Improved freedom from rejection after a loading dose of sirolimus

A comparative, randomized trial of concentration-controlled sirolimus combined with reduced-dose tacrolimus or standard-dose tacrolimus in renal allograft recipients

BACKGROUND

The clinical safety and efficacy of sirolimus plus reduced-dose tacrolimus was evaluated in de novo renal allograft recipients enrolled in a comparative, open-label study.

METHODS

One hundred twenty-eight renal allograft recipients were randomly assigned (1:1) to receive reduced-dose tacrolimus plus sirolimus (rTAC) or standard-dose tacrolimus and sirolimus (sTAC) for 6 months. The primary efficacy endpoint was calculated creatinine clearance values at 6 months.

RESULTS

Demographic variables were similar between groups. At 6 months, mean (± standard deviation) calculated creatinine clearance was significantly improved in the rTAC group (63.8 vs 52.7 mL/min, P = .005), although mean serum creatinine values were not significantly different. Patient survival (95.2% and 96.9%) and graft survival (93.7% and 98.5%) were similar between the rTAC and sTAC groups, respectively. Acute rejection rates were 17.5% with rTAC and 7.7% with sTAC (P = .095).

CONCLUSIONS

The rTAC regimen provided effective immunosuppression and was associated with improved creatinine clearance. Adequate immunosuppressant exposure must be achieved in the early postoperative period to minimize the risk of acute rejection.

Higher tacrolimus trough levels on days 2-5 post-renal transplant are associated with reduced rates of acute rejection

We analyzed the association between whole-blood trough tacrolimus (TAC) levels in the first days post-kidney transplant and acute cellular rejection (ACR) rates. Four hundred and sixty-four consecutive, deceased-donor kidney transplant recipients were included. All were treated with a combination of TAC, mycophenolate mofetil and prednisolone. Patients were analyzed in four groups based on quartiles of the mean TAC on days 2 and 5 post-transplant: Group 1: median TAC 11 ng/mL (n = 122, range 2-13.5 ng/mL), Group 2: median 17 ng/mL (n = 123, range 14-20 ng/mL), Group 3: median 24 ng/mL (n = 108, range 20.5-27 ng/mL) and Group 4: median 33.5 ng/mL (n = 116, range 27.5-77.5 ng/mL). A graded reduction in the rates of ACR was observed for each incremental days 2-5 TAC. The one-yr ACR rate was 24.03% (95% CI 17.26-32.88), 22.20% (95% CI 15.78-30.70), 13.41% (95% CI 8.15-21.63) and 8.69% (95% CI 4.77-15.55) for Groups 1-4, respectively (p = 0.003). This study suggests that higher early TACs are associated with reduced rates of ACR at one yr.

Loading doses for costly cancer biologicals: sound pharmacology or unnecessary extravagance?

The rising cost of new molecularly-targeted anticancer drugs has become a major issue in oncology. One small but significant factor contributing to this problem is the routine co-administration of loading doses, which may inflate the cost of the first treatment by as much as US$1000. Here, we question the cost-effectiveness of this practice in cancer patients on several grounds, including non-urgent pace of disease, lack of evidence for survival benefit, weak dose-dependency of biopharmaceutical efficacy in cancer and the unproven validity of the 'volume of distribution' concept applied to target-specific drugs.

Risk factors for impaired wound healing in sirolimus-treated renal transplant recipients

AIM

As sirolimus has been implicated in impaired wound healing, the aim of this study was to evaluate risk factors for wound complications after renal transplantation in patients treated with this drug de novo.

METHODS

This single center retrospective review of wound complications included 194 renal transplant recipients, all of whom received sirolimus immunosuppression in combination with reduced doses of cyclosporine (CsA) and corticosteroids de novo. A wound complication was defined as an infection, incisional hernia, or lymphocele.

RESULTS

The overall incidence of wound complications within the first year post-transplantation was 36% (n = 70) including infection in 12% (n = 23), lymphocele formation in 18% (n = 34), and incisional hernia in 18% (n = 34) of patients. Seventeen patients suffered more than one wound complication. A multivariate analysis showed that independent risk factors for the development of wound complications were recipients over the age of 40 yr (odds ratio 2.536, p = 0.011), subjects with body mass index (BMI) >26 (odds ratio 2.498, p = 0.027) and especially BMI >30 (odds ratio 3.738, p = 0.007), the use of thymoglobulin for induction immunosuppression (odds ratio 3.627, p = 0.002), and a cumulative dose of sirolimus of at least 35 mg by post-transplant day 4 (odds ratio 2.694, p = 0.023). African-American (odds ratio 0.139, p < 0.001) or Hispanic recipients (odds ratio 0.337, p = 0.014) were less likely to experience a wound problem than Caucasian recipients.

CONCLUSION

A number of potentially modifiable risk factors independently increase the incidence of wound complications among renal transplant recipients receiving sirolimus-based immunosuppression de novo.

Rapamycin Does Not Induce Anergy but Inhibits Expansion and Differentiation of Alloreactive Human T Cells

BACKGROUND

Studies in mice have shown that rapamycin inhibits cell cycle progression and promotes the development of clonal anergy. We here addressed the question if rapamycin can induce anergy of human T cells and studied the effects of rapamycin on activation, proliferation and expression of cytotoxic effector molecules of alloresponsive T cells in mixed lymphocyte cultures.

METHODS

Peripheral blood mononuclear cells from healthy individuals were labeled with CFSE to monitor subsequent cell divisions. Cells were cocultured with allogeneic irradiated cells in the presence or absence of rapamycin. Flowcytometric analysis was performed after staining for surface CD4, CD8, and CD25 and for intracellular perforin, granzyme B, active caspase-3, and TGF-beta. Bio-Plex cytokine assay was done to measure the secretion of IL-2, IL-4, IL-10, and IFN-gamma.

RESULTS

Addition of rapamycin at a final concentration of 10 ng/ml strongly decreased precursor frequencies of alloreactive CD4+ and CD8+ T cells. However, when these cells were washed and subsequently specifically restimulated in the absence of rapamycin, the proliferative capacity appeared normal. Next to lowering precursor frequencies, rapamycin also inhibited T cell expansion by inducing apoptosis in divided alloreactive CD4+ and CD8+ T cells. Rapamycin did not interfere with the formation of CD25brightCD4+ T cells during allogeneic stimulation and did not inhibit their suppressive function. Furthermore, the drug decreased production of effector molecules perforin and granzyme B by alloreactive T cells and diminished alloreactive cytotoxicity.

CONCLUSION

Our data show that rapamycin strongly inhibits proliferation and effector functions of alloreactive T cells in vitro, but does not induce alloantigen specific nonresponsiveness.

Pilot randomized study of early tacrolimus withdrawal from a regimen with sirolimus plus tacrolimus in kidney transplantation

We performed a randomized trial to compare two regimens of low-risk kidney allograft recipients in the first year after transplantation. Both regimens initially included sirolimus, tacrolimus and steroids; one with long-term maintenance with these drugs vs. tacrolimus withdrawal. Group I: sirolimus levels of 4-8 ng/mL, plus tacrolimus 8-12 ng/mL for 3 months, and 5-10 ng/mL after month 3. Group II: sirolimus concentration of 8-16 ng/mL, plus tacrolimus 3-8 ng/mL with tacrolimus elimination from month 3 onwards. Owing to difficulties in achieving target levels, the protocol was amended to increase the doses. Eighty-seven patients were recruited. In the intention-to-treat analysis, glomerular filtration rate (GFR) at 12 months, adjusted to zero for graft loss, was similar in both groups (58.8 and 59.9 mL/min). Analysis of patients remaining on protocol showed that GFR was higher in group II only in the patients postamendment (58.4 and 72.9 mL/min, p = 0.03). Rates of biopsy-confirmed rejection (BCAR) were 9.3% and 22.7% in groups I and II, respectively (p = NS). After amendment, BCAR rates were 10.3% and 11.1% (p = NS). Diastolic blood pressure was significantly lower in patients who eliminated tacrolimus (80.4 vs. 75.6 mmHg) (p = 0.03). Combining sirolimus and tacrolimus with adequate loading doses was associated with a low incidence of BCAR, and allowed tacrolimus elimination in a high proportion of patients, which may be followed by amelioration in renal function and blood pressure.