Key Takeaways
- Cancer vaccines are an emerging form of immunotherapy being developed to treat mesothelioma. Unlike preventive vaccines (like the flu shot), these are therapeutic vaccines designed to train the immune system to recognize and attack existing tumors.
- Mesothelioma vaccines work by introducing tumor DNA or proteins into the body — often packaged inside bacteria or viruses — so the immune system recognizes the tumor as a foreign threat and mounts an attack against it.
- Vaccines can be patient-specific: doctors extract a sample from the patient’s tumor to formulate a vaccine tailored to that individual’s cancer.
- Whether a vaccine is used alone or combined with other therapies depends on the tumor burden (how many mutations are present) and the patient’s overall immune health — particularly whether their T cells and cytokines are functioning properly.
- Galinpepimut-S (GPS) is a protein-based mesothelioma vaccine that targets antigens secreted by mesothelioma cells. Unlike patient-specific vaccines, GPS is more broadly applicable because it leverages a protein that mesothelioma tumors are known to produce.
- In a clinical trial, patients who received the GPS vaccine after pemetrexed-based chemotherapy had a 35% higher survival rate compared to patients who received the same chemotherapy but with a different follow-up treatment.
Vaccines as Immunotherapy
Vaccines to treat cancer–beyond mesothelioma–are a form of immunotherapy. Immunotherapy
refers to the external manipulation of the body’s immune system to target, destroy, or isolate
cancerous cells.
In terms of mesothelioma vaccines, doctors will extract a sample of the tumor(s) in order to
formulate a patient-specific vaccine. Depending on the tumor burden, or the amount of mutations
present in the cancerous cells, the vaccine would likely be used in conjunction with other
therapies, like radiotherapy or chemotherapy. A high tumor burden, or a relatively high amount
of mutations present in the tumor, lends itself to a combination of therapies. A low tumor burden
might be successfully targeted by a vaccine alone. Another “prerequisite” for vaccine-based care
is the holistic health of the patient: they need to have working cell-mediated immunity, or
working T cells and cytokines. T cells and cytokines are responsible for identifying antigens, or
any foreign substance that elicits an immune response.
Vaccines work by invoking the natural immune response: by introducing a small amount of an
antigen, cell-mediated immunity recognizes, kills, and remembers the antigen for future
encounters. Vaccine-based mesothelioma care works the same way: the tumor’s DNA or proteins
are artificially fabricated to be an antigen recognized by the cell-mediated immunity system.
Because antigens present as bacteria or viruses, the tumor’s DNA/proteins need to be introduced
to the body in the same way. Oftentimes, these proteins or DNA molecules are put into bacteria
or viruses so the body easily recognizes them. Once the body recognizes the tumor’s DNA as an
antigen, the cascading immune response ensues. The immune system mobilizes an attack against
the tumors, which helps in effective treatment.
Treatment for Mesothelioma: Clinical Trials
Galinpepimut-S (GPS) is a protein-based mesothelioma vaccine that uses a different medium to
target tumors. While we’ve covered bacterial and viral introduction, GPS targets antigens that
mesothelioma cells release. So, instead of utilizing the natural immune response, GPS attacks
secretions of tumor cells directly. This approach is more widely applicable, as the vaccine
doesn’t have to be tailored to each patient’s immune system. Instead, it leverages a protein that
doctors know mesothelioma tumors produce.
In one clinical trial, patients received the GPS vaccine after pemetrexed-based chemotherapy
treatments. Their survival rate–compared to patients initially treated with the same
pemetrexed-based chemotherapy but with a different secondary treatment–was 35% higher. This
is important for doctors and researchers hoping to effectively pair different techniques for
mesothelioma treatment.
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Frequently Asked Questions
What is a mesothelioma vaccine?
A mesothelioma vaccine is a form of immunotherapy — a treatment that manipulates the body’s own immune system to fight cancer. Unlike preventive vaccines (which protect against future infections), mesothelioma vaccines are therapeutic — they are designed to train the immune system to recognize and destroy existing tumor cells. Doctors may extract a sample from a patient’s tumor to create a personalized vaccine, or use a more broadly applicable vaccine that targets proteins known to be produced by mesothelioma tumors.
How do mesothelioma vaccines work?
Mesothelioma vaccines work by harnessing the body’s natural immune response. The process involves:
- Identifying tumor DNA or proteins that can be used as targets (antigens)
- Packaging those antigens inside bacteria or viruses so the immune system recognizes them as threats — just as it would with a natural infection
- Introducing the vaccine into the patient’s body, triggering the immune system to mobilize T cells and cytokines to identify, attack, and remember the tumor cells
Once the immune system has been “trained,” it can continue to attack cancer cells — including ones that may develop or spread in the future.
What is Galinpepimut-S (GPS)?
Galinpepimut-S (GPS) is a protein-based mesothelioma vaccine that takes a different approach from patient-specific vaccines. Instead of being tailored to an individual’s tumor, GPS targets antigens that mesothelioma cells are known to secrete. This makes it more broadly applicable — it doesn’t need to be customized for each patient’s immune system. In a clinical trial, patients who received GPS after pemetrexed-based chemotherapy had a 35% higher survival rate compared to patients who received the same chemotherapy with a different secondary treatment.
Can a vaccine cure mesothelioma?
Mesothelioma vaccines are not yet a cure, but they represent a promising area of active research. Clinical trial results — particularly the 35% survival improvement seen with GPS after chemotherapy — suggest that vaccines could play a significant role in extending survival and improving treatment outcomes, especially when used alongside existing therapies like chemotherapy and radiation. Vaccine-based treatments are still in clinical trial stages and are not yet widely available.
Is a mesothelioma vaccine used alone or with other treatments?
It depends on the patient’s specific situation. Two key factors determine whether a vaccine is used alone or in combination:
- Tumor burden — a high tumor burden (more mutations in the cancer cells) typically requires a combination of vaccine therapy with chemotherapy or radiation. A low tumor burden may respond to vaccine treatment alone.
- Immune health — the patient needs functioning cell-mediated immunity (working T cells and cytokines) for the vaccine to be effective. If the immune system is compromised, the vaccine may not trigger the necessary response.
In the GPS clinical trial, the vaccine was administered after pemetrexed-based chemotherapy — suggesting that combination approaches may offer the best outcomes.
What is tumor burden and why does it matter for vaccine treatment?
Tumor burden refers to the amount of mutations present in cancerous cells. A high tumor burden means the cancer has more genetic variations, which can make it harder to treat with a single approach. For vaccine-based treatment, tumor burden helps determine whether the vaccine is likely to be effective on its own or whether it needs to be paired with other therapies. The concept is similar to how a small infection might be treated with one antibiotic, while a severe infection may require multiple medications.
Are mesothelioma vaccines available to patients now?
Mesothelioma vaccines are currently in clinical trial stages and are not yet widely available as standard treatment. Patients interested in vaccine-based therapy may be able to participate in ongoing clinical trials. Your oncologist can help determine whether you may be eligible for a trial based on your diagnosis, treatment history, and overall health.
What should I do if I’ve been diagnosed with mesothelioma and want to explore all treatment options?
If you or a loved one has been diagnosed with mesothelioma, understanding the full range of treatment options — including emerging therapies like cancer vaccines, immunotherapy, and clinical trials — is an important step. Call (800) 505-6000 or fill out our contact form for a free consultation and to request our Pennsylvania Mesothelioma Information Guide.
