melanoma treatment gets better results when it's personalized
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the survival and disease recurrence rates significantly improved among patients with vaccine combination. getty
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a new form of personalized cancer treatment that incorporates mrna technology has proven remarkably effective at treating high-risk melanomas.
the research, which was presented at the 2023 american society of oncology (asco) congress in chicago, works by combining common immunotherapy with an mrna vaccine that has been tailored to suit the tumour genetics of an individual patient. after undergoing the procedure, survival and disease recurrence rates significantly improved among patients who had a high-risk cancer removed.
a year and a half after treatment, 78.6 per cent of patients who received the vaccine combined with immunotherapy were still cancer-free compared to 62.2 per cent of those who only received immunotherapy. at the two year mark, just 22.4 per cent of patients who received the vaccine had died or experienced the return of their cancer. this number rose to 40 per cent in the group that did not receive the vaccine.
with no significant adverse side effects reported, the new procedure could represent a turning point in the fight against cancer.
“the current standard of care is immunotherapy using an antibody known as pembrolizumab,” said adnan khattak, clinical professor at edith cowen university centre for precision health. “there are two main issues: first, despite having active immunotherapy for stage three melanoma, about half of patients will relapse at five years.
“and secondly, it’s a very crude approach: currently, if i treat 10 new high risk melanoma patients, i give them the same drug; it’s not rocket science that it’s going to work for some but not others and some may see side effects and others may not.
“this is the biggest trial to show treatment improves with an individualized approach — and i think research into personal cancer vaccines is going to increase dramatically after this positive study.”
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a new approach to melanoma
melanoma, the most serious form of skin cancer, is diagnosed in around 9,000 canadians every year, according to the canadian cancer society. the disease, which originates in the skin’s melanocyte cells, can lead to cancerous tumours capable of destroying surrounding tissue and spreading to other parts of the body.
roughly 1,300 canadians die from the disease every year, with the majority of diagnoses and deaths occurring in men, most likely because melanomas tend to develop on the extremities of women, as opposed to the trunk, head or neck of men. in canada, the five-year net survival rate for melanoma skin cancer is 88 per cent.
in an attempt to improve treatment, researchers recruited 157 patients with stage 3 or 4 cutaneous cancer. these subjects had already had their tumours removed but, because the cancer had spread to a lymph node, they were considered at high-risk for recurrence. the team took tissue samples from each individual and used it to identify their cancer’s neoantigens — proteins that form on cancer cells that are unique to a patient’s tumour. the process allowed for up to 34 neoantigens to be added to an mrna molecule, which was then incorporated into the vaccine. one group received injections of the vaccine every three weeks, for a total of nine doses, in addition to immunotherapy; the other received only immunotherapy.
the end result was a more targeted form of immunotherapy that was better equipped to fight a particular patient’s cancer by overcoming its ability to avoid detection. according to researchers, the treatment became more effective over time as multiple doses were used.
“in this study, the survival rate between the two groups is the same after 40 weeks, so early relapses happen for both,” khattak said. “some patients have fairly resistant tumours that aren’t going to respond to either treatment.
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“but after the first 40 weeks, by then the patients have had two or three vaccine doses and the anti-tumour effect really kicks in.
“we see quite a significant proportion of patients relapsing after they finish pembrolizumab, whereas we’re not seeing such late relapses in patients who have done the double treatment because in addition to pembrolizumab, the effect of the vaccine kicks in with a much stronger anti-tumour immune response.”
the future of cancer care
the team is currently working on a new global trial for the treatment, which will involve more patients, some of whom are in the early stages of their fight with skin cancer.
“stage 2 and stage 3 patients combined constitute quite a significant proportion of patients who could be potentially cured, rather than waiting for them to develop metastatic or advanced disease where most of them will not be curable,” khattak said.
“this is going to be the stepping stone for a number of trials. this has the potential of becoming a new standard of care moving forward.”
dave yasvinski is a writer with healthing.ca
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