Transcript Cancer Vaccines: A novel approach to cancer

Cancer Vaccines:
A novel approach to cancer
Cancer Statistics
• Cancer still remains a major cause of death
worldwide despite many therapies and
treatment modalities available.
• ACS predicted in 2006: 565,000 Americans
would die of cancer and approximately 1.4
million would be diagnosed.
Immunotherapy: New class of
cancer treatment
• Considered by many to be the “fourth modality of
cancer treatment” after chemotherapy, radiation,
and surgery.
• Based on utilizing the patient’s immune system to
fight the cancer.
• Cancer vaccines fall under this category of
treatment.
Cancer Vaccines
• Majority used for treatment not prevention.
• May offer method that can enhance the immune
response against cancer.
• Cancer Vaccines: Different than HPV vaccine and
traditional prophylactic vaccines.
• HPV Vaccine: Immunity to the virus, which
causes cervical cancer.
• Traditional prophylactic vaccines: As with the
HPV vaccine, provide immunity to a particular
disease.
• At this time, cancer vaccines are only available in
clinical trials.
Science behind Cancer Vaccines
Key players
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Dendritic Cell:
~Remarkable ability to capture and process antigen.
~ Antigen presenting cell-presents antigen to
T-cell to mount an immune response.
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T-Cell:
~ Mediates immune response.
5 Main Types of Cancer Vaccines
• Tumor cell vaccines
-Autologous vs. Allogenic
• Dendritic cell vaccines
• Antigen vaccines
• Anti-Idiotype vaccines
• DNA vaccines
Tumor Cell Vaccines
• Utilizes whole tumor cells rendered safe by irradiation.
• Specific immune response initiated when injected into
body.
• Body attacks similar cells that remain in body.
• Autologous-removed tumor cells from patient’s own body.
• Allogenic-removed tumor cells from someone other than
the patient.
• Many different epitopes are recognized.
• Cancers these vaccines are being studied in: melanoma,
colorectal, kidney, ovarian, breast, lung, and leukemia.
Dendritic Cell Vaccines
• Dendritic cells can be generated outside of the
body.
• Dendritic cells are made capable of recognizing
antigen by gene therapy and exposure to antigen.
• Dendritic cells injected into the individual
stimulating an immune response.
• Cancers these vaccines are being studied in:
prostate, melanoma, breast, lung, colorectal,
kidney, leukemia, and non-Hodgkin lymphoma.
Antigen Vaccines
• This includes peptide vaccines: only one specific
epitope is injected.
• Vast amounts of antigen can be created in
laboratories.
• Some antigens are specific for a certain type of
cancer; others may induce an immune response in
several cancers.
• Cancers these vaccines are being studied in
include: kidney cancer, pancreatic cancer,
melanoma, ovarian cancer, breast cancer, prostate
cancer, and colorectal cancer.
Anti-Idiotype Vaccines
• Based on the idea that antibodies can also act
as antigens triggering an immune response.
• This idea would be used to create a vaccine in
which the antibodies (which resemble the
cancer cells) would be injected into the cancer
patient eliciting an immune response.
• Primary target is lymphoma.
DNA vaccines
• Introduction of tumor genes instead of tumor antigen
itself.
• Cells in the body take up the injected DNA. Specific
antigens would then be made on a continuous basis.
• The idea of these vaccines is that the body would be
provided with a constant supply of antigens to allow
the immune response to continue against the cancer.
• Cancers these vaccines are being studied in: prostate
cancer, leukemia, melanoma, and head and neck
cancer.
OncoVAX by Intracel
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Autologous vaccine for Stage II colon cancer.
Received fast-track status from FDA in 2006.
Used in an adjuvant setting.
Study: 254 patients received either OncoVAX or
placebo.
• Improves 5-year survival and recurrence-free
interval.
• 57.1% relative risk reduction.
Sipuleucel-T (Provenge)
by Dendreon
• Dendritic cell vaccine for treatment of asymptomatic
Androgen-Independent Prostate Cancer (AIPC).
• Received fast-track status by FDA in 2005.
• Target-prostatic acid phosphatase (PAP), which is found in
95% of prostate cancers.
• Study of Provenge vs. Placebo.
~98 men with AIPC.
~3.3 month or 21% improvement in median
survival.
~3-year follow-up: 32% of men that received Provenge alive
compared to 21% placebo.
~52% increase in survival rate.
Lung Cancer Vaccine at UK
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Dendritic cell vaccine.
Treatment of non-small cell lung cancer (NSCLC).
Study: Patients with Stage IA to IIIB were given vaccine.
Patients treated prior with surgery, chemoradiation, or
multimodality therapy.
• Results published for 16 patients.
~5/16: no clear immunologic response.
~5/16: antigen-independent response.
~6/16: response may have been tumor specific.
~response shown in various stages of NSCLC.
Conclusion
• Clear that the immune system displays a highly developed
response against cancer.
• May be more effective in cancers that are not advanced.
• Majority will probably be used as adjuvants.
• Clinically not yet at our fingertips.
• Much progress has been made in this area of research.
• More research still needs to be done including larger
studies.
• Researchers are actively trying to overcome hurdles in the
making of these vaccines.
• Could make a big impact on our approach to cancer.
• Most importantly these vaccines could mean better
quality of life and longer survival for our patients!!
References
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