Sunday, 14 October 2012

Treating LMS: Part II

In my last post I discussed how the classical types of cancer treatment (surgery, radiotherapy and chemotherapy) can be used to treat LMS and explained some of the limitations of these treatments in regard to my own case. In this post I look at some of the more recent forms of cancer treatment and consider how these might apply to LMS.
  1. Targeted Therapies. Gastro Intestinal Stromal Tumours (GIST for short) are a form of cancer that has some similarities to LMS. Up until a few years ago patients who had inoperable GIST found themselves with an extremely poor prognosis. In the late 1990's a new drug was discovered, Imatinib (sold as Glivec in Europe). This drug was one of the first examples of a "targeted therapy". Rather than indiscriminately killing fast dividing cells (the mechanism through which chemotherapy works), Imatinib targets only cells that express a particular genetic mutation. That mutation is absent from normal cells but present in many GIST tumour cells. Imatinib represented a massive improvement in the treatment of patients with GIST and has resulted in significantly extended lifespans. The range of cancer types for which targeted therapies exist is slowly expanding and now includes some forms of common cancers like breast cancer and lung cancer.

    There is no targeted therapy available for LMS today. However, earlier this year a group of researchers published a paper in which they identified two drugs as candidate targeted therapies for some LMS tumours (Cantharidin and MG-132). There is a huge amount of work to be done to investigate these drugs further but this research paper does raise the possibility of a targeted therapy for some LMS tumours becoming available in the next few years.
  2. Immunotherapy. The immune system is often 'disarmed' by cancer cells so that they are not attacked by it. In some cases, cancer cells may actually evolve mechanisms that trick the immune system into working on behalf of the cancer by helping it to invade tissue. Immunotherapy looks at how the immune system can be triggered to recognise cancer cells as something it should attack.

    As with targeted therapies, there is no proven immune system therapy available today for LMS however, in January 2012, a research paper was published in which a protein, CD47, was identified as playing an important role in preventing immune system cells from attacking some types of LMS cancer cells. Furthermore, the researchers found that by using anti-CD47 antibodies it was possible to reactivate the immune system so that it attacked LMS cells in mice producing a significant reduction in tumour size. Further work is now underway to investigate this therapy with the intention of performing a clinical trial in humans in the next year or two.

  3. Anti-Angiogenesis Agents.  Cancer cells need a rich blood supply in order to grow. To get this blood supply the cancer cells issue chemical signals that stimulate the growth of blood vessels ('angiogenesis' is the name given to the growth of new blood vessels). Finding a way to block the growth of these blood vessels offers a way to 'starve' tumours of the nutrients they need and is, therefore, a route through which cancer can be treated.

    Earlier this year the USA's Food & Drug Administration approved the use of the anti-angiogenic drug Pazopanib in the treatment of a number of types of sarcoma including LMS. Approval was granted based on the outcome of a trial which showed that Pazopanib could block tumour growth for some patients although in general this effect was only sustained for a relatively small number of months. Whilst it has not been approved in the UK National Health Service yet, Pazopanib is already being used to treat some UK based LMS patients and so is a potential option for me to consider in the future. 
The research outlined above offers real potential for advances in LMS treatment. It is important to realise that developing a new treatment is a long road with many hurdles that must be overcome and the vast majority of therapies fail on route. Despite that, these new forms of treatment do offer potential for a breakthrough and therefore provide some hope to people in my situation. I will post more about these treatment types as and when there is news on their development.
I'll end this post with a splash of colour from a recent trip to the zoo, a blue and gold macaw.

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