Decades before mRNA was used to develop vaccines against COVID-19, researchers had been trying to deploy the technology against cancer.

It has been a slog.

This week, Moderna announced something of a breakthrough.

For the first time, mRNA technology has shown “clinically meaningful” success with a new ‘personalised’ vaccine against melanoma.

The small Phase II study involved patients who had undergone surgery for melanoma, and were at high risk of it returning and killing them.

Phase III trial next

The next step is to seek approval from the Food and Drug Administration (FDA) in the US for a large Phase III trial – and “rapidly expand” to use the technology against other tumour types.

News of the breakthrough saw Moderna’s stock price go up by about 25 per cent.

This was a welcome result given that the uptake of COVID-19 vaccines has slowed. Moderna reportedly depends on Spikevax (its COVID vaccine) for most of its revenue.

Moderna, which has enjoyed rock-star status during the pandemic, has been the focus of this new development.

But the story is more complicated, because the new vaccine is only one half of the breakthrough treatment.

The partnership

For the past six years, Moderna has been working with another drug company, Merck – which had its own rock-star moment in 2015.

This was when former US president Jimmy Carter, aged 90, received an experimental immunotherapy treatment called Keytruda for melanoma that had spread to his brain and liver.

Treatment with Keytruda – a humanised monoclonal antibody – reportedly cured him, and quickly.

Within days of this news, cancer patients were clamouring for the drug.

Keytruda: The buzz and the reality check

In 2016, the FDA approved Keytruda for use on patients with metastatic non‐small cell lung cancer.

Since then Keytruda has been used to treat stomach cancer, cervical cancer, and certain types of breast cancers.

It’s a remarkable treatment, for sure.

However, in the wake of Carter’s recovery, there was an important caveat:

“In a clinical trial, only one-quarter of patients receiving a standard dose of Keytruda saw their tumors shrink,” the FDA stated.

“That’s typical of immunotherapy drugs: They only help a minority of patients, but those who respond often do extremely well.”

The partnership

The widely reported Phase II trial involved using the new vaccine known as mRNA-4157/V940 and Keytruda.

The companies recruited 157 patients who had undergone surgery related to melanoma.

One group of participants received nine doses of the cancer vaccine, along with Keytruda. Others were given only Keytruda. The participants were tracked for a year.

Moderna says mRNA-4157/V940 is designed “to stimulate an immune response by generating specific T-cell responses based on the unique mutational signature of a patient’s tumour”.

Keytruda works “by increasing the ability of the body’s immune system to help detect and fight tumour cells”.

When used together, the risk of death or recurrence of melanoma in high-risk patients was cut by 44 per cent compared with treatment using only Keytruda.

Final thoughts

According to the Moderna press release:

Serious treatment-related adverse events occurred in 14.4 per cent of patients who received the mRNA-4157/V940 and Keytruda combo.  There were 10 per cent adverse events with Keytruda alone.

The Financial Times cautioned: Moderna has released only a small amount of trial data and the results had not yet been reviewed by independent scientists.”

As newsGP reported in March: Melanoma cases are set to increase by 57 per cent around the world by 2040 with an estimated 68 per cent rise in mortality.

Australia has the highest melanoma incidence in the world – with a new case diagnosed every 30 minutes.