Anemia post-transplantation

A 20-year-old female had Henoch-Schönlein purpura since age 9 leading to ESRD. She underwent kidney transplantation in 2018 from a live donor (mother) and received induction immunosuppression with thymoglobulin (100 mg once) followed by maintenance with tacrolimus (6 mg twice a day), mycophenolate sodium (720mg twice a day) and prednisone (30mg daily). The patient was discharged 5 days after surgery, with creatinine 0.9 mg/dL with tacrolimus trough level of 9.2 ng/mL.

Before surgery, the hemoglobin level ranged from 12.1g/dL to 11.6g/dL. At the time of medical discharge Hb was 9.8g/dL. During the follow-up, the patient was asymptomatic, with no increase in creatinine level and with good trough tacrolimus level (range of 8-12 ng/ml). However, at 2 months post-transplant, she developed worsened anemia with a hemoglobin of 6.1g/dl. At this time, the patient remained asymptomatic. She was then referred to the ED.

The exams at the time showed: hemoglobin 6.2 g/dL; reticulocyte 0.29%; haptoglobin 89 mg/dL; LDH 220 U/L. Subsequently, a bone marrow aspirate was performed and showed a giant pronormoblast with prominent nuclear inclusions, characteristic of parvovirus B19 infection.(FIGURE 1)

The patient received 2 doses of intravenous immunoglobulin (1g/kg/day) and was switched from tacrolimus to everolimus.

Anemia is a very common finding during post-kidney transplant consults. It is not uncommon to have patients that remain with anemia in the first 3 moths after the procedure. Read more here. (FIGURE 2)

The lack of large case series would make us imagine that parvovirus B19 infection after kidney transplant is rare. The incidence in post-transplant is not easy to estimate (range from 1-10%) and mostly occur in the first year, suggesting donor transmission, as described here.  Also, anemia is a common finding after kidney transplant and may have many other differentials that would appear higher on the list, including drug-induced myelosuppression and bleeding. Additionally, parvovirus B19 surveillance is not performed in routine clinical practice.

 A 2006 review from Mayo Clinic showed that among 98 patients with PVB19 infection after transplantation, 54% were kidney transplants, 9% liver transplants, 12% heart or lung transplants and 24% autologous or allogeneic HSCT recipients. The mean age of the patients was 35.2 ± 17.1 years. The majority (58%) were male. The median time to onset of parvovirus B19 disease was 1.75 months (range, 1 week–96 months) after transplantation. Overall, this study suggested that kidney recipients are in particular susceptible to parvovirus infection and that timing of presentation is variable though highest in the early period post-transplant. (FIGURE 3). Finally, it is reasonable to think that the magnitude of parvovirus B19 infection is underestimated.

Dr Felipe Paste
São Paulo, Brazil

Azathioprine Toxicity

Azathioprine is one of the oldest immunosuppressant medications, which has been used in the field of solid organ transplantation over the past 5 decades. It is metabolized into its inactive forms by the enzyme thiopurine methyltransferease (TPMT). Genetic polymorphisms of the gene coding for this enzyme are common in the general population (~ 10% are heterozygotes causing low enzyme activity and ~ 0.3% cause complete lack enzyme activity). Testing for the enzyme activity is recommended prior to treatment with azathioprine or any thiopurines in children. However, it is not consistently tested for in adult patients who are immunosuppressed with azathioprine for inflammatory bowel disease, organ transplantation or rheumatologic conditions. Genotypic (testing for polymorphisms in the TPMT gene) and phenotypic (measuring levels of substrates and products of the enzyme in RBCs) testing for TPMT are commercially available but the concordance between them is not 100%.

The following are the metabolites that are tested for in the phenotypic testing:
6- Mercaptopurine – (Ref: 3.0- 6.6) nmol/ml/hr
6- Methylmercaptopurine riboside – (Ref: 5.04 – 9.57) nmol/ml/hr
6- Methylthioguanine riboside – (Ref: 2.7 – 5.8) nmol/ml/hr

Phenotypic testing performed within 30-90 days after a blood transfusion can result in inaccurate interpretation of the results because of donor RBCs influencing the test results. Moreover ethnicity, type of disease, concurrent drug treatment, red cell kinetics and transfusions should be taken into account while interpreting the results of TPMT enzyme activity. Single nucleotide polymorphisms (SNPs) account for the major TPMT low activity variant forms. Four TPMT alleles, TPMT*2, *3A, *3B, and *3C, account for over 90% of inactivating polymorphisms.

The approximate commercial cost is ~ $200 for phenotyping and ~$450 for genotyping. Clinical Pharmacogenetic Implementation Consortium (CPIC) has developed an evidence-based guideline on how to adjust thiopurine doses based on TPMT activity.

Posted by Karthikeyan Venkatachalam
Transplant Fellow
Washington University School of Medicine
St Louis

The ELITE & the Rest in Kidney Transplantation

The ELITE-Symphony study enshrined standard triple therapy immunosuppression of tacrolimus, mycophenolic acid and prednisolone, for renal transplant recipients. We get familiar with these agents relatively quickly in our renal training, but what about the other less common agents that are used?  Why do we not use them as first line, when should we consider them and what side effects do we need to be aware of?

Sirolimus and everolimus are mTOR inhibitors (see previous RFN post), and prevent cell cycle progression and lymphocyte proliferation.  Their anti-proliferative effects mean they have a role in conditions such as tuberous sclerosis, psoriasis and certain cancers.  The antiproliferative and antiangiogenic effects pose issues post-surgery however with poor wound healing and lymphocele formation meaning they should not be used for around 6 months post-transplant.  Other side effects include pneumonitis, hyperlipidaemia, bone marrow suppression, thrombotic microangiopathy and proteinuria due to FSGS-type lesions. Alongside this relatively long list of side effects, the main concern with sirolimus is related to mortality. A meta-analysis of 21 studies with a total of 5876 patients showed sirolimus was  associated with increased mortality post-transplant, mainly from cardiovascular and infectious complications (adjusted hazard ratio 1.43, 95% CI 1.21-1.71). So why do some patients end up on sirolimus?  The same meta-analysis showed that sirolimus is associated with a 40% reduced risk of malignancy, particularly in non-melanoma skin cancers. The most common reasons for switching to mTORi are malignancy, often recurrent skin cancers, and for calcineurin-inhibitor (CNI) induced injury (although if eGFR<40mls/min or overt proteinuria outcomes are likely to be poor or no better with a switch). Moreover, as seen in ELITE-Symphony and other, acute rejection rates and patient dropouts are consistently higher with mTORi compared to CNIs.

Another agent we may be hearing more about in the future is belatacept: a co-stimulation pathway blocker. It is attractive as it is designed to replace the CNI in the treatment regime. It binds to CD80 and CD86 on antigen-presenting cells, thereby blocking CD28 mediated activation of T Cells. It is administered as an IV infusion every 4-6 weeks alongside steroid and an anti-metabolite.

The BENEFIT and BENEFIT-EXT (extended criteria donors) trials compared high and low intensity belatacept regimes with cyclosporine in non-sensitised recipients undergoing DBD or living donor renal transplants. Over 7 years of follow-up, they found improved patient and graft survival with belatacept in BENEFIT and better measured GFR and reduced formation of DSA with belatacept in both studies. There was an increased incidence of acute rejection in BENEFIT although this obviously didn’t translate into inferior outcomes. There were also initial concerns regarding a small increase in cases of PTLD in EBV seronegative recipients although longer term data was reassuring that the overall risk of this was very low.

A potential benefit of belatacept is it’s a directly observed therapy, so compliance will be known. Although it is expensive, if patients experience improved graft outcomes then any longer term savings need to be considered. However what about patients who are highly sensitised? Many patients we want to avoid CNIs in are sensitised but here is a dearth of data in using belatacept in this circumstance. Moreover, the studies compared belatacept to cyclosporine, not tacrolimus, the current standard of care. Currently belatacept is not available for new patients due to supply issues, another issue likely preventing its more widespread use.  

Post by Ailish Nimmo

Interstitial Nephritis in the Renal Allograft: Rejection, Infection or Both?

In renal transplant recipients with allograft dysfunction, differentiating between a viral infection or acute cellular rejection as the etiology of interstitial nephritis can be difficult – especially as they can commonly occur concurrently.

We recently saw a 40-year-old woman who received a deceased donor kidney transplant less than one year ago who presented with an initial complaint of gross hematuria and an elevated creatinine (2.2 mg/dL from nadir of 1.4 mg/dL). The allograft ultrasound showed thickening of the urothelium. Prompt biopsy of the allograft revealed acute cellular rejection (ACR 1B), and she was treated with high dose steroids and anti-thymocyte globulin.  

Over the next several weeks, she continued to complain of intermittent gross hematuria. Cystoscopy was unremarkable. One month later she presented with worsening renal function, cough and shortness of breath. A nasopharyngeal respiratory viral panel ultimately revealed…adenovirus – which was also then found both the blood and urine (millions of copies in each). A repeat allograft biopsy was consistent with adenovirus nephropathy.

Adenovirus is a double-stranded DNA virus with more than 50 distinct serotypes. Though adenovirus infection is relatively common, adenoviral infection of the renal allograft is rare and also difficult to diagnose if viral inclusions are not present in the biopsy (see image above, black arrows indicating nuclear viral inclusion bodies). Based on a limited number of reported cases, patients typically present with fever, hematuria, dysuria, and acute kidney injury. Adenoviremia and viruria are present, as well as decoy cells similar to those seen with BK virus infection. Though it is possible that this patient may have had only ACR from the beginning (a close re-review of the 1^st biopsy revealed no viral inclusions), it’s plausible that the adenovirus was responsible for the gross hematuria and thickened urothelium that were present from the start.

Adenoviral infection usually affects multiple organs and can be life threatening, though some patients are able to clear the virus and recover complete allograft function. After anti-viral treatment with intravenous cidofovir, our patient’s creatinine rose to 9 mg/dL. Unfortunately, she remains dialysis dependent and is undergoing re-evaluation for a second transplant.  This challenging case is a reminder that both rejection and infections must be considered when interstitial nephritis – and that one may be a decoy for the other!

Posted by Samira Farouk
Chief Fellow, Division of Nephrology
Icahn School of Medicine at Mount Sinai

Measuring cellular immunity to predict CMV infection post-transplantation

CMV infection still remains one of the most common and unpredictable complications in transplant recipients, and the negative consequences in terms of graft lost and recipient survival are well known. In this setting, I would like to present a remarkable kidney transplant case from our institution: an unsensitized 40 y/o female, IgG seropositive for CMV was transplanted from a seropositive deceased donor. She had taken the standard immunosuppressive therapy, and after 2 months was diagnosed with CMV-disease. Considering the situation above, one may question why this happened and how could it have been possible to predict this outcome.

Currently, the immune-risk stratification before transplant is based only on CMV-specific antibody (IgG+) of donor and recipient. However, the cellular immunity is crucial in controlling the viral replication and conferring long-lasting protection. The proportion of both CD4+ and CD8+ T cells committed to the anti Human CMV (HCMV) response is large, ranging from 10 to 40% in peripheral blood.

In this scenario, novel immune assays may play a mainstay role. They consist in evaluating physiological response of HCMV specific T cells (cell activation, cytokine expression or proliferation) through antigen stimulation in vitro (virus-infected cells lysates or virus-like particles). As depicted in Table 1, these tests have different characteristics; therefore a physician must know how to choose the best test for a specific situation.

Similar cases have already been described and one may conclude that these patients lack cellular-immunity. On the other hand, seronegative recipients who have low rate of specific T cell have also been described. In this scenario, these new tests could give information on how to predict the ability to control viral replication. Hence, T cells analysis can justify a whole new perspective of prophylaxis indications. Also, in posttransplant situations (Figure 1), serial evaluation of viral load and T cell test are important to guide therapy and foresee relapse after its cessation.

Low levels of CMV-specific T cell response correlates well with reactivation of CMV-infection and late-onset disease; immediate treatment or prolonged prophylaxis would hold back these outcomes. Therefore, an individualized approach with measurement of CMV specific cellular and antibody response will be crucial in the improvement of transplant outcomes, in particular in centers that do not routinely use CMV prophylaxis.

Abel Portela

References:

1-     Sester M; Lebooeuf, C; Schmidt T, Hirsch HH. The “ABC” of virus-specific Tcell immunity in solic organ transplantation. Am J Transplant 2016; 16(6):1697-1706.

1-     Lucia M, Crespo E, Cruzado JM, Grinyo JM, Bestard O. Human CMV-specificT-cel reponses in kidney transplantation; toward changing currentrisk-stratification paradigm. Transplant Int 2014;  27(2): 643-656.

1-     Kotton CN, Kumar D, Caliendo AM et al. Updated International ConsensusGuidelines on the management of cytomegalovirus in solid-organ transplation.Transplantation 2013; 96: 333-360.

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

Clinical Kidney Transplantation Course

The Universiteit Leiden and Medical University Medical Center in the Netherlands recently launched an open online course in Clinical Kidney transplantation. This course is endorsed by the European Society of Organ transplantation (ESOT) and it is divided in five modules that you have to complete in 5 weeks, although turning off deadlines is optional:

1- Before the transplant.
2- The surgical procedures and the challenged patient, including the patient with diabetes
3- Early challenges
4- Late challenges after transplantation
5- Final Quiz

The modules include videos, 3D movies, interactive patient cases and a forum for discussions. You can add subtitles to the videos as well. Signing up is very easy (and free!) and you can watch the videos on your desktop or laptop or using your mobile device (I suggest to install the app Coursera for easy access)

For further details, please go to: https://www.coursera.org/learn/clinical-kidney-transplantation

Enjoy!

Pharmacokinetic Alterations in the Elderly; You’re Not Too Young to Understand

Renal transplantation reduces mortality in elderly patients by more than 50%, however, challenges are magnified in elderly renal transplant recipients (RTR) when managing their pharmacotherapy regimen. 

Aging is associated with changes in several pharmacokinetics parameters including absorption, distribution, metabolism, and excretion. Developing an effective pharmacotherapeutic plan for elderly transplant recipients requires a clear understanding of the principles of pharmacokinetics and how a specific drug’s handling may be altered with age (Table ). 

Below, few of the specifics of pharmacokinetics of maintenance immunosuppressants in elderly:

Calcineurin Inhibitors (CNI): Several studies evaluated cyclosporin and tacrolimus in elderly RTR. Results show that CNI trough concentrations are 50% higher, Cmax and AUC are also higher, and mandate a dose reduction. These differences in concentration and exposure can be attributed to the good oral absorption, and a reduction in intestinal and hepatic metabolism and elimination. 

mToR inhibitors: Many studies of the mToR inhibitors included a pharmacokinetic subgroup analyses of the elderly. In these studies, there was no association seen between age and drug clearance. 

Antimetabolites: the elderly demonstrate lower mycophenolic acid (MPA) trough concentrations, Cmax and AUC compared to younger RTR. This is likely due to reduced MPA bioavailability of MPA in older patients. Another reason to explain the lower exposure to MPA in the elderly is that MPA is highly protein bound, yet there is a reduction in protein binding sites in the older population, which increased the free fraction of MPA making it more available for glucuronidation and clearance.  

Corticosteroids: there is little data on alteration of corticosteroid pharmacokinetics in elderly RTR; however, decisions can be made based on speculated changes. Prednisolone is extensively metabolized in the liver with significant intra- and inter-individual variability, and mainly binds to albumin. Age-related reductions in metabolism and elimination will likely result in an increased exposure to prednisolone and methylprednisolone. 

Belatacept has been studied in older population, and these analyses found that age-related changes, such as changes in renal function and albumin, did not affect exposure to belatacept. 

In sum, age broadly impacts immune responses as well the pharmacokinetics of the maintenance immunosuppressants, in particular CNI and MMF. There are some data to help aid in the creation of an immunosuppressant protocol in the older transplant recipient, but more specific studies of this patient population are needed. 

Dema Alissa, B.Sc. Pharm., SSC_PhP, MBA 

Felix Krenzien, MD 

Steven Gabardi, PharmD, FAST, FCCP, BCPS

KDPI score and donor urinary biomarkers: poor predictors of graft outcome

KDPI (kidney donor profile index) is a numerical measure that combines ten variables about a donor, including clinical parameters and demographics, to express the quality of the donor kidneys relative to other donors.  It has been reported by UNOS in attempt to classify the quality spectrum of cadaveric kidneys in order to use it for better matching with recipients’ characteristics (previously reviewed by Andrew here). 

One of the major limitations of the KDPI score is its poor predictive power with a C-statistics of 0.6 (0.5 would be the flip of a coin) (Reese et al. JASN 2015). The score relies heavily on age (diverse renal function within same age group is common), donor terminal creatinine (may reflect acute kidney injury), and it does not take into account HLA matching or other immunological risk factors. Therefore, KDPI score is not a good predictor of graft outcome.

In attempt to improve this prediction, Reese et al. (JASN 2015) conducted a nice prospective study in deceased kidney donors and respective recipients to assess associations between urinary biomarkers (NGAL, KIM1, IL18, L-FABP) in deceased-donor urine with three outcomes: donor AKI, recipient delayed graft function and recipient's graft function at 6 months post-transplant. Although donor urinary injury biomarkers was strongly associated with donor AKI, biomarkers provided limited value in predicting delayed graft function or early allograft function after transplant. The search for better predictive tools continues...

Figure above from Kidney Transplant iBook

Keep cool and carry on...

Delayed graft function (DGF) after kidney transplant is associated with long-term allograft dysfunction. Niemann et al. (NEJM 2015;373:405) reported that therapeutic hypothermia reduced DGF (defined here as the requirement of dialysis in the recipient within 7 days after renal transplantation).

Study group enrolled 370 kidney donors after neurological determination of death (DNDDs), randomized to either normothermia (36.5 to 37.5 deg., n= 280) vs. mild hypothermia (34-35 deg. either by allowing to spontaneously reach the temperature, or by passive-cooling devices or forced-air systems, n=286). Incidence of DGF was significantly lower in hypothermia group (28.2% vs 39.2%, p=0.008), and study was terminated early.  

Therapeutic hypothermia (targeted temperature management) is an established intervention for outside-hospital cardiac arrest to protect neurological function.

In transplant field, in contrast, current organ procurement protocol (e.g. one from NATCO) has a stipulation that normal body temperature should be maintained in donors, frequently requiring active warming with warm blankets.

 What is the protective mechanism?  Authors discussed possible contribution of ischemia-reperfusion injury. Is this procedure applicable to other organs? Many questions arise and there is a nice open forum with NEJM group to discuss these (til August 7^th EDT).

Naoka Murakami, MD PhD