Humoral and cellular immunogenicity of SARS-CoV-2 vaccines in chronic lymphocytic leukemia: a prospective cohort study

Abstract

Chronic lymphocytic leukemia (CLL), the most common leukemia worldwide, is associated with increased COVID-19 mortality. Previous studies suggest only a portion of vaccinated CLL patients develop severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike antibodies. Whether the elicited antibodies are functional and/or accompanied by functional T-cell responses is unknown. This prospective cohort study included patients with CLL who received SARS-CoV-2 and PCV13 vaccines (not concurrently). The primary cohort included adults with CLL off therapy. Coprimary outcomes were serologic response to SARS-CoV-2 (receptor binding domain [RBD] immunoassay) and PCV13 vaccines (23-serotype IgG assay). Characterization of SARS-CoV-2 antibodies and their functional activity and assessment of functional T-cell responses was performed. Sixty percent (18/30) of patients demonstrated serologic responses to SARS-CoV-2 vaccination, appearing more frequent among treatment-naïve patients (72%). Among treatment-naïve patients, an absolute lymphocyte count ≤24 000/µL was associated with serologic response (94% vs 14%; P < .001). On interferon-γ release assays, 80% (16/20) of patients had functional spike-specific T-cell responses, including 78% (7/9) with a negative RBD immunoassay, a group enriched for prior B-cell-depleting therapies. A bead-based multiplex immunoassay identified antibodies against wild-type and variant SARS-CoV-2 (α, β, γ, and δ) in all tested patients and confirmed Fc-receptor binding and effector functions of these antibodies. Of 11 patients with negative RBD immunoassay after vaccination, 6 (55%) responded to an additional mRNA-based vaccine dose. The PCV13 serologic response rate was 29% (8/28). Our data demonstrate that SARS-CoV-2 vaccination induces functional T-cell and antibody responses in patients with CLL and provides the framework for investigating the molecular mechanisms and clinical benefit of these responses. This trial was registered at www.clinicaltrials.gov as #NCT05007860.

© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.

Figures

Graphical abstract

Figure 1.

Humoral responses to SARS-CoV-2 vaccination in patients with CLL. (A) Anti–SARS-CoV-2 spike antibody response rate (RBD immunoassay) in patients with CLL not on active therapy (n = 30) by vaccine type and treatment history. One patient developed COVID-19 after enrollment but prior to vaccination and had a >4-fold spike antibody titer increase with vaccination and thus was counted as a response. (B) Distribution of anti–SARS-CoV-2 spike antibody responses in patients not on active therapy. Each circle or bar represents an individual patient and is color coded based on disease history. Dotted line represents RBD immunoassay cutoff for a detectable result (≥0.40 U/mL), with undetectable results (<0.40 U/mL) indicated as circles and results within the measuring interval (≥0.40 to >2500 U/mL) indicated as bars. Caret (^) indicates a serologic response to PCV13. Two patients with positive qualitative spike antibody results are not included here. (C) Distribution of anti–SARS-CoV-2 spike antibody responses (n = 11) following an additional mRNA vaccine dose. Each bar or circle represents an individual patient and is color coded based on disease history. Initial and subsequent SARS-CoV-2 vaccine types (1, Ad26.COV2.S; 2, mRNA-1273; 3, BNT162b2) are indicated on the y-axis, with the subsequent vaccine type placed in brackets after the initial vaccine type. Dotted line represents RBD immunoassay cutoff for a detectable result (≥0.40 U/mL), with undetectable results (<0.40 U/mL) indicated as circles and results within the measuring interval (≥0.40 to >2500 U/mL) indicated as bars. Every patient received 1 additional dose of mRNA vaccine except for patient indicated by an asterisk (*), who received 2 doses. (A-C) Prior treatment refers to CD20 antibody therapy plus venetoclax +/− BTKi within the past 2 years.

Figure 2.

Clinical characteristics associated with SARS-CoV-2 vaccine response. Forest plot of univariable logistic regressions of characteristics associated with a spike serologic response (RBD immunoassay) to SARS-CoV-2 vaccination in patients not on any CLL therapy (n = 30). The odds ratio reflects the presence of the variable compared with the absence.

Figure 3.

SARS-CoV-2 vaccine response by absolute lymphocyte count and treatment history. Spike antibody serologic response value by RBD immunoassay (y-axis) plotted against absolute lymphocyte count and treatment history (x-axis). Each circle corresponds to an individual patient (n = 34). P = .001 by Kruskal–Wallis rank-sum test comparing the distributions of the continuous data among the 4 groups; P < .001 for Wilcoxon rank-sum test comparing 2 groups (treatment-naïve patients with ALC ≤ 24 000/µL vs ALC > 24 000/µL and/or current or prior therapy). Patients enrolled in both cohorts were included in this analysis. Two patients without quantitative spike antibody serologies were not included in the plot.

Figure 4.

SARS-CoV-2 wild-type spike-specific antibody responses in patient with CLL or non-cancer (NC) donor plasma after 2 doses of SARS-CoV-2 mRNA vaccine. (A) SARS-CoV-2 spike-specific plasma IgG1, IgG3, IgM, or IgA titer from vaccinated patients with CLL (V2; n = 21) and NC donors (V2; n = 14) were analyzed with a bead-based multiplex immunoassay, represented as median florescence intensity (MFI) in log10. Antibody titers against Ebola virus glycoprotein (EBOV GP) were used as a negative antigen control readout. WT S, wild-type spike. (B) SARS-CoV-2 spike-specific plasma FcγR2A, FcγR2B, FcγR3A, or FcγR3B titers from vaccinated patients with CLL (V2; n = 21) and NC donors (V2; n = 14) were assessed with a bead-based multiplex immunoassay and analyzed as median florescence intensity (MFI) in log10. (C) Univariate analysis of RBD immunoassay responder (R; n = 12) and nonresponder (NR; n = 3) antibody features among vaccinated patients with treatment-naïve CLL. Circle represents the median of each group. SARS-CoV-2 spike-specific IgG1 titer is reported as MFI in log10. Flow cytometric assays to determine SARS-CoV-2 spike-specific antibody-dependent THP-1 monocyte phagocytosis (ADCP), ADNP, or ADCD effector functionality were performed to measure the relative effector function. Cellular or neutrophilic phagocytosis is reported as phagoscore in log10. Complement deposition is reported as the MFI of C3-FITC-positive cells in log10. (D) Comparison of SARS-CoV-2 spike-specific ADCP functionality between vaccinated patients with CLL (V2; n = 21) and NC donors (V2; n = 14). Complement deposition is reported as the MFI of C3-FITC–positive cells in log10. (E) Comparison of vaccinated patient with CLL (V2; n = 21) or NC donor (V2; n = 14) antibody-dependent THP-1 monocyte-mediated phagocytosis functionality against SARS-CoV-2 spike. ADCP is reported as the phagoscore in log10. (F) Comparison of ADNP effector functionality against SARS-CoV-2 spike protein between vaccinated patients with CLL (V2; n = 21) and NC donors (V2; n = 14). ADNP is reported as the phagoscore in log10. (A-F) Postvaccine samples were available for 21 patients with CLL vaccinated with mRNA SARS-CoV-2 vaccines. Statistical significance of comparisons between the 2 groups was calculated using the nonparametric two-tailed Mann-Whitney U test with P value cutoffs indicated as follows: P = .1234 (ns); *P = .0332; **P = .0021; ***P = .0001. (A-B, D-F) The black solid line represents the median with dashed lines for the 95% confidence interval in the truncated violin plots. (D-F) The dotted line on the y-axis represents background PBS signal.

Figure 5.

T-cell responses to SARS-CoV-2 vaccination in patients with CLL. (A) Co-occurrence plot of spike RBD immunoassay serologic responses with T-cell responses (ELISpot and IGRA), vaccine history, and clinical characteristics (n = 36). Shaded squares represent the presence of the indicated characteristic. Each column represents an individual patient. (B) Summary table of spike RBD immunoassay serologic and T-cell responses based on SARS-CoV-2 vaccine type (mRNA vs adenovirus) for patients not on any active therapy. (A-B) Postvaccine samples were available for 20 patients with CLL vaccinated with either adenovirus or mRNA SARS-CoV-2 vaccines.

Figure 6.

Humoral response to PCV13 vaccination in patients with CLL. PCV13 SRR in patients with CLL not on active therapy (n = 30) by treatment history.