Use of Oral Antivirals Ritonavir-Nirmatrelvir and Molnupiravir in Patients with Multiple Myeloma Is Associated with Low Rates of Severe COVID-19: A Single-Center, Prospective Study

In patients with multiple myeloma (MM), SARS-CoV-2 infection has been associated with a severe clinical course and high mortality rates due to the concomitant disease- and treatment-related immunosuppression. Specific antiviral treatment involves viral replication control with monoclonal antibodies and antivirals, including molnupiravir and the ritonavir-boosted nirmatrelvir. This prospective study investigated the effect of these two agents on SARS-CoV-2 infection severity and mortality in patients with MM. Patients received either ritonavir-nirmatrelvir or molnupiravir. Baseline demographic and clinical characteristics, as well as levels of neutralizing antibodies (NAbs), were compared. A total of 139 patients was treated with ritonavir-nirmatrelvir while the remaining 30 patients were treated with molnupiravir. In total, 149 patients (88.2%) had a mild infection, 15 (8.9%) had a moderate infection, and five (3%) had severe COVID-19. No differences in the severity of COVID-19-related outcomes were observed between the two antivirals. Patients with severe disease had lower neutralizing antibody levels before the COVID-19 infection compared to patients with mild disease (<i>p</i> = 0.04). Regarding treatment, it was observed that patients receiving belantamab mafodotin had a higher risk of severe COVID-19 (<i>p</i> < 0.001) in the univariate analysis. In conclusion, ritonavir-nirmatrelvir and molnupiravirmay prevent severe disease in MM patients with SARS-CoV-2 infection. This prospective study indicated the comparable effects of the two treatment options, providing an insight for further research in preventing severe COVID-19 in patients with hematologic malignancies.