Polyclonal anti T-lymphocyte antibody therapy monitoring in kidney transplant recipients: comparison of CD3+ T cell and total lymphocyte counts

Rejection in Liver Transplantation Recipients

Rejection following liver transplantation continues to impact transplant recipients although rates have decreased over time with advances in immunosuppression management. The diagnosis of rejection remains challenging with liver biopsy remaining the reference standard for diagnosis. Proper classification of rejection type and severity is imperative as this guides management and ultimately graft preservation. Future areas of promise include non-invasive testing for detection of rejection to reduce the morbidity associated with invasive testing and further advances in immunosuppression management to reduce toxicities associated with immunosuppression while minimizing rejection related morbidity.

Interruption of anti-thymocyte globuline treatment in solid organ transplantation is effectively monitored through a low total lymphocyte count

Introduction

Anti-Thymocyte Globulin (ATG) is a cornerstone in immune suppression for solid organ transplantation. The treatment is a delicate balance between complications arising from over-immunosuppression such as infections and cancer versus rejection stemming from under-immunosuppression. CD3+ T-lymphocyte measurements are frequently employed for treatment monitoring. However, this analysis is costly and not always accessible. The aim of this study was to investigate whether the total count of lymphocytes could replace CD3+ T-lymphocyte measurements based on data from our transplantation center combined with a review of the literature. The hypothesis was that the total lymphocyte count could serve as a diagnostic surrogate marker for CD3+ T-lymphocytes.

Methods

A retrospective cohort study was conducted, including patients who underwent kidney and/or a pancreas transplantation and received ATG as induction therapy or for rejection treatment. The inclusion criterium was that the total lymphocyte count and CD3+ T-lymphocyte measurements were measured simultaneously on the same day. Additionally, PubMed and Embase were searched up to 18/10/2023 for published studies on solid organ transplantation, ATG, T-lymphocytes, lymphocyte count, and monitoring. In the retrospective cohort study, a total of 91 patients transplanted between 2016 and 2023, with 487 samples, were included.

Results

Total lymphocyte counts below 0.3 x 109/L had a high sensitivity (86%) as a surrogate marker of CD3+ T-lymphocytes below 0.05 x 109/L, but the specificity was low (52%) for total lymphocyte counts above 0.3 x 109/L as a surrogate marker for CD3+ T-lymphocytes above 0.05 x 109/L. A review of the literature identified seven studies comparing total lymphocyte counts and CD3+ T-lymphocytes in ATG monitoring. These studies supported the use of a low total lymphocyte count as a surrogate marker for CD3+ T-lymphocytes and an indicator to omit ATG treatment. However, there was no consensus regarding high total lymphocyte counts as an indicator for continued treatment.

Discussion

Results supports that the total lymphocyte count can be used to omit ATG treatment when below 0.3 x 109/L whereas the CD3+ T-lymphocyte analysis should be reserved for higher total lymphocyte counts to avoid ATG overtreatment.

Single-dose antithymocyte globulin in standard immunological risk kidney transplant recipients: efficacy and kinetics of peripheral blood CD3+ T lymphocyte modulation

BACKGROUND

Polyclonal anti-T cell antibodies (ATG or thymoglobulin®) are used as induction therapy in kidney transplant recipients. This study evaluates the safety, efficacy, and CD3+ T lymphocyte modulation of two ATG regimens.

METHODS

The trial included two cohorts of kidney transplant recipients that were followed for one year. The study group, including standard immunological risk recipients, received one 3 mg/kg dose of ATG. The comparator group, including standard and high immunological risk kidney transplant recipients, received a fractionated dose regimen (up to four 1.5 mg/kg doses). Patient and graft outcomes and the kinetics of CD3+ T lymphocyte modulation in the peripheral blood were evaluated.

RESULTS

One hundred kidney transplant recipients were included in each group. The one-year incidence of treated acute rejection, and patient and graft survival did not differ between groups. Bacterial infections were significantly more frequent in fractionated-dose group patients (66% versus 5%; P = 0.0001). At one-year follow-up, there was no difference in the incidence of cytomegalovirus infection (P = 0.152) or malignancies (P = 0.312). CD3+ T lymphocyte immunomodulation in the single-dose group was more effective in the first two days after transplantation. After the third post-transplant day, CD3+ T lymphocyte modulation was more efficient in the fractionated dose group.

CONCLUSION

Both regimens resulted in low rejection rates and equivalent survival. The single and reduced dose regimen protects from the occurrence of bacterial infections. CD3+ T lymphocyte modulation occurred with different kinetics, although it did not result in distinct outcomes.

Immune cell function assay and T lymphocyte counts lack association with rejection or infection in pediatric heart transplant recipients

INTRODUCTION

Immune cell function assay (ICFA) and CD3 lymphocyte counts have been considered to be useful in discerning the overall intensity of immunosuppression in pediatric orthotopic heart transplant (OHT) recipients.

METHODS

The aim of this retrospective analysis was to evaluate trends of ICFA and CD3 lymphocyte counts and their association with adverse outcomes post-OHT.

RESULTS

A total of 381 ICFA and 493 CD3 laboratory values obtained in 78 patients within six months post-OHT were analyzed. There were 14 patients treated for biopsy-proven acute rejection, four of whom had ISHLT grade 2R/3A rejection. In patients with rejection versus those without, CD3 and ICFA values were 122 (IQR 74.5-308) cells/mm² and 224.5 (IQR 132-343.5) ng/ml compared to 231.8 (IQR 68-421) cells/m² and 191 (IQR 81.5-333) ng/mL (p = NS for both). Twenty-six patients had at least one detectable cytomegalovirus or Epstein-Barr virus DNAemia within the study timeframe. In patients with viremia versus those without, CD3 and ICFA values were 278.5 (IQR 68-552) cells/mm² and 130 (IQR 48-284) ng/ml compared to 195 (IQR 74.5-402.5) cells/mm² and 212 (IQR 89-342) ng/ml (p = NS for both).

CONCLUSIONS

No association was found between these immune markers and adverse outcomes. In the absence of larger pediatric studies justifying the role of these tests in identifying elevated risk profiles post OHT, we do not recommend their routine use.

A call for transplant stewardship: The need for expanded evidence-based evaluation of induction and biologic-based cost-saving strategies in kidney transplantation and beyond

Rising expenditures threaten healthcare sustainability. While transplant programs are typically considered profitable, transplant medications are expensive and frequently targeted for cost savings. This review aims to summarize available literature supporting cost-containment strategies used in solid organ transplant. Despite widespread use of these tactics, we found the available evidence to be fairly low quality. Strategies mainly focus on induction, particularly rabbit antithymocyte globulin (rATG), given its significant cost and the lack of consensus surrounding dosing. While there is higher-quality evidence for high single-dose rATG, and dose-rounding protocols to reduce waste are likely low risk, more aggressive strategies, such as dosing rATG by CD3+ target-attainment or on ideal-body-weight, have less robust support and did not always attain similar efficacy outcomes. Extrapolation of induction dosing strategies to rejection treatment is not supported by any currently available literature. Cost-saving strategies for supportive therapies, such as IVIG and rituximab also have minimal literature support. Deferral of high-cost agents to the outpatient arena is associated with minimal risk and increases reimbursement, although may increase complexity and cost-burden for patients and infusion centers. The available evidence highlights the need for evaluation of unique patient-specific clinical scenarios and optimization of therapies, rather than simple blanket application of cost-saving initiatives in the transplant population.

Ideal Body Weight-Based Dosing of Rabbit Antithymocyte Globulin for Cost Minimization in Kidney Transplantation

INTRODUCTION

Contemporary dosing strategies for rabbit anti-thymocyte globulin (rATG) in kidney transplantation aim to reduce cumulative exposure, minimizing long-term adverse events. The use of ideal body weight-based dosing has been trialed, however concern for increased rejection post-transplant exists due to lower doses of rATG. Research Questions: The primary aim of this study was to compare rejection rates between rATG dosing protocols using actual body weight and ideal body weight and secondarily to evaluate cost savings following protocol implementation.

DESIGN

This was a retrospective study surrounding implementation of an ideal body weight-based dosing protocol for rATG. We compared 75 kidney transplant recipients in whom rATG was dosed based on actual body weight (pre-protocol group) to 64 in whom dosing was based on ideal body weight (post-protocol group), following a nine-month washout.

RESULTS

The mean cumulative rATG dose in the pre-protocol group was 6.3 mg/kg of actual body weight. When ideal body weight was used in the post-protocol group, the mean dose was 4.5 mg/kg of actual body weight. The rejection rate was 18.7% pre-protocol and 23.4% postprotocol, which did not represent a statistically significant difference (p = 0.491). The actual annual cost savings after protocol implementation exceeded $162,000, approximately $2,500 per patient.

CONCLUSION

Results suggest ideal body weight-based dosing of rATG may reduce exposure and cost, without significantly impacting the risk of rejection in kidney transplant recipients. More studies are needed to confirm these findings.

COVID-19 pneumonia in kidney transplant recipients: Focus on immunosuppression management

Background

The coronavirus disease of 2019, also known as COVID‐19, has been declared a global pandemic. Significant controversies exist regarding treatment modalities for this novel disease, especially in immunocompromised patients. Experience with management of COVID‐19 in kidney transplant recipients is scarce; effects of this virus on immunosuppressed individuals are not well understood.

Methods

We identified 30 renal transplant recipients with confirmed COVID‐19 pneumonia who were admitted to inpatient between March 2020 and April 2020. All patients received a 5‐day course of hydroxychloroquine and azithromycin; half of the patients received methylprednisolone. During hospitalization, calcineurin inhibitors and antimetabolites were held; prednisone was continued.

Results

Clinical presentation of flu‐like symptoms was similar to those in the general population. Hyponatremia, lymphopenia, acute kidney injury, and elevated inflammatory markers were common. Over the course of follow‐up, 23 have been discharged home with a functioning allograft and in stable condition; 4 experienced acute kidney injury requiring renal replacement therapy; 7 patients were intubated, and 6 expired. The mortality rate in our cohort was 20%.

Conclusion

Our findings described the characteristics and outcomes of this highly fatal illness in a multi‐ethnic kidney transplant cohort, with insights on immunosuppression management that could further our understanding of this unique disease in immunocompromised populations.

Rabbit anti-thymocyte globulin (rATG) versus IL-2 receptor antagonist induction therapies in tacrolimus-based immunosuppression era: a meta-analysis

BACKGROUND

The aim of this meta-analysis is to explore the effect of IL-2RA vs rATG on the rate of acute rejection, post-transplant infections, and graft as well as patient's survival in standard- and high-risk renal transplant patients receiving tacrolimus-based maintenance immunotherapy.

METHODS

Random effects model was the method used for identifying risk difference. Confidence interval including the value 1 was used as evidence for statistically significant risk difference. Heterogeneity was assessed using Der Simonian analysis. Heterogeneity was evident at the level of P value < 0.1 RESULTS: The random effects model showed no significant differences in both acute rejection rates between IL-2RA and rATG induction therapies with relative risk of 1.24 graft survival with relative risk 0.90. Patient survival also did not demonstrate any significant difference with a relative risk of 1.19. Random effects for CMV infection showed a lesser tendency for CMV infection in IL-2RA group compared to ATG group the with a relative risk of 0.73.In subgroup analysis, the random effects model for acute rejection rates in high-risk transplants showed a higher risk of acute rejection in the IL-2RA group compared to rATG (relative risk equals 1.55) In standard-risk transplants, there were no significant differences between both groups with relative risk equals 1.02 CONCLUSIONS: This meta-analysis revealed no significant difference in patient and graft survival when using IL-2RA vs rATG with the tacrolimus-based maintenance immunosuppression era. However, subgroup analysis showed less incidence of rejection in high-risk renal transplant recipient's population using rATG compared to IL-2RA.