Background/Purpose: To explore the impact of SLE disease and belimumab given in addition to standard of care therapy on antibody response after vaccination with PCV13 in SLE patients and healthy controls.

Methods: In total, 47 SLE patients (mean age 50.8 years; 94% female; mean disease duration 16.1 years; mean SLEDAI 1.9) and 21 healthy controls (mean age 43.6 years, 86% female) were immunised with a single dose of PCV13. Of these, 11 patients were treated with belimumab in addition to traditional DMARDs (hydroxychloroquine, HCQ; azathioprine, AZA, o or prednisolone). Mean (range) belimumab treatment duration was 9 (2-31) months. Remaining 36 patients received the following treatments: no DMARD (n=7); HCQ (n=10), HCQ+AZA (n=10), AZA or DMARDs other than HCQ (n=9). In total, 31of 47 (66%) of SLE patients had concomitant prednisolone (mean dose 51mg/week; range 17,5-140 mg/week). The quantification of serotype specific IgG levels to 12 pneumococcal capsular polysaccharides (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19A, 19F and 23F) was performed in serum samples taken immediately before and 4-6 weeks after vaccination using multiplex fluorescent microsphere immunoassay (Luminex). Geometric mean levels (GML) and differences between post- and prevaccination antibody levels (fold increase) were calculated from log transformed pre- and postvaccination antibody levels and then compared using paired T-test. General linear model for repeated measurements was used to determine the impact of SLE diagnosis and different treatments on antibody response for all 12 serotypes tested with adjustment for age. Concomitant prednisolone, AZA/other DMARD or HCL were included separately in the analysis as covariates.

Results: Postvaccination antibody levels to 12 serotypes increased significantly in both SLE patients and controls (p between <0.001 and 0.005). Compared to controls patients with SLE as a group showed significantly lower post-vaccination antibody levels and lower fold increase in antibody levels after vaccination (p=0.004 and p=0.009, respectively; adjusted for age and sex). Higher age was associated with lower antibody levels after vaccination (p<0.001) among SLE patients but not controls. When each treatment group was compared to controls including adjustment for age and sex, SLE on belimumab and SLE on HCQ were not different compared to controls, whereas SLE without DMARD, SLE patients on AZA+HCQ, and SLE on AZA or DMARDs other than HCQ had significantly lower fold increase in antibody levels after vaccination (p=0.007, p=0.004 and 0.047, respectively). When different SLE treatments were compared to each other, including adjustment for age, sex, concomitant prednisolone and concomitant DMARDs, the differences were not significant.

Conclusion: Compared to controls, SLE patients had in general lower antibody levels following vaccination with 13-valent pneumococcal conjugate vaccine. However, belimumab given in addition to traditional DMARDs or prednisolone did not further impair antibody response. Only higher age was significantly associated with lower post-vaccination antibody levels among SLE patients.

Clinical trial registration: NCT02240888

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/treatment-with-belimumab-in-sle-does-not-impair-antibody-response-to-13-valent-pneumococcal-conjugate-vaccine/