Melbourne mRNA vaccine candidate for clinical trials

Supported by Victorian Government

Australia is within months of clinical trials for a COVID-19 mRNA vaccine developed in Melbourne.

Victoria’s Acting Premier James Merlino announced on Sunday that $5 million from a $50 million mRNA research fund had been allocated to help the Monash Institute of Pharmaceutical Sciences manufacture doses of its mRNA vaccine candidate for trials.

“This is an incredibly important, incredibly exciting step that we are making in our nation,” Mr Merlino said.

“This will get us on a pathway to local manufacturing capability.”

Mr Merlino said the investment in sovereign capability to produce mRNA vaccines was particularly important because the virus would remain for some time and there could be the need for yearly booster vaccines in the years ahead.

The vaccines developed by Moderna and Pfizer — which is available in Australia — are types of messenger RNA or mRNA vaccine

The mRNA vaccines use a genetic code called RNA to spark the production of the coronavirus’s specific spike protein.

Once the mRNA enters the body’s cells, the cells use the instructions contained in the RNA to make the spike protein.

Immune cells then recognise the spike protein as foreign and begin building an immune response against it.

Monash University’s Colin Pouton, who is leading the research team behind the new mRNA candidate, said mRNA technology’s advantages were that it was simpler to engineer and easy to adapt than protein vaccines.

They are hoping to have Phase 1 clinical trial up and running by October or November, with around 150 trial participants.

Secondly, Professor Pouton said the trial of an mRNA vaccine presented an opportunity to equip manufacturers with the ability to make mRNA vaccines.

“So during this period of making a clinical trials product for Phase 1, we’ll be skilling up those companies to start getting into manufacturing so that they could manufacture other products and other COVID products going forward,” he said.

The question of what COVID-19 mRNA vaccine we might make with that capability is not yet resolved.

Professor Pouton said if commercial agreements were struck with Pfizer or Moderna, it was possible Australia could start manufacturing those vaccines at CSL.

Or, if trials for the Monash-developed vaccine go well and pass through all the other hurdles, it may be that our first mRNA vaccine manufactured in Australia is designed here, too.

Variant vaccine

Professor Pouton said the vaccine under development was a “variant vaccine”, modelled from the Beta strain, which was first detected in South Africa.

Existing vaccines have been modelled on the original version of the virus first detected in Wuhan.

Professor Pouton said the second key difference was that existing approved vaccines were what you might call “whole spike vaccines”, which prompted the body to build antibodies for the whole spike of the virus.

“The problem with that is that you’re sort of raising antibodies against other parts of the protein, which isn’t necessarily a problem if the only vaccine is the only virus circulating is Wuhan [strain],” he said.

But variants that have emerged contain mutations at what’s referred to as the “receptor-binding domain”, which Professor Pouton said accounted for roughly 10 per cent of the overall mass of the coronavirus spike protein.

The new vaccine candidate is aimed at presenting solely the receptor-binding domain to the immune system.

“The advantage of that is that it should lead to neutralising antibodies which bind directly to the receptor-binding domain, which is what we’re really trying to achieve with an antibody response,” Professor Pouton said.

He said his team believed this approach was likely to produce a better kind of booster shot for future variants, which could be given to those already vaccinated against the original strain.

The team is also in the early stages of testing an mRNA vaccine candidate modelled on the Kappa variant.

Other initiatives

While Monash University has developed an mRNA vaccine candidate, the Doherty Institute has developed a protein vaccine candidate.

Both of them are focused on the receptor-binding domain of the Beta strain, so Professor Pouton said it made sense to work together and run the Phase 1 trial side by side.

The hope is, we’ll learn more about whether the approach of targeting the receptor-binding domain is going to be useful to prepare us against future variations.

Professor Pouton said the trials should start in October or November and would run until all the data was collected for a year.

He said because the mRNA vaccine candidate was not “radically different” from that of Moderna or Pfizer, his research team did not expect there would be any issues with safety.