Milestone of Cancer Research: Arresting Cancers Rather Than Killing Them
Feb. 1, 2013 — The research team of Prof. Dr. Martin Röcken from the Department of Dermatology of the University Medical Center Tübingen has shown for the first time that the immune system is able to drive tumours and tumour cells into a form of permanent dormancy (1). The resulting growth arrest allows tumour control in the absence of cancer cell destruction. This permanent dormancy -- scientifically known as senescence (2, 3) -- may persist for the whole life of the organism. Thus, immunotherapy can prevent tumour development without destroying the cells (1, 4).
The red staining depicts former malignant tumour cells (melanoma) which were driven into permanent growth arrest, i.e. senescence, by the immune system. Tumour cells from growing melanoma do not stain red (not shown).
Prof. Martin Röcken, Director of the Department of Dermatology of the University Medical Center Tübingen, outlines the current state of tumour therapy as follows: "About 50 years ago the former President of the United States of America Richard Nixon declared the "War on cancer." Strong financial and logistic efforts were undertaken and thought to overcome this devastating disease in relatively short time. At this time, researchers and clinicians learned to use chemotherapeutics or natural killer cells to directly attack the tumour cells and to destroy cancers including their environment. This led to several very important, partly brilliant achievements in the understanding of tumour development and to improved cancer diagnostics. What's more, the treatment of several different cancers was markedly improved by new and innovative operation techniques, radiation, chemo- and immunotherapy. However, the main goal, ie. the decisive victory on cancer, remained absent." "[For some time]," Prof. Röcken explains further, "doubts were raised about the strategy of the "War on cancer" which exclusively focussed on cancer destruction, as for example published in an essay in the journal The Lancet and other recent publications (5, 6, 7)."
Importantly, the work of the Röcken group revealed that immune responses also drive tumours of human origin into senescence. The human body apparently defends itself from cancer by inducing the senescence program in tumour cells thereby inhibiting tumour growth (1).
In this line, two well known signalling molecules of cancer therapy and immunology of infectious diseases move again in the center of attention: the interferons and tumor necrosis factor. Repeatedly, a bulk of researchers and clinicians tried to use these molecules and other techniques to destroy the tumour cells and their supplying blood vessels, and so did the scientists from Tübingen. Surprisingly, however, the Röcken group found that a combination of both signalling molecules, interferon and tumor necrosis factor, stopped the tumour growth in vivo without any signs of tumour or tissue destruction.
In animal experiments, the efficacy of immunotherapy-induced senescence proved to be much better than any other therapy based on "cancer destruction" (4). Most importantly, the common action of both signalling molecules, interferon and tumor necrosis factor, also stopped the growth of human tumours (1).
In the course of a natural immune response, the research team even detected senescence induction in regressing malignant tumours of cancer patients . Seven years ago, it was shown in principle that cancer cells can be shifted towards permanent dormancy or senescence (2, 3). Those theoretical insights were now successfully transferred into a therapeutic approach, here an immunotherapeutic regimen (1, 4).
The new therapeutic option will enable clinicians to approach their goal of a life-prolonging, mainly adverse effect-free cancer therapy. "It is very likely that we can't win the "War on cancer" by exclusive military means.," Prof. Röcken resumes. "Instead, it will be an important milestone to restore the bodies´ immune control of malignant tumours."
