2nd Midwest Transplant Symposium

Free accommodation is available for nephrology fellows and residents (IM or Surgery) for Friday night (October 14) at Home 2 Suites (rooms are limited). To apply for free accommodation, please email Laura Kipper lkipper@wustl.edu 
Go here for registration and more information

Midwest Transplant Symposium

Washington University at St Louis will be holding the inaugural Midwest Transplant Symposium on October 16th and 17th 2015.

This course is designed to be an in-depth review and update in kidney and pancreas transplant.
8.5 AMA PRA Category 1 Credits are available for this course.
Fellows and residents registration fee is $45 (plus $100 if CME credits are required).
For more information

Tacrolimus Formulations

Tacrolimus comes in oral, intravenous and topical formulations. Prograf is the most commonly used oral tacrolimus formulation and is dosed twice daily.

Prograf pharmacokinetics 

Absorption:
Absorption occurs in the small intestine.
Drug levels reach a maximum concentration in 1 to 2 hrs.
Tacrolimus is poorly soluble and oral bioavailability is about 11 to 20%.

Metabolism:
Cytochrome P450 3A4 metabolizes tacrolimus to at least 10 metabolites, some of which retain significant activity. Biliary excretion is the route of elimination for these tacrolimus metabolites. Gastrointestinal tract mucosal cells also contain CYP P450 3A4 activity and contribute significantly to metabolism.

Elimination:
The terminal elimination half-life of tacrolimus is approximately 12 hours. Elimination is prolonged in hepatic dysfunction.

Poor solubility, first pass metabolism, small bowel CYP450 metabolism and p-glycoprotein activity (pumps drug back into the bowel lumen) all cause reduced oral bioavailability of tacrolimus. Low oral bioavailability is a common pharmacological problem and 30% of marketed PO drugs have poor solubility defined as water solubility below 20ug/ml. An oral drug can only be absorbed once dissolved.

LCP-Tacrolimus 
LCP-Tacrolimus was designed to achieve greater bioavailability by increasing the solubility of tacrolimus. LCP is Life Cycle Pharma, a Danish company now trading as Veloxis Pharmaceuticals. This new tacrolimus formulation uses ‘Meltdose’ technology to achieve this goal. LCP Meltdose technology works by decreasing the particle size of the drug to the molecular scale thus increasing particle surface area. Increased surface area increases solubility. Tacrolimus is heated into a ‘liquid like’ state and then atomized and sprayed onto an inert particle carrier. This then solidifies in a state of ‘solid solution’ into granulates and is compressed into tablets. These granulates retain their particle sizes and dissolution characteristics. Thus, once delivered to the small bowel these very small particles of tacrolimus go into solution easily and are better absorbed.

Phase 2 trials of LCP-tacrolimus in de novo kidney transplant patients have shown a more consistent concentration profile, increased bioavailability of about 30% and reduced peak to peak and peak to trough variation compared with bid tacrolimus (Prograf).

This month in AJT
Budde et al report on a phase III study of LCP-Tacrolimus vs bid tacrolimus in de novo kidney transplants.

This was a worldwide, double blind, double-dummy, randomized study in 543 de novo kidney transplants comparing LCP-tacrolimus with Prograf (bid tacrolimus). It was designed as a non-inferiority trial with a primary endpoint of treatment failure at 12 months (death, graft failure, biopsy-proven acute rejection).

More LCPT patients were in ‘target range’ (6-11) after initial doses. Trough/dose ratio increased (reflecting better absorption) over time with LCPT and was statistically higher than Prograf. Trough levels were similar. Total daily doses were lower for LCPT at 1 and 12 months and the cumulative dose over the whole study was 14% lower for LCPT.

The overall incidence of treatment failure was 18.3% for patients in the LCPT group and 19.6% for patients in the tacrolimus twice-daily group. The treatment difference (95% CI) was −1.35% (−7.94% to +5.27%), well below the noninferiority margin of 10%.

There were no significant differences in adverse events between groups. Interestingly 97% of each group had an AE over the 12 months the most common being diarrhea, anemia, UTI, hypertension and constipation. There was a numerical trend towards more NODAT with LCPT that may be explained by higher LCPT exposure in the first 3 weeks. There was a trend towards a smaller rise in lipid abnormalities in the LCPT group.

This was a well-powered and well conducted trial. LCP-Tacrolimus is safe and as efficacious as Prograf. Cumulative doses are lower and therapeutic range was reached earlier and is more likely to remain stable. This is a promising once daily preparation, however, pricing is likely to determine whether this formulation becomes standard of care in kidney transplantation.

What about Advagraf/Astagraf?
Leonardo V Riella and colleagues from Boston posted on Astagraf and LCPT last year. 

Advagraf was approved for the European market in 2007 and the FDA approved Astagraf in 2013. Advagraf contains the same active drug, tacrolimus, as Prograf. Advagraf contains ethylcellulose, which controls water penetration and changes its dissolution properties. The drug also contains a hypromellose protective coat. Both these factors cause the active drug to be released more slowly and further along the GI tract.

In mostly industry sponsored trials Advagraf showed lower peak drug concentrations but equivalent AUC(0-24) and Cmin(trough) concentrations when compared to Prograf. Thus, a 1:1 conversion is suggested in the package insert. However, subsequent experience with Advagraft has demonstrated lower Cmin values and high inter-individual variability leading to the need for higher Advagraft dosing and difficulty with trough interpretation. Furthermore, a phase III study in de novo kidney recipients has shown higher rates of acute rejection with Advagraf, possibly explained by the differing C(max) values achieved with the two preparations. Biopsy-proven acute rejection rate at 24 weeks (primary endpoint, per-protocol analysis) was 15.8% for Tacrolimus BID versus 20.4% for Tacrolimus QD (p = 0.182; treatment difference 4.5%, 95% confidence interval-1.8%, 10.9%) just outside the prespecified 10% noninferiority margin.

In Europe where this formulation has been approved since 2007 use of the drug is still minimal. It will remain to be seen whether the same trend occurs in the US. Experiences so far make it unlikely that this formulation will become first line therapy in kidney transplantation.

SHROOM3, Making sense of GWAS risk alleles

In this months edition of JCI a group led by Dr B Murphy from Icahn School of Medicine at Mount Sinai describe a beautiful set of experiments that explain the mechanism by which the CKD and eGFR risk allele rs17319721 causes chronic kidney allograft damage.

The single nucleotide polymorphism rs17319721 is in intron 1 of a gene called SHROOM3. The risk allele A (major allele G) of rs17319721 was found in large GWAS studies of European ancestry to be associated with GFR (p=1*10−12), incident CKD (p=0.005) and GFR in type 2 diabetic patients (P= 3.18E-03). The risk allele, A, frequency is about 40% in caucasian populations but is less frequent in non-caucasian populations.

The authors decided to investigate the effect of rs17319721, the SHROOM3 risk genotype, on kidney allograft fibrosis and chronic allograft nephropathy (CAN). Furthermore, they sought to determine what role, if any, SHROOM3, plays in allograft fibrosis. The risk locus was genotyped in over 500 allograft recipients and 500 allograft donors from the GoCAR transplant cohort. Also, SHROOM3 transcript levels in 3month protocol allograft biopsies were recorded in some of these patients. Donor genotype carrying one risk allele A (A/A or A/G) was associated with higher 3month SHROOM3 expression levels compared to the normal donor G/G genotype. Interestingly, correlation occurred only in Caucasian donors when analyzed separately and there was no association with the recipient risk genotype.

The authors then looked at 12month allograft GFR and chronic allograft dysfunction index score at 12 months (CADI-12). 3month SHROOM3 expression levels were inversely related to 12 month GFR, predictive of CADI-12 and were predictive of worsening CADI score (3m to 12m)(termed ‘progressors’). These associations were not found in non-Caucasian donors.

To assess whether 3M SHROOM3 levels could predict CAN they generated logistic models that included recipient age, sex, race, AR and CIT with or without 3M SHROOM3 levels to predict 12M CADI ≥2 or 3-12M CADI change (ΔCADI) of ≥2. AUC for prediction of high CADI-12 and ΔCADI were improved in each subgroup when SHROOM3-3M level was added. For Caucasian donors AUC for ‘progression’ was 0.81 with SHROOM3 and 0.74 without SHROOM3. Furthermore, the A allele in the donor was associated with greater risk of CADI-12≥2 in all allografts (OR 1.98; CI, 1.10–3.59), indicating a higher risk of CAN with the risk allele.

This work demonstrates that the A risk allele (rs17319721) in donors is associated with higher 3M SHROOM3 levels and increase risk of CAN. Also, 3M SHROOM3 levels predict CAN and 12M GFR.

So what is the mechanistic consequence of having the A allele vs the G allele? rs17319721 is located in a transcription factor binding motif. The authors found that the transcription factor TCF7L2 binds more strongly to this motif when A is present vs when G is present. Wnt agonist increased TCF7L2/β-catenin complex binding to the A allele binding site but not the G allele site. TGF-β1 is a known key growth factor regulating renal fibrosis. The authors found that TGF-β1 induced increases in SHROOM3 expression via the Wnt/β-catenin/TGF-β1 pathway in renal tubular cells.

Then they showed SHROOM3, in turn, enhances the TGF-β1/SMAD3–induced expression of profibrotic genes including CTGF, Vimentin, and Collagen IV (downstream targets of TGF-β1/SMAD3 signaling) and these genes were significantly upregulated in allografts within the highest quartile of SHROOM3 expression. Finally the authors verified these data in a mouse model of fibrosis.

Taken together, this data suggest an increased profibrotic program in the presence of the enhancer function of the risk allele and/or increased SHROOM3 expression. This schema is illustrated below.

This paper nicely describes the mechanism of action conferred by a single risk allele found in large GWAS studies. Until recently there has been little data to explain the relevance of the many risk SNPs described in GWAS studies. Without an understanding of the mechanism through which these SNPs confer disease there can be no progress towards identifying potential therapeutic targets. This study has identified SHROOM3 as a potential therapeutic target for chronic allograft nephropathy.

Michelle P Winn Endowed Lectureship, ASN 2014

At this year's ASN Kidney Week in Philadelphia Andrey Shaw, MD, presented the inaugural Michelle P Winn Endowed Lectureship. Dr Shaw was not only a longtime collaborator of Michelle’s but also a very close personal friend making him the perfect choice for this inaugural lectureship. Dr Shaw delivered an excellent talk interweaving highlights from Michelle’s stellar career with examples of Michelle’s fun loving and genuine kindhearted nature. I was lucky enough to work in Michelle’s lab from 2012 to 2014. She cared greatly about all her mentees both professionally and personally. She was a huge inspiration and a friend.

Michelle did her undergraduate studies at the University of North Carolina before going to medical school at East Carolina University. She then entered Duke University for residency and fellowship before joining the Duke faculty. Despite spending most of her career at Duke she remained a true Tar Heel (UNC) fan!

She received her training in classical human genetics from Drs Jeffery and Peggy Vance at the Duke Center for Human Genetics. In collaboration with another longtime friend and collaborator and early mentor at Duke, Dr Peter Conlon, Michelle began investigating the genetic heterogeneity of FSGS.

• Together Drs Winn and Conlon collected what is now one of the largest Familial FSGS datasets in the world.
• Michelle’s early work linked familial FSGS in one large family from New Zealand to a locus on chromosome 11.
• Following this she identified TRPC6 as the cause for FSGS in this family. This was a seminal paper published in Science and introduced an ion channel and calcium into the burgeoning field of podocyte biology. 
• Michelle’s further work on TRPC6 made a huge contribution to the understanding of the biology of TRPC6 in kidney disease. 

Michelle was also very interested in other inherited kidney diseases.

• She described linkage of a gene causing MPGN type III, 
• identified TNXB mutations causing vesicoureteral reflux, 
• was involved in studies of genetic factors influencing the development and progression of IgA nephropathy 
• a hybrid CFHR3-1 gene causing familial C3 glomerulopathy. 
• Her work also helped to define the disease burden and impact of other FSGS causing genes such as INF2, NPHS2 and PLCe1. 

Towards the end of her career and even while fighting her illness she remained very involved and continued to contribute in a huge way to the field we all love.

• She discovered Anillin a new gene causing FSGS, 
• a new mutation in the WT1 gene 
• added further insights into the function and regulation of TRPC6 in podocytes. 

Michelle was a leader in her field of podocyte biology and renal genetics. In 2007 Michelle won the ASN Young Investigator Award. I am sure that if her life had not been tragically cut short she would have been awarded the highest honors our specialty has to offer. The creation of the Michelle P Winn Endowed Lectureship is testament to this probability. Michelle was a beautiful person and will be missed by all who knew her.

Tick borne diseases for the nephrologist - Babesiosis

The following few posts are a summary of tick borne illnesses that can cause renal failure and/or electrolyte problems. 

Babesiosis

First identified on Nantucket Island in 1969 and was initially know as Nantucket fever.

Endemic areas.
CDC map. Reported cases in 2012

Cases have been reported in Europe (Croatia, France, Great Britain, Ireland, Portugal, Spain, Sweden, Switzerland)(Babesia divergens).

The tick.

Ixodes scapularis. The Blacklegged tick.

The pathogen.

Babesia microti and B. duncani (USA). B divergens (Europe). Protozoan parasites infecting red blood cells

Humans are not a natural host. Infection by blood transfusion has been reported.

Incubation period 1 – 9 weeks

Clinical features.

Fever, chills, sweats, Malaise, fatigue, Myalgia, arthralgia, headache, Gastrointestinal symptoms, such as anorexia and nausea (less common: abdominal pain, vomiting)

Dark urine

Less common: cough, sore throat, emotional lability, depression, photophobia, conjunctival injection

Mild splenomegaly, mild hepatomegaly, or jaundice may occur in some patients

Lab features

Haemolytic anemia, thrombocytopenia, renal failure, transaminitis.

Diagnosis - Light microscopy of blood cells, serology and PCR for B. microti or B. duncani

Treatment - Atovaquone plus azithromycin or quinine plus clindamycin orally for 7 to 10 days.

Atovaquone plus azithromycin is preferred as this combination is better tolerated.

The source for this review is mainly from the CDC website as well as various references cited in the posts. The tick pictures provided may differ from what might be found on a bitten human. Ticks become larger and engorged after feeding and will look different.

The Lone Star Tick

Recently a 65-year-old female was referred to an ED in the state of Missouri complaining of fevers, chills, headache, diarrhea and vomiting occurring over the last week. 3 weeks prior she had received an orthotopic liver transplant. Her post transplant course was unremarkable and she was discharged on prograf 2mf bid, myfortic 360mg bid, prednisone tapering, Bactrim single strength daily and valcyte 450mg od. She also took thyroid replacement, Januvia, warfarin and aspirin. Past medical history included diabetes, heart failure, dysfunctional uterine bleeding, hypothyroid and PUD. She also had CKD with a creatinine about 1.4mg/dl. On examination her Temp was 38.6, HR 110, BP 113/76 and O2sats 99% on RA. She had no nuchal rigidity but reported a sore neck. She had an erythematous area on her lower back. The rest of her exam was normal.

Her initial labs were:

Hb 6.3, WCC 2.7 (94%neuts, 5.8%lymphs), platelets 35

NA 122, K 5.6, Cl 100, CO2 11, BUN36, Creat 2.3, Gluc 173

Arterial pH 7.31, CO2 20, O2 102

AST 52, ALT 41, AP 155, GGT 171, Bili 0.6, Alb 3.3

UA, No blood, 1+protein, 2 rbc, 2 wbc

She had a normal CT brain and was started on multiple antibiotics in the ED.

On further questioning her daughter reported removing a tick from her back after the patient went out looking at deer close to her house.

Lets pretend the daughter brought in a picture of the tick (see above)!

Lab trends; admission to discharge.

Hb 6.3

WCC 2.7                   1.4           0.6           0.5           0.3           1.2           2.4

94%neut                90            91            87            83            60            59

5.8%lym                 6               6.7           9.2           14            16            28

plt 35                       16            18            24            28            26            31

NA 122                    128         132         135

K 5.6                   

Cl 100

Co2 11

BUN36

Creat 2.3                 2.2           1.8           1.6                                               1.3

Gluc 173

pH 7.31

CO2 20

O2 102

AST 52                                                                                                               31

ALT 41                                                                                                               31

AP 155                                                                                                              249

GGT 171                                                                                                                            

Bili 0.6                                                                                                               0.8

Alb 3.3

UA

No blood

2 rbc

2 wbc

1+protein

No lumbar puncture was performed.

To summarize, this lady had constitutional symptoms, fever, neurological symptoms, GI symptoms with a rash and a tick bite. She had pancytopenia, transaminitis, hyponatreamia and renal failure.

Her antiproliferative medication and anti-infective medications were held (Myfortic, valcyte and Bactrim).

IV Doxycycline was commenced.

Sodium and creatinine improved and potassium became low, likely due to GI losses.

Interestingly her leucopenia followed the classical pattern of lymphopenia followed by leucopenia and she required G-CSF. Her transaminases were normal at the time of discharge.

Diagnosis = Ehrlichiosis 

The first case of human ehrlichiosis was described in 1986.

The two most important species to infect humans are Ehrlichia chaffeensis which causes human monocytic ehrlichiosis (HME) and Anaplasma phagocytophilum which causes human granulocytic anaplasmosis (HGA). Both of these diseases have the same vector and have very similar clinical and laboratory features. Ehrlichia ewingii is a less common cause of ehrlichiosis than Ehrlichia chaffeensis.

Ehrlichiae are obligate intracellular bacteria found in membrane bound vacuoles in human and animal leukocytes.

The most endemic area is the southeastern USA – ‘the tick belt’. See the CDC map for the endemic regions in the USA. Cases have also been reported in Europe, Africa, South America and Mexico.

The lone star tick (Amblyomma americanum) is recognized by the CDC as the principal vector of Ehrlichia chaffeensis and Ehrlichia ewingii in the U.S.; both disease agents are responsible for causing ehrlichiosis in humans. White-tailed deer are a primary host of the lone star tick and appear to serve as a natural reservoir for E. chaffeensis. The lone star tick is also a vector of Francisella tularensis, causal agent of tularemia. Adult ticks parasistize deer, cattle, horses, feral swine, sheep, dogs, and humans.

Most infections occur in the spring and summer in the USA.

The clinical manifestations in the elderly and immunosuppressed can be very severe but the following are the usual clinical features:

Fever - Some fevers can be protracted over weeks

Malaise, myalgia, headache and chills – 2/3

Nausea, vomiting and arthralgia – ¼ to ½

Rash (Macular, mucopapular, petechial) – 1/3

Meningism – ¼

More rarely – Seizures, coma, renal failure, heart failure and respiratory failure

There has been a single case of myocarditis and multi-organ failure in a healthy adolescent.

Laboratory findings:

  

Most common triad is leucopenia, thrombocytopenia and elevated transaminases.

CBC

Leucopenia. This tends to be caused by lymphopenia initially followed by neutropenia as in this patient.

Thrombocytopenia

Anaemia

CHEMISTRY.

Elevated transaminases, LDH and Alk phos

Hyponatreamia

Elevated creatinine

CSF, when neurological symptoms

Lymphocytic pleocytosis and elevated CSF protein

Diagnosis

Usually by PCR methods. Note this test may not detect the recently reported third species, E. muris, found in Wisconsin and Minnesota.

Differential diagnosis

This can be a difficult diagnosis to make. It is clinically and geographically similar to RMSF. It can also present like mononucleosis, TTP, hematologic malignancy, cholangitis, the early phases of hepatitis A infection. This is especially so in immunocompromised patients whose clinical features may not be as obvious initially. Common transplant drugs such as Bactrim/Septra, valganciclovir, mycophenolate and azathioprine can also cause cytopenias.

Treatment (adults)

Doxycycline 100mg iv or po bid for about 10 days.

Note this will also treat RMSF which is often confused with ehrlichiosis.

Outcomes. Mortality is about 5%. Most commonly due to viral or fungal super-infections (Invasive aspergillosis, candida, HSV).

This interesting case illustrates the difficulty in diagnosing tick borne infections. They can be lethal and severe in our immunosuppressed transplant population and can be a cause of renal failure in any patient. Also of interest in this case is the lymphocytopenic and neutropenic trending that is usually more peculiar to Anaplasma phagocytophilum which causes human granulocytic anaplasmosis (HGA). We did not test for A phagocytophilum as ehrlichae PCR was positive.

Deceased Donor Kidney Allocation 2014

In the USA in June 2013 the OPTN/UNOS Board of Directors approved amendments to the OPTN policy for deceased donor kidney allocation. These ideas have been discussed for the last 9 years and Nate wrote about some of these ideas here and posted a poll here. The central premise for the changes were outlined in a press release on the OPTN website here. The exact dates for nation wide implementation are not currently available.

Longevity-matching

This is the main and most interesting part of the new system.

Priority will be given to transplant recipients most likely to live the longest post transplant. Each recipient is given an EPTS (estimated post-transplant survival) score ranging from 1 to 100%. This score is calculated from recipient characteristics; Age, years on dialysis, presence of diabetes and prior solid organ transplant.

Here is the OPTN online EPTS calculator

Remember the EPTS score needs to be updated daily.

·      The lower percentage EPTS score the longer estimated survival.

Recipients in the top 20^th percentile will be prioritized for the best kidneys, that is kidneys with a KDPI (Kidney Donor Profile Index) of less than 20%. The KDPI is a re-working of the Kidney Donor Risk Index, which is a risk quantification score defined in a study published by Rao et al in 2009. The KDRI expresses the relative risk of kidney graft failure for a given donor compared to the median kidney donor from the previous year. Values greater than 1 have higher risk of failure. A KDPI of 80% means that the donor kidney has a greater chance of graft failure than 80% of all kidneys retrieved in the previous year.

The KDPI is calculated using 10 donor characteristics; donor age, height, weight, ethnicity, history of hypertension and diabetes, cause of death, serum creatinine, hepatitis C status, and donation after circulatory death status.

The equation is complicated but here is the OPTN online KDPI calculator.

·      The lower the KDPI the better the kidney.

These two concepts will replace the current categories of SCD and ECD.

SCD will be the equivalent of KDPI of 85% or less. ECD will be equivalent to greater than 85%.

Waiting time calculation

With the new rules the waiting time will be calculated from when the recipient reached a GFR of 20ml/min or less or when they started on RRT even if they were listed after this. Thus, waiting times will be backdated. Waiting time points will be score as fractions of a year, number of days divided by 365.

The current system assigns the wait time when the candidate is listed.

Access for highly sensitized recipients

The new system includes additional priority for recipients that are highly sensitized. This is a sliding scale points system based in calculated PRA starting at a CPRA of 20%. Points on this scale are weighted significantly in favour of those with CPRA over 98%. 

The new system will also facilitate the offer of kidneys from certain blood type A donors (A2 and A2B) to type B recipients in an effort to reduce the wait time for these recipients.

CPRA (%)	Points
0–19	0
20–29	0.08
30–39	0.21
40–49	0.34
50–59	0.48
60–69	0.81
70–74	1.09
75–79	1.58
80–84	2.46
85–89	4.05
90–94	6.71
95	10.82
96	12.17
97	17.3
98	24.4
99	50.09
100	202.1

Wider sharing

The ‘payback’ rule will be removed. If a local service receives a well-matched kidney from another donation service they will no longer ‘owe’ a kidney.

Priority point system for new kidney allocation

This scoring system is used to rank recipients in four quartiles of KDPI.

KDPI <20%; 21 – 34%; 35 – 85%;  >85%

Within each quartile there is also a kidney allocation classification system based on location/OPO, ABDR mismatch, CPRA and blood group.

It is my understanding that EPTS determines which quartile a recipient is ranked in.

Factor	Points Awarded
For qualified time spent waiting	1 per year (as (1/365 per day)
Degree of sensitization (CPRA)	0–202
Prior living organ donor	4
Pediatric candidate if donor KDPI 35%	1
Pediatric candidate (age 0–10 yr at time of match) when offered a zero antigen mismatch	4
Pediatric candidate (age 11–17 yr at time of match) when offered a zero antigen mismatch	3
Share a single HLA-DR mismatch with donor	1
Share a zero HLA-DR mismatch with donor	2

This new system seems fair and is an effort to get the most out of each kidney transplanted. It also attempts to get more use out of poorer quality kidneys by more inter OPO sharing.

The full UNOS policy 3.5 statement can be found here.