Epigenetic signature of ionizing radiation in therapy-related AML patients.

Therapy-related acute myeloid leukaemia (t-AML) is a late side effect of previous chemotherapy (ct-AML) and/or radiotherapy (rt-AML) or immunosuppressive treatment. t-AMLs, which account for ∼10-20 % of all AML cases, are extremely aggressive and have a poor prognosis compared to de novo AML. Our hypothesis is that exposure to radiation causes genome-wide epigenetic changes in rt-AML. An epigenome-wide association study was undertaken, measuring over 850K methylation sites across the genome from fifteen donors (five healthy, five de novo, and five t-AMLs). The study predominantly focussed on 94K sites that lie in CpG-rich gene promoter regions. Genome-wide hypomethylation was discovered in AML, primarily in intergenic regions. Additionally, genes specific to AML were identified with promoter hypermethylation. A two-step validation was conducted, both internally, using pyrosequencing to measure methylation levels in specific regions across fifteen primary samples, and externally, with an additional eight AML samples. We demonstrated that the MEST and GATA5 gene promoters, which were previously identified as tumour suppressors, were noticeably hypermethylated in rt-AML, as opposed to other subtypes of AML and control samples. These may indicate the epigenetic involvement in the development of rt-AML at the molecular level and could serve as potential targets for drug therapy in rt-AML.

Real-Life Multicenter Experience of Venetoclax in Combination with Hypomethylating Agents in Previously Untreated Adult Patients with Acute Myeloid Leukemia in Greece.

BACKGROUND: The landscape of first-line treatment for acute myeloid leukemia (AML) patients ineligible for intensive chemotherapy has changed remarkably after venetoclax approval. Accumulating real-world data further apprises us with more knowledgeable use. To assess the efficacy and safety challenges in the real-life setting of the combination of hypomethylated agent (HMA) and venetoclax, we conducted a multi-center retrospective study. METHODS: Forty adult AML patients treated with the combination of HMA and venetoclax as a first-line treatment after full approval (2020) were included. To confirm VIALE-A results, this group was compared to a historical cohort of 17 chemotherapy-ineligible AML patients treated with HMA monotherapy before 2020. RESULTS: The combination of HMA-venetoclax achieved a composite complete response rate of 86.8% (p < 0.001), median overall survival, and event-free survival of 33.8 and 19.7 months, respectively, in a median follow-up of 17.8 months (pos < 0.001, HR = 0.276, CI: 0.132-0.575, pEFS = 0.004, HR = 0.367, CI: 0.174-0.773). High rates of neutropenia (90%) and consequent infection rates (57.5%) were noted. Only 55% of our patients received antifungal prophylaxis, as its use remains controversial, and invasive fungal infections were presented in 7.5%. CONCLUSIONS: Evidently, venetoclax-HMA yields high response rates and profound survival benefits in real life and has changed our approach to alternative chemotherapy options.

miRNA-Based Technologies in Cancer Therapy.

The discovery of therapeutic miRNAs is one of the most exciting challenges for pharmaceutical companies. Since the first miRNA was discovered in 1993, our knowledge of miRNA biology has grown considerably. Many studies have demonstrated that miRNA expression is dysregulated in many diseases, making them appealing tools for novel therapeutic approaches. This review aims to discuss miRNA biogenesis and function, as well as highlight strategies for delivering miRNA agents, presenting viral, non-viral, and exosomic delivery as therapeutic approaches for different cancer types. We also consider the therapeutic role of microRNA-mediated drug repurposing in cancer therapy.

Bone Marrow Iron Stores Are Not Associated with Increased Risk for Invasive Fungal Infections in Patients with Newly Diagnosed Acute Leukemia or Myelodysplastic Syndrome in Transformation: Is There a Relationship?

Iron plays an important role in the pathogenesis of infections, including invasive fungal infections (IFIs). Studies suggested that iron overload might represent an additional risk factor for IFIs among patients with hematological malignancies. We conducted a prospective, multi-center study amongst adult patients with newly diagnosed acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) in transformation to determine whether baseline iron overload as measured using the bone marrow iron store (BMIS) score is an independent risk factor for the development of IFIs. We also measured baseline serum iron and ferritin levels. A total of 98 patients were enrolled (76 with AML) and were followed for 12 months. Twenty-two patients developed IFI during the follow-up period (invasive aspergillosis n = 16, candidemia n = 5, mucormycosis n = 1). A baseline BMIS score ≥ 3 indicated that iron overload was relatively common (38/98 patients, 38%), and its frequency was comparable between patients with no IFIs (31/76, 40.7%) and in those with IFIs (8/22, 36.4%). Univariate analysis showed that only the presence of AML was associated with increased risk for IFIs [OR (95% CI) 7.40 (1.05-325.42)]. Both univariate and multivariate analyses showed that an increased BMIS score (≥3) at baseline was not an independent risk factor for IFIs. Similarly, there was no difference in serum iron and ferritin between the two groups that had similar demographic characteristics. Indices of iron overload were not independent risk factors for IFIs in our cohort of Greek patients with newly diagnosed AML/MDS in transformation.

Reduced Antibodies and Innate Cytokine Changes in SARS-CoV-2 BNT162b2 mRNA Vaccinated Transplant Patients With Hematological Malignancies.

Immunocompromised individuals including patients with hematological malignancies constitute a population at high risk of developing severe disease upon SARS-CoV-2 infection. Protection afforded by vaccination is frequently low and the biology leading to altered vaccine efficacy is not fully understood. A patient cohort who had received bone marrow transplantation or CAR-T cells was studied following a 2-dose BNT162b2 mRNA vaccination and compared to healthy vaccine recipients. Anti-Spike antibody and systemic innate responses were compared in the two vaccine cohorts. The patients had significantly lower SARS-CoV-2 Spike antibodies to the Wuhan strain, with proportional lower cross-recognition of Beta, Delta, and Omicron Spike-RBD proteins. Both cohorts neutralized the wildtype WA1 and Delta but not Omicron. Vaccination elicited an innate cytokine signature featuring IFN-γ, IL-15 and IP-10/CXCL10, but most patients showed a diminished systemic cytokine response. In patients who failed to develop antibodies, the innate systemic response was dominated by IL-8 and MIP-1α with significant attenuation in the IFN-γ, IL-15 and IP-10/CXCL10 signature response. Changes in IFN-γ and IP-10/CXCL10 at priming vaccination and IFN-γ, IL-15, IL-7 and IL-10 upon booster vaccination correlated with the Spike antibody magnitude and were predictive of successful antibody development. Overall, the patients showed heterogeneous adaptive and innate responses with lower humoral and reduced innate cytokine responses to vaccination compared to naïve vaccine recipients. The pattern of responses described offer novel prognostic approaches for potentiating the effectiveness of COVID-19 vaccination in transplant patients with hematological malignancies.

Characterizing Kinetics and Avidity of SARS-CoV-2 Antibody Responses in COVID-19 Greek Patients.

In-depth understanding of the immune response provoked by SARS-CoV-2 infection is necessary, as there is a great risk of reinfection and a difficulty in achieving herd immunity due to a decline in both antibody concentration and avidity. Avidity testing, however, could overcome variability in the immune response associated with sex or clinical symptoms, and thus differentiate between recent and past infections. In this context, here, we analyzed SARS-CoV-2 antibody kinetics and avidity in Greek hospitalized (26%) and non-hospitalized (74%) COVID-19 patients (N = 71) in the course of up to 15 months after their infection to improve the accuracy of the serological diagnosis in dating the onset of the infection. The results showed that IgG-S1 levels decline significantly at four months (p = 0.0239) in both groups of patients and are higher in hospitalized ones (up to 2.1-fold, p < 0.001). Additionally, hospitalized patients' titers drop greatly and are equalized to non-hospitalized ones only at a time-point of twelve to fifteen months. Antibody levels of women in total remain more stable months after infection, compared to men. Furthermore, we examined the differential maturation of IgG avidity after SARS-CoV-2 infection, showing an incomplete maturation of avidity that results in a plateau at four months after infection. We also defined 38.2% avidity (sensitivity: 58.9%, specificity: 90.91%) as an appropriate "cut-off" that could be used to determine the stage of infection before avidity reaches a plateau.

Evaluation of the Dynamiker® Fungus (1-3)-ß-D-Glucan Assay for the Diagnosis of Invasive Aspergillosis in High-Risk Patients with Hematologic Malignancies.

INTRODUCTION: The Dynamiker® Fungus (1-3)-ß-D-glucan assay (DFA) allows the testing of samples in smaller batches compared to the well-established Fungitell® assay (FA) making the assay cost-effective in centers with small numbers of samples. Evaluations of its performance for the diagnosis of invasive aspergillosis (IA) are limited. Therefore, we compared the two assays and evaluated their clinical performance in diagnosing IA. METHODS: A total of 60 adult hematology patients were screened for IA, 13 with probable IA, 19 with possible IA, and 28 with no IA. Serum specimens (n = 166) were collected twice-weekly and tested for (1-3)-ß-D-glucan (BDG) using FA and DFA which were compared quantitatively with Spearman rank correlation analysis and qualitatively with the Chi-square test. Agreement and error rates were determined using FA as the reference method. Sensitivity, specificity, and positive predictive and negative predictive values in diagnosing IA were calculated. RESULTS: The performance of the DFA was highly consistent with that of the FA, both quantitatively (rs = 0.913) and qualitatively (kappa = 0.725). The agreement was 85% with 8% minor, no major, and 7% very major errors (FA+/DFA-). Using a cut-off value of 20 pg/mL for DFA, very major errors were reduced to 1%, although 5% major errors were detected. BDG levels were lower with DFA than FA (slope 0.653 ± 0.031). Sensitivity, specificity, positive predictive value, and negative predictive value (NPV) was 67%, 53%, 44%, and 74% for FA, and 53%, 67%, 49%, and 71% for DFA, respectively. The optimal BDG positivity threshold calculated did not lead to significant test quality improvement for either assay. However, a higher % of patients with probable IA (62%) had ≥ 2 consecutive positive specimens compared to patients with no IA (FA-BDG 26%, p = 0.10, and DFA-BDG 10%, p = 0.01) leading to improved sensitivity and NPV (71% and 85% for DFA, and 95% and 96% for FA, respectively). CONCLUSION: DFA could be a valuable alternative to the FA, particularly in laboratories with small numbers of samples. The results of the BDG testing should be carefully interpreted in the high-risk setting of patients with hematologic malignancies. Higher NPV was found using as criterion ≥ 2 consecutive positive samples for diagnosing IA.

Convalescent plasma therapy in an immunocompromised patient with multiple COVID-19 flares: a case report.

Convalescent plasma (CP) transfusion has been utilized as a salvage therapy in immunocompromised patients with severe COVID-19 pneumonia. We describe the case of a 45-year-old immunocompromised patient, who received CP, in order to control multiple COVID-19 flares and prolonged SARS-CoV-2 viraemia lasting for 2 months after the initial diagnosis.

6-month follow-up of VIALE-C demonstrates improved and durable efficacy in patients with untreated AML ineligible for intensive chemotherapy (141/150).

VIALE-C compared the safety and efficacy of venetoclax or placebo plus low-dose cytarabine (+LDAC) in patients with untreated AML ineligible for intensive chemotherapy. Overall, 211 patients were enrolled (n = 143, venetoclax; n = 68, placebo). At the primary analysis, the study did not meet its primary endpoint of a statistically significant improvement in overall survival (OS), however, ~60% of patients had been on study for ≤6-months. Here, we present an additional 6-months of follow-up of VIALE-C (median follow-up 17.5 months; range 0.1-23.5). Median OS was (venetoclax +LDAC vs. placebo +LDAC) 8.4 vs. 4.1 months (HR = 0.70, 95% CI 0.50,0.99; P = 0.040); a 30% reduction in the risk of death with venetoclax. Complete response (CR)/CR with incomplete hematologic recovery (CRi) rates were 48.3% vs. 13.2%. Transfusion independence rates (RBC) were 43% vs.19% and median event-free survival was 4.9 vs. 2.1 months (HR = 0.61; 95% CI 0.44,0.84; P = 0.002). These results represent improved efficacy over the primary analysis. Incidence of grade ≥3 adverse events were similar between study arms and overall safety profiles were comparable to the primary analysis. These data support venetoclax +LDAC as a frontline treatment option for patients with AML ineligible for intensive chemotherapy.This trial was registered at www.clinicaltrials.gov as #NCT03069352.

Demographic, Clinical and Immunogenetic Profiles of a Greek Cohort of COVID-19 Patients.

The present cross-sectional study consists of a comprehensive analysis of epidemiological, laboratory, and clinical characteristics of COVID-19 patients in relation to their immunogenetic profiles. We studied 125 COVID-19 patients comprising different stages of disease severity; non-hospitalized (mild n = 69) and hospitalized (n = 56). Analysis of disease characteristics revealed no major differences between males and females of each group of patients while hospitalized patients were older and presented with comorbidities. A positive allele association was observed for HLA-DRB1*01 in total COVID-19 patients versus healthy controls. Subgrouping of COVID-19 patients in mild and hospitalized further identified a statistically significant increase in HLA-DRB1*01 in mild COVID-19 patients versus controls. The frequency of A*11, A*23, and DRB1*09 alleles was higher, while the frequency of C*12 was lower, in hospitalized patients versus healthy controls albeit with uncorrected statistical significance. The identification of specific allele associations may provide useful future markers for disease susceptibility in order to allow successful clinical management of COVID-19 patients.

Poor Neutralizing Antibody Responses in 132 Patients with CLL, NHL and HL after Vaccination against SARS-CoV-2: A Prospective Study.

Emerging data suggest suboptimal antibody responses to COVID-19 vaccination in patients with hematological malignancies. We evaluated the humoral response following the BNT162b2 vaccine in patients with chronic lymphocytic leukemia (CLL), non-Hodgkin's lymphoma (NHL), and Hodgkin's lymphoma (HL). An FDA-approved, ELISA-based methodology was implemented to evaluate the titers of neutralizing antibodies (NAbs) against SARS-CoV-2 on day 1 of the first vaccine, and afterwards on day 22 and 50. One hundred and thirty-two patients with CLL/lymphomas and 214 healthy matched controls vaccinated during the same period, at the same center were enrolled in the study (NCT04743388). Vaccination with two doses of the BNT162b2 vaccine led to lower production of NAbs against SARS-CoV-2 in patients with CLL/lymphomas compared with controls both on day 22 and on day 50 (p < 0.001 for all comparisons). Disease-related immune dysregulation and therapy-related immunosuppression are involved in the low humoral response. Importantly, active treatment with Rituximab, Bruton's tyrosine kinase inhibitors, or chemotherapy was an independent prognostic factor for suboptimal antibody response. Patients with HL showed superior humoral responses to the NHL/CLL subgroups. In conclusion, patients with CLL/lymphomas have low humoral response following COVID-19 vaccination, underlining the need for timely vaccination ideally during a treatment-free period and for continuous vigilance on infection control measures.

Kinetics of Nucleocapsid, Spike and Neutralizing Antibodies, and Viral Load in Patients with Severe COVID-19 Treated with Convalescent Plasma.

COVID-19 is an ongoing pandemic with high morbidity and mortality. Despite meticulous research, only dexamethasone has shown consistent mortality reduction. Convalescent plasma (CP) infusion might also develop into a safe and effective treatment modality on the basis of recent studies and meta-analyses; however, little is known regarding the kinetics of antibodies in CP recipients. To evaluate the kinetics, we followed 31 CP recipients longitudinally enrolled at a median of 3 days post symptom onset for changes in binding and neutralizing antibody titers and viral loads. Antibodies against the complete trimeric Spike protein and the receptor-binding domain (Spike-RBD), as well as against the complete Nucleocapsid protein and the RNA binding domain (N-RBD) were determined at baseline and weekly following CP infusion. Neutralizing antibody (pseudotype NAb) titers were determined at the same time points. Viral loads were determined semi-quantitatively by SARS-CoV-2 PCR. Patients with low humoral responses at entry showed a robust increase of antibodies to all SARS-CoV-2 proteins and Nab, reaching peak levels within 2 weeks. The rapid increase in binding and neutralizing antibodies was paralleled by a concomitant clearance of the virus within the same timeframe. Patients with high humoral responses at entry demonstrated low or no further increases; however, virus clearance followed the same trajectory as in patients with low antibody response at baseline. Together, the sequential immunological and virological analysis of this well-defined cohort of patients early in infection shows the presence of high levels of binding and neutralizing antibodies and potent clearance of the virus.

SARS-CoV-2 antibody kinetics eight months from COVID-19 onset: Persistence of spike antibodies but loss of neutralizing antibodies in 24% of convalescent plasma donors.

Elucidating the characteristics of human immune response against SARS-CoV-2 is of high priority and relevant for determining vaccine strategies. We report the results of a follow-up evaluation of anti-SARS-CoV-2 antibodies in 148 convalescent plasma donors who participated in a phase 2 study at a median of 8.3 months (range 6.8-10.5 months) post first symptom onset. Monitoring responses over time, we found contraction of antibody responses for all four antigens tested, with Spike antibodies showing higher persistence than Nucleocapsid antibodies. A piecewise linear random-effects multivariate regression analysis showed a bi-phasic antibody decay with a more pronounced decrease during the first 6 months post symptoms onset by analysis of two intervals. Interestingly, antibodies to Spike showed better longevity whereas their neutralization ability contracted faster. As a result, neutralizing antibodies were detected in only 76% of patients at the last time point. In a multivariate analysis, older age and hospitalization were independently associated with higher Spike, Spike-RBD, Nucleocapsid, N-RBD antibodies and neutralizing antibody levels. Results on persistence and neutralizing ability of anti-SARS-CoV-2 antibodies, especially against Spike and Spike-RBD, should be considered in the design of future vaccination strategies.

A Phase II Study on the Use of Convalescent Plasma for the Treatment of Severe COVID-19- A Propensity Score-Matched Control Analysis.

COVID-19 is a global pandemic associated with increased morbidity and mortality. Convalescent plasma (CP) infusion is a strategy of potential therapeutic benefit. We conducted a multicenter phase II study to evaluate the efficacy and safety of CP in patients with COVID-19, grade 4 or higher. To evaluate the efficacy of CP, a matched propensity score analysis was used comparing the intervention (n = 59) to a control group (n = 59). Sixty patients received CP within a median time of 7 days from symptom onset. During a median follow-up of 28.5 days, 56/60 patients fully recovered and 1 patient remained in the ICU. The death rate in the CP group was 3.4% vs. 13.6% in the control group. By multivariate analysis, CP recipients demonstrated a significantly reduced risk of death [HR: 0.04 (95% CI: 0.004-0.36), p: 0.005], significantly better overall survival by Kaplan-Meir analysis (p < 0.001), and increased probability of extubation [OR: 30.3 (95% CI: 2.64-348.9), p: 0.006]. Higher levels of antibodies in the CP were independently associated with significantly reduced risk of death. CP infusion was safe with only one grade 3 adverse event (AE), which easily resolved. CP used early may be a safe and effective treatment for patients with severe COVID-19 (trial number NCT04408209).

Performance, Correlation and Kinetic Profile of Circulating Serum Fungal Biomarkers of Invasive Aspergillosis in High-Risk Patients with Hematologic Malignancies.

As conventional microbiological documentation of invasive aspergillosis (IA) is difficult to obtain, serum fungal biomarkers are important adjunctive diagnostic tools. Positivity rates and the kinetic profiles of galactomannan (GM), 1,3-ß-D-glucan (BDG) and Aspergillus DNA (PCR) were studied in high-risk patients with hematologic malignancies. GM, BDG and PCR data from serial serum specimens (n = 240) from 93 adult hematology patients with probable (n = 8), possible (n = 25) and no (n = 60) IA were retrospectively analyzed. Positivity rates and sensitivity/specificity/positive/negative predictive values (NPV) of each fungal biomarker alone and in combination were estimated. The three markers were compared head-to-head and correlated with various biochemical, demographic and patient characteristics. The positivity rates for patients with probable/possible/no IA were 88%/8%/0% for GM (X2 = 55, p < 0.001), 62%/46%/35% for BDG (X2 = 2.5, p = 0.29), 62%/33%/27% for PCR (X2 = 3.9, p = 0.15), 50%/4%/0% for GM + BDG and GM + PCR (X2 = 31, p < 0.001), 50%/8%/22% for BDG + PCR (X2 = 6.5, p = 0.038) and 38%/4%/0% for GM + BDG + PCR (X2 = 21, p < 0.001). Higher agreement (76%) and negative correlation (rs = -0.47, p = 0.0017) was found between GM index and PCR Ct values. The sensitivity and NPV was 45-55% and 90-92% when biomarkers assessed alone and increased to 75-90% and 93-97%, respectively when combined. Weak significant correlations were found between GM, PCR and BDG results with renal/liver function markers (r = 0.11-0.57) with most GM+ and PCR+ samples found in the first and second week of clinical assessment, respectively and BDG later on. Different positivity rates, time profiles and performances were found for the three biomarkers advocating the combination of GM with PCR for the early diagnosis of IA, whereas the high NPV of combined biomarkerscould help excluding IA.

A Prospective Multicenter Cohort Surveillance Study of Invasive Aspergillosis in Patients with Hematologic Malignancies in Greece: Impact of the Revised EORTC/MSGERC 2020 Criteria.

Data concerning the incidence of invasive aspergillosis (IA) in high-risk patients in Greece are scarce, while the impact of the revised 2020 EORTC/MSGERC consensus criteria definitions on the reported incidence rate of IA remains unknown. A total of 93 adult hematology patients were screened for IA for six months in four tertiary care Greek hospitals. Serial serum specimens (n = 240) the sample was considered negative by PCR were collected twice-weekly and tested for galactomannan (GM) and Aspergillus DNA (PCR) detection. IA was defined according to both the 2008 EORTC/MSG and the 2020 EORTC/MSGERC consensus criteria. Based on the 2008 EORTC/MSG criteria, the incidence rates of probable and possible IA was 9/93 (10%) and 24/93 (26%), respectively, while no proven IA was documented. Acute myeloid leukemia was the most (67%) common underlying disease with most (82%) patients being on antifungal prophylaxis/treatment. Based on the new 2020 EORTC/MSGERC criteria, 2/9 (22%) of probable and 1/24 (4%) of possible cases should be reclassified as possible and probable, respectively. The episodes of probable IA were reduced by 33% when GM alone and 11% when GM + PCR were used as mycological criterion. The incidence rate of IA in hematology patients was 10%. Application of the 2020 EORTC/MSGERC updated criteria results in a reduction in the classification of probable IA particularly when PCR is not available.

Identification of two novel mutations in human acute myeloid leukemia cases.

Acute myeloid leukemia (AML) is an aggressive cancer that progresses rapidly with a poor prognosis. Cytogenetic analysis provides the most accurate determination of diagnosis and prognosis however, about 42-48% of AML patients have a cytogenetically normal karyotype. Genetic analysis can provide further information and the identification of new mutations could result in improved risk stratification, prognosis and better understanding of the mechanisms of AML leukaemogenesis. In this study, we analyzed genetic alterations in 16 human AML cases by Haloplex sequencing with confirmation of two previously unreported mutations in the genes DNMT3A and RUNX1 by Sanger sequencing or pyrosequencing. The two novel mutations consist of two frameshift mutations identified in two different AML patients and reported as deleterious by bioinformatic analysis. These mutations confirm the exclusion and co-occurrence of specific gene mutation patterns in AML and may provide further information for patient diagnosis and prognosis.

Anti-SARS-CoV-2 Antibody Responses in Convalescent Plasma Donors Are Increased in Hospitalized Patients; Subanalyses of a Phase 2 Clinical Study.

We evaluated the antibody responses in 259 potential convalescent plasma donors for Covid-19 patients. Different assays were used: a commercial ELISA detecting antibodies against the recombinant spike protein (S1); a multiplex assay detecting total and specific antibody isotypes against three SARS-CoV-2 antigens (S1, basic nucleocapsid (N) protein and receptor-binding domain (RBD)); and an in-house ELISA detecting antibodies to complete spike, RBD and N in 60 of these donors. Neutralizing antibodies (NAb) were also evaluated in these 60 donors. Analyzed samples were collected at a median time of 62 (14-104) days from the day of first symptoms or positive PCR (for asymptomatic patients). Anti-SARS-CoV-2 antibodies were detected in 88% and 87.8% of donors using the ELISA and the multiplex assay, respectively. The multivariate analysis showed that age ≥50 years (p < 0.001) and need for hospitalization (p < 0.001) correlated with higher antibody titers, while asymptomatic status (p < 0.001) and testing >60 days after symptom onset (p = 0.001) correlated with lower titers. Interestingly, pseudotype virus-neutralizing antibodies (PsNAbs) significantly correlated with spike and with RBD antibodies by ELISA. Sera with high PsNAb also showed a strong ability to neutralize active SARS-CoV-2 virus, with hospitalized patients showing higher titers. Therefore, convalescent plasma donors can be selected based on the presence of high RBD antibody titers.