An experimental mRNA cancer-fighting vaccine jointly developed by Moderna and Merck has reportedly succeeded in a Phase II trial. According to the companies, melanoma survivors who received the vaccine in combination with immunotherapy were 44% less likely to have their cancer return or to die than those who only took the immunotherapy. The findings indicate that mRNA vaccines could be an effective tool against cancer and will pave the way for larger, Phase III trials of the treatment.
Merck and Moderna announced the results from the Phase IIb trial Tuesday morning. It involved 157 patients with advanced melanoma who had their tumours completely surgically removed. These patients were randomly split into two groups who received treatment for about a year. One group was given regular infusions of Merck’s Keytruda, a lab-made antibody that helps immune cells better recognise and kill certain cancers. The other group was given Keytruda and nine doses in total of the vaccine candidate, called mRNA-4157/V940.
The vaccine and immunotherapy combination reportedly cleared the primary goal set by the researchers, with these patients experiencing significantly more time without their cancer returning on average than those who only received Keytruda (a metric known as recurrence-free survival). The vaccine in conjunction with Keytruda also appeared to reduce the combined risk of cancer recurrence and death by 44%.
“Today’s results are highly encouraging for the field of cancer treatment. mRNA has been transformative for COVID-19, and now, for the first time ever, we have demonstrated the potential for mRNA to have an impact on outcomes in a randomised clinical trial in melanoma,” said Stéphane Bancel, Moderna CEO, in a statement.
The safety profile of Keytruda in this trial was consistent with previous research, the company added, though those on the combination treatment did experience a higher risk of serious adverse events (14.4% compared to 10% of patients only on Keytruda). These risks are often outweighed by the benefits that immunotherapy can provide for patients with cancers that might otherwise be untreatable.
There are available vaccines that can prevent major contributing factors to certain cancers, such as the vaccine against humanpapilloma virus (HPV), which is the leading cause of cervical cancer. But Moderna and Merck’s candidate is an example of a personalised cancer vaccine. These vaccines are designed to prevent a person’s existing and difficult-to-eradicate cancer from returning following treatment. They’re intended to train the immune system to recognise a cancer’s neoantigens — proteins uniquely produced by tumour cells. In this case, the mRNA platform is used to deliver instructions to the body’s cells so they can produce these neoantigens, tuned specifically to the person’s own cancer. The hope is that the immune system will then target and remember those neoantigens in the future. Many researchers have argued that combining these vaccines with immunotherapy drugs should further amplify their effect.
Scientists have been greatly interested in personalised cancer vaccines for years, and this research has played a pivotal role in the development of mRNA vaccine technology, even before it was used as the base for covid-19 vaccines. But it’s only in the last few years that they’ve looked promising enough to reach the public in the near future. There are now dozens of clinical trials underway testing various vaccine candidates, with Moderna and Merck’s perhaps the closest to fruition. But before that can happen, their vaccine will have to succeed in several Phase III trials, which are needed to secure regulatory approval.
According to Moderna, the companies are planning to present the full data from this trial at upcoming oncology conferences and to regulatory agencies in the near future. Phase III trials of the vaccine for melanoma patients are set to begin next year. The companies hope this approach could be used for other difficult cancers as well.