As Reported by TIME. 2009 Sept 14
The search for an effective cancer vaccine has been elusive until now, but positive results for separate vaccines against melanoma and lymphoma were finally reported this past June. Although the theory behind a cancer vaccine seems logical—enlist the immune system to seek and destroy cancer cells—it also contains an inherent problem, specifically, that cancer cells aren’t foreign pathogens, such as bacteria or viruses, but cells from a person’s own body. Getting a vaccine to work against cancer requires a deep understanding of how the immune system works and how malignant cells evade detection. A feature article in the September 14 issue of TIME, written by Alice Park, explains the quest thus far for cancer vaccines.
Defining a cancer vaccine
The Food and Drug Administration has approved vaccines against cervical cancer and liver cancer, but both of these diseases are caused by a virus (human papillomavirus and hepatitis B virus, respectively). Thus, the vaccines are actually targeting the virus. Nonviral cancers attributed to genetic mutations, environmental exposures, and other factors would require a vaccine that can accomplish primary prevention or prevention of recurrence. Such vaccines would need to prime the immune system to find every last cancer cell.
Cancer vaccines that didn’t work, but might
A vaccine for melanoma seemed on the horizon when researchers used extracts of melanoma tumors in developing Canvaxin. More than 1500 patients received the vaccine following treatment with surgery and chemotherapy, but the study was terminated after interim analysis showed that survival was no better for the vaccinated patients than for the nonvaccinated patients. Addition of interleukin-2, however, improved the rate of tumor shrinkage. Researchers working on a vaccine for follicular lymphoma took the combination approach one step further, by adding GM-CSF to a vaccine developed from each patient’s cancer cells. This combination extended disease-free survival by 47% over that achieved by patients who received a nonindividualized vaccine. Experience with this vaccine also indicated that the best time to administer the vaccine was when patients were in remission.
Creating a “foreign” tumor
Various strategies to manipulate a tumor to cause it to become more “foreign” are being investigated. One technique is to make the tumor look like a virus to the immune system. Another is to inhibit immune suppressors that tumors secrete. Along the lines of the bone marrow transplantation approach, some studies have used in vitro techniques to develop immune system cells, taken from the cancer patient, that will target those specific cancer cells; the newly sensitized immune cells are then reinfused back into the patient. In melanoma, this approach has caused 70% of tumors to regress.
The final analysis
Regardless of how effectively a vaccine causes tumor regression, patients and their physicians are most interested in its effect on survival. Also important is how use of a vaccine compares with the targeted therapies that have been developed. For cancer to become a truly chronic condition, manageable over the long term, a vaccine or treatment must be safe. Vaccines, as it turns out, are generally less toxic than chemotherapy or targeted agents. Immune-based treatments for cancer are still in their infancy, but if they are ultimately proven successful, their development would be well worth the effort.
Source:http://www.oncologystat.com/news-and-viewpoints/what_patients_are_reading/Search_for_a_Cancer_Vaccine_Beginning_to_Show_Promise.html
My take:Creating a “foreign” tumor
If you can get the tumor to shed antigenic peptide and then activate the T-cells using anti-CTLA-4 Blockage, I believe you will see the Melanoma survival rate expand and that Melanoma will become just a "chronic condition,manageable over the long term."
Take Care,
Jimmy B
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