To account for imbalanced groups, the synthetic minority oversampling technique (SMOTE, Python package imblearn 0.8.0) was utilized in combination with the RCF method. Development of escape mutants also strongly correlated with neutralizing capacity of the therapeutic mAbs and T cell immunity, suggesting immune pressure as an important driver of escape mutations. Lastly, we showed that an antiinflammatory and healing-promoting host milieu facilitates Spike mutations, where 4 CIBs identified patients at high risk of developing escape mutations against therapeutic mAbs with high accuracy. == Conclusions == Our data demonstrate that host-driven immune and nonimmune responses are essential for development of mutant SARS-CoV-2. These data also support point-of-care decision making in reducing the risk of mAb treatment failure and improving mitigation strategies for possible dissemination of escape SARS-CoV-2 mutants. == Funding == The ORCHESTRA project/European Unions Horizon 2020 research and innovation program. Keywords:COVID-19 Keywords:Cellular immune response == Introduction PI3k-delta inhibitor 1 == The coronavirus replication machinery encodes proofreading functions that result in fewer errors compared with other RNA viruses; however, multiple SARS-CoV-2 variants of concern (VOCs) have emerged throughout the pandemic carrying VOC-defining mutations. For example, Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta, Zeta, Eta, Theta, Iota, and Omicron variants have been shown to carry distinct sets of mutations that evade existing natural neutralizing antibody responses (14). SARS-CoV-2 mutation rates are higher in immunocompromised or severely ill patients who show prolonged SARS-CoV-2 infections or carriage (512). Immunocompromised individuals are also unable to develop sufficient antibody titers after administration of COVID-19 vaccines. To tackle this, synthetic neutralizing monoclonal antibodies (mAbs) against SARS-CoV-2 targeting the Spike (S) protein have been developed that demonstrate clinical benefit for mild-to-moderately ill COVID-19 patients at high risk of developing severe disease (1320). For example, the first widely available mAb, bamlanivimab, which targets an epitope around the receptor-binding domain E.coli polyclonal to V5 Tag.Posi Tag is a 45 kDa recombinant protein expressed in E.coli. It contains five different Tags as shown in the figure. It is bacterial lysate supplied in reducing SDS-PAGE loading buffer. It is intended for use as a positive control in western blot experiments name (RBD), led to a reduced rate of hospitalization, ICU admission, and mortality compared with usual care (21). The addition of etesevimab to bamlanivimab resulted in improved clinical outcomes due to overlapping binding epitopes within the RBD of the S protein, concomitant with the emergence of SARS-CoV-2 VOCs, mainly B.1.351 and P.1 (22). PI3k-delta inhibitor 1 The PI3k-delta inhibitor 1 success of combination mAb therapy and decreasing efficacies against emerging variants led to use of casirivimab/imdevimab, with distinct binding sites in S RBD, in at-risk populations, resulting in decreased rates of hospitalization (23). As the pandemic evolved and new VOCs were identified, sotrovimab was developed with a modified Fc domain name along with an increased half-life (13,14). Recently, an intramuscularly administered combination of noncompeting antibodies tixagevimab and cilgavimab, again with distinct binding sites, has also been introduced in patient care (16). These modifications target highly conserved S epitopes, causing conformational transitions necessary for association with the receptor angiotensin-converting enzyme 2 (ACE2) (15,16), resulting in reduced risk of disease progression and death (13,24). Several reports have also identified de novo mutations under therapeutic mAb pressure, including E484Q/K and Q493K/R under bamlanivimab/etesevimab pressure (2527) and P337R/S, E340D/K/V, and G446S/V under casirivimab/imdevimab and/or sotrovimab pressure (2831). However, despite the widespread use of mAbs, these studies are rather few PI3k-delta inhibitor 1 and were conducted in limited patient numbers. Moreover, to our knowledge the role of host immune pressure in selection of mAb-driven de novo SARS-CoV-2 S RBD mutations has not been explored so far. Here, we characterize the development of SARS-CoV-2 S RBD mutations in patients treated with bamlanivimab, bamlanivimab/etesevimab, casirivimab/imdevimab, or sotrovimab in relation to their neutralization potential against SARS-CoV-2 VOCs. We focus on natural humoral and cellular host immunity, including responses mediated by cytokines and other correlates PI3k-delta inhibitor 1 of adaptive evolution. == Results == == Immunocompromised COVID-19 patients.