Moderna and Merck have announced positive results from a late-stage clinical trial of their personalised mRNA cancer vaccine, developed to reduce the risk of melanoma returning or spreading after surgery.
The experimental treatment was tested alongside Merck's immunotherapy drug Keytruda, also known as pembrolizumab. According to the companies, the combination met the trial's primary goal of reducing cancer recurrence and also achieved its secondary goal of lowering the risk of the disease spreading to distant parts of the body.
The findings mark a major milestone for personalised mRNA cancer treatment, although detailed trial data and long-term survival results are still awaited.
How does the personalised mRNA cancer vaccine work?
Unlike conventional vaccines that protect against infectious diseases, a personalised cancer vaccine is designed specifically for an individual patient.
After a patient's tumour is removed through surgery, scientists analyse its genetic mutations to identify tumour-specific targets, often called neoantigens. The vaccine is then designed to help the immune system recognise these specific features and attack any remaining cancer cells.
Moderna's mRNA technology essentially provides the immune system with instructions to recognise mutations associated with the patient's tumour.
The aim is to create a stronger immune response capable of detecting and destroying cancer cells before they can grow again or spread elsewhere in the body.
Phase 3 trial included more than 1,100 melanoma patients
The Phase 3 trial involved 1,137 patients with high-risk stage IIB to IV melanoma whose tumours had been surgically removed.
Participants were randomly assigned to receive either:
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Keytruda plus the personalised mRNA cancer vaccine, or
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Keytruda alone
The treatment was administered for approximately one year.
Moderna and Merck said the combination successfully met the study's primary endpoint of reducing the risk of recurrence. It also met a secondary endpoint involving a reduction in distant metastasis, or the spread of cancer to other parts of the body.
The companies also said no new safety concerns were identified during the trial.
Why the results are significant
The findings are particularly important because Keytruda is already an established immunotherapy treatment for melanoma.
The trial suggests that adding a personalised mRNA vaccine could potentially improve outcomes beyond those achieved with immunotherapy alone.
The companies have described the study as the first positive Phase 3 result for an individualised mRNA cancer vaccine.
If the detailed data supports the initial findings and regulators approve the treatment, it could become one of the first personalised mRNA cancer therapies to enter routine clinical use.
Earlier study showed a 49% reduction in recurrence or death risk
The latest results build on encouraging findings from an earlier-stage study.
In January, Moderna and Merck released five-year data showing that the combination of Keytruda and the personalised vaccine reduced the risk of recurrence or death by 49% compared with Keytruda alone.
The new Phase 3 results strengthen expectations that personalised mRNA vaccines could play a role in preventing high-risk cancers from returning after surgery.
However, the companies have not yet released the complete Phase 3 data, making it important to wait for the detailed results before drawing conclusions about the full magnitude of the benefit.
Could the treatment reach patients soon?
Moderna and Merck have said they are already in discussions with regulators.
The therapy has received Breakthrough Therapy designation, which could potentially speed up its regulatory review. Moderna President Stephen Hoge said the treatment could potentially become available as early as next year, depending on regulatory approval.
That does not mean the vaccine is currently approved or available for routine use.
Important questions, including overall survival benefits, long-term safety, manufacturing capacity, cost and access, still need to be addressed.
What does this mean for melanoma patients?
Melanoma is the most serious form of skin cancer and can become life-threatening if it spreads to other organs.
For patients with high-risk melanoma who have undergone surgery, one of the biggest concerns is cancer recurrence.
The personalised mRNA vaccine is designed to provide an additional layer of immune protection by training the immune system to identify tumour-specific mutations.
If eventually approved, the treatment could become an important addition to existing immunotherapy for selected melanoma patients.
Could mRNA cancer vaccines be used for other cancers?
The potential of personalised mRNA vaccines extends beyond melanoma.
Researchers are studying similar approaches for several solid tumours, including:
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Lung cancer
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Breast cancer
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Pancreatic cancer
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Other high-risk solid tumours
The broader goal is to make cancer treatment increasingly personalised by developing therapies based on the specific genetic characteristics of an individual patient's tumour.
For Moderna, the positive trial represents another important step in expanding its mRNA technology beyond COVID-19 vaccines. For Merck, the combination could potentially create new treatment opportunities involving Keytruda.
The latest trial results represent a promising milestone, but the treatment still needs regulatory approval and further analysis of detailed clinical data before it can become part of standard cancer care.
