P-149: Immunogenicity of SARS-CoV-2 vaccine in patients with multiple myeloma

We evaluated the safety and immunogenicity of the BNT162b2 vaccine in 52 patients with multiple myeloma (MM). Median age was 71.3 (range, 39.6-90.8) years. 26 (50%) patients had received active treatment including an immunomodulatory drug (IMiD) (n=21), an anti-CD38 monoclonal antibody (n=11) and/or a proteasome inhibitor (n=4). 21 had received previous treatment interrupted at a median of 27.5 (range, 3.5-169.3) months before first vaccine inoculum. 5 patients had indolent untreated MM. 35 patients had a history of autologous hematopoietic cell transplantation (HSCT) performed at a median of 44.4 (range, 3.5-169.3) months before first vaccine inoculum. The vaccination was well tolerated with few non-severe adverse events. Immune efficacy evaluated by antibody seroconversion showed a significant increase of anti-Spike (S) IgG antibodies between day (d)28 and d42 (p<0.0001). However, anti-S IgG at d42 was significantly lower in patients compared to healthy controls (p=0.0035). Neutralizing antibodies (NAb) correlated with anti-S IgG d42 titers (Spearman r=0.832, p<0.0001). An anti-S IgG d42 level ≥3100 UA/mL was predictive of NAb ≥30%, the positivity cut-off for NAb (p<0.0001). Only 44% (n=23) of the patients achieved an anti-S IgG d42 level ≥3100 UA/mL after the two BNT162b2 inocula, compared to 87% of healthy controls. We then performed a multivariable logistic regression to identify parameters parameters associated with achievement of protective anti-S IgG d42 level (>= 3100 UA/mL). We found that patients’ age (>=71 years versus 25 versus = 120/L) had no impact on achievement of a protective anti-S IgG level after two BNT162b2 inocula. In contrast, male gender, and ongoing chemotherapy were associated with a significantly decreased probability of achieving the defined protective anti-S IgG level after two BNT162b2 inocula [odds ratio (OR) 0.126, 95% confidence interval (95% CI) 0.022-0.709, p=0.02; OR 0.146, 95%CI 0.025-0.866, p=0.03, respectively]. Finally, using the IFN-g ELISPOT assay in 12 patients, we found a significant increase in T cell response in 12 MM patients against the S protein, with 7 patients (58%) having an anti-S IgG positive ELISPOT after the second BNT162b2 inoculum. CONCLUSION: These findings suggest that vaccination with two BNT162b2 inocula translates into a significant increase in humoral and cellular response in patients with MM, but only around half of the patients are likely to achieve effective immune protection against COVID-19.