By Shivani Singh, Anuron Kumar Mitra and Neha Arora

BENGALURU (Reuters) -Two Indian drugmakers have requested permission to end their late-stage trials on Merck & Co’s experimental antiviral drug molnupiravir in moderate COVID-19 patients.

Aurobindo Pharma Ltd. and MSN Laboratories, two Indian drug companies, plan to carry out late-stage trials of the drug in India for patients with mild COVID-19. This was confirmed by the expert committee from the Indian drug regulator. Following interim trial data showing the effectiveness of this drug on moderate COVID-19 cases, each company sought to end the trials. The committee revealed that the two companies had submitted interim data, which cast doubts over the clinical efficacy.

Separately, a top source from India’s Drug Regulatory Authority told Reuters that molnupiravir has not shown any “significant efficacy” against moderate COVID-19.

Merck shares shot up last week as Ridgeback Biotherapeutics and Merck announced that an interim analysis from a clinical trial of Molnupiravir in late-stage trials showed the medication nearly reduced the death or hospitalisation risk for COVID-19 patients.

Merck and Indian drug makers did not use the same criteria for defining moderate COVID-19.

Reuters reached out to Aurobindo Pharma MSN, Merck but they did not respond immediately.

Merck signed voluntary licensing agreements for molnupiravir with at least eight Indian drugmakers. The aim is to transform the South Asian country into a manufacturing center for the drug that supplies low- to middle-income countries.

Aurobindo started a https:// clinical trial on the drug for 100 COVID-19 patients in August 2018. The trial information stated that the drug was being tested in moderate patients with symptoms such as fever and coughing.

The eight Indian businesses, including five – Cipla Pharmaceuticals (NYSE:), Sun Pharma Pharmaceuticals, Cipla Pharmaceuticals, Torrent Pharmaceuticals, Emcure Pharmaceuticals and Dr Reddy’s Laboratories – have joined forces to conduct a clinical trial in an outpatient setting for antiviral drugs only in mild COVID-19-related patients.

Hetero was the second licensed company and announced interim data in late July from its own trial with mild COVID-19 inpatients. It also submitted an application to emergency approval.

Hetero separately is conducting a study with moderate COVID-19 sufferers. Hetero said it will share clinical results.