Cancer Vaccine

Cancer Vaccine

A cancer vaccine is designed to prevent infections caused by cancer-causing viruses, treat existing cancer, or prevent cancer development in high-risk individuals. Vaccines that treat existing cancer are termed therapeutic cancer vaccines.

Certain cancers, like cervical and some liver cancers, result from viral infections, and vaccines like the HPV and Hepatitis B vaccines can prevent these cancers. However, these antiviral vaccines are not further discussed here. Similarly, cancers partly caused by bacterial infections, such as stomach cancer linked to Helicobacter pylori, are not addressed in this article.

Researchers are exploring vaccines targeting existing cancers. Some propose that cancer cells typically emerge and are eliminated by the healthy immune system, with cancer forming when immune defenses fail.

One approach involves isolating proteins from cancer cells and immunizing cancer patients against these proteins, aiming to provoke an immune response that destroys cancer cells. Therapeutic cancer vaccines are under development for breast, lung, colon, skin, kidney, prostate, and other cancers.

In a phase III trial involving follicular lymphoma, BiovaxID extended remission to 44.2 months compared to 30.6 months for the control group, as reported at the June 2009 meeting of the American Society of Clinical Oncology.

On April 14, 2009, Dendreon Corporation announced positive results from their Phase III trial of Provenge, a cancer vaccine for prostate cancer, showing increased survival rates. Provenge received FDA approval for advanced prostate cancer treatment on April 29, 2010, sparking interest in this therapy.

Another therapeutic approach involves generating an immune response within the patient. BioVex Inc, Woburn, MA, has used this method successfully with OncoVEX GM-CSF. This modified herpes simplex virus selectively replicates in tumor tissue and expresses the immune-stimulating protein GM-CSF. Phase 3 trials in melanoma and head and neck cancer have shown promising efficacy after strong results in Phase 2 trials.

Effective cancer vaccines must overcome several challenges. They target tumor-specific antigens distinct from self-proteins. Selection of appropriate adjuvants, molecules that activate immune responses, is crucial. Currently, only Bacillus Calmette-Guérin (BCG), aluminum-based salts, and a squalene-oil-water emulsion are approved for clinical use. The vaccine should also provide long-term memory to prevent tumor recurrence, possibly by activating both the innate and adaptive immune systems for total tumor elimination.