An article in the New York Times in October 2022 reflects that developing a cancer vaccine for high-risk patients seems like an “impossible dream”. However, recent steps suggest that we may be closer to this possibility than previously thought. While these investigations continue, attempts to develop vaccine therapies against cancer also progress. So which area should gain most attention, and which will improve or save more lives?
In previous posts we have investigated current projects for cancer vaccines and found that, despite investment, the challenge is great. Dr Sachet Shukla from the University of Texas told the NYT that the “time has come” for cancer vaccines. For Dr Susan Domchek of the University of Pennsylvania, “it’s super aspirational, but you’ve got to think big”.
Patients with pancreatic cancer have very few options, the article suggests. Removing the pancreas is one that leads to a “realm of severe diabetes and digestive problems”. Leaving lesions alone might allow them to become cancerous, or it might not.
Dr Elizabeth Jaffee of Johns Hopkins University finds potential in this pancreatic problem. The first change in normal cells, she describes, is a mutation in a well-known cancer gene: KRAS. This is followed by other mutations. Knowing this, researchers were able to consider a vaccine to train T cells to target these mutating cells. The initial safety study was in 12 patients with early cancer who had already been treated with surgery. Although this early intervention is effective, there is a 70%-80% chance of a recurrence in the following years. Then it is “metastatic and fatal”. For the 12 patients in the study, this has not been the case, as they have not experienced a recurrence.
Take it back to the beginning
The NYT traces cancer vaccine history back to Dr Olivera Finn of the University of Pittsburgh School of Medicine. In 1993 her initial vaccine targeted the core of a muc1. In ordinary cells it goes undetected by the immune system thanks to its covering of sugar molecules, but in some cancers it can become visible. This made it “seem like a perfect vaccine target”. In a trial of 63 patients with Stage 4 cancer it became clear that the cancers were too advanced for immunisations to be effective. Dr Finn told the NYT that she didn’t want to repeat that.
“It is not the vaccines. We have to look at different patients.”
With a colleague she is now trying to prevent precancerous colon polyps. By focusing on people whose colonoscopies had detected advanced polyps, they aim to stimulate the immune system into preventing further polyps. This was effective in mice, but in a human study did not have the same level of reduction in polyp recurrences.
At the University of Washington, Dr May Disis is hoping to prevent breast cancer in patients with gene variants that put them at high risk. Her aim is to replace surgery, chemotherapy, or radiation as treatments for “pre-cancer” with a vaccine. Starting with breast cancer stem cells, which are resistant to certain therapies, she found several proteins being produced at higher levels than in noncancerous cells.
The NYT reports that the vaccine was tested in women with well-established advanced cancers. Although it did not cure the cancers, it demonstrated an ability to provoke a helpful immune response. Next, she will try vaccinating patients with ductal carcinoma in situ, or another precancerous condition called atypical ductal hyperplasia. Hopefully, the lesions would be made to shrink or disappear before a surgery.
“This would be proof the vaccine has a cleansing effect.”
This presents a positive outlook on the future of cancer therapy and prevention, but as patients continue to receive life-changing diagnoses the question of which we should target remains. There is little time to spare in the race to develop a vaccine that protects against or remedies the effects of cancer. So, which will be the first to appear, and which will be the most effective?
To hear more about cancer vaccine candidates at the World Vaccine Congress get your tickets here.