Mg Of Sirolimus Research Articles

A Phase I Study of the Combination of Pexidartinib and Sirolimus to Target Tumor-Associated Macrophages in Unresectable Sarcoma and Malignant Peripheral Nerve Sheath Tumors.

To evaluate the safety and tolerability in phase I first-in-human combination therapy with pexidartinib, an inhibitor of colony-stimulating factor-1 receptor, and sirolimus, an mTOR inhibitor, to target tumor-associated macrophage (TAM) polarization in soft tissue sarcomas (STS). This multicenter phase I study used the time-to-event continual reassessment method (TITE-CRM) to study the combination of sirolimus, doses ranging from 2 to 6 mg, with pexidartinib, doses ranging from 600 to 1,000 mg, both provided continuously on a 28-day cycle, in patients with advanced sarcoma. A total of 24 patients [8 malignant peripheral nerve sheath tumor, 3 tenosynovial giant cell tumor (TGCT), 5 leiomyosarcoma, and 8 with other sarcoma subtypes] were enrolled. The median age was 46 years, 56% were male, and 61% had >2 prior lines of therapy. The recommended phase II dose was 2 mg of sirolimus combined with 1,000 mg of pexidartinib daily. Of the 18 evaluable subjects, 5 experienced dose-limiting toxicities (2 elevated aspartate aminotransferase/alanine aminotransferase, 2 elevated sirolimus trough levels, and 1 grade 5 dehydration). Most common grade 2 or higher treatment-related adverse events included anemia, fatigue, neutropenia, and lymphopenia. Clinical benefit was observed in 12 of 18 (67%) evaluable subjects with 3 partial responses (all in TGCT) and 9 stable disease. Tissue staining indicated a decreased proportion of activated M2 macrophages within tumor samples with treatment. Pexidartinib can be safely administered with sirolimus. These findings support further investigation of this combination to determine clinical efficacy. Clinicaltrials.gov identifier NCT02584647.

Optimizing overnight oral appliance for sustained-release varnish delivery system of sirolimus

<h3>Objectives</h3> Intraoral trays can be used to deliver treatment materials and medications for dental or mucosal conditions. Maintaining appropriate salivary levels of the active ingredient is challenging when using local application. We have previously analyzed salivary levels and local effects of slow-release varnishes (with clotrimazole or sirolimus as the active ingredient) during the daytime. The aims of the present study were as follows: (1) to optimize overnight appliances for slow-release medications by measuring saliva and blood levels and (2) to evaluate the safety of overnight use. <h3>Methods</h3> An acrylic tray containing 0.5 mg of sirolimus in a sustained-release varnish was applied to 6 anterior teeth for 12 hours in 10 healthy volunteers. Whole unstimulated saliva was collected 1, 2, 10, and 12 hours after application, and a blood sample was taken after 12 hours. Drug levels were analyzed. Results from slow- and fast-release formulations, varnish application position on the tray (buccal, palatal, or lingual), and tray placement (mandibular vs maxillary) were compared. The volunteers evaluated the varnish and tray. The study was approved the hospital ethics committee. <h3>Results</h3> Salivary sirolimus was undetected with use of the slow formulation. The faster formulation produced salivary concentrations of 0.3-45 ng/mL. The highest salivary levels were observed with a mandibular tray with lingual varnish application (up to 178 ng/mL). The sialometry of all participants was within normal range (0.2-2 mL/min), and the highest drug levels were found when salivary flow was lowest. The medication was undetected in the blood. No local reactions or side effects were reported. <h3>Conclusions</h3> Salivary concentrations of medications delivered using an oral tray can be affected by the release rate of formulation and, more important, by the position of the tray and the varnish within it and salivary flow rate. Overnight oral trays can be used to deliver medications especially when 24-hour drug exposure is desired. Further studies regarding local factors affecting drug release and salivary levels are required.

Cyclodextrin Polymer Preserves Sirolimus Activity and Local Persistence for Antifibrotic Delivery over the Time Course of Wound Healing.

Fibrosis and dysphagic stricture of the esophagus is a major unaddressed problem often accompanying endoscopic removal of esophageal cancers and precancerous lesions. While weekly injections of antiproliferative agents show potential for improved healing, repeated injections are unlikely clinically and may alternatively be replaced by creating an esophageal drug delivery system. Affinity-based polymers have previously shown success for continuous delivery of small molecules for weeks to months. Herein, we explored the potential of an affinity-based microparticle to provide long-term release of an antiproliferative drug, sirolimus. In molecular docking simulations and surface plasmon resonance experiments, sirolimus was found to have suitable affinity for beta-cyclodextrin, while dextran, as a low affinity control, was validated. Polymerized beta-cyclodextrin microparticles exhibited 30 consecutive days of delivery of sirolimus during in vitro release studies. In total, the polymerized beta-cyclodextrin microparticles released 36.9 mg of sirolimus per milligram of polymer after one month of incubation in vitro. Taking daily drug release aliquots and applying them to PT-K75 porcine mucosal fibroblasts, we observed that cyclodextrin microparticle delivery preserved bioactivity of sirolimus inhibiting proliferation by 27-67% and migration of fibroblasts by 28-100% of buffer treated controls in vitro. Testing for esophageal injection site losses, no significant loss was incurred under simulated saliva flow for 10 min, and 16.7% of fluorescently labeled polymerized cyclodextrin microparticle signal was retained at 28 days after submucosal injection in esophageal tissue ex vivo versus only 4% of the initial amount remaining for free dye molecules injected alone. By combining affinity-based drug delivery for continuous long-term release with a microparticle platform that is injectable yet remains localized in tissue interstitium, this combination platform demonstrates promise for preventing esophageal fibrosis and stricture.

Sirolimus based immunosuppression is associated with need for early repeat therapeutic ERCP in liver transplant patients with anastomotic biliary stricture

Introduction. Sirolimus has inhibitory effects on epithelial healing and cholangiocyte regeneration. In liver transplantation (LT) patients, these effects may be greatest at the biliary anastomosis. We therefore investigated whether sirolimus use is associated with need for early or emergent repeat therapeutic endoscopic retrograde cholangiography (ERC) in LT patients with anastomotic biliary stricture (ABS).Material and methods. Medical records of patients who underwent LT from 1998–2009 at Johns Hopkins were reviewed and patients with ABS identified. Primary outcome was early repeat ERC, defined as need for unscheduled (i.e. unplanned) or emergent repeat therapeutic ERC. Univariate and multivariate logistic regression analyses (adjusting for age, sex, LT to ERC time, and stent number) were performed to assess association between sirolimus and early repeat ERC.Results. 45 patients developed ABS and underwent 156 ERCs total. Early (median 26 days) repeat ERC occurred in 14/56 (25%) and 6/100 (6%) ERCs performed with and without concomitant sirolimus-based immunosuppression, respectively (OR 1.22; 95% CI 1.02–1.45; p = 0.03). In multivariate analysis, sirolimus use was associated with early repeat ERC (OR 1.24; 95% CI 1.04–1.47; p = 0.015); this association remained significant when sirolimus dose was modeled as a continuous variable (OR 1.04 for each mg of sirolimus per day; 95% CI 1.02–1.08; p = 0.038).Conclusions. Sirolimus-based immunosuppression appears to be associated with a modest but significantly increased, dose-dependent risk of early repeat ERC in LT patients with ABS. Prospective studies are needed to further investigate these findings and determine if sirolimus use or dose should potentially be reconsidered once ABS is diagnosed.

Sirolimus solid self-microemulsifying pellets: Formulation development, characterization and bioavailability evaluation

To enhance the dissolution and oral absorption of water insoluble drug sirolimus (SRL), self-microemulsifying pellets of SRL were developed and evaluated. Solubility test, self-emulsifying grading test, ternary phase diagrams and central composite design were adopted to screen and optimize the composition of liquid SRL-SMEDDS. The selected liquid SRL-SMEDDS formulations were prepared into pellets by extrusion-spheronization method and the optimal formulation of 1mg SRL-SMEDDS pellets capsule (1.0, 22.4, 38.4, 19.2, 121.6, 30.4 and 8.0 mg of SRL, Labrafil M1944CS, Cremophor EL, Transcutol P, MCC, Lactose and CMS-Na, respectively) was finally determinated by the feasibility of the preparing process and redispersibility. The optimal SRL-SMEDDS pellets showed a significant quicker redispersion rate than the dissolution rate of commercial SRL tablets Rapamune in water. The droplet size and polydispersity index of the reconstituted microemulsion was almost unchanged after solidification, and pellet size and friability were all qualified. Visual observation and scanning electron microscopic analysis confirmed good appearance of the solid pellets. DSC, XRPD, and IR analysis confirmed that there was no crystalline sirolimus in the pellets. Pharmacokinetic study in beagle dogs showed the oral relative bioavailability of SRL-SMEDDS pellets to the commercial SRL tablets Rapamune was about 136.9%. In conclusion, the solid SMEDDS pellets might be an encouraging strategy to improve the oral absorption of SRL and the extrusion-spheronization method was a feasible technology for the solidification of liquid SMEDDS.

Comparative Sirolimus Pharmacokinetics After Single-Dose Administration of Two Prototype 0.5-mg Tablets in Healthy Volunteers.

Availability of a lower dose tablet would add to the dosing flexibility of currently available 1- and 2-mg sirolimus tablets for optimal concentrations and patient compliance. A randomized, 3-period crossover study was conducted in 30 fasting healthy volunteers (29 men, aged 31 ± 8 years, weight 79 ± 12 kg). Subjects were given 5 mg of sirolimus, either as doses of the 0.5-mg nonshellac-core prototype, 0.5-mg shellac-core prototype, or approved 1-mg tablet. Whole blood samples were collected at selected time points for 144 hours after dosing and analyzed using LC/MS/MS assay. Noncompartmental pharmacokinetic analysis was performed, followed by bioequivalence assessment. Twenty-four subjects completed all dosing periods, and no formulation-associated adverse events were reported. Ratios of maximum plasma concentration (Cmax ), area under the concentration-time curve to the last measured concentration (AUCT ), and area under the concentration-time curve from time 0 to infinity (AUC) for the nonshellac-core prototype compared with the 1-mg tablet were within the 80% to 125% range dictated by bioequivalence conventions. Similar results were observed when comparing the ratios of AUCT and AUC for the shellac-core prototype, while 90% confidence interval of the ratio of Cmax values was 105% to 129%. Within the context of clinical equivalence standards established by a phase 3 study comparing liquid to tablet formulations, it was concluded that both prototypes were clinically bioequivalent to the reference formulation.

Sirolimus/steroids Maintenance Therapy after Early Cyclosporine Withdrawal: 12-month Efficacy and Safety Results of Multicenter Single Arm Pilot Study in Primary Renal Allograft Recipients in Korea

Purpose: Sirolimus has potent anti-rejection activity as well as the ability to prolong allograft survival and reduce nephrotoxicity. This study was designed to evaluate the efficacy and safety of sirolimus in Korean de novo renal transplantation. Methods: We included 79 patients who received sirolimus at nine Korean transplantation centers in the intention-to-treat and valid-for-safety analyses. The study was an open, single treatment arm multicenter trial with 12 months of patient follow-up. Initially, patients received 2 ㎎ of sirolimus (after 6 ㎎ of loading does) with cyclosporine and steroids. Sirolimus was administered for up to 12 months. Antibody induction was not used. At 3 months after transplantation, cyclosporine was progressively withdrawn over 4 to 8 weeks while sirolimus was adjusted to obtain trough concentrations within 15∼30 ng/㎖ up to 6 months and concentrations within 12∼24 ng/㎖ between 7 and 12 months. Results: The proportion of patients who completed the 12-month sirolimus medication per protocol was 74.7% (59/79). Cyclosporine withdrawal was possible in 64 recipients (81.0%). Fifteen patients discontinued sirolimus before cyclosporine withdrawal, and 5 recipients did so after successful cyclosporine withdrawal. Most common causes of sirolimus discontinuation were graft rejection (n=8). Incidence of biopsy-proven acute rejection within 6 months after transplantation was 15.2%. Patient and graft survival rates at 12 months post transplantation were 97.5% and 96.2%, respectively. During the study period, three graft losses occurred by patient death. Conclusion: Based on this study, cyclosporine and sirolimus induction followed by cyclosporine withdrawal at 3 months post-transplant is considered to be efficient and safe after primary renal transplantation.

Effect of coadministered HIV‐protease inhibitors on tacrolimus and sirolimus blood concentrations in a kidney transplant recipients

A patient with human immunodeficiency virus infection and end-stage renal disease received a renal transplant. At the time of surgery, the patient was on quadruple antiretroviral therapy (lamivudine, zidovudine, and amprenavir/ritonavir). Immunosuppression was initiated with basiliximab, corticosteroid, mycophenolate mofetil, and a single 0.5 mg dose of tacrolimus. In the following days, an increase in tacrolimus concentration was observed with a peak of 37 ng/mL. Tacrolimus half-life was 6.5 days and tacrolimus maintenance dose was 0.5 mg every 4 days. Eleven months later, the patient had developed Kaposi sarcoma. Tacrolimus was replaced by sirolimus (first dose 1 mg), and the patient was stabilized with 1.5 mg of sirolimus once a week. Increased tacrolimus half-life and increased dose interval of sirolimus and tacrolimus were due to CYP3A4/5 and/or P-glycoprotein inhibition by protease inhibitors. Close monitoring is required in the management of tacrolimus and sirolimus dosing regimens when combined with ritonavir boosted HIV-1 protease inhibitors.

A novel bioengineered small-caliber vascular graft incorporating heparin and sirolimus: Excellent 6-month patency

A bioengineered microporous polycarbonate-siloxane polyurethane graft has been developed for coronary artery bypass grafting. Biological agents can be impregnated into its absorbable collagen and hyaluronan microstructure and stable macrostructure to promote patency. The objective of this study was to examine the in vivo biological performance and biomechanical characteristics of this graft. Three types of graft (3.6-mm internal diameter, 24-mm length) were manufactured: heparin alone (H) grafts, heparin and sirolimus (HS) grafts, and grafts without any drug impregnation (C). All H and HS grafts were impregnated with 54 U of heparin in the microstructure for early elution to prevent acute graft thrombosis and 56 U of heparin in the macrostructure to prevent late thrombosis. In addition to the heparin, the HS graft was impregnated with 2.1 mg of sirolimus in the macrostructure for prolonged elution to inhibit intimal hyperplasia. All grafts (3.6-mm internal diameter, 24-mm length) were implanted into the abdominal aortas of rabbits (n = 55). Expanded polytetrafluoroethylene grafts (4.0-mm internal diameter, 24-mm length; n = 7) were implanted as controls. At 1, 3, and 6 months after surgery, the grafts were removed for histologic, scanning electron microscopic, immunohistochemical, and biomechanical evaluations. The patency rate was 100% in the H, HS, and C grafts at each time point. Although the expanded polytetrafluoroethylene grafts were patent at 1 and 3 months after surgery, 1 of 2 grafts (50%) were occluded at 6 months. None of the H or HS grafts had any stenosis or thrombus. Scanning electron microscopic examination proved that endothelial cells propagated smoothly from the anastomotic sites after 6 months in the H and HS grafts in comparison with the expanded polytetrafluoroethylene grafts, which had rare endothelialization. Neointima formation was inhibited in the HS graft compared with the H or C graft at 6 months (123 +/- 126 microm vs 206 +/- 158 microm or 202 +/- 67 microm; P < .05). In addition, the H, HS, and C grafts had greater cellular infiltration inside the graft than the expanded polytetrafluoroethylene grafts. All grafts except the expanded polytetrafluoroethylene graft had marked neocapillary formation 6 months after surgery. The graft compliance between 80 and 120 mm Hg was 6.0% +/- 2.5% and 6.2% +/- 0.9% at 6 months in the H and HS grafts, respectively. The graft macrostructure was unchanged according to the biomechanical evaluation in the H and HS grafts. A unique drug-eluting graft had excellent patency throughout the 6 months after implantation. The heparin-sirolimus graft encouraged luminal endothelialization without excessive intimal hyperplasia. This graft performed significantly better than the expanded polytetrafluoroethylene graft. This graft has the potential to become an implantable graft for coronary artery bypass grafting.

Phase II trial of erlotinib plus sirolimus for recurrent glioblastoma multiforme (GBM)

2062 Background: Erlotinib, an EGF receptor kinase inhibitor, has limited single-agent activity in recurrent GBM patients. The antiglioma activity of EGFR inhibitors is enhanced by inhibitors of the mammalian target of rapamycin (mTOR), such as sirolimus, in preclinical studies. Methods: This phase II study assesses the antitumor activity of erlotinib plus sirolimus among recurrent GBM patients. Eligibility criteria: histologically confirmed GBM; age ≥18 years; KPS ≥ 70%; adequate hepatic, renal, and bone marrow function and lack of prior EGFR or mTOR-directed therapy. Patients not on enzyme-inducing anticonvulsants (EIAC; phenytoin, carbamazepine, oxcarbazepine and phenobarbitol) receive 150 mg of erlotinib and 5 mg of sirolimus per day, while those on EIAC receive 500 mg of erlotinib and 10 mg of sirolimus per day. Patients are evaluated after every other 28-day cycle. The primary endpoint is 6-month progression-free survival. Results: To date 27 patients have enrolled with a median age of 53.2 years (r...

Pharmacokinetics of mycophenolic acid, tacrolimus and sirolimus after gastric bypass surgery in end‐stage renal disease and transplant patients: a pilot study

Promising data regarding the safety and efficacy of gastric bypass surgery (GBS) as an option to address obesity in the transplant population are emerging. The data lack on how GBS may alter the pharmacokinetics (PK) of modern immunosuppression. The objective of this study was to describe the alterations in the PK of modern immunosuppressants and the GBS population. Data are presented on six subjects who participated in this trial--four were on dialysis and two were renal transplant recipients. Dialysis-dependent bypass subjects received a single dose of 6 mg of sirolimus, two 4-mg doses of tacrolimus and two 1000-mg doses of mycophenolate mofetil (MMF) over the 24-h study period. Transplant recipients continued their current regimen. Maximum plasma concentration (C(max)), time to reach the maximum plasma concentration (T(max)) and the area under the plasma concentration vs. time curve (AUC(0-12) and AUC(0-infinity) where appropriate) were calculated for tacrolimus, sirolimus, mycophenolic acid (MPA) and mycophenolic acid glucuronide (MPAG). Significant inter-patient variability in the C(max), T(max) and AUC of tacrolimus, sirolimus MPA and MPAG was observed. A notable difference in the AUC:dose ratio for tacrolimus was seen when comparing data with published data in the non-bypass population. Similar differences in PK were seen with sirolimus, MPA and MPAG. When comparing the PK of sirolimus, tacrolimus, MPA and MPAG to published PK data in the non-bypass population, significant differences are observed. It is likely that transplant recipients with GBS would need higher doses of tacrolimus, sirolimus and MMF to provide similar exposure to a non-bypass patient.

Phase 1 Trial of Gefitinib Plus Sirolimus in Adults with Recurrent Malignant Glioma

To determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of gefitinib, a receptor tyrosine kinase inhibitor of the epidermal growth factor receptor, plus sirolimus, an inhibitor of the mammalian target of rapamycin, among patients with recurrent malignant glioma. Gefitinib and sirolimus were administered on a continuous daily dosing schedule at dose levels that were escalated in successive cohorts of malignant glioma patients at any recurrence who were stratified based on concurrent use of CYP3A-inducing anticonvulsants [enzyme-inducing antiepileptic drugs, (EIAED)]. Pharmacokinetic and archival tumor biomarker data were also assessed. Thirty-four patients with progressive disease after prior radiation therapy and chemotherapy were enrolled, including 29 (85%) with glioblastoma multiforme and 5 (15%) with anaplastic glioma. The MTD was 500 mg of gefitinib plus 5 mg of sirolimus for patients not on EIAEDs and 1,000 mg of gefitinib plus 10 mg of sirolimus for patients on EIAEDs. DLTs included mucositis, diarrhea, rash, thrombocytopenia, and hypertriglyceridemia. Gefitinib exposure was not affected by sirolimus administration but was significantly lowered by concurrent EIAED use. Two patients (6%) achieved a partial radiographic response, and 13 patients (38%) achieved stable disease. We show that gefitinib plus sirolimus can be safely coadministered on a continuous, daily dosing schedule, and established the recommended dose level of these agents in combination for future phase 2 clinical trials.

SWITCH TO SIROLIMUS-BASED MAINTENANCE IMMUNOSUPPRESSIVE THERAPY IN KIDNEY ALLOGRAFT RECIPIENTS. SINGLE CENTER REPORT

A69 Aims: Immunosuppression with sirolimus (SRL) may provide an opportunity to avoid exposure to the nephrotoxicity of calcineurin inhibitors (CI). We report a retrospective review in switching kidney transplant recipients from CI to SRL. Methods 27 (M/F: 19/8, age: 40+/-10): 23 patients were primary recipients, whereas 4 (14%) were retransplant recipients with anti-HLA antibodies (range 25-95%). The indications for the switch were biopsy proven CI-nephrotoxicity (n=18) and chronic graft nephropathy (n=2), hemolytic uremic syndrome (n=1), miscellaneous reasons (n=6). The mean time of conversion to SRL was 33.4+/-27 months posttransplantation (2-106). In 17 patients, SRL was introduced (4 mg/d, then the dose was adjusted according trough levels) simultaneously with progressive CI withdrawal: 25% dose reduction/week (slow switch). On the other hand, in 10 patients, CI were stopped at the day of switch and 15 mg of SRL were administered, then 10 mg/d, next the dose was adjusted according trough levels (abrupt switch). All patients were given MMF 0.5g b.i.d., without (n=14) or with (n=13) prednisone (median dose 10mg/d) like prior to switch. SRL trough levels were maintained at 8-12 ng/ml during the 1st posttransplant year and 5-10 ng/ml thereafter. The mean follow-up time was 17.8+/-9.8months (3-35).. Results: Graft function improved in 19 patients (creatinine at conversion 170+/-60 μmol/L) by 15.3% (range 7- 32%) at 3 months post-conversion (p=0.05), the improvement was 18.8% at month 6 (p=0.017). Otherwise, in 4 patients (creatinine at conversion 385+/-130 μmol/L) further progressive graft dysfunction occurred and patients returned to dialysis. In 4 patients SRL was discontinued due to serious adverse events [lymphedema (n=2), interstitial pneumonitis (n=1), severe hepatic toxicity (n=1)]. Other adverse events were increased proteinuria (n=13), aphthous ulcers (n=11), acne (n=11), skin lesions (n=9), anemia (n=9), leukopenia (n=9), thrombocytopenia (n=2), epistaxis (n=7), diarrhea (n=7), increased LDL-cholesterol (n=6). Abrupt switch protocol was associated with early appearance of adverse events (during the 1st month); however, the overall incidence of events was not influenced by switch method. The occurrence of adverse events tended to correlate only with high (median > 10 ng/ml) SRL trough level (R=0.36, p=0.09). Neither acute rejection nor patient mortality occurred. Conclusions: These findings demonstrate that conversion from CI to SRL after kidney transplantation improved graft function if performed in patients without severe graft failure. There was no increased risk of acute rejection even in retransplant patients. Nevertheless, either abrupt or slow protocols were associated with several side effects.

Sirolimus and ketoconazole co-prescription in renal transplant recipients.

Ketoconazole inhibits cytochrome P 3A4, leading to a 10-fold increase in sirolimus blood levels. Although it has not been reported in the clinical setting so far, sirolimus and ketoconazole co-prescription can lead to cost saving by reducing the dose of sirolimus administered. After informed consent was obtained, sirolimus and ketoconazole co-prescription was studied in six patients who could not afford the current recommended doses. Patients received one-eighth to one-fourth of the recommended dose of sirolimus (0.25-0.5 mg) with 100 to 200 mg of ketoconazole. Sirolimus levels were monitored, and the dose of ketoconazole was increased to achieve target levels of sirolimus. The loading dose was 3 mg of sirolimus with 100 mg of ketoconazole. After sirolimus rescue therapy was started, serum creatinine decreased in five patients. The mean serum creatinine for the group decreased from 2.6 +/- 0.3 mg/dL at the initiation of rescue therapy to 2.2 +/- 0.5 mg/dL on the last follow-up. Sirolimus ketoconazole co-prescription with monitoring of sirolimus levels is possible and safe and needs to be explored further.

Sirolimus add-on rescue therapy can benefit patients with chronic renal allograft dysfunction.

Nephrotoxicity caused by calcineurin inhibitors (CNIs) contributes to chronic renal allograft dysfunction (CRAD). This retrospective cohort study evaluated the immunosuppressive and nephrotoxic effects of sirolimus add-on therapy with minimization of CNI in patients with CRAD. Twenty patients with CRAD were recruited to receive sirolimus add-on rescue (SRL-AR) therapy. The SRL-AR therapy added 6 mg of sirolimus for loading and 2 mg/day for maintenance to CNI-based maintenance immunosuppressive regimens and reduced the dose of CNI, either cyclosporine or tacrolimus, by half at the initiation of sirolimus loading. The primary endpoint of the study was estimated glomerular filtration rate (GFR) determined using the Cockcroft-Gault formula. The efficacy of this SRL-AR therapy was evaluated by comparison to a historic group of 30 patients with CRAD who received a tacrolimus-based rescue therapy. Of the 20 patients receiving sirolimus therapy, 2 had graft failure during the 12-month follow-up. The post-rescue GFR values of the patients receiving sirolimus therapy showed greater improvement than those of the historic group during follow-up except for month 8, with the differences in GFR changes reaching significance at months 1 to 5 (p < 0.05). Multiple regression analysis identified graft age and GFR upon rescue in addition to the SRL-AR therapy as significant factors associated with post-rescue GFR changes. This study demonstrated that SRL-AR therapy combined with reduced CNI doses could effectively improve short-term renal function of patients with CRAD. The long-term outcome of rescuing CRAD is likely to depend on factors including graft age and GFR upon rescue.

Immunologic monitoring of the transplant recipient: challenges and approaches with antibody induction

T wo different depletional induction protocols were evaluated in transplant recipients treated at the National Institutes of Health Transplant and Autoimmunity Branch in Bethesda, MD. The first protocol studied the use of a polyclonal antibody as induction therapy followed by monotherapy maintenance immunosuppression with sirolimus.1 This study was designed to evaluate several theoretic advantages associated with the use of a polyclonal antibody. These include effective and durable lymphocyte depletion combined with coating of up-regulated adhesion, costimulation, and injury-related molecules during the ischemia-reperfusion period. The second protocol used a monoclonal antibody– based therapy followed by no maintenance immunosuppression.2 The benefits associated with the use of a monoclonal agent include antigenic consistency, rapid lymphocyte clearance, and relatively low side effect profile. Serum creatinine levels, lymphocyte and monocyte counts, and recovery patterns of all cells including memory and naive cells were performed throughout both studies. Protocol-directed biopsies were obtained at 2 weeks, 30 days, and 6 months and then yearly after transplantation to monitor for potential rejection episodes. Biopsies were also performed whenever clinically indicated. In addition to histologic evaluation of the biopsy tissue, evaluation of the quantitative expression of various extracted messenger RNA transcripts was performed. In the polyclonal antibody–based protocol, 18 patients were treated with a total of 20 mg/kg of rabbit antithymocyte globulin (ATG) given at a dose of 2.5 mg/kg per day for 8 days. Methylprednisolone was administered as premedication for the first 3 doses of ATG, and 15 mg of sirolimus was given on the first posttransplant day. The dose of sirolimus was decreased to 5 mg/d thereafter and adjusted to a maintenance level of 10 to 15 ng/mL. All patients experienced rapid and prolonged depletion of lymphocytes and monocytes. Whereas the absolute lymphocyte count remained depressed for more than 18 months after the administration of ATG, the peripheral blood monocyte level was largely recovered within 2 to 3 months. Figures 1 and 2 show the mean absolute lymphocyte and monocyte counts, respectively, over time. In the first 12 patients evaluated, 3 mild clinical rejection episodes (Banff IA and IB) were observed, 2 of which were manifested clinically with an increased serum creatinine level and 1 that was diagnosed on a protocol biopsy without any associated increase in the serum creatinine value. All 3 of these rejection episodes responded rapidly to a short course of steroids, and the patients were maintained on sirolimus monotherapy regimen without recurrent rejection episodes. This experience formed the basis of our initial report.1 Subsequently, 6 additional patients were accrued into this study, 5 of them manifesting a rejection episode within the first 6 months after transplantation. Two of these were instances of humoral rejection associated with the observation of donor human leukocyte antigen–specific antibody. The remaining 3 instances were cellular rejection episodes. Most cellular rejection episodes were temporally associated with subtherapeutic sirolimus levels, which points out the perils associated with monotherapy immunosuppression. From the Transplant Section and Medicine Section, Transplant and Autoimmunity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD; Transplantation Service, Department of Surgery, Walter Reed Army Medical Center, Washington, DC; Laboratory of Pathology, National Cancer Institute, National Institutes of Health; Bethesda, MD; and Naval Medical Research Center, Silver Spring, MD. Address reprint requests to Douglas A. Hale, MD, Transplant Section, Transplant and Autoimmunity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892. This is a US government work. There are no restrictions on its use. 0955-470X/03/1704-0000$30.00/0 doi:10.1016/S0955-470X(03)00078-8

Thymoglobulin, sirolimus, and reduced-dose cyclosporine provides excellent rejection prophylaxis for pancreas transplantation.

We investigated a novel immunosuppressive protocol including thymoglobulin induction in combination with sirolimus and corticosteroids, followed by introduction of markedly reduced exposures to cyclosporine to prevent pancreas-transplant rejection. A 7-day course of thymoglobulin (1.5 mg/kg per day) was begun on postoperative day (POD) 0, together with 15 mg of sirolimus on POD 1, and followed by 5 mg per day, targeting these doses to achieve a trough of 10 to 20 ng/mL. When the serum creatinine was below 2.5 mg/dL, cyclosporine was introduced at 50 mg twice daily with dose adjustment to maintain a trough concentration of 100 to 125 ng/mL. The 18 patients included 14 simultaneous pancreas-kidney and 4 pancreas-after-kidney transplant recipients. Two patients were African-American, three patients had a pretransplant panel reactive antibody greater than 20%, and the human leukocyte antigen (HLA) mismatch was 4.5+/-1 (mean+/-standard deviation). With a mean follow-up of 13.6+/-4.7 months, patient, kidney, and pancreas graft survivals are 100%, 100%, and 94%, respectively. A single pancreas graft was lost to thrombosis. There were no acute rejection episodes and no opportunistic infections. Mean hospital stay was 9+/-3 days. At 3 months posttransplantation, the mean value of serum creatinine was 1.2+/-0.3 mg/dL, fasting glucose was 88+/-15 mg/dL, and sirolimus dose at month 3 was 6.3+/-3 mg per day and at month 12 2.7+/-1 mg per day. The average total daily cyclosporine A dose at month 3 was 208+/-62 mg per day and 133+/-13 mg per day at 1 year. This immunosuppressive regimen provided excellent prophylaxis against acute rejection with no opportunistic infections. We believe that careful monitoring of sirolimus and cyclosporine levels was critical to success of this protocol.