Summary and Closing Remarks - Kidney

Mark HaasCedars-Sinai Medical CenterLos Angeles, California, USA

4 years after the initiation of the Banff working groups, their efforts are coming to fruition!

Isolated vasculitis responds to anti-rejection treatment

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Group 3 pristine kidneys(borderline and ATNexcluded)

* p<0.05, compared to group 3

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Slide courtesy of Banu Sis

Death-censored Graft survival is worse in isolated vasculitis than in no rejection and comparable to Banff II rejections

Isolated v (N=100, F=21)

V + T-I rejection (N=98, F=21)

No V and T-I rejection (N=99, F=9)

p=0.028

N= 297F=51Median F/U time: 39.1 months

Post biopsy time (days)

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Slide Courtesy of Banu Sis

Proposal for standard definition and scoring system of Glomerulitis and Glomerular Double Contours

• Glomerulitis is defined as intra-capillary loop mononuclear inflammatory cell infiltration AND endothelial cell enlargement with occlusion or near-occlusion of 1 or more capillary lumens. The extent of glomerulitis is scored based on percentage using PAS and/or silver sections (w/wo CD68) as follows;

• g0 - no glomerulitis (0%)• g1 - segmental or global glomerulitis in 1-25% of glomeruli• g2 - segmental or global glomerulitis in 25-75% of glomeruli• g3 - segmental or global glomerulitis in >75% of glomeruli

Transplant glomerulopathy is defined as presence of glomerular peripheral capillary loop duplications observed using PAS and/or silver stained sections and absence of significant IC deposits along capillary walls by IF and/or EM studies. Double contours scored as follows;

• cg0 – NO double contours of the GBM (0%) in any glomeruli using LM PAS/silver or EM.• cg1 – double contours of the GBM in 1-25% of capillaries in the most involved glomerulus by LM. If

there is less than 10% of capillaries with double contours, confirmation by EM with demonstration of few double contours PLUS endothelial activation is needed.

• cg2 – double contours of the GBM in 26-50% of capillaries in the most involved glomerulus• cg3 – double contours of the GBM in >50% of capillaries in the most involved glomerulus

Slide courtesy of Banu Sis

Implantation Biopsy Working Group-Helen Liapis1. Wedge biopsy adequate; frozen wedge biopsy actually shows less inter-observer variability than frozen core biopsy for

evaluation of several parameters (globally sclerotic glomeruli, arterial intimal fibrosis) – what constitutes an adequate wedge?

2. Inter-observer agreement for evaluation of most parameters is better on paraffin sections than on frozen sections, however for wedge biopsy the difference is modest

3. Inter-observer agreement is excellent to good for assessing glomerular parameters; fair to good for vascular and interstitial parameters

4. Digital evaluation of these biopsies works well

5. No correlation between histologic parameters and DGF, SCr at 6 and 12 months. However, sample size small and all biopsies had <20% globally sclerotic glomeruli. Additional studies needed in a larger and possibly more histologically variable set of biopsies.

Polyoma Working Group – Volker Nickeleit

Recommended Scoring System

PVN 1 - PV inclusions by LM and IHC <1% (pvl 1); ci 0-1

PVN 2 - pvl 1 and ci 2-3 pvl 2 (1 – 10% inclusions); ci 0-3 pvl 3 (>10% inclusions); ci 0-1

PVN 3 – pvl 3 and ci 2-3

No rejection before bx/during F/UPVN peak SCr incr from peak, 12mo graft loss by 24mo 1 1.7 0.2 12% 2 2.1 0.4 19% 3 2.6 1.2 50% p = 0.023

Full-blown acute AMR (acute AMR type 1); all 4 features must be present for diagnosis

•Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)

•Histologic evidence, including one or more of the following:Microvascular injury (g > 0* and/or ptc >0)Intimal or transmural arteritis (v >1)**Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS)Acute tubular injury, in the absence of any other apparent cause for this

•Immunohistologic evidence, including one or more of the following:Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen sections, C4d >0 by IHC on paraffin sections)IgG and/or complement deposition in arteries (excluding arteries with hyalinization)

•Evidence of acute graft dysfunction, including an acute rise in serum creatinine or new onset of proteinuria, if no evidence or recurrent or de novo glomerular disease

*Recurrent/de novo glomerulonephritis should be excluded **These arterial lesions may be indicative of AMR, CMR, or frequently mixed AMR/CMR. “v” lesions and immunofluorescence are not scored in arterioles.

Acute AMR without Evident Complement Deposition (acute AMR type 2); all 4 features must be present for diagnosis

- Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)

- Histologic evidence, including one or more of the following: Microvascular injury (g > 0* AND ptc >0) Intimal or transmural arteritis (v >1)** Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS) Acute tubular injury, in the absence of any other apparent cause for this

- No evidence of complement deposition C4d staining in <10% of peritubular capillaries (C4d0 or C4d1) by IF on frozen sections, no C4d staining (C4d = 0) by IHC on paraffin sections No IgG and/or complement deposition in arteries (does not include arteries with hyalinization)

- Evidence of acute graft dysfunction, including one or more of the following: Acute rise in serum creatinine New onset of proteinuria, if no evidence or recurrent or de novo glomerular disease *Recurrent/de novo glomerulonephritis should be excluded

C4d-positive subclinical AMR (subclinical AMR type 1); all 4 features must be present for diagnosis

•Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)

•Histologic evidence, including one or more of the following: Microvascular injury (g > 0* and/or ptc >0) Intimal or transmural arteritis (v >1)** Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS)

•Immunohistologic evidence, including one or more of the following: Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen sections, C4d >0 by IHC on paraffin sections

•Stable serum creatinine, no new onset of proteinuria

*Recurrent/de novo glomerulonephritis should be excluded **It should be noted that these arterial lesions may be indicative of AMR, CMR, or frequently mixed AMR/CMR. “v” lesions and immunofluorescence are not scored in arterioles.

Subclinical AMR without Evident Complement Deposition (subclinical AMR type 2); all 4 features must be present for diagnosis

•Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)

•Histologic evidence, including one or more of the following: Microvascular injury (g > 0* and/or ptc >0) Intimal or transmural arteritis (v >1)** Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS)

-No evidence of complement deposition C4d staining in <10% of peritubular capillaries (C4d0 or C4d1) by IF on frozen sections, no C4d staining (C4d = 0) by IHC on paraffin sections

•Stable serum creatinine, no new onset of proteinuria

*Recurrent/de novo glomerulonephritis should be excluded **It should be noted that these arterial lesions may be indicative of AMR, CMR, or frequently mixed AMR/CMR. “v” lesions and immunofluorescence are not scored in arterioles.

C4d-positive chronic AMR (chronic AMR type 1); all 3 features must be present for diagnosis

- Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)

- Morphologic evidence, including one or more of the following: Transplant glomerulopathy (cg >1), if no clinical evidence of chronic TMA Peritubular capillary basement membrane multilayering (requires EM) Arterial intimal fibrosis of new onset

- Immunohistologic evidence, including one or more of the following: Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen sections, C4d >0 by IHC on paraffin sections)

Chronic AMR without Evident Complement Deposition (chronic AMR type 2); all 3 features must be present for diagnosis

- Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)

- Morphologic evidence, including one or more of the following: Transplant glomerulopathy (cg >1), if no clinical evidence of chronic TMA Peritubular capillary basement membrane multilayering (requires EM) Arterial intimal fibrosis of new onset

- Immunohistologic evidence, including one or more of the following: Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen sections, C4d >0 by IHC on paraffin sections

If a biopsy shows histologic evidence for acute AMR and also meets above criteria for chronic AMR, the term “chronic active AMR” (C4d-positive or without evident complement deposition) may be appropriately used.

C4d Staining Without Histologic Evidence of Rejection; all 3 features must be present for diagnosis

•Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen sections, C4d>0 by IHC on paraffin sections)

•g = 0, ptc = 0, cg = 0 (by light microscopy and EM), v = 0; no TMA, no peritubular capillary basement membrane multilayering, no acute tubular injury (in the absence of another apparent cause for this)

•No acute cell-mediated rejection (Banff 97 type 1A or greater)

Comments on Proposed AMR Classification21 total responses – could not open 1

MVI ThresholdOK as is – 2Any g or ptc – 1Too low for C4d-negative cases – 5

suggest (g + ptc >3) - 2(g + ptc + v) >3 – 1

v1, v2, v3 as histological evidence for AMR – 6/6(one suggested IHC typing of intimal cells)

C4d1 by IFConsider as negative – 4Negative should be completely negative (C4d0) - 1More data needed - 1

Terminology

Favor AMR without evident complement deposition – 6

Favor C4d-negative AMR – 4

Favor complement–negative AMR - 1

Consider EM findings in cg scoringYes, as cg1 if double contours present – 10Yes, as cg1 if GBM duplication in >3 capillaries - 1 Yes, but need more specific criteria – 3Consider ptc serrations in addition to glomerular changes – 1

No need to separate clinical from subclinical AMR – 4

Eliminate new onset proteinuria as clinical criterion for acute AMR – 4

Eliminate Arterial Ig/Complement Deposition as immunohistologic criterion for acute AMR – 4

Change smoldering to subclinical - 7

Eliminate the term “Accommodation” - 3

Some additional comments (n = 1)

- Clarify if ptc>0 includes both focal and diffuse; consider WG evaluation of ptc scoring similar to that done for g, cg

- C4d+ chronic AMR should be considered chronic/active

- Include IF/TA as histologic criterion for chronic AMR

- Include post-transplant increase in cv score by >1 as histologic criterion for chronic AMR

- C4d-negative clinical acute AMR is very rare

- Add comment that C4d is not reliable diagnostic tool in ABOi

- Make it shorter

What to do with MVI in absence of C4d and DSA

Merits comment, not diagnosis (6/6)

Test for non-HLA DSA (3)

Consider molecular testing

Consider follow-up biopsy

Based on the scientific sessions and the three discussion sessions, 3 new renal Banff working groups are being proposed.

Proposed Working Group for CMR

Questions to address:

1. Should ti be included in classification for CMR diagnosis? - As a replacement for the i score - As part of a new category of chronic/active CMR - Include in diagnosis line but not within classification per se - Include as a comment, not necessarily in diagnosis line - Other suggestions

Proposed Working Group for CMR

Questions to address:

2. Should the borderline category be modified to try and identify those lesions most specific for active CMR? - By assessing edema and tubular injury (as in CCTT) - By including immunohistochemical stains (e.g., granzyme B) - By assessing the extent of tubulitis (as in CCTT) - By inclusion of molecular data where available, and if so what are the most useful transcripts/transcript sets to examine?3.Are there clinical and pathologic differences in borderline infiltrates in for cause vs. protocol biopsies?

A new working group comprised of clinicians, pathologists, and clinical immunologists to:

1. Develop evidence-based recommendations for transplantation of patients with broad sensitization

and high titer DSAs, for whom the only transplant option is desensitization?

- How frequently to monitor DSA- Role of protocol biopsies, when (and to how far out

post-transplant) should this be done - Should an increase in DSA without a change in graft function prompt a biopsy?

- What are the minimal capabilities a center needs to have to support care for these patients (including but not limited to HLA lab/pathology evalation and TAT, available therapies, specialized personnel)

A new working group comprised of clinicians, clinical immunologists, and pathologists to:

2. Systematically evaluate possible differences in AMR (clinically, serologically, pathologically, and from a molecular standpoint) in this group of patients versus those of other sensitized patients and of non-sensitized patients with de novo DSA that may be relevant to how the patients are treated?

Working Group for Evaluation of Non-Morphologic Data in Renal Allografts

1. Develop consensus guidelines for: - Circumstances under which it is advisable to perform serologic testing for DSAs and molecular analysis on renal biopsy tissue and/or serum/urine collected at the time of biopsy. - What are the best molecular studies to perform under specific circumstances (e.g., early and late C4d-negative AMR)

2. Find applicable molecular markers that are associated with improved prediction of clinical outcomes and/or improved inter-observer variability of biopsy interpretation, and can be tested for at different centers with acceptable inter-center agreement

EM is clearly useful as a predictive tool for development of TG, and may help guide additional testing (e.g., for DSA)

and therapeutic approach to patients with early ultrastructural capillary lesions

2 proposals:

1.Divide the cg1 category into:

cg1a – GBM double contours (new lamina densa) and subendothelial widening (LRI expansion) by EM; no GBM double contours by light microscopy

cg1b – GBM double contours in at least one glomerulus by light microscopy; confirmation by EM recommended

2. Make recommendation that tissue be taken for EM from renal allograft biopsies:

- If any clinical suspicion of recurrent or de novo glomerular disease - If any significant proteinuria - If specific risk factors for TG: Pre-sensitized patients with positive crossmatch History of DSA+, preformed or de novo History of C4d+ or microvascular inflammation (g,ptc) in a previous biopsy - All grafts > 3 months (or 6 months?) post-tx;

looking for ultrastructural features of early TG & PTCBMML and/or changes predictive of development of TG

From Ian Gibson

Obrigado (thank you) to everyone who sent me their comments on the proposed AMR classification, and especially to our hosts Daisa, Elias, and Cristina!