US Merck axes two COVID-19 vaccines, focuses on therapies instead

Merck & Co is to axe development of two COVID-19 vaccine candidates, focusing on development of two therapies instead following disappointing results in early trials.

US-based Merck & Co said the decision followed findings from phase 1 clinical studies of the vaccines codenamed V590 and V591.

The company - known as MSD outside North America - said that although the vaccines were well tolerated, the immune responses seen were weaker than natural immunity and those reported for other SARS-CoV-2 vaccines.

The World Health Organization’s regularly updated vaccine tracking webpage says there are 64 vaccines in clinical development, with several approved or close to the market.

With such tough competition, Merck made an easy call following the poor results and has decided to focus instead on advancing two therapies for COVID-19, MK-7110 and MK-4482 (molnupiravir).

The company is also continuing research into a measles-virus vector, which was added to its pipeline following its takeover of Themis last year.

It is also continuing to look at the vesicular stomatitis virus vector-based technology it developed in partnership with the not-for-profit International AIDS Vaccine Initiative (IAVI).

The company was more upbeat about the prospects for its two therapies, however.

MK-7110 (formerly CD24Fc) is a potentially first-in-class investigational recombinant fusion protein that modulates the inflammatory response to SARS-CoV-2, principally by targeting a novel immune pathway checkpoint.

Interim results from a phase 3 study showed a greater than 50% reduction in the risk of death or respiratory failure in patients hospitalized with moderate to severe COVID-19. Full results from this study are expected in the first quarter of 2021.

In December, Merck announced a supply agreement with the U.S. government to advance the manufacturing and initial distribution of MK-7110.

Molnupiravir is being developed in collaboration with Ridgeback Bio and is an oral novel investigational antiviral agent in phase 2/3 clinical trials in both hospital and outpatient settings.

The phase 2/3 study is expected to be completed by May and the first efficacy data could be published in the first quarter if Merck deems it to be “clinically meaningful”.

Merck and its collaborators plan to submit the results of the phase 1 studies for V590 and V591 for publication in a peer-reviewed journal.