An assessment of the reproductive toxicity of the anti-COVID-19 drug molnupiravir using stem cell-based embryo models

Abstract

It is important that women of reproductive potential know what risks the medications they are consuming pose to reproductive health. However, reproductive risk information is particularly limited for new drugs, such as those to treat COVID-19. Because the FDA no longer requires in vivo animal testing during preclinical tests, the information obtained through suitable in vitro models are particularly crucial. The overall objective of this study was to evaluate the embryotoxic effects of molnupiravir, an anti-COVID-19 drug, using in vitro embryo models made of pluripotent stem cells. In Specific Aim 1, the efficacy of morphological assay using mouse P19C5 stem cell model, or embryoid bodies (EBs), was assessed in reference to known embryotoxic drugs. The ICH recently released a list of drugs with their in vivo concentrations known to cause embryotoxic effects. This ICH list can be used to validate the sensitivity and specificity of an in vitro assay to identify embryotoxicity. Adverse effects of drugs on the P19C5 EB model were determined from disruptions in morphology. The in vitro results with P19C5 EBs closely reflected those of the ICH’s in vivo results for many of the drugs examined, validating the efficacy of the assay. In Specific Aim 2, the adverse effects of molnupiravir, and its metabolite N-hydroxycytidine (NHC) were examined using in vitro embryo models made of P19C5 cells and also of human embryonic stem cells. Morphology-based analyses indicated that molnupiravir had an adverse effect at concentrations much higher than the therapeutic level, whereas NHC had a dose-dependent adverse effects at therapeutically relevant concentrations. Molecular studies using P19C5 EBs further demonstrated that NHC altered the expression patterns of several embryo-patterning genes, providing mechanistic insights into the embryotoxic action of molnupiravir. These results emphasize the need for further studies into the effectiveness of the in vitro embryo models and the embryotoxic effects of the COVID-19 antiviral drugs.