COVAXIDa prospective clinical trial on mRNA vaccination (BNT162b2) against SARS-CoV- 2 in patients with immunodeficiency: Results from the CLL cohort

ABSTRACT

Background and study design: Patients with immunodeficiencies including CLL have an increased risk of severe infections and may not respond well to conventional vaccines. Two early international surveys reported that hospital-admitted Covid-19 patients with CLL had a high fatality rate (Mato et al., 2020;Scarfo et al., 2020). We recently showed that a robust and durable B and/or T cell immunity occurred in most convalescent CLL patients (Blixt et al., 2021). In contrast, the first publication on vaccination against SARS-CoV-2 in CLL reported seroconversion in only 39.5% of patients (Herishanu et al., 2021). We conducted a prospective clinical trial (COVAXID, clinicaltrials.gov NCT04780659) in patients with various types of immunodeficiency and matched controls (n=539). Five equally sized cohorts were included primary immunodeficiency, HIV, allogeneic transplantation or CAR-T, solid organ transplantation as well as CLL. The primary endpoint was seroconversion measured 2 weeks after the 2nd dose of the Pfizer-BioNTech vaccine (Comirnaty). Antispike antibodies in saliva (which may better correlate with protection, Khoury et al., 2020) and T cells (IFN-gamma ELISpot) were also measured. We report here the results of the CLL cohort. Results: Ninety CLL patients were included in four predefined subgroups indolent untreated disease (n=30);prior chemoimmunotherapy including a CD20 mAb 9-30 months ago (n=20);ongoing BTKi therapy (n=30);and stopped/paused ibrutinib (all >3 months ago) (n=10). The median age was 70 years (range 23-87) and 67% were men. Median IgG was 6.7 g/L (range 1.0-20.8) and 50% had a value below the lower normal range. Reactogenicity occurred in 82.9 and 77.1% of the CLL patients and 81.6 and 85.0% of the controls after doses 1 and 2, respectively. The severity of reactogenicity was similar in patients and controls. AEs≥grade 2 was seen in five patients within 2 weeks after dose 2 but none was considered related to the vaccine. No hematological toxicity was observed. Data analysis on seroconversion is ongoing. Preliminary analysis of saliva showed that on D35 (i.e. 14 days after 2nd dose) 62% of CLL patients (95% of healthy controls) had developed IgG to S1S2 spike antigen compared to only 23% on D21 (i.e. 21 days after dose 1). Subgroup analysis (D35) indicates that ibrutinib-treated patients showed the lowest response in saliva whilst indolent and prior chemoimmunotherapy-treated groups were the best responders. A different pattern was observed for IFNgamma positive T cells with the highest responses in the (few) patients who had paused/stopped ibrutinib with other subgroups having lower T cell responses. Conclusions: This prospective clinical trial verified that the BNT162b2 mRNA vaccine was well-tolerated in patients with CLL. Our preliminary results indicate that anti-spike antibodies in saliva and T cell responses were frequently observed after full vaccination but with different response patterns in CLL subgroups. Details of the study including seroconversion and the overall response rate will be presented at the meeting.