Australia at the heart of 'transformational' cancer vaccine breakthrough

A world-first cancer vaccine has been shown to radically reduce the risk of melanoma recurrence and death.

The results from an Australian-led phase 3 human trial revealed a 42 per cent reduction in the risk of melanoma recurrence.

Melanoma Institute Australia medical director and principal investigator Georgina Long said the results were better than she had hoped.

"We did not expect it to be that high. We knew it would be important and significant, but this is phenomenal," she said.

"This breakthrough is absolutely transformational. It's a foundational shift in the way we use the immune system to target and kill cancer."

The treatment works by adding intismeran, a type of personalised mRNA-based vaccine made with genetic information from a patient's tumour, to pembrolizumab immunotherapy after the surgical removal of melanoma.

"Adding the two drugs together rather than one improves or decreases their risk of recurrence or death by 42 per cent," Professor Long said.

"This was aimed at melanoma patients who are at a very high risk of the melanoma coming back as advanced melanoma. That used to be deadly."

She said the vaccine was developed by taking a biopsy of the patient's tumour and comparing its cells to the patient's healthy cells to see what was different.

"There's a list of things that are very different, that are unique to the patient's tumour. They're not shared with anyone else's tumour," Professor Long said.

"We rank them, and the top 34 differences we can then encode and that's called the fingerprint."

The mRNA platform is used to code that fingerprint, or neoantigen, which is injected into the patient and establishes a target for the immune system.

"It's like a wanted poster that gets printed into the body so … the immune cells can see," Professor Long said.

The trial involved 1,137 patients whose melanoma had been surgically removed and compared the combined treatment with with patients receiving only immunotherapy treatment.

It was conducted across 157 sites globally and involved a number of Australian sites, including Melanoma Institute Australia, Peter MacCallum Cancer Centre and Paul Fox Melanoma and Cancer Centre in Victoria, Westmead Hospital in NSW, Princess Alexandra Hospital in Queensland and One Clinical Research in Western Australia.

Professor Long, who is also chair of Melanoma Medical Oncology and Translational Research at the University of Sydney, is due to present the results of the trial at the European Society of Medical Oncology Congress this weekend.

"It's really important for people to understand what a fork in the road this is, because we've been trying to do this for decades, before I was born, and we've done it," she said.

The investigational mRNA-based neoantigen therapy is being jointly developed by MSD (Merck and Co) and Moderna.

"I chaired the steering committee for this trial advising both Moderna and Merck on this particular trial, but it's Australia's cancer," Professor Long said of melanoma.

"We have the highest incidence in the world. Someone dies from this cancer every six hours in our country. Someone is diagnosed every 30 minutes in Australia."

Experts say the breakthrough may have an important flow on effect for treatment for other forms of cancer.

Professor Alex Menzies from Melanoma Institute Australia's medical oncology and clinical trials team said: "The hope for the near future is that it may not only improve outcomes for melanoma patients with advanced disease but also those with other types of cancer where current immunotherapies are poorly effective."

Jessamy Tiffen from the Centre for Cancer Innovations at the Centenary Institute said: "What is truly remarkable about this vaccine is the deeply personalised nature of the treatment, something cancer researchers have been striving to achieve for decades."

While it is a significant breakthrough, she said it was not good news for all melanoma patients.

"A significant portion do not respond to the vaccine in the first instance,' Dr Tiffen said.

"Cancer cells have an insidious ability to adapt and evade whatever treatment we throw at them.

"Only time will tell how effective the treatment is beyond two years… [but it's] a very exciting development.

"And don't throw away the sunblock just yet. This vaccine is in no way preventative and is intended for advanced stage II-IV melanoma patients … the best way to prevent melanoma is still to protect yourself from the sun."

Melanoma Institute Australia said a regulatory review process would now be undertaken, which could take several years.

"Until then the treatment is not available. Patients with melanoma who want to know more should talk to their medical oncologist," it said in a statement.

The institute said the results would be published in the New England Journal of Medicine.