It’s not just the type of treatments that doctors look to improve, but the way they can be delivered so they are safer and more effective, too. We hear from two leading experts on already established advancements in eye cancer treatment, and a developing example of progress in brain tumour therapy.
Targeted chemotherapy to avoid losing an eye by Dr Helen Jenkinson
Intravenous (IV) chemotherapy (via the vein) was first used routinely to treat eye cancer (called retinoblastoma) in the early 1990s. Before this, most children with advanced disease required either removal of the eye or radiotherapy. Despite the success of IV chemotherapy, there were still far too many cases where treatment failed, particularly in those children with more advanced disease or those with retinoblastoma cells remaining in the jelly (vitreous) of the eye after chemotherapy.
Teams worldwide pioneered new ways of safely increasing chemotherapy doses to the tumour and, in 2006, US doctors gave the first chemotherapy directly into the ophthalmic artery that supplies blood to the eye. This technique, called intra-arterial chemotherapy (IAC), was very successful and introduced in the UK three years later. Doctors can give a bigger dose of chemotherapy directly to the eye but a smaller dose to the rest of the body. The advantages are that children receiving IAC don’t need a central line and are very unlikely to experience the typical side effects of IV chemotherapy, such as low blood counts and infection.
Although side effects, particularly around the eye, can be expected, they’re often short-lived and well controlled with medication. Most importantly, since the introduction of IAC, most children have avoided losing their eye.
There’s also been progress in the treatment of retinoblastoma cells which have broken away from the main tumour and spread into the jelly of the eye’s centre. These cells don’t have a blood supply and neither IV nor IAC chemotherapy reaches this part of the eye in high enough doses to be fully effective. Since 2012, UK doctors have used chemotherapy injected directly into the jelly of the eye as a way of giving even higher doses to these hard-to-reach cells. This is called intra-vitreal chemotherapy (IViC), and the side effects are very few and generally limited to the eye. This significantly reduced the number of treatment failures due to vitreous disease. The introduction and refinement of IAC and IViC techniques over the last decade have transformed the outlook for children with retinoblastoma. Nowadays, more children keep their natural eye and many will have good vision too.
Using a chemotherapy paste on childhood brain tumours by Dr Ruman Rahman
Many anti-cancer drugs aren’t able to get inside the brain. This is because of a protective barrier surrounding the brain called the ‘blood-brain-barrier’, which stops toxic substances entering. We’ve developed a paste to deliver chemotherapy drugs to the brain immediately after surgery, bypassing this barrier. The paste is applied to the space created after surgically removing most of the tumour, and releases drugs targeting the remaining cancer cells which surgery can’t remove safely. Importantly, the paste is biodegradable, and the human body safely removes it over a period of two to three months, meaning a second surgery isn’t required to remove the paste.
We first achieved success in using the paste on research samples of an adult brain tumour called glioblastoma. Survival was significantly longer compared with the current standard of care for this tumour type, and in some cases showed no further disease in the brain. This is an exciting finding, and we are now testing whether drugs delivered by the paste can show similar effectiveness in difficult-to-treat childhood brain cancers.
Other types of brain tumours, such as medulloblastoma and atypical rhabdoid/teratoid tumours which occur in the back of the head, are difficult to treat safely. There’s a devastating consequence of radiotherapy, in particular, which leads to speech loss and learning delays. In addition, chemotherapy delivered through the blood causes damage to healthy body parts. Therefore, there’s an urgent need to develop safer treatments. We are currently testing drugs for these types which are potentially effective, but don’t cross the blood-brain-barrier very well.
From Contact magazine issue 100 - Autumn 2023
