Molnupiravir clears COVID-19 virus equally well in immunocompromised and immunocompetent patients

A new analysis of data on the 'COVID-19 pill' molnupiravir shows it appears to clear active SARS-CoV-2 virus equally well in immunocompromised patients and those who are immunocompetent. The analysis, which will be presented at this year's European Congress of Clinical Microbiology & Infectious Diseases (ECCMID 2022, Lisbon, 23-26 April), was led by Dr Matthew Johnson,of the pharmaceutical company MSD, a trade name of Merck & Co., Inc, Kenilworth, NJ, USA, who manufacture molnupiravir (brand name Lagevrio)

Data on the efficacy of molnupiravir on cutting the risk of progression of COVID-19 in non-hospitalised, unvaccinated patients at the highest risk of poor outcomes (the MOVe-OUT study), was published in NEJM in December 2021*. All patients in the study were given the drug within 5 days of symptom onset. The drug has been granted an emergency use authorisation by the by the US Food and Drug Administration (FDA) and is also authorised for use in the UK, Australia, and Japan and 12 other jurisdictions.*

This new analysis of that study focuses on people categorised as immunosuppressed, meaning their immune systems do not function normally for a wide variety of reasons. Immunocompromised participants were identified based on prior/concomitant medication use and medical history, and included patients with active cancer (29), HIV (12), those using immunosuppressants (14), and transplant patients (5).

Among 1433 participants randomised in MOVe-OUT, 57 (4%) were identified as immunocompromised (see table 1 – 25 in the molnupiravir group, 32 in the placebo group). In the molnupiravir group, fewer immunocompromised participants were hospitalised or died by day 29 (2/25 [8%]) compared with placebo (8/32 [25%]).

Mean change from baseline in SARS-CoV-2 RNA was greater in the molnupiravir group versus placebo at day 3 in both the immunocompromised and non-immunocompromised participants (Table 2). No infectious virus was recovered in any immunocompromised participants in the molnupiravir group at Day 3 or later, versus 14% (4/29) with infectious virus at Day 3 with placebo (note for 3 of the 32 patients in the placebo group, a day 3 sample was not available – hence 29 instead of 32 participants in placebo group included here). The safety profile was comparable in the molnupiravir and placebo groups, regardless of immunocompromised status.

The authors say: "Immunocompromised participants receiving molnupiravir in the MOVe-OUT trial demonstrated a lower incidence of hospitalisation or death by day 29 compared to those receiving placebo, and molnupiravir was generally well tolerated. Reductions in the amount of SARS-CoV-2 virus over time were similar in immunocompromised and non-immunocompromised participants, and no infectious virus was detected after baseline in the molnupiravir group, suggesting that molnupiravir stops viral replication equally well in both the immunocompromised and immunocompetent patients in our trial population."

The authors acknowledge that immunocompromised participants (4%) represented only a small proportion of the participants in this study, which was a was an exploratory post hoc analysis of the original MOVe-OUT study. They say no additional clinical studies focused on immunocompromised patients are planned at this time. They also add that while this final phase 3 study of the MOVe-OUT/molnupiravir recruited only unvaccinated participants, they believe a range of medicines and vaccines will be needed to confront the COVID-19 pandemic.