Novel therapies have now made it from the laboratory to clinical practice. This article looks at three such agents at the cutting edge of current anti-cancer treatment.
The annual medical oncology group meeting was held this year at the Novotel resort in the Barossa Valley. It was an excellent meeting with over 140 medical and radiation oncologists in attendance. There were a number of international speakers complemented by a strong showing of Australian speakers.
Lung cancer was a hot topic at the meeting. It was identified that therapeutic nihilism is still a significant barrier to patients receiving adequate treatment for this disease. I.e. there is still a misconception in a significant proportion of the medical profession that this illness does not respond to chemotherapy. Non-small cell lung cancer now has a significant response rate to some of the latest chemotherapy combinations, which have actually been shown to improve symptoms and prevent decrease in quality of life (QOL).
Probably the best news to come out of the conference was that there are a number of new cancer treatments about to be released in Australia. Specific treatments against different types of cancer are emerging at an ever increasing rate. These biological therapies are a lot closer to the concept of “the magic bullet” that is often reported in the lay press.
In lung cancer, for instance, there are two new biological therapies which have activitywhen used alone and in combination with chemotherapy. Iressa and Tarceva are two examples. A large number of different tumours over express a receptor found on the cell surface called the epithelial growth factor receptor (or EGFR). This makes the malignant cell overreact to the presence of normal epithelial growth factor. This is one of the contributing factors to excessive growth rate seen in malignant tumours.
When the epithelial growth factor binds to the receptors, it activates an enzyme within the cell called tyrosine kinase. This makes the cell switch on metabolically and begin the process of rapid cell division. Both Iressa and Tarceva block the action of tyrosine kinase and switch off the abnormal cell division. Both are taken in tablet form.
Initial trials look very promising with up to a 30 percent response rate when used as a single agent. A number of trials of these agents in combination with chemotherapy are due to be published soon. The results of some of these trials will be presented at the European society of medical oncology meeting (ESMO) in October. There are also trials of EGFR inhibitors in head and neck cancers and in pancreatic cancer. Full details will be published on a new website as the data is presented.
A lot of information was presented about Herceptin which is the first oncogene targeted therapy for metastatic breast cancer. Up to 20 percent of breast cancers have abnormal expression of a different type of EGF receptor (called ErbB-2. Her-2 or Neu) which is targeted by Herceptin. Breast cancers which are Her-2 positive have a much more aggressive behaviour than Her-2 negative tumours. There is a very strong case for measuring the Her-2 status of breast cancers at diagnosis as this identifies a subgroup with a significantly worse prognosis.
The good news is there is a growing body of evidence which shows that Herceptin in combination with chemotherapy is much more effective and chemotherapy alone for these aggressive tumours.
Generally speaking, these new agents are very well tolerated with a fairly mild side-effect profile. Iressa and Tarceva sometimes caused skin rash and diarrhoea, which was usually easy to manage. Herceptin was likewise tolerated very well and was predictable in any problems that it caused in patients with advanced disease or who had already received extensive treatment.
Further news about these developments will appear on the site in the near future.