The evidence behind the use of plasmapheresis in glomerular diseases

Therapeutic plasma exchange (PLEX) is a type of therapy where a patient’s plasma volume is removed over a period of a few hours, through a process of centrifugation of blood with subsequent separation of its constituents, and replaced by different types of colloid fluids, most commonly Albumin or Fresh Frozen Plasma (FFP). Its most frequent use in nephrology is for certain glomerulopathies such as ANCA-associated vasculitis, anti-GBM disease, recurrence of idiopathic FSGS post-transplant and atypical HUS. The data with regards to PLEX use for these indications is mostly historical and based on mechanistic concepts which led to multiple observational studies and reports claiming efficacy. There are very few randomized trials directly comparing PLEX to other therapies and a review of the data (see table summary of KDIGO recommendations) has really brought me a new perspective on what justifies our use of PLEX for renal disease.

Table: KDIGO recommendations on PLEX use for glomerular disease

	KDIGO recommendation	Grade
Anti-GBM disease	We recommend initiating immunosuppression with cyclophosphamide and corticosteroids plus plasmapheresis in all patients with anti-GBM GN except those who are dialysis-dependent at presentation and have 100% crescents in an adequate biopsy sample, and do not have pulmonary hemorrhage	1B
	Start treatment for anti-GBM GN without delay once the diagnosis is confirmed. If the diagnosis is highly suspected, it would be appropriate to begin high-dose corticosteroids and plasmapheresis while waiting for confirmation	Not graded
ANCA-associated vasculitis	We recommend the addition of plasmapheresis for patients requiring dialysis or with rapidly increasing SCr	1C
	We suggest the addition of plasmapheresis for patients with diffuse pulmonary hemorrhage	2C
	We suggest the addition of plasmapheresis for patients with overlap syndrome of ANCA vasculitis and anti-GBM GN, according to proposed criteria and regimen for anti-GBM GN	2D
Post-transplant FSGS	We suggest plasma exchange if a biopsy shows minimal change disease or FSGS in those with primary FSGS as their primary kidney disease	2D
Atypical HUS	Not mentioned in KDIGO guidelines

Adapted from: Kidney Disease: Improving Global Outcomes (KDIGO) Transplant Work Group. KDIGO clinical practice guideline for the care of kidney transplant recipients. American journal of transplantation: official journal of the American Society of Transplantation and the American Society of Transplant Surgeons. 2009 Nov;9:S1; and Kasiske BL, Zeier MG, Chapman JR, Craig JC, Ekberg H, Garvey CA, Green MD, Jha V, Josephson MA, Kiberd BA, Kreis HA. KDIGO clinical practice guideline for the care of kidney transplant recipients: a summary. Kidney international. 2010 Feb 2;77(4):299-311.

Anti-GBM disease

Anti-GBM disease has always been regarded as a sine qua non indication for PLEX.  I still remember my first teachings on anti-GBM disease in medical school which were were it causes lung hemorrhage, it causes acute kidney injury and it is treated with plasmapheresis. When reviewing the literature, I was surprised to find only a single randomized trial on the use of PLEX in anti-GBM disease. This a study published in 1985 in Medicine by Johnson et al where they randomized 17 (yes, only 17!) patients with biopsy and serology proven anti-GBM disease to either Prednisone + PO Cyclophosphamide (N=9) vs PLEX + Prednisone + PO Cyclophosphamide (N=8). Patients at baseline were not equally matched as the patients in the conventional group had higher serum creatinine (SCr) at start of therapy and had more severe disease on biopsy. Indeed, 5/8 biopsies available had >70% gloms with crescents in the conventional group vs only 1/7 in the PLEX group had > 50% gloms with crescents. They did find that more patients were dialysis dependent at the end of the study in the conventional group (6/9) vs the PLEX group (2/8). Four patients in the PLEX group had improvement in their renal function vs only 1 in the conventional group. These patients who had improvement were the ones with lower SCr at presentation. Eight patients had pulmonary hemorrhage (4 in each group) and all these episodes were treated with IV Methylprednisone pulse and responded promptly. There were only 3 deaths in all, 1 in conventional and 2 in PLEX group. Anti-GBM titers became undetectable much more quickly with PLEX, after about 2 months. Overall, it is somewhat surprising that what we consider such a strong indication for PLEX is supported by only 1 randomized trial showing improved renal survival with PLEX, where the groups were unevenly matched. What is also important to consider with anti-GBM disease is the possible futility of treatment in patients with most severe disease. A review of anti-GBM disease in the UK from 1980-1984 by Savage et al looked at outcomes for 108 patients. There were 69 patients who were dialysis dependant on presentation. At 8 weeks, none were off dialysis (51 on dialysis and 18 dead). Out of 12 who presented with a SCr>600umol/L, only 1 had improvement in renal function (other 11 either on dialysis or dead). Another British study published in 2001 in the Annals of Medicine by Levy et al retrospectively looked at all anti-GBM disease treated at the Hammersmith hospital in since 1975. They had 71 patients, 39 of which were dialysis-dependant on presentation. Only 2 were off dialysis at 1 year follow-up. When looking at outcomes based on biopsies, they found that 23% of patients with >50% crescents survived off dialysis and that 3 patients survived off dialysis despite >70% crescents. However, no patients with 100% crescents recovered renal function. Together, these results certainly seem to suggest that patients with severe anti-GBM disease presenting dialysis dependent have very little chance of recovery and may not benefit at all from immunosuppressive therapy and PLEX. While a trial of treatment may still be indicated, I believe a rapid re-assessment of the patient’s condition and need for continued immunosuppressive therapy is indicated given the high infectious risks with treatment. Patients with 100% crescents on an adequate biopsy are very unlikely to get any benefit and should probably just be managed conservatively.

ANCA-associated vasculitisAnother frequent indication for PLEX in glomerular disease is ANCA-associated vasculitis and thankfully there is a bit more data to guide us here. The best data comes from the MEPEX trial by Jayne et al published in JASN in 2007 where 137 patients with biopsy/serology proven ANCA vasculitis and SCr > 500umol/L were randomized to either PLEX (7 exchanges in 14 days) or IV methylprednisolone (1g IV daily x 3), both in combination with oral Cyclophosphamide and Prednisone. Patients with severe lung hemorrhage requiring mechanical ventilation were excluded. Just over 2/3 of patients were dialysis-dependent on presentation. They found that treatment with PLEX had a better renal recovery (alive and off dialysis and SCr<500umol/L) at 3 months than IV steroids (70% vs 49% respectively, P=0.02). The HR for ESRD at 12 months for PLEX vs IV steroids was 0.47 (0.24-0.91, P=0.03). Survival however was not significantly different (19 deaths in PLEX group vs 16 in IV steroids group) and most deaths were due to infections (19), lung hemorrhage (6) or cardiovascular disease (4) and very few due to vasculitis. A sub-study of the MEPEX trial by Van Wingaarden et al found that for patients requiring dialysis on presentation and with severe tubular atrophy on biopsy, the point at which patients would get more benefit for renal survival from treatment over risk of death from treatment was when they had 18% or more normal glomeruli for IV steroids group as opposed to only 2% normal glomeruli for PLEX. This suggests that patients with most severe disease are more likely to reap renal benefit from treatment when they are given PLEX. In 2013, Walsh et al published the long term follow-up data from the MEPEX trial and found that the short term benefit seen in MEPEX was lost. Indeed, for patients treated with PLEX there was no significant improvement in the composite of ESRD or death (HR 0.81, 0.53-1.23; P=0.32) nor in the outcome of ESRD (0.64, 0.40-1.05; P=0.08). At final follow-up, half the patients died and 2/3 were either dead or on dialysis, reaffirming the poor prognosis of severe ANCA vasculitis. A meta-analysis of all randomized trials looking at PLEX for ANCA vasculitis by Walsh et al in 2011 found PLEX to be associated with a 20% risk reduction in the composite of ESRD-death (HR 0.80, 0.65-0.99) and a 36% reduction in ESRD (HR 0.64, 0.47-0.88) but no effect on death (RR 1.0, 0.71-1.42). The authors did warn though that overall most trials were small, none of them individually found a significant result for the composite of ESRD-death and they had notable methodological flaws such as randomization concealment was only performed in 4/9 trials and the methods of concealment weren’t described in any. Hopefully, the PEXIVAS study which is now nearing completion and should be presented at the upcoming ASN Kidney Week 2017 (hopefully as a late-breaking trial) will help clarify the role for PLEX in ANCA vasculitis. For now, it would seem that PLEX is indicated for patients presenting with severe renal failure due to ANCA-vasculitis as it improves renal survival, without a mortality benefit though.

Post-transplant FSGS

It is sad to say that there are unfortunately no other prospective trials studying the role of PLEX for glomerular disease. While the use of PLEX for recurring idiopathic FSGS post-transplant is recommended (the rationale being the removal of some as of yet unidentified pathogenic plasma permeability factor), the data is purely observational. A review of 77 case-reports and case-series, totalling 423 patients with recurrence of FSGS post renal transplant, published in BMC Nephrology in 2016 showed that overall 71% of patients achieved complete or partial remission. Factors most associated with response were male sex and starting treatment within 2 weeks of recurrence. However, the lack of control group prevents us from establishing a clear benefit from PLEX itself. Also, the treatment regimens were extremely varied and it is unclear exactly how much PLEX, for how long should it be given and which replacement fluid to use. Finally, the frequent use of PLEX in these patients who are already on immune-suppressing drugs may predispose to even more infections given the removal of Immunoglobulins by PLEX.

Atypical HUS

Similar to FSGS, the use of PLEX for atypical HUS is based purely on observational data (case reports and case series). The rationale behind its use for this indication certainly makes sense by removing defective complement factors and replacing properly functioning complement factors to halt the overactivity of the alternative pathway. Patients diagnosed with TMA are often started on PLEX promptly while awaiting results of diagnostic testing (Shiga toxin E. Coli cultures, ADAMSTS13 level and complement pathway factor levels and mutations). If diagnostic tests suggest an alternative complement pathway disease, it will be maintained until Eculizumab is available. Unfortunately, while most observational studies suggest an initial response around 60% to PLEX, this is mostly a hematologic response and patients will often become dialysis dependent.

Conclusion

Overall the evidence to support the use of PLEX for the treatment of glomerular diseases is not great. While anti-GBM disease and lung hemorrhage are considered some of the strongest indications for PLEX, this is not firmly supported by good prospective data. The best evidence is for its use is in severe ANCA-vasculitis and with the upcoming PEXIVAS study results hopefully this will further help us in our decision making. I think it is great that such a large study such as PEXIVAS (over 700 patients) for such a rare disease has been able to come to completion and this highlights the importance of proper collaboration to conduct prospective studies in GN. Hopefully this will inspire us to continue to strive for well-designed studies to guide us in the treatment of our patients.

David Massicotte-Azarniouch

Nephrology Fellow, University of Ottawa

Sweet’s syndrome and the Kidney

This is an interesting case which I have been managing over the last six months. A 50-year-old male, with no previous medical illnesses, presented with fatigue, weight loss and arthralgia for several weeks. Clinical examination was unremarkable. Investigations revealed a rise in Creatinine from a baseline of 86 to 120 µmol/l (eGFR= 70 down from 90). His urine dipstick revealed protein (1+) and blood (1+). He had a normal Chest X-ray, but his p-ANCA was positive with a high MPO titre. Renal imaging was normal and he underwent a kidney biopsy which showed non-specific findings i.e. some tubulointerstitial inflammation and glomerulosclerosis with mild features of thrombotic microangiopathy (TMA). There were NO crescents and both immunofluorescence and electron microscopy showed NO immune deposits. Putting it all together, a diagnosis of vasculitis was made and treatment with Steroids & Rituximab was initiated. ANCA titre started to fall and urine sediments disappeared. Unfortunately, he developed a steroid-induced psychosis and had a failed suicide attempt. Subsequently, corticosteroids were discontinued and he was commenced on Azathioprine.

Four months later he presented with fever, constitutional symptoms and skin rash in the form of reddish papules & nodules involving the trunk, neck & face. Lesions got progressively worse and coalesced to form plaques. A skin biopsy confirmed the presence of neutrophilic dermatosis and a diagnosis of Sweet’s syndrome was made. Interestingly there was no evidence of vasculitis in the skin biopsy. He was treated with high-dose systemic steroids and improved dramatically. This was done in a closely monitored environment in-hospital, given his history of steroid-induced psychosis. Currently, he is being thoroughly investigated for any possible underlying malignancies.

What is Sweet’s syndrome?

Sweet’s syndrome, also known as acute febrile neutrophilic dermatosis, is a reactive skin disorder characterized by the sudden onset of papules and nodules which are tender and reddish/purple in colour. These lesions coalesce later to form plaques. It mainly involves the upper extremities, face, or neck and is typically accompanied by pyrexia and peripheral neutrophilia.

It is more common in females and often occurs after a respiratory illness, which is usually mild. More severe disease often occurs with underlying malignancies, drugs or inflammatory conditions e.g. inflammatory bowel disease. Sometimes it could be the first manifestation of the underlying disorder, so whenever it is diagnosed it should prompt further investigation.

Sweet’s syndrome responds dramatically to systemic corticosteroids and may improve or resolve with treatment of the underlying condition. Without treatment, the syndrome may persist for weeks or months but eventually improves, in the majority of cases, without leaving any scars; rarely it may persist and never resolve completely. Recurrences are common.

The diagnosis of Sweet syndrome is based on both clinical and histopathologic findings. A characteristic that distinguishes the lesions of Sweet syndrome from other neutrophilic dermatosis is the absence of vasculitis. However, the presence of vasculitis should not exclude the diagnosis as this may represent an epiphenomenon instead of a primary disease. ANCA have been reported positive in Sweet syndrome and other neutrophilic dermatoses, but this finding is not consistent. This case raised a number of interesting questions:

1-      Was this case a Sweet’s syndrome from the outset rather than an ANCA vasculitis?

ANCAs have been reported to be positive in Sweet syndrome. The kidney biopsy findings, in this patient, were not convincing and the renal course of the disease was not typical of vasculitis. Moreover, it was previously reported that Sweet’s syndrome is associated with renal involvement manifesting most commonly as proteinuria, and less often as haematuria and membranoproliferative glomerulonephritis. Unfortunately, this disease is uncommon and there is a paucity of studies describing the association between Sweet's syndrome and kidney diseases.

2-      Was this case an ANCA vasculitis and the Sweet’s syndrome was a reactive process to the inflammation?

This is another possibility and the association between this syndrome and inflammatory conditions is well known.

3-      Is it a drug-induced Sweet’s syndrome secondary to Azathioprine?

There are several drugs that have been implicated as a cause of this syndrome. Examples are: Azathioprine, Frusemide, Hydralazine, Quinolones and many others.

4-      After complete recover from Sweet’s syndrome and exclusion of underlying malignancy, is it reasonable to continue treating a possible ANCA vasculitis or will it is more appropriate to attribute the positive ANCA and the non-specific renal findings to Sweet’s syndrome per se?

This is a difficult question to answer. The benefits of long-term immunosuppression should be weighed against the risk of infection, other serious adverse effects and the risk of missing an active vasculitis in a young patient.

In conclusion, Sweet’s syndrome is an uncommon disease which could be primary or secondary to an underlying inflammatory process or malignancy. It may cause a positive ANCA test in the absence of active vasculitis. Its association with kidney diseases is not well described and need to be explored.

Post by Mohammed Kaballo

The use of Rituximab in Kidney Disease

Rituximab, the monoclonal chimeric anti-CD20 antibody, is an effective B-Cell depleting agent and continues to gather data for its use in a wide range of conditions relevant for the Nephrologist. It was also a pre-season favourite in the recent NephMadness event run by our friends at eAJKD, so I figured a quick recap was timely. As the literature is vast and grows by the week, I will only give a brief review of the current data, much of which is weak consisting of small observational reports.

Lupus Nephritis
The jury is still out. The LUNAR study randomized 144 patients with proliferative LN to Rituximab 1g x 4 or placebo with both groups receiving MMF & steroids. The experimental group had a decrease in anti-dsDNA and complement levels. Remission rates were numerically, but not statistically, better with add-on Rituximab (57% V 46%). While a lack of benefit with additional use of Rituximab was demonstrated, whether it could be an alternative to MMF is not known. In cases of resistant LN, we again have multiple favourable case series but no hard evidence.

Steroid-Resistant Nephrotic Syndrome (SRNS)
Evidence suggests Rituximab may be effective in steroid-dependent or calcineurin inhibitor-dependent patients, allowing withdrawal of one/both agents. An open-label RCT in 54 children with SRNS examined standard therapy (with steroids & calcineurin inhibitors) to Rituximab with lowering doses of usual therapy. The experimental arm had lower proteinuria, less relapse and was more likely to be drug free at 3 months. However, relapse did occur in 18.5% of Rituximab treated patients at the time of recovery of the B-Cell population.
The data does not all demonstrate a benefit however, which brings us to a recent small case series in the NEJM. Another anti-CD20 monoclonal antibody, this time the humanized preparation Ofatumumab, was reported to be an effective treatment in 5 cases of SRNS refractory to Rituximab. Although both are anti-CD20 antibodies, they have different epitope specificities which may explain the outcome in this small series. This reinforces the idea that B-Cell depletion is more complex than some may presume.

Minimal Change Disease
No RCT data exists but observational series suggest a benefit in steroid-dependent, but not resistant cases. A new case series in NDT reports on 16 adult patients with MCD who were steroid-dependent (n=12) or resistant and given 2-4 doses of Rituximab. Overall, 13 had a complete and 2 a partial remission with one non-responder. No serious adverse events were reported but 7 relapsed after 9–28 months.

Membranous Nephropathy (MN)
Guess what? No RCT data exists but limited data suggests it may be a useful agent. (See Nate’s previous post). The largest observational study I could find included 100 patients, 32 of whom had disease resistant to other immunosuppressive agents. Baseline proteinuria of 9g/day had been present for a mean of 2 years. Complete/partial/no remission was achieved in 27/38/35 patients respectively, remissions after a mean of 7 months. Prior immunosuppressant use did not appear to alter outcome. Other smaller studies also report that patients, including those with resistant disease, may respond.
There is evidence that Rituximab may cause a decrease in Anti-M-type Phospholipase A2 Receptor (PLA2R) antibodies. In this study, 25/35 patients with idiopathic MN had Anti-PLA2R antibodies, and these autoantibodies declined or disappeared in 17 (68%) of these patients within 1 year of rituximab treatment. The patients who demonstrated antibody response had much improved rates of complete and partial remission in this small study. Perhaps these autoantibodies may prove to be a useful biomarker for treatment response in MN.

ANCA associated vasculitis (AAV)
As per the RAVE study (& RITUXIVAS), there is now robust evidence that a 4 week course of rituximab is non-inferior to cyclophosphamide in the treatment of AAV, including a finding that it may be superior to conventional immunosuppression in relapsing patients. Note that only 2/3 of patients had renal impairment in RAVE with creatinine clearances of 54-69mls/min in the 2 groups. See my previous post for more detail.

FSGS
Limited evidence suggests it may be beneficial in steroid-dependent but not steroid-resistant cases. We must be wary of publication bias from early series which reported  positive findings, especially as they have often failed to be replicated. It has been used with some success for recurrent FSGS post-transplantation, often together with plasma exchange. There is growing evidence for a direct effect on the podocyte, as well as its known anti-B Cell effect, possibly via binding of podocyte proteins such as SMPDL-3b.

Transplantation
It is beyond the scope of this post to delve into the use of Rituximab in transplantation. It can be used in desensitization protocols, PTLD and treatment of acute antibody-mediated rejection (AMR) as adjuncts to IVIG and plasma exchange (trial data awaited regarding allograft outcome). There is no clear evidence for its use in chronic AMR, which tends to have little response to any agent.

Another indication is essential mixed cryoglobulinemia. Here, Rituximab has been reported to be beneficial in cases usually associated with Hepatitis C infection. See Gearoid’s previous post.
Overall, B-Cell depletion in general is an exciting treatment strategy for many of the disease processes we deal with. Like much in Nephrology, we lack strong data for if, when and how to use it. We also lack thorough knowledge as to its precise mechanism of action. Suggestions of a direct podocyte effect in glomerular disease and different mechanistic effects of alternate anti-CD20 preparations illustrate how much we have to learn.

Rituximab for ANCA Associated Vasculitis (AAV): Contender for top 10 of 2013

In a year which gave us the bardoxolone failure, NEPHRON-D and the CORAL trial to name a few, a study with a positive result should be celebrated and the RAVE follow-up must be a contender for top 10 nephrology stories of 2013. The original RAVE trial was a multicenter, blinded, RCT which was published in 2010 (n=197). It demonstrated non-inferiority of rituximab (375 mg/m²/week for 4 weeks) as compared to oral cyclophosphamide for remission of severe AAV at 6 months. Moreover, among patients who had relapsing disease at baseline, rituximab was superior to conventional immunosuppression, at least at 6 months.  Of note, in the same issue of the NEJM in 2010, the smaller RITUXIVAS study (n=44) compared IV cyclophosphamide for 3-6 months to a rituximab based regime (same dosing as RAVE but including 2 IV cyclophosphamide pulses) with equivalent remission rates at 1 year. In both studies, conventional steroid treatment was employed.

The follow-up to RAVE was reported in the NEJM in August. Patients achieving a remission with rituximab received only placebo from month 6 through 18 while the comparison group received continued immunosuppressive therapy comprising cyclophosphamide followed by azathioprine. Overall results demonstrated that the rituximab group non-inferior to cyclophosphamide followed by maintenance therapy with azathioprine for 18 months. Echoing the original RAVE report, rituximab was superior to conventional immunosuppression in relapsing patients (>50% of patients at enrollment) at 12 months (P=0.009). However, at 18 months when most patients in the rituximab group had reconstituted B cells, the significance was lost (P=0.06). There was no significant difference between the groups in the numbers of total adverse events, serious adverse events or the number of discontinuations.

A few points to consider:

·         Regarding the relevancy of the results for nephrologists, it must be noted that only 66% had renal involvement and creatinine clearance was 54-69mls/min in the 2 groups. The mean increase in creatinine clearance was similar at approximately 11mls/min in both groups and response rate was similar between the 2 groups in patients with ‘severe’ renal disease.

·         Rituximab is often considered a ‘clean’ drug. What strikes me after reading many studies using rituximab is that the adverse event rate is usually similar to the comparison group, in this case cyclophosphamide.

·         A persistent concern with rituximab is whether or not to re-treat, and if so when, after B cell re-population occurs. In this 18 month follow-up, non-inferiority was maintained at up to 18 months, when most patients in the rituximab group had reconstituted B cells. However, B cells were detectable in 88% of rituximab patients who relapsed between 6-18 months. 

Verdict: A knowledge gap may still exist for patients presenting with a rapidly progressive GN requiring dialysis although the RITUXIVAS trial contained patients with worse renal function, some needing dialysis, and suggested equivalent early outcomes (but compared to IV cyclophosphamide). Also, we lack clarity on whether to re-treat and if steroids are necessary with rituximab. Overall, however, there is robust evidence that a 4 week course of rituximab is non-inferior to cyclophosphamide in the treatment of (most?) AAV patients.

For my other highlights of the year, see previous blogs regarding Abatacept  as targeted therapy for FSGS and the merits of high-volume online hemodiafiltration versus conventional high-flux dialysis. Don’t forget to vote for your top stories.

Plasma Exchange for Severe ANCA-Associated Vasculitis (AAV)?

There has been lots of new data in the AAV literature of late. We have new nomenclature, including the dropping of Freidrich Wegeners name for the more generic but descriptive granulomatosis plus angiitis (GPA), by the Chapel Hill consensus conference. A large genome wide association study by the European Vasculitis Genetics Consortium has reported genetic variants associated with AAV and show that polymorphism segregate with ANCA specificity (Anti-MPO and Anti-PR3). A recent follow-up to the RAVE study demonstrates non-inferiority of rituximab as compared to oral cyclophosphamide for severe AAV. Moreover, among patients who had relapsing disease at baseline, rituximab was superior to conventional immunosuppression, at least for the first year.

Removing pathogenic antibodies via plasma exchange (PE) is an attractive, if crude, treatment option for severe AAV and is generally recommended for severe alveolar hemorrhage (although without much evidence). In patients without severe lung involvement, it has gained a role in attempting to prevent ESRD in patients with severe renal disease at presentation, due largely to the MEPEX trial. MEPEX was published in 2007 and included patients with AAV who required dialysis at presentation or had a serum creatinine >500 µmol/L (5.8 mg/dL). This study included 137 patients who were randomized to 7 PE treatments or IV methlyprednsiolone pulse therapy. Both groups received oral steroids and cyclophosphamide. PE was associated with a risk reduction of ESRD of 24% at 1 year. Patient survival and severe adverse event rates were similar in the 2 groups. A follow up to MEPEX has been published in Kidney International this month where the original patients were followed for a median of 3.95 years. During this follow-up, over a half of patient died and almost two-thirds had either died or developed ESRD (the composite primary outcome), with no significant difference between the groups. Also, there was no significant differences in relapse rate.

It must be noted that the original MEPEX trial was designed to examine rate of ESRD alone and demonstrated a benefit with PE at 1 year. The current study looks at a composite of ESRD & death at 4 years. If the early effect on ESRD is real, it would be intuitive that later mortality would be improved which it seems is not. Overall this study questions the benefit of PE in severe AAV and certainly dampens our enthusiasm for its use in this sick patient cohort. A criticism of MEPEX is that IV methlyprednisolone is considered a standard of care in initial treatment of severe AAV and not an alternative to PE. In the real world, patients would receive IV methylprednisolone plus PE. It is also very possible that a beneficial effect of PE exists in cases of AAV earlier in their natural history before significant scarring has occurred, as suggested by a meta-analysis. At this point, PE can certainly be considered as part of the armamentarium of AAV treatment but its exact indication is unclear. The ongoing PEXIVAS trial is planned to enroll 500 patients and will hopefully clarify the role of PE, if any, in severe AAV.

Does nephrology need personalized medicine?

Systems biology is one of science’s growth areas. Sequencing technologies and software tools developed on the back of the human genome project have reduced the cost of, and therefore increased access to, large and complex datasets (ending in -ome) of genome sequences (genomics), gene expression (transcriptomics) and proteins and metabolites (proteomics and metabolomics). Systems biological techniques integrate these datasets and provide insights into how phenotypes may emerge from interacting biological processes rather than isolated genes or proteins.

A recent editorial in the journal Nephrology Dialysis Transplantation examined this field in general and its relevance to nephrology. The authors mention that –omic datasets have been useful in modeling “self-organized highly interconnected networks”, and that such networks have implicated unexpected candidates in disease pathogenesis (see for example, this paper on cardiac hypertrophy). 

The review goes on to suggest that using the tools of systems biology to finely phenotype individuals will usher in an era of truly personalized medicine. However, it is not clear to me that a definite sequel to this type of analysis will be the personalization of treatment or even that the concept of personalized medicine is particularly suited to our current view of what constitutes clinical evidence.

Diseases such as the ANCA-associated vasculitides (AAV) are now known to exhibit genomic variability. Randomised controlled trials (RCTs) in AAV (such as here and here) have been hampered by: 

1. Short follow-up times 
2. Inter-group heterogeneity which may have affected outcomes. These factors have contributed to ongoing debate about the applicability of the results of these trials (see correspondence here). 
3. Additionally a recent trial in membranous nephropathy, likely to represent another disease with distinct –omic subsets, was marked by slow recruitment. 

 

All these points together suggest that it may be difficult to conduct meaningful clinical studies of distinct –omic subtypes in nephrological diseases. Currently, primacy is given to RCTs when evaluating the efficacy of new treatments; and in nephrology the community is finally beginning to produce the RCTs which have been absent historically. 

If the focus is to switch away from RCTs with their large, well-matched study groups and towards splitting groups up by some -omic fingerprint I am able to envisage a time when one has to choose between giving more credence to the results of larger, “non-personalised” trials or smaller studies featuring –omic data but lacking the controlled element of RCTs.  Would this represent progress?

If ANCA cause vasculitis, what causes ANCA?

Over the past decade, controversy about whether ANCA is itself directly pathogenic has largely abated, primarily based on convincing animal models of small vessel vasculitis in mice and rats mediated by MPO ANCA. But as this issue is laid to rest, a new burning question has emerged in the field: if ANCA cause disease, what causes ANCA? Specifically, why are the ANCA antigens PR3 and MPO turned on in the neutrophils of ANCA patients, and not in their normally silenced state (as in healthy controls). This question hints at the regulation of gene expression itself, and brings us to the rapidly expanding field of epigenetics.

Epigenetics, the study of changes in phenotype and/or gene expression that are independent of the underlying DNA sequence, is one of the hottest areas of basic science research at the moment. Recently, the Jennette and Falk group in Chapel Hill examined whether high expression of the major auto antigens in ANCA patients, MPO and PR3, might have an epigenetic basis. The reason this is a good bet is that, although mature neutrophils from healthy subjects do not express MPO and PR3, these proteins are expressed in developing neutrophils. This suggests that there is transcriptional silencing of MPO and PR3 during development, which is the hallmark of epigenetic control.

They showed that levels of a specific histone methylation (H3K27me3) were reduced at the MPO and PR3 loci in ANCA neutrophils compared to those from healthy controls. H3K27me3 is associated with the formation of heterochromatin, which is inaccessible to transcription and often causes gene silencing. They went on to show that Jmjd3, the demethylase responsible for removing this particular histone methylation is upregulated in ANCA patients. This suggests that Jmjd3-mediated changes in histone methylation status may be responsible for aberrant expression of MPO and PR3 in mature ANCA neutrophils. This study throws up a number of areas for further research. For example, elucidation of what causes the initial failure of gene silencing mechanisms will give further insight into the pathogenesis of the disease, whilst insight into the pathways which both establish and maintain silence of MPO and PR3 in healthy patients may suggest new therapeutic approaches.

Thomas Oates MD

Choose your poison

The way drug discoveries happen is always fascinating. Today, I heard Dr Nadler describe how he discovered Rituximab. He was a young oncology fellow at Dana-Farber back in 1979 when he convinced a colleague dentist to teach him how to produce antibodies in vitro. The technology had been developed a couple of years earlier and his friend was hoping to use antibodies to produce a mouthwash, which would stop cavities! Among the antibodies developed in collaboration, they created one that had specificity for B cells and named them as CD20.

Later, Dr Nadler and others tested this antibody in humans that was accompanied by many side effects but with successful initial results in patients with lymphoma. Some of the side effects were related to the murine origin of the antibody. This problem was solved years later when Dr Winter developed humanized antibodies.

Last week’s NEJM carried 2 articles reporting the use of Rituximab for ANCA vasculitis. The treatment of ANCA vasculitis is very challenging, especially c-ANCA positive (Wegener’s) due to the high rate of relapse 30-75%. Patients who undergo fast taper or with very high ANCA levels are at increased risk, but no good marker exists at this time. Therapy of WG and MPA has two components: the induction of remission; and the maintenance (to prevent relapse).

Induction of complete remission, defined as the absence of active disease, is the goal of initial immunosuppressive therapy and it usually consists of cyclophosphamide (CYC) and steroids. Plasmapheresis should be considered in patients with severe renal dysfunction, lung hemorrhage, CNS vasculitis or mononeuritis multiplex. Dr Steele shared his personal experience on a prior blog.
The maintenance than consists of azathioprine and prednisone for 12-24 months. The results of the trial of Stone et al. was interesting since it compared CYC with Rituximab with discontinuation of steroids at 5mo showing better results in the Rituximab group. However, follow up was short and no conclusions can be obtained about relapse in the long term. One interesting point is the high mortality of ANCA patients, reaching ~18% on both groups! Quoting Paracelsus: “All substances are poisons, there is none which is not a poison. The right dose differentiates a poison from a remedy”. These patients need close monitoring and defining the ideal individualized dose is the Holy Grail.

The conclusion taken from both trials is that Rituximab could be considered an alternative therapy for ANCA vasculitis, however their superiority in the long-term still need further testing. Also check Nates's blog on "How much Cytoxan is too much?"

What's in a name?: Dr. Wegener's Murky Past

This months issue of JASN has a review of ANCA-associated vasculitis. The authors discuss the controversy regarding the naming of Wegener’s Disease and whether it’s time for a new name to be chosen for this condition.

Dr. Friedrich Wegener was a German pathologist who is best known for first describing the pathological condition that bears his name. He was in receipt of numerous honors throughout his life including the title ‘Master Physician’ which he received from the American College of Chest Physicians (ACCP) in 1989, the year before his death. He was known as an excellent physician and educator having taught for many years in the university of Lubeck.

However, it seems that he had a murky past of which few were aware. After finishing medical school in 1932, he joined the Sturm Abteilung (SA), also known as the brownshirts, the paramilitary wing of the Nazi party. The following year he joined the Nazi party itself when Hitler came to power. He rose through the SA and achieved the rank of Lieutenant Colonel by 1938. During the 1930s his mentor was Dr Martin Staemmler, a prominent supporter of the Nazi party who had written extensively on racial hygiene. When the war started, he was sent to Lodz in occupied Poland where he worked as a pathologist until 1944. His office was just a few blocks from the Lodz ghetto where more than 40,000 Jewish inmates died during the war with most of the remainder deported to concentration camps. Although there is no evidence that he was involved in ‘selections’ he is known to have performed autopsies on inmates of the ghetto and could not have been unaware of what was going on. After 1944, he served as a field surgeon in the German army until the end of the war. His name was placed on a list of war criminals by the Polish government but he was never prosecuted and underwent de-Nazification in 1947 after which he was allowed to return to practicing medicine.

Although many professionals in Germany joined the Nazi party in the 1930s for the purpose of enhancing their careers, it is instructive that Dr Wegener joined the SA prior to Hitler’s rise to power suggesting that his sympathies lay with the Nazis. That said, there is no specific evidence that he took part in any war crimes.

In 2007, after this paper was published, the ACCP decided to posthumously rescind the award of master clinician awarded in 1989. Since then there have been calls by physicians and patient advocacy groups to change the name of the Wegener’s Granulomatosis.

The original paper published in the Lancet in 2006 can be found here while another paper detailing the search that the authors conducted in order to discover this hidden history is here.


Posted by Gearoid McMahon MD

How much Cytoxan is too much?

Cytoxan is a very potent but also potentially toxic medication used for a variety of immune-mediated (and nephrology-relevant) diseases. It is often classified as a "cytotoxic agent", as it works as an alkylating agent that explains its utility also as a chemotherapeutic agent.

Because it is traditionally used at very high doses in oncology as compared with nephrology, the risk of side effects is dramatically increased in oncology patients. However, the risk of malignancy--most notably bladder cancer, but also leukemias and non-melanoma skin cancers--is still present in nephrology patients treated for conditions such as lupus nephritis or ANCA-associated vasculitis. How can you minimize this risk?

A 2008 study by Faurschou et al looked at a cohort of 293 patients diagnosed with Wegener's granulomatosis, many of which were treated with cyclophosphamide. They found that the risk of bladder cancer or leukemias was elevated for those explosed to a cumulative dose greater than 36 grams, but there was no increased risk of either cancer for those with a cumulative dose less than 36 grams. A cumulative dose of 36 grams would correspond to taking Cytoxan 100mg a day for 1 year. The authors also report that patients developed bladder cancer between 6.9 - 18.5 years after cyclophosphamide exposure.

One strategy for giving Cytoxan in Wegener's that I have seen used quite often is giving Cytoxan and prednisone when the disease is initially diagnosed for a period of 6 months--then transitioning to, say, steroids and azathioprine. This way, the Cytoxan can be used to get the disease under relative control without causing the dramatically increased risk in cancers, and still could be used a 2nd time if there is another serious flare in the future. Also, because the appearance of cancer is relatively delayed, one may be less hesitant to use Cytoxan for longer periods of time in the elderly.

Churg-Strauss Syndrome

Churg-Strauss Syndrome lies within the spectrum of Wegener's Granulomatosis, microscopic polyangiitis, and ANCA-associated vasculitis: all diseases which result from inflammation of small-to-medium-sized vessels. The "classic triad" of Churg-Strauss syndrome is asthma, eosinophilia, and vasculitis, and although "renal involvement" is not amongst these, it does occur in a subset of Churg-Strauss patients.

In this 2006 AJKD article looking at 116 Churg-Strauss patients, about 25% had some type of renal involvement. Of those who had rapidly progressive glomerulonephritis and crescents on biopsy, all were ANCA-positive. Renal involvement in Churg-Strauss should therefore generally be managed as an ANCA-associated vasculitis, e.g. steroids, Cytoxan, with a possible role for for plasma exchange or Rituxan.

From the RFN Archives: Drug-Induced ANCA

A subset of patients with ANCA-associated vasculitis have drug-induced ANCA disease. There are a few features of drug-induced ANCA disease which set it apart from "idiopathic" ANCA disease, but overall the clinical symptoms are similar.

Drug-induced ANCA almost always involves the production of anti-MPO antibodies (p-ANCA) as opposed to anti-PR3 antibodies. Occasionally, the disease will resolve on its own with removal of the drug--but more often than not, standard immunosuppressive therapy (e.g., Cytoxan and steroids) is required. Rash is a frequent manifestation of the vasculitis. Often, hydralazine-induced ANCA is associated with the production of MANY autoantibodies (e.g., ANA and many others) beyond just ANCA. Also, drug-induced ANCA does not typically occur until the patient has been on the drug for a few years--not your typical drug-induced allergic reaction which would occur within the first few days of starting the drug.

There is a long list of drugs which have had associations with ANCA-associated disease, but a few of the more convincing drug associations of which to be aware are:

1. HYDRALAZINE!

2. propylthiouracil

3. penicillamine

4. minacycline

Ciprofloxacin, allopurinol, sulfasalazine, and phenytoin have also been implicated but the evidence is not as strong as the previous 4.

A 3rd ANCA Subtype: LAMP-2

We all know about the p-ANCA and the c-ANCA, which are antibodies against either myeloperoxidase (MPO) or proteinase-3 (PR3), respectively.  Now get ready for a 3rd ANCA subtype, an antibody against LAMP-2!

In a recent Nature Medicine article by Kain et al, the investigators show that in most patients with the disease focal necrotizing glomerulonephritis FNGN)--a severe form of pauci-immune glomerulonephritis with positive ANCA titers--there are antibodies against an epitope of human LAMP-2.  Evidence for its pathogenicity is convincing:  when either the patient's antibody OR a designed monoclonal antibody raised against LAMP-2 is injected into rats, they develop glomerulonephritis.

Interestingly, the LAMP-2 antigen is highly homologous to a bacterial antigen termed FimH.  The authors' hypothesis is that patients who develop bacterial infection with an organism containing FimH develop antibodies against this antigen which are also cross-reactive with LAMP-2, expressed on neutrophils.  This is another example of "molecular mimicry" which may also be found in conditions such as rheumatic heart disease.  

PAN versus MPA

Polyarteritis nodosa (PAN) and Microscopic polyangiitis (MPA) are two vasculitides which were previously grouped together.

However, they are currently thought of as two separate entities.

PAN is a vasculitis of the medium-sized arteries, sparing the smaller vessels and therefore does NOT cause a glomerulonephritis. Any renal compromise which results is generally due to ischemia from inflammation of the medium-sized renal vessels. PAN is often associated with hepatitis B infection.

In contrast, MPA is a vasculitis of the small-sized vessels, and therefore results in a pauci-immune glomerulonephritis. It is very commonly ANCA-positive.

Double Antibody Disease

The incidence of ANCA-positive disease is in the ballpark of 1:10,000. The incidence of anti-GBM disease is even more rare, at about 1:1,000,000. One would expect if these 2 disease-causing antibodies were entirely independent of one another, the incidence of a "double positive" (e.g., both ANCA & anti-GBM-positive) would be predicted to be (1:10,000 x 1:1,000,000 =) 1 in 10,000,000,000, or one in 10 billion.

Double positive disease is much more common than this, however. One study by Levy et al in a 2006 Kidney International paper showed that 5% of all ANCA-positive serum samples were also positive for anti-GBM antibodies, and about 1/3 of all anti-GBM positive samples had detectable ANCA. Most of the time (82%) the double-positive patients had an anti-MPO (myeloperoxidase) specific antibody. Perhaps not surprisingly, the double antibody-positive patients have a worse outcome than single-positive patients.

One theory to explain the existence of double-positivity is that the disease starts off as an ANCA-mediated process and damages the glomerular basement membrane, thereby exposing antigens to which an anti-GBM can form. Treatment in the acute setting is generally aggressive (e.g., treat them as if they have anti-GBM disease) and chronically is often managed as an ANCA disease.