Recent data suggest a suboptimal antibody response to COVID-19 vaccination in patients with hematological malignancies. Neutralizing antibodies (NAbs) against SARS-CoV-2 were evaluated in 276 patients with plasma cell neoplasms after vaccination with either the BNT162b2 or the AZD1222 vaccine, on days 1 (before the first vaccine shot), 22, and 50. Patients with MM (n = 213), SMM (n = 38), and MGUS (n = 25) and 226 healthy controls were enrolled in the study (NCT04743388). Vaccination with either two doses of the BNT162b2 or one dose of the AZD1222 vaccine leads to lower production of NAbs in patients with MM compared with controls both on day 22 and on day 50 (p < 0.001 for all comparisons). Furthermore, MM patients showed an inferior NAb response compared with MGUS on day 22 (p = 0.009) and on day 50 (p = 0.003). Importantly, active treatment with either anti-CD38 monoclonal antibodies (Mabs) or belantamab mafodotin and lymphopenia at the time of vaccination were independent prognostic factors for suboptimal antibody response following vaccination. In conclusion, MM patients have low humoral response following SARS-CoV-2 vaccination, especially under treatment with anti-CD38 or belamaf. This underlines the need for timely vaccination, possibly during a treatment-free period, and for continuous vigilance on infection control measures in non-responders.

The urgency of the COVID-19 pandemic has led to accelerated vaccine development within less than a year. Immunocompromised patients with hematological malignancies are more susceptible to COVID-19 and at higher risk of severe complications and worse outcomes compared with general population. In this context, we evaluated the humoral response by determining the titers of neutralizing antibodies (NAbs) against SARS-CoV-2 in patients with Waldenstrom Macroglobulinemia (WM) after vaccination with the BNT162b2 or AZD1222 vaccine. An FDA-approved, ELISA-based methodology was implemented to evaluate NAbs on the day of the first vaccine shot, as well as on day 22 and 50 afterwards. 106 patients with WM (43% males, median age 73 years) and 212 healthy controls (46% males, median age 66 years) who were vaccinated during the same period, at the same center were enrolled in the study (which is registered at www.clinicaltrials.gov as NCT04743388). Our data indicate that vaccination with either 2 doses of the BNT162b2 or 1 dose of the AZD1222 vaccine leads to lower production of NAbs against SARS-CoV-2 in patients with WM compared with controls both on day 22 and on day 50 (P&lt;0.001 for all comparisons). Disease-related immune dysregulation and therapy-related immunosuppression are involved in the low humoral response. Importantly, active treatment with either Rituximab or Bruton's Tyrosine Kinase inhibitors was proven as an independent prognostic factor for suboptimal antibody response following vaccination. In conclusion, patients with WM have low humoral response following COVID-19 vaccination, which underlines the need for timely vaccination ideally during a treatment-free period and for continuous vigilance on infection control measures.

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Elucidating long-term immunity following COVID-19 vaccination is essential for decision-making regarding booster shots. The aim of this study was to investigate the kinetics of neutralizing antibodies (Nabs) against SARS-CoV-2 up to six months after the second vaccination dose with the BNT162b2 mRNA vaccine. Nabs levels were measured on days 1 (before the first vaccine shot), 8, 22 (before the second shot), 36, 50, and 3 and 6 months after the second vaccination (NCT04743388). Three hundred and eight healthy individuals without malignant disease were included in this study. At six months, 2.59% of the participants had a Nabs value less than 30%, while 11.9% had Nabs values of less than 50%. Importantly, 58% of the subjects had Nabs values of more than 75%. Nabs were initially eliminated at a relatively slow rate, but after three months their elimination was 5.7 times higher. Older age was inversely associated with Nabs levels at all examined timepoints. Interestingly, a population modeling analysis estimated that half of the subjects will have Nabs values less than 73.8% and 64.6% at 9 and 12 months, respectively, post vaccination completion. In conclusion, we found a persistent but declining anti-SARS-CoV-2 humoral immunity at six months following full vaccination with BNT162b2 in healthy individuals, which was more pronounced among older persons. These data may inform the public health policies regarding the prioritization of booster vaccine shots.

Vaccination against SARS-CoV-2 is considered as the most important preventive strategy against COVID-19, but its efficacy in patients with hematological malignancies is largely unknown. We investigated the development of neutralizing antibodies (NAbs) against SARS-CoV-2 in patients with Waldenstrom Macroglobulinemia (WM), Chronic Lymphocytic Leukemia (CLL) and Non-Hodgkin Lymphoma (NHL). After the first dose of the vaccine, on D22, WM/CLL/NHL patients had lower NAb titers compared to controls: the median NAb inhibition titer was 17% (range 0-91%, IQR 8-27%) for WM/CLL/NHL patients versus 32% (range 2-98%, IQR 19-48%) for controls (P < 0.001). Only 8 (14%) patients versus 114 (54%) controls developed NAb titers ≥ 30% on D22 (p < 0.001). Our data indicate that the first dose of both BNT162b2 and AZD1222 leads to lower production of NAbs against SARS-CoV-2 in patients with WM/CLL/NHL compared to controls of similar age and gender and without malignant disease. Even though the response rates were not optimal, vaccination is still considered essential and if possible should be performed before treatment initiation. These patients with suboptimal responses should be considered to be prioritized for booster doses.