are now being studied in
clinical trials. Similar to vaccines that protect against viruses,
such as polio and measles, melanoma vaccines inject the patient with
small amounts of the substance to be destroyed. To get the body to
attack melanoma, protein from melanoma cells is injected into the
patient’s body. The patient’s immune system recognizes the protein
as foreign and signals the immune system to attack and destroy the
proteins. Some immune system cells retain the ability to recognize
those foreign proteins. If the melanoma returns, the patient’s
immune system should be able to recognize these cells as foreign and
destroy them — preventing recurrence.
While immunotherapy shows much promise for treating skin cancer,
especially melanoma, it is not appropriate treatment for everyone.
Your physician can determine if immunotherapy is a treatment option
for you.
Reference:
Geisse, J et al. “Imiquimod 5% cream for the treatment of
superficial basal cell carcinoma: Results from two phase III,
randomized, vehicle-controlled studies.” Journal of the American
Academy of Dermatology. 2004 May;50(5):722-33.
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