Merck Says it Will Stop Development of COVID-19 Vaccine Candidates

Merck has announced that it will halt development of its coronavirus disease 2019 (COVID-19) vaccine candidates, V590 and V591, due to inadequate immune responses to the vaccines.

Results of phase 1 clinical studies showed that V590 and V591, “were generally well tolerated, but the immune responses were inferior to those seen following natural infection and those reported for other SARS-CoV-2/COVID-19 vaccines,” said the company in the January 25, 2020, press release.

Merck is among several drug manufactures in the global race to produce a safe and effective COVID-19 vaccine as US confirmed cases have surpassed 25 million and global cases have reached 99 million.

While Merck is shelving both of its vaccine candidates, the company said it will shift its SARS-CoV-2/COVID-19 research strategy and production capabilities to advancing 2 therapeutic candidates, MK-4482 (molnupiravir) and MK-7110.

Molnupiravir is a novel oral antiviral agent being developed in collaboration with Ridgeback Bio and is currently being evaluated in phase 2/3 clinical trials against SARS-CoV-2 infection in both hospital and outpatient settings.

MK-7110 is, “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,” noted the press release. Interim phase 3 data show a more than 50% reduction in risk of death or respiratory failure in patients hospitalized with moderate-to-severe COVID-19. Full results are expected in the first quarter of 2021.

In December, Merck announced a supply agreement with the US government to supply of approximately 60 000-100 000 doses of MK-7110 until June 30, 2021 to meet the government’s Operation Warp Speed goals.

In addition, Merck noted in the press release that it plans to submit the results of the phase 1 studies for V590 and V591 for publication in a peer-reviewed journal.

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