What’s a broad-spectrum ‘flu’ antiviral worth?

The short answer is "billions" -  if Merck's recent move is anything to go by.

Pharmaceutical giant Merck & Co recently announced the acquisition of Cidara Therapeutics, in a deal worth US$9.2 billion. [1]

The reason for the buyout is Cidara's investigational drug candidate known as CD388, an antiviral that is being evaluated as a long-acting, preventative therapy for seasonal influenza.

CD388 is a small molecule combined with a protein fragment, designed to target the  neuraminidase enzyme, which is identical in every influenza strain. While still in late-stage testing, this approach has already shown the ability to prevent flu-symptoms in around 75% of those who received it, compared to a placebo, over a six-month period.

Photo Credit: Cynthia Goldsmith/CDC

The obvious benefits of a potentially broad-spectrum and preventative approach could position CD388 as an alternative to the flu vaccine, as well as offering flu protection to high-risk populations. This is an opportunity projected to be worth $3.8 billion annually, which starts to put Merck's huge acquisition into perspective.

Influenza (or 'flu') is an acute respiratory infection caused predominantly by influenza viruses A and B. Around 1 billion people worldwide are infected by seasonal influenza each year. Of those people, 3 to 5 million get severe cases, the complications of which include pneumonia, exacerbation of chronic conditions, sepsis, myocarditis, encephalitis, and even death.

It's estimated that 300,000 - 650,000 deaths occur globally due to flu each year, making it the leading viral killer and a significant problem to solve.

Currently, the dominant weapon in our arsenal against flu is the vaccine. Hundreds of millions of flu vaccines are administered each year, and while these can be effective, vaccination faces some challenges, mostly due to the constant mutation of virus strains.

In order to have them ready in advance, manufacturers are forced to predict which flu strains will emerge in the following season, and getting it wrong renders vaccine coverage incomplete. This, coupled with other factors such as allergies and vaccine hesitancy, has resulted in a decline in uptake over recent years.

However, with challenges comes opportunity, and this is an area where broad-spectrum antivirals can come into their own. Antivirals that target an aspect of the virus that is highly conserved by viral evolution (less likely to mutate) are much less likely to be rendered ineffective as the virus inevitably evolves new strains.

Merck’s $9.2 billion acquisition points to the massive market potential for innovative, broad-spectrum antivirals. It will be interesting to follow CD388’s progress as it enters phase 3 trials.

References:

1. https://www.merck.com/news/merck-to-acquire-cidara-therapeutics-inc-diversifying-its-portfolio-to-include-late-phase-antiviral-agent/