Absence of severe COVID-19 in patients with clonal mast cells activation disorders: effective anti-SARS-CoV-2 immune response. (preprint)

Mast cells are key actors of innate immunity and Th2 adaptive immune response which counterbalance Th1 response, critical for anti-viral immunity. Clonal Mast Cells Activation Disorders (cMCADs) such as mastocytosis and clonal mast cells activation syndrome are characterized by an abnormal mast cells accumulation and/or activation. No data have been published on the anti-viral immune response of patients with cMCADs. The aims of the study were to collected, in a comprehensive way, outcomes of cMCADs patients who experienced a biologically-proven COVID-19 and to characterize both anti-endemic coronaviruses and specific anti-SARS-CoV-2 immune responses in these patients. Clinical follow-up and outcome data were collected prospectively for one year within the French rare disease network CEREMAST encompassing patients from all over the country. Anti-SARS-CoV-2 and anti-endemic coronaviruses specific T-cells were assessed with an enzyme-linked immunospot assay (EliSpot) and anti-SARS-CoV-2 humoral response with dosage of circulating levels of specific IgG, IgA and neutralizing antibodies. Overall, 32 cMCADs patients were identified. None of them required non-invasive or mechanical ventilation; two patients were hospitalized to receive oxygen and steroid therapy. In 21 patients, a characterization of the SARS-CoV-2-specific immune response has been performed. A majority of patients showed a high proportion of circulating SARS-CoV-2-specific interferon (IFN)-{gamma} producing T-cells and high levels of anti-Spike IgG antibodies with neutralizing activity. In addition, no defects in anti-endemic coronaviruses responses were found in patients with cMCADs compared to non-cMCADs controls. Patients with cMCADs frequently showed a spontaneous IFN-{gamma} T-cell production in absence of any stimulation that correlated with circulating basal tryptase levels, a marker of mast cells burden. These findings underscore that patients with cMCADs might be not at risk of severe COVID-19 and the spontaneous IFN-{gamma} production might explain this observation. Author SummaryMast cells are immune cells involved in many biological processes including the anti-microbial response. However, previous studies suggest that mast cells may have a detrimental role in the response against viruses such as SARS-CoV-2, responsible for COVID-19. When a mutation occurs in mast cells, it can lead to a group of diseases called clonal mast cells activation disorders (cMCADs), characterized by deregulated activation of these cells. Hence, patients with cMCADs might be more susceptible to severe COVID-19 than general population. We therefore conducted a 1-year study in France to collect data from all cMCADs patients included in the CEREMAST rare disease French network and who experienced COVID-19. Interestingly, we did not find any severe COVID-19 (i.e. requiring non-invasive or mechanical ventilation) in spite of well-known risk factors for severe COVID-19 in a part of cMCADs patients. We then have studied the immune response against SARS-CoV-2 and other endemic coronaviruses in these patients. We did not observe any abnormalities in the immune response either at the level of T and B lymphocytes. These findings underscore that these patients might not be at risk of severe COVID-19 as one might have feared.

Anti-CD38 therapy impairs SARS-CoV-2 vaccine response in multiple myeloma patients (preprint)

Multiple myeloma (MM) patients are at risk of fatal outcome after SARS-CoV-2 infection. Preliminary data suggest that MM patients have an impaired response to vaccination. This prospective study analyzed the humoral and cellular immune responses to two doses of BNT162b2 in 72 MM patients, including 48 receiving anti-CD38 immunotherapy. Results evidenced that MM patients display lower levels of SARS-CoV-2 specific IgG and IgA antibodies and decreased neutralization of alpha and delta variants when compared to healthy controls. They also showed decreased numbers of circulating IFN{gamma}-producing Spike SARS-CoV-2 specific T lymphocytes. This defective immune response was particularly marked in patients receiving anti-CD38 immunotherapy. Furthermore, a retrospective investigation of MM patients among COVID-19-related death in the Paris area suggested a limited efficacy of BNT162b2 in patients treated with anti-CD38. Overall, these results show a decreased immunogenicity of BNT162b2 in MM patients and stress the need for novel strategies to improve SARS-CoV-2 prophylaxis in immunocompromised individuals.

Immunogenicity of BNT162b2 vaccine Against the Alpha and Delta Variants in Immunocompromised Patients (preprint)

BackgroundThe emergence of strains of SARS-CoV-2 exhibiting increase viral fitness and immune escape potential, such as the Delta variant (B.1.617.2), raises concerns in immunocompromised patients. To what extent Delta evades vaccine-induced immunity in immunocompromised individuals with systemic inflammatory diseases remains unclear. MethodsWe conducted a prospective study in patients with systemic inflammatory diseases (cases) and controls receiving two doses of BNT162b2. Primary end points were anti-spike antibodies levels and cross-neutralization of Alpha and Delta variants after BNT162b2 vaccine. Secondary end points were T-cell responses, breakthrough infections and safety. ResultsSixty-four cases and 21 controls not previously infected with SARS-CoV-2 were analyzed. Kinetics of anti-spike IgG and IgA after BNT162b2 vaccine showed lower and delayed induction in cases, more pronounced with rituximab. Administration of two doses of BNT162b2 generated a neutralizing response against Alpha and Delta in 100% of controls, while sera from only one of rituximab-treated patients neutralized Alpha (5%) and none Delta. Other therapeutic regimens induced a partial neutralizing activity against Alpha, even lower against Delta. All controls and cases except those treated with methotrexate mounted a SARS-CoV-2 specific T-cell response. Methotrexate abrogated T-cell responses after one dose and dramatically impaired T-cell responses after 2 doses of BNT162b2. ConclusionsRituximab and methotrexate differentially impact the immunogenicity of BNT162b2, by impairing B-cell and T-cell responses, respectively. Delta fully escapes the humoral response of individuals treated with rituximab. These findings support efforts to improve BNT162b2 immunogenicity in immunocompromised individuals (Funded by the Fonds IMMUNOV; ClinicalTrials.gov number, NCT04870411).