Merck will focus its research strategy and production capabilities on advancing therapeutic drug candidates, MK-4482 and MK-7110. (Representative image)
US pharmaceutical gaint Merck, which is known in India as MSD, on January 25 said it is discontinuing development of its COVID-19 vaccine candidates, V590 and V591, and plans to focus its research strategy and production capabilities on advancing therapeutic drug 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 COVID-19 vaccines," Merck said.
Merck's V590 uses rVSV viral vector and V591 vaccine candidate uses a measles virus vector to deliver the antigens to the body to spur immune response.
Merck said it would continue to advance clinical programmes and to scale-up manufacturing for two investigational medicines, MK-7110 (antibody drug) 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, healthcare systems and communities.”
Due to the discontinuation, the company will record a charge in the fourth quarter of 2020, Merck said.
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 COVID-19 research.
Merck said it would also continue to evaluate the potential of the measles-virus vector and vesicular stomatitis virus vector-based platforms and pursue broader pandemic-response capabilities.
Merck would be second the drug maker to abandon COVID-19 vaccine development. Earlier, a COVID-19 vaccine developed by the University of Australia was abandoned after trial participants returned false positive test results of HIV.
In December last year, French drug maker Sanofi and British drug maker GSK, which are developing COVID-19 vaccine together, said that their recombinant protein vaccine showed poor response in older adults likely due to an insufficient concentration of antigen.