Failure of first meningococcal vaccination in patients with atypical haemolytic uraemic syndrome treated with eculizumab

Abstract

Background

The C5 complement inhibitor eculizumab is a first-line treatment in atypical haemolytic uraemic syndrome (aHUS). Therapy with eculizumab is associated with a highly increased risk for meningococcal infection. Therefore, vaccination is highly recommended before beginning treatment. Efficacy of quadrivalent meningococcal vaccines (MenACWY) in patients treated with the C5 complement inhibitor eculizumab in aHUS has not yet been determined.

Methods

Patients with aHUS received one dose of a MenACWY conjugate vaccine before eculizumab treatment commenced. Bactericidal titres against meningococcal serogroups A, C, W and Y were determined using baby rabbit complement in 25 patients.

Results

Full immune response to meningococcal vaccination was detected in five patients (20%), while seven patients (28%) showed no immune response in any of the tested serogroups. The remaining 13 patients showed incomplete immune response with proof of protective antibody titres for one to three serogroups without perceptible preference for any serogroup. Bactericidal titres after re-vaccination were available for 17 patients. Nine patients with incomplete immune response after first vaccinations showed protective antibody titres for all serogroups after re-vaccination. Kidney function had improved in >50% of patients at the time of re-vaccination compared with the time of first vaccination and immunosuppressive therapy was only applied to re-vaccinated patients following kidney transplantation.

Conclusions

Immunogenicity of first quadrivalent meninongococcal vaccination is insufficient in patients with aHUS. Booster response is promising, but incomplete. Therefore, establishing antibiotic prophylaxes seems pivotal.

atypical haemolytic uraemic syndrome, bactericidal titres, complement inhibition, immunosuppression, meningococcal vaccination

INTRODUCTION

Atypical haemolytic uraemic syndrome (aHUS) is a rare, but potentially life-threatening disease. Uncontrolled activation and dysregulation of the alternative complement pathway lead to thrombotic microangiopathy generally characterized by haemolytic anaemia, thrombocytopaenia and acute renal failure [1] often resulting in end-stage renal disease. In patients receiving kidney transplantation, post-transplant relapse rates are 60–80% [2], being associated with high rates of graft loss [3, 4]. De novo post-transplant aHUS, developing after transplantations in patients who never experienced any signs of disease prior to transplantation, might also occur putting graft survival at a threat [5].

The recombinant humanized monoclonal antibody against complement protein C5 eculizumab (Soliris, Alexion Pharmaceuticals, Munich, Germany), licensed for treatment of paroxysmal nocturnal haemoglobinuria, refractory generalized myasthenia gravis and aHUS in Europe, is the first-line treatment for aHUS [6, 7]. As the complement system is involved in innate immunity, it plays a key role in defense against pathogens [8]. Therapy with the complement inhibitor eculizumab blocks the formation of C5 convertase and thereby its cleavage into C5a and C5b. This interferes not only with anaphylatoxin production, but also with formation of the terminal membrane attack complex, being the major defense mechanism against Neisseria spp. [9]. Therefore, treatment with eculizumab is associated with a highly increased risk for meningococcal infections [10, 11]. Administration of the MenACWY vaccine is strongly recommended in patients receiving eculizumab [10, 12, 13].

In general, responses to vaccination are unreliable and low in patients with reduced renal function or receiving immunosuppressive therapy [14, 15]. Data on the immunogenicity of MenACWY in these patients are very limited [16]. The efficacy of quadrivalent meningococcal vaccination in patients treated with eculizumab in aHUS has not been determined.

MATERIALS AND METHODS

Bactericidal titres against meningococcal serogroups A, C, W and Y were determined in 25 patients with aHUS (9 males/16 females; born between 1948 and 1998) who had received a meningococcal quadrivalent conjugate polysaccharide vaccine immediately before the beginning of treatment with the complement inhibitor eculizumab. Patients were vaccinated with either Menveo (GlaxoSmithKline GmbH & Co. KG, Munich, Germany) or Nimenrix (Pfizer Pharma GmbH, Berlin, Germany).

Serum bactericidal antibody assay with baby rabbit complement (rSBA) applied as an exogenous complement source was performed to determine bactericidal titres against serogroups A, C, W and Y as described before [17]. As a side note, measurement of efficacy of the protein-based serogroup B-vaccination, which was performed additionally, is currently not possible in patients with eculizumab treatment as a human complement (hSBA) source is required, which is blocked by eculizumab. The correlation between serum bactericidal activities against serogroup B meningococci (MenB) measured with hSBA versus rSBA is low with significantly higher titres generated by rSBA. Zollinger and Mandrell [18] showed that in vaccinated humans, bactericidal MenB antibodies with rSBA were directed against the MenB capsular polysaccharide whereas hSBA directed them against sub-capsular antigens. Since the authors observed a high proportion of pre-vaccination sera from healthy adults with antibodies against MenB polysaccharide, the use of rSBA might distort the intended measurement of antibodies directed against sub-capsular protein antigens. Titres were calculated as the reciprocal of the final serum dilution killing 50% of bacteria within 1 h. Titres ≥1:8 are regarded to reflect protective antibody response.

Re-vaccination was performed in patients with low or weakening titres for at least one serogroup and serum bactericidal antibody assays were performed again 6–10 weeks after re-vaccination.

Analysis of bactericidal titres and patient data for scientific use was approved by the local Ethics Committee of the University of Duisburg-Essen (18-8013-BO).

RESULTS

The cohort consisted of 25 patients with aHUS (9 males/16 females; born between 1948 and 1998) (Table 1). No patient had a history of meningococcal disease or previous meningococcal immunization. The first vaccination with meningococcal quadrivalent conjugate vaccine was applied immediately before the beginning of treatment with the complement inhibitor eculizumab. Initiation of treatment was accompanied by 2 weeks of antibiotic prophylaxis with appropriate antibiotics, usually ciprofloxacin, ceftriaxone or piperacillin/tazobactam depending on additional circumstances. At the time of initiation of eculizumab treatment, all patients showed reduced kidney function with 10 patients being dependent on renal replacement therapy. Besides reduced kidney function, three-quarters of patients received immunosuppressive therapy in the form of plasmaphereses, steroids or triple immunosuppressive therapy for kidney transplantation at the time of vaccination.

Table 1

Patient characteristics

No.	First vaccination		Second vaccination
	Immunosuppressive therapy	Kidney function	Immunosuppressive therapy	Kidney function
1	PP + steroids	RRT		RRT
2	PP + steroids	sCrea 3.8 mg/dL		RRT
3	PP + steroids	RRT
4		RRT		RRT
5	PP + steroids	RRT		RRT
6		sCrea 4.4 mg/dL		sCrea 2.8 mg/dL
7	PP + steroids	sCrea 4.8 mg/dL
8	PP + steroids	sCrea 2.2 mg/dL		sCrea 1.1 mg/dL
9	PP + steroids	RRT		sCrea 1.4 mg/dL
10		RRT		RRT
11	MMF, tacrolimus, steroids	sCrea 2.1 mg/dL
12	Azathioprin, tacrolimus, steroids	sCrea 4.7 mg/dL	MMF, tacrolimus, steroids	sCrea 2.7 mg/dL
13	MMF, tacrolimus, steroids	sCrea 1.6 mg/dL	MMF, tacrolimus, steroids	sCrea 1.5 mg/dL
14		RRT	MMF, belatacept, steroids	sCrea 1.2 mg/dL
15	MMF, everolimus, steroids	sCrea 2.1 mg/dL
16	MMF, tacrolimus, steroids	sCrea 1.7 mg/dL	MMF, tacrolimus, steroids	sCrea 1.8 mg/dL
17		RRT	Tacrolimus, steroids	sCrea 1.4 mg/dL
18	MMF, tacrolimus, steroids	sCrea 3.9 mg/dL
19	MMF, tacrolimus, steroids	sCrea 2.4 mg/dL	MMF, steroids	RRT
20	Tacrolimus, everolimus, steroids	sCrea 2.4 mg/dL	Cyclosporin, steroids	sCrea 1.8 mg/dL
21		RRT	MMF, steroids	sCrea 2.4 mg/dL
22	MMF, tacrolimus, steroids	sCrea 1.8 mg/dL	MMF, tacrolimus, steroids	sCrea 1.8 mg/dL
23	MMF, tacrolimus, steroids	sCrea 1.7 mg/dL
24	Steroids	RRT	Azathioprin	RRT
25	PP + steroids	RRT

First vaccination with a meningococcal quadrivalent conjugate polysaccharide vaccine was performed immediately before the beginning of treatment with the complement inhibitor eculizumab. PP, plasmapheresis; RRT, renal replacement therapy; MMF, mycophenolate mofetil; sCrea, serum creatinine.

Bactericidal antibody titres were not measured in any patient before first vaccination. Time from first vaccination to titre measurement varied between 2 and 63 months (mean 19 months). After first vaccination, full immune response to the quadrivalent meningococcal vaccination was detected in five patients (20%), while seven patients (28%) showed no immune response in any of the tested serogroups (Table 2). The remaining 13 patients showed incomplete immune response with proof of protective bactericidal antibody titres for one to three serogroups without perceptible preference for any serogroup. Protective bactericidal antibody titres were most commonly detected for serogroup C (56%), while only 36% of patients showed protective titres against serogroups A. The majority of bactericidal antibody titres, although regarded to be protective, were relatively low (≤64) (Figure 1). Age did not correlate with response to vaccination.

FIGURE 1

Bactericidal titres. Serum bactericidal antibody assay with rabbit serum applied as an exogenous complement source was performed to determine bactericidal titres against serogroups A, C, W and Y. Titres were calculated as the reciprocal of the final serum dilution killing 50% of bacteria within 1 h. Titres ≥1:8 are regarded to reflect protective antibody response. Lines show geometric means of bactericidal antibody titres.

Table 2

Overview of protective versus unprotective titres against meningococcal serogroups following first and second vaccination

ID#	First vaccination				Second vaccination
	A	C	W	Y	A	C	W	Y
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Protective titres (%)	36	56	40	52

Grey boxes represent titres ≥1:8 regarded to be protective, black boxes represents titres <1:8, white boxes mark patients only receiving first vaccination.

A total of 17 patients were re-vaccinated after first antibody measurement and bactericidal antibody titres were measured 6–10 weeks thereafter. Kidney function had improved in >50% of patients being re-vaccinated compared with the time of first vaccination. Immunosuppressive therapy was only applied to re-vaccinated patients following kidney transplantation and to one patient with concurrent rheumatic arthritis.

Bactericidal titres improved after second vaccination in all serogroups (Figure 1). Nine patients with incomplete immune response after first vaccination showed protective antibody titres for all serogroups after re-vaccination. Five patients with incomplete immune response after second vaccination were detected (Table 2). Two patients showed a decreasing titre for one serogroup each, while all other titres were either stable or increased following re-vaccination.

DISCUSSION

Immunogenicity of first quadrivalent meningococcal vaccination in patients with aHUS treated with the complement inhibitor eculizumab was very low, leaving 80% of patients with missing or only partial protective bactericidal antibody titres. Booster response to second vaccination was promising, nevertheless leaving ∼30% of patients with incomplete immune response.

Administration of MenACWY is strongly recommended in patients receiving eculizumab [10, 12, 13]. Neither national guidelines on meningococcal vaccination nor the prescribing information of eculizumab further elucidate the mode of initial immunization or include precise recommendations on re-vaccination [10, 13]. Therefore, initial immunization was performed with single-dose application as recommended by the manufacturer [19, 20]. Guidelines on re-vaccination in adults with aHUS are not available, while booster vaccination is recommended every 3 years in patients with paroxysmal nocturnal haemoglobinuria receiving eculizumab [21] and every 5 years according to US guidelines for patients with persistent complement component deficiencies [22].

A single dose of quadrivalent MenACWY applied to healthy subjects leads to the development of protective antibody titres in 69–94% depending on serogroup [19, 20], while only 36–56% were achieved in our cohort of patients with aHUS. In comparison with the current study, serological response in patients with paroxysmal nocturnal haemoglobinuria and chronical eculizumab treatment showed differing, but generally better immune response according to serogroups: A 78%, C 87%, W 48% and Y 70% [21]. However, 43% of patients in this cohort were vaccinated more than once and additional immunosuppressive therapy was considerably lower. In five patients being vaccinated once, 14 days prior to eculizumab initiation and not receiving immunosuppressive therapy, immunogenicity was fairly good showing protective antibody titres in 67–100% of patients depending on serogroup. In contrast, two of three patients treated with cyclosporine before vaccination showed non-protective antibody titre levels against three serogroups. Failure of vaccination in these patients might more reflect the immunological background of the immunological compromised patients in the current cohort.

In addition, patients with initial diagnosis of aHUS are not only commonly exposed to multiple immunosuppressive agents and/or treatments such as steroids, calcineurin inhibitors or plasmapheresis, but also often suffer from reduced kidney function, which due to its association with chronic inflammation leads to decreased immunity itself [23]. Serological response to vaccination is generally reduced in patients with renal failure and/or following (renal) transplantation [14]. In a small cohort of 10 patients following kidney and liver transplantation, only 50% of patients developed a protective immune response against at least one serogroup following vaccination with a conjugate meningococcal vaccine [16]. No patient responded to all serogroups. Responders showed low bactericidal antibody titres predicting a rapid decline [24–26].

The presence of bactericidal antibody titres despite vaccination is a known phenomenon most likely due to carriage of Neisseria meningitidis in the nasopharynx encountered in ∼10% of the general population [16, 27]. Pre-existing bactericidal antibody titres are often low and only showing limited response to boostering especially in patients with immunosuppressive therapy [16]. Baseline bactericidal antibody titres of our cohort are unknown, but would not have changed the course of action concerning vaccination nor contradict our results of low immunogenicity of the first quadrivalent meningococcal vaccination.

As re-vaccination seems to improve serological response, a two-dose primary series administered 8–12 weeks apart as recommended in the US for patients with persistent complement component deficiencies [22] should be applied to patients with aHUS from the start. Reduced kidney function and a high load of immunosuppressive therapy counteract immune response to vaccination. Postponing vaccination to a later time point when kidney function might have improved and immunosuppressive therapy has been reduced might also be favourable. Antibiotic prophylaxis should be administered until protective antibody titres are achieved using antibiotics able to eliminate Neisseria spp. in the nasopharynx, for example, ciprofloxacin, before down-staging to preferably penicillin V. Applying antibiotic prophylaxis for 2 weeks post-vaccination only, as described in the package insert of eculizumab [10], is putting patients at risk of meningococcal disease and therefore cannot be recommended. In addition, vaccination and measurable protective antibody titres decrease the risk of meningococcal disease, but do not fully prevent it [28]. A current in vitro study by Konar and Granoff [29] even fundamentally questions the benefit of meningococcal vaccinations in patients treated with eculizumab as the eculizumab-induced blocking of C5 strongly interferes with the bactericidal and opsonophagocytic-mediated protection expected from vaccination-induced antibodies. Due to the controversy on vaccination efficacy in patients with acute kidney injury, chronic kidney disease and/or immunosuppressive therapy and the uncertainty of protection by antimeningococcal antibodies in the context of complement blockade, the recent Kidney Disease: Improving Global Outcomes controversies conference likewise recommends the maintenance of antibiotic prophylaxis for patients on eculizumab treatment and up to 3 months after discontinuation [30]. In addition, patients should be well informed about the risk and clinical signs of meningococcal disease, carry the emergency card for patients receiving eculizumab and always be equipped with adequate additional stand-by antibiotics against meningococcal disease, while clinicians must always consider meningococcal disease in patients with eculizumab treatment and suspicious clinical symptoms.

AUTHORS’ CONTRIBUTIONS

A.G. and O.W. designed the study and drafted the manuscript, all authors analysed and/or interpreted data and revised the manuscript. All authors provided intellectual content of critical importance to the work described and approved the final version to be published.

CONFLICT OF INTEREST STATEMENT

A.G. and A.K. report grants and personal fees from Alexion. T.F. reports grants and personal fees from Alexion, Akari and Omeros. O.W. reports grants and personal fees from Alexion and Pfizer. M.K., H.R., U.V. and H.C. declare no conflicts of interest. The results presented in this article have not been published previously in whole or part, except in abstract form.