Jun 12, 2012 - Better Way to Treat Mesothelioma with Antibody-based Cancer Agents
Scientists have been experimenting with various antibody-based methods of treating cancer for years. The evidence that the body’s own immune system, or something that very closely mimics it, could play the key role in defeating cancer – even malignant mesothelioma – is promising. Not only would it reduce or eliminate the need for highly toxic chemical infusions, it could prove more effective than current mesothelioma treatment methods.
However, many forms of cancer, especially mesothelioma, are resistant to this type of treatment. Cancer cells often put up defenses that the patient’s natural antibodies cannot get past. However, researchers have discovered that a naturally occurring process called antigen shedding prior to delivery of these antibody-based anti-cancer agents can improve their effectiveness greatly—especially in solid tumors.
The study looked at the efficiency of recombinant immunotoxins (RIT). RITs are modified cancer agents that are constructed from a targeting antibody fragment and a protein toxin fragment. Specifically scientists were working with SS1P, a recombinant immunotoxin that attacks mesothelin. Mesothelin is a protein expressed on the surface of normal cells but mesothelioma cells have a much higher concentration of this protein.
However, mesothelin does not stay permanently attached to the cell surface. It “sheds.” In fact, several tests have been developed to look for excess mesothelin in the blood as a possible predictor for a mesothelioma diagnosis, though none yet are reliable enough to be definitive.
This individual study examined the relationship between the changes in tumor size and the dosage of this specific RIT (SS1P). The researchers were able to create a mathematical formula that was able to calculate how large the dosage should be based on the volume of the tumor.
During the course of their work, they discovered that “antigen shedding is a favorable biological process for targeted therapy of solid tumors.” The free-floating mesothelin antigens actually worked like a buffer between the tumor cell and the antibody-based RIT. They shielded the anti-cancer agent and allowed it to more easily bond with the tumor cells – thus working more effectively at killing the asbestos cancer. This effect also allowed for even dispersal of the anti-cancer agent across the entire surface of the tumor cell.
These combined microbiological mechanical effects resulted in a dramatic decrease in overall tumor size in laboratory animals.
The researchers concluded that the value of this information was extremely high for further antibody-based cancer treatments. Indeed, they recommended further study into these recombinant immunotoxins and their relationship with mesothelioma, hinting that clinical trials may be the next logical step.
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