Perhaps One Day We'll Also Be Able to Rid the World of Cancer By Giving Vaccine Shots

Vaccines have all but rid the world of several scourge diseases that used to kill millions. Researchers have always dreamed of one day creating a vaccine to not just cure cancer but to prevent it as well. Theory suggested that one possible way to go is to boost antitumor immunity with activated T cells, which had been expected to infiltrate a tumor and destroy it. However, once these concepts were put to the test the results were less than miraculous. Some tumors did shrink, but once the disease had reached an advanced stage failure was the norm. Fifty years had gone by and little had changed. A great deal of effort to increase the potency of T cells, using all sorts of activating cytokines like the interleukins, seemed doomed to failure. A new approach was needed. The answer might lie in finding another agent to prime the naive T cells into activation, one with the ability to do more than just activate. It's one thing to activate, but an activated T cell has to be able to do its job properly. To be effective the T cell must get at the tumor in some way. First of all, it has to become specifically dedicated to destruction of the tumor whose ability to cause damage depends on its ability to link up with body cells by means of antigens. In other words, the activated T cell has to become an effector cell, which is antigen-specific.

Tyler and David Curiel note that certain antigen presenting cells such as macrophages, fibroblasts, or B cells are necessary for activation of T cells, but only one is able to both activate and at the same time get them to become antigen-specific effector cells. In a commentary written for the February 2002 Journal of Clinical Investigation these authors point to the fact that we have been well aware for some time now that dendritic cells (DC) have this dual capability. The groundwork seems to be set, but nothing ever goes as smoothly as we might like. Unfortunately, dendritic cells are rare and hard to cultivate in large

The problem of producing large numbers of dendritic cells was finally solved back in 1998. Banchereau and Steinman, writing in the journal Nature, discussed these cells and their ability to control immunity. Banchereau and colleagues went much further in 2001 when they reported in Cancer about research that demonstrated the fact that patients with metastatic melanoma had both immune and clinical response to a progenitor-derived dendritic cell vaccine. Writing in the same journal in 2001 Schadendorf and Nestle updated earlier reports on using autologous dendritic cells to treat advanced cancer. At last, we had graduated to using this approach in humans. One more metastatic tumor may soon become the target of autologous dendritic cells; prostate cancer. The reason the Curiels decided to comment on DC-based immunotherapy is because Heiser's group presented their work on prostate cancer in the same JCI issue.

Of course, none of this is as simple as it may seem just because we now have a dual acting cell available. All kinds of problems have already begun to raise their ugly heads. For example, dendritic cell immunotherapy may possibly lead to harmful autoimmune reactions, and active immunization may never become a reality since tumors are quite capable of reversing the mechanisms used to present activated T cells specific to their antigens.

And so it goes. Some like to say that fortune presents with one hand whilst taking away with the other. Nevertheless, we humans are rather stubborn. We always seem somehow to overcome our disasters and to move on to more and better things.