Today, most cancer drugs have been designed to target a specific cancer type or generally cells which are replicating too fast, leading to many unwanted side effects. However, cancer therapies could be changing.
Cancer affects 1 in 4 of us, so it is unlikely anyone is lucky enough to not be aware of the devastating disease, and the not so pleasant side-effects which come with current treatments. The Cancer Research UK website lists various procedures for the treatment of cancer (chemotherapy, radiotherapy etc.), but all are relatively invasive and have undesirable side-effects, such as hair loss. Such therapies target rapidly multiplying cells which is characteristic of cancerous cells but can result in hair loss as hair cells also replicate quickly.
What if we could be more specific, targeting only cancerous cells with little to no side-effects? Some experimental procedures are looking at targeting tumours more directly, causing less harm to surrounding cells/tissues (see Why Cancer’s Future Could Be Golden). However, there’s a new class of cancer drugs on the scene: tumour-agnostic drugs. These drugs are not targeted towards a specific type of cancer (e.g. blood, bowel, skin etc.) but instead target a genetic abnormality common between numerous cancers. One such genetic abnormality is called a NTRK1 gene fusion, where one section of DNA has merged with another and led to a cancerous growth. Such mutations are reasonably rare. Usually, the NTRK1 gene provides instructions to make a protein which is essential for developing nerve cells. However, if the NTRK1 gene fuses with another gene, this mutation leads to the production of oncoproteins (i.e. cancer causing proteins) which make cells divide too quickly/constantly. This genetic mutation occurs across various cancer types.
What is all the hype about the new tumour-agnostic drug? Moving away from targeting a certain cancer type, this drug class will focus on genetics, thus being more specific in their approach to cancer therapy. The drug currently in clinical trials is Larotrectinib, already used selectively in the USA and Europe, whilst awaiting approval in the UK. Even before approval, NHS England has described tumour-agnostic drugs as “revolutionary” from the results so far, and hopes to “fast-track” them once approved within the next few months (fingers crossed). Such drugs are thought to be of huge benefit to children suffering from cancers linked to this mutation. From the drugs in current testing, the NHS suggests that within a year at least 850 people in the UK will benefit from this treatment and thousands more as other tumour-agnostic drugs are developed, for the numerous other biochemical pathways that various cancer types share. Two-year-old Charlotte from Belfast has already benefited from a year of larotrectinib treatment. She was diagnosed with cancer of her connective tissue (i.e. fibrosarcoma), and the tumour-agnostic drug has impacted greatly on her tumour meaning she now has a “relatively normal life”.
So what does this mean for cancer therapy? It’s a huge shift from current cancer treatments, and with approval in the US and Europe, tumour-agnostic drugs like larotrectinib could become more common in the UK. To use a treatment such as this though, genomic testing needs to be in place. Genomic testing looks specifically for alterations or mutations in the genetic code such as the NTRK1 mutation. Thus, such procedures need to be readily conducted across the country to make use of this new class of drugs. Another genetically targeted drug Olaparib, is already used in the UK against ovarian cancer. The genetic fault is found in the gene which codes for DNA repair. New reports have shown that this fault can cause some prostate cancers and thus, Olaparib is now to be issued for use against some prostate cancer cases too.
Such findings and research show how cancer therapies have improved hugely over the last 10-20 years, and that survival rates are impressive for many types of cancer. With continued research into new, less invasive therapies and drugs which are more targeted to the individual, we can hope to see greater survival statistics, fewer side-effects and an improvement in patient experience. Cancer treatment is entering a new era.