Tixagevimab/Cilgavimab as Pre-Exposure Prophylaxis against COVID-19 for Multiple Myeloma Patients: A Prospective Study in the Omicron Era

<b>Background:</b> tixagevimab/cilgavimab, distributed under the name "Evusheld", was the first available pre-exposure prophylaxis for COVID-19 other than vaccination. It received an EUA from the FDA after sufficient trial data showed efficacy in preventing SARS-CoV-2 infections and subsequent severe disease. Its potential benefits for high-risk immunocompromised patients generated a lot of interest. Individuals with multiple myeloma fall into this category, as they are characterized by attenuated immune responses and, in some cases, vaccines have limited efficacy. <b>Methods:</b> this single-center, prospective study included consecutive patients with multiple myeloma. All individuals were considered high-risk for COVID-19 due to their underlying disease. Baseline demographic and clinical characteristics, as well as data regarding COVID-19 infection and antibodies, were collected. Patients were administered two intramuscular 150 mg doses of Evusheld and were monitored during the follow-up period. <b>Results:</b> one hundred and eleven multiple myeloma patients were included in this analysis, with a median age of 64 years (range 58-69) and fifty-three were females (47.7%). Fourteen patients (12.6%) had a prior history of COVID-19 and all patients were vaccinated with either three or four doses of mRNA-based vaccines. An increase was observed in the median neutralizing-antibody levels before and after tixagevimab/cilgavimab administration, from 92.6% to 97.3%. The high levels were sustainable, with a median neutralizing-antibody level of 95.4% at 3 months post Evusheld administration. Overall, nine patients (8.1%) were diagnosed with COVID-19 during the follow-up period, at a median of 31 days. There were no SARS-CoV-2- infection-related hospitalizations or deaths. The monoclonal antibody combination was well tolerated, with no infusion-related reactions or major adverse events, and pain at the injection site only was reported by 33 patients (30%). <b>Conclusions:</b> tixagevimab/cilgavimab (Evusheld) seemed beneficial for patients with multiple myeloma, who presented high neutralizing-antibody levels and a low incidence of COVID-19 during the initial Omicron wave. No new safety concerns emerged. However, novel combinations of monoclonal antibodies against the new circulating variants of SARS-CoV-2 are deemed necessary in view of the emergence of immune tolerance.