OAB-049: Poor post-vaccination anti-SARS-CoV-2-antibody response in patients with Multiple Myeloma correlates with low CD19+ B-lymphocyte count and anti-CD38 treatment

BACKGROUND: Up to now, only few data are available regarding the efficacy of anti-SARS-CoV-2 vaccines in patients with plasma cell neoplasia. This ongoing observational study aimed to describe the level of post-vaccination anti-SARS-CoV-2-antibodies depending on B lymphocyte count, current therapy, and remission status of patients with multiple myeloma (MM) and related plasma cell dyscrasias, after the first dose of anti-SARS-CoV-2 vaccination. METHODS: In this single-center study, patients aged 18 years and older with a confirmed diagnosis of MM, monoclonal gammopathies of clinical significance (MGCS) or systemic light-chain amyloidosis (AL) who were eligible for Anti-SARS-CoV-2 vaccination according to the International Myeloma Society recommendations were included. Data were collected between January 1st and May 21th, 2021, at the department of oncology and hematology at the University Medical Center Hamburg-Eppendorf, Germany. The primary aim of this study was to evaluate a possible correlation between antibody titers and CD19+ B lymphocyte count and secondary to identify other possible factors influencing immune response. This study is part of the COVIDOUT trial (NCT04779346). Written informed consent was provided by each patient according to local requirements. RESULTS: A total of 82 patients were included in this study. The median age was 67.5 years (range 40-85 years). 78 patients had MM, 2 MGCS, and 2 AL. Overall, 63 patients were vaccinated with mRNA-based and 19 with vector-based vaccines, respectively. At the time of vaccination, 69 (84.1%) patients were under current anti-myeloma treatment. In total, 34 (41%) patients received anti-CD38-targeting therapies and 52 (63%) patients received IMiD-based therapies. 57 (69.5%) patients were in deep remissions (very good partial remission or better) at the time of vaccination. Assessment of anti-SARS-CoV-2 spike protein antibody titer (SP-AbT) took place on a median of 25 days after the first vaccination (SD ± 11.8). A positive SP-AbT was detected in 23% (17/74) of assessable patients. A cut-off value of ≥ 30 CD19+ B cells/µl was significantly positively correlating with higher SARS-CoV-2 SP-AbT. Individuals with current anti-CD38-antibody treatment showed lower SP-AbT and the likelihood for positive titer results was significantly lower in patients with current anti-CD38 treatment compared to those without. Treatment with immunomodulatory drugs did not harm the development of antibody titers. Furthermore, in multivariable linear regression, higher age and insufficiently controlled disease (≤ partial remission) were significantly negatively correlated with SARS-CoV-2 SP-AbT. CONCLUSION: Based on our results, the majority of myeloma patients respond poorly after receiving the first dose of any anti-SARS-CoV-2 vaccination. Since both low CD19+ B lymphocyte count and CD38-directed therapy negatively impact vaccination response, booster vaccination seems therefore of utter importance.