Merck announced the company is discontinuing development of its SARS-CoV-2/COVID-19 vaccine candidates, V590 and V591, and plans to focus its SARS-CoV-2/COVID-19 research strategy and production capabilities on advancing two therapeutic candidates, MK-4482 and MK-7110. This decision follows Merck’s review of findings from Phase 1 clinical studies for the vaccines. In these studies, both 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. Merck continues to advance clinical programs and to scale-up manufacturing for two investigational medicines, MK-7110 and MK-4482 (molnupiravir); molnupiravir is being developed in collaboration with Ridgeback Bio.

“We are grateful to our collaborators who worked with us on these vaccine candidates and to the volunteers in the trials,” said Dr. Dean Y. Li, president, Merck Research Laboratories. “We are resolute in our commitment to contribute to the global effort to relieve the burden of this pandemic on patients, health care systems and communities.”

Due to the discontinuation, the company will record a charge in the fourth quarter of 2020. The charge will be included in Merck’s generally accepted accounting principles (GAAP) results, but will not impact non-GAAP results.

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. In addition to advancing the development and production of MK-7110 and MK-4482, Merck will continue to conduct SARS-CoV-2/COVID-19 research. Merck will also continue to evaluate the potential of the measles-virus vector and vesicular stomatitis virus vector-based platforms and pursue broader pandemic-response capabilities. The COVID-19 pandemic underscores the need for our company and our industry to continue to invest in research to address threats to health security.

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 percent 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 (link).

Molnupiravir (MK-4482) is an oral novel investigational antiviral agent being developed in collaboration with Ridgeback Bio. Molnupiravir is currently being evaluated in Phase 2/3 clinical trials in both the hospital and out-patient settings. The primary completion date for the Phase 2/3 studies is May 2021. The company anticipates initial efficacy data in the first quarter of 2021, which Merck plans to share publicly if clinically meaningful.