An off-the-shelf vaccine has shown promise in preventing the return of pancreatic and colorectal cancer, researchers have revealed.
Cancer vaccines have been the subject of promising research in recent years. The NHS in England has been trialling various jabs in patients through the Cancer Vaccine Launch Pad (CVLP).
Such vaccines train the body’s immune system to recognise cancer cells so any that return after treatments such as surgery can be hunted down and killed, reducing the risk of the disease coming back.
Many cancer vaccines, including some of those based on mRNA technology, are personalised to the patient’s tumours.
However, a study has suggested a non-personalised, experimental vaccine that is already being made at scale could help prevent the return of pancreatic and colorectal cancer.
If borne out by further trials, experts say, the approach could be beneficial since the vaccine is likely to be cheaper and faster to access than mRNA jabs, as well as less toxic than some other therapies.
“After a long-term follow-up of this study, we were able to demonstrate that the group of patients who mounted an immune response have a greater likelihood of not having their cancer return and living longer compared to historical expectation of what that patient would do,” said Prof Zev Wainberg, an oncologist at the University of California, Los Angeles, and a co-author of the study.
The authors noted 90% of people with pancreatic cancer and 50% of those with colorectal cancer had mutations in the Kras gene. These mutations result in the production of altered Kras proteins that cause cells to divide and proliferate.
Writing in the journal Nature Medicine, Wainberg and colleagues reported how they gave a vaccine called ELI-002 2P to 20 patients who had had surgery for pancreatic cancer and five who had been operated on for colorectal cancer.
The vaccine contains peptides – long chains of amino acids, which are the building blocks of proteins. The vaccine works by training the T-cells of the body’s immune system to recognise and kill cancer cells with mutations that result in them producing the altered Kras proteins.
At a median follow-up of almost 20 months, the team found patients fell into two groups: 17 who had a strong immune response to the jab and eight who had a weaker response.
The team found the former group experienced a longer period before their cancer returned and survived longer overall. Overall, four of those 17 patients died during follow-up, compared with seven of the eight who had a lower immune response.
However, the study is early stage research designed primarily to assess safety, involved only 25 participants, had no controls, and looked at two very different types of cancer.
Even so, experts said the results were worth noting. Siow Ming Lee, a professor of medical oncology at University College London, who was not involved with the work, suggested the ELI-002 2P vaccine could be combine with other kinds of immunotherapy, and might help a wider range of patients.
“With promising early results and potentially fewer side-effects than current oral inhibitors, this off-the-shelf cancer vaccine could expand treatment options for Kras-driven cancers and warrants further testing in larger trials, including exploring its potential use in lung cancers driven by mutations in Kras gene,” he said.
Dr Shivan Sivakumar of the University of Birmingham, who works on mRNA-based pancreatic cancer vaccines, said it was fascinating so many of the patients in the study showed a clear immune response to the off-the-shelf vaccine.
But Sivakumar noted that a key advantage of personalised mRNA vaccines was that they did not have to rely on mutations in the Kras gene.
He said it was now important to carry out randomised control trials of the ELI-002 2P vaccine and follow patients over a longer period.
“How many times have we been down this garden path where we’ve got really excited about the science? But actually, ultimately, the real scientific experiment is in patients,” Sivakumar added.