ABSTRACT
Background and Objective: In patients with mild-to-moderate COVID-19 and at high risk of progression, casirivimab/imdevimab and bamlanivimab/etesivimab were utilized in Umbria from late April to November 2021. This period was characterized by an initial prevalence of alpha (B1.1.1.7) and its progressive substitution with the delta variant (B1.617.2). Many delta infections occurred in patients already recently vaccinated.Our study aimed to observe the clinical outcome of patients treated with mAbs associations in a subgroup in which viral isolation was obtained, the pre and post-infusion neutralizing antibody activity against their viral isolate. Methods: In this retrospective observational study, the clinical outcome before and 30 days after infusion, the baseline neutralizing activity of sera against their viral isolate, and the titers of neutralizing antibodies (NAbTs) one-hour post-infusion relative to the type of mAbs associations were evaluated. Results: Better efficacy of the mAbs combinations relative to monotherapy regarding global hospitalization (p = 0.021) and 30 days symptoms (p<0.001) were seen. Infections after vaccination mostly occurred in the absence of neutralizing antibody titers (NAbT). SARS-CoV-2 delta variants were isolated within 2-4 months from vaccinations without NAbTs, or in the presence of high specific neutralizing activity after 5-6 months. NAbTs were higher after casirivimab/imdevimab infusion (p=0.001). Conclusions: Alpha infections occurred prevalently in unvaccinated patients or after 5-6 months, while delta infections prevailed in vaccinated ones. A poor neutralizing activity in most of these patients was seen. A higher NAbT after infusion of casirivimab/imdevimab was observed.
ABSTRACT
BACKGROUND AND OBJECTIVE: The use of monoclonal antibodies to the SARS-Cov-2 spike protein for early treatment of COVID-19 disease is being evaluated, with only phase 2 studies available to date. The emergency authorization of bamlanivimab monotherapy was obtained in November 2020 by the FDA and in March 2021 by Italian agency AIFA. Its use was then revoked in April 2021 by both. This study reports the results of bamlanivimab utilization in monotherapy in Umbria (Italian region) to verify whether, in a population with multiple risk factors, comparable results to the phase 2 BLAZE1 trial had been obtained. METHODS: Between March and April 2021, a retrospective observational study was performed on patients treated with bamlanivimab. Demographic and clinical characteristics before and after infusion were evaluated. Moreover, a telephone interview was conducted about 30 days after the infusion to evaluate the overall course. RESULTS: All patients had an early infection (mean 4±1.73 days), almost all by alpha variant (97%). No adverse events to treatment were observed. Altogether within 30 days, the hospitalization rate was 20%, 15% for COVID-19 related pathologies, versus 4% at 11 days in the BLAZE1 phase 2 study. In addition, worsening of some symptoms observed at baseline such as asthenia (77 vs. 51.3%), shortness of breath (38 vs. 23%) was registered, as well as the onset of non-restorative sleep (41%). CONCLUSION: The clinical outcome after bamlanivimab monotherapy was far below the expectation despite the patients had been infected by a theoretically sensitive viral variant.