An 81-year-old man from Surrey became the first patient in the UK to receive a new ‘vaccine’ designed to treat solid-tumour cancers, such as the skin cancer melanoma. Therapeutic cancer vaccines act as a kind of immunotherapy, meaning they help train the immune system to fight cancer cells. They’re different from vaccines that prevent cancer, such as the HPV vaccine that’s incredibly effective at preventing cervical cancer. In the US there are a handful of therapeutic cancer vaccines approved for melanoma, prostate cancer and bladder cancer. The new vaccine being tested in the UK and elsewhere around the world is called mRNA-4359. Similar to the Pfizer-BioNTech and Moderna vaccines against COVID-19, the treatment contains a genetic molecule called mRNA. This cousin of DNA can relay instructions to the proteinbuilding factories in cells, prompting them to churn out specific proteins.
In the case of mRNA-4359, the vaccine instructs cells to make proteins commonly found on cancerous solid tumours. These proteins then get presented to the body’s immune system, which builds up an arsenal to go after the cancer cells. mRNA-4359 is considered a ‘ready-made’ cancer vaccine; it’s designed to be used in any patient with a particular type of cancer, off-the-shelf, because it goes after proteins commonly present on those tumour types. Other mRNA cancer vaccines currently in development are more personalised. For example, there’s a pancreatic cancer vaccine that’s made using genetic information drawn from a patient’s own tumours – thus it’s tailored to target proteins found on that specific patient’s cancer cells.
The mRNA-4359 trial is testing whether the vaccine appears safe and tolerable to human patients. It will both be tested in isolation and as an add-on to an existing immunotherapy called pembrolizumab. As a secondary measure, the trial organisers will also see whether the treatment shrinks the tumours of lung and skin cancer patients. The effectiveness of the vaccine will be probed further in future studies. “This research is still in the early stages and may be a number of years from being available to patients,” said Dr David Pinato, a clinician scientist at Imperial College London’s Department of Surgery and Cancer. “But this trial is laying crucial groundwork that is moving us closer towards new therapies that are potentially less toxic and more precise.”