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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 • Dendritic Cell: ~Remarkable ability to capture and process antigen. ~ Antigen presenting cell-presents antigen to T-cell to mount an immune response. • 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.
Onco. VAX by Intracel • • 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 Onco. VAX 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 • • 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!!
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