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Tacrolimus is the most commonly used immunosuppression drug after solid organ transplantation; however, its dosing is challenging due to substantial inter-individual variability, often resulting in blood levels that deviate from the target therapeutic range. We explored whether a dynamically customized, phenotypic-outcome-guided drug dosing method could improve maintenance of drug trough levels within pre-determined target ranges, focusing on tacrolimus immediately after liver transplantation. This single-center, partially blinded, completed clinical trial involved 62 adults undergoing liver transplantation, block randomized into parallel groups: standard-of-care (SOC) clinician-determined or Phenotypic Personalized Medicine (PPM)-guided tacrolimus dosing. The primary outcome was percentage of post-transplant days with large (>2 ng/mL) deviations from the target range. At trial completion, analysis found statistically significant improvement in the PPM group ( n  = 27): 24.2% of days showing large deviations compared to 38.4% in the SOC group ( n  = 29) (difference −14.2%, 95% CI: −26.7 to −1.5 %, P  = 0.029) with no increase in adverse events. These results demonstrate that PPM-guided tacrolimus dosing more effectively maintains drug levels within the target range compared to SOC, suggesting a promising approach to improving drug dosing. The trial was registered at ClinicalTrials.gov with the identifier NCT03527238. Tacrolimus is a critical immunosuppressant for liver transplant recipients, but its dosing is challenging due to individual variability. Here, the authors show that a phenotypic personalized medicine approach improves tacrolimus dosing precision, reducing large deviations from target levels and shortening hospital stays in a Phase 2 randomized trial.

Tacrolimus is metabolized in the liver with the participation of cytochrome P450 isoforms 3A4 and 3A5 (CYP3A4, CYP3A5). Omeprazole, unlike famotidine, is a substrate and inhibitor of CYP2C19, CYP3A4, CYP3A5 enzymes. The aim of the study is to compare the effect of omeprazole and famotidine on the tacrolimus concentration and the kidney transplant function. A randomized study was conducted in 24 adult patients with stable kidney transplant function who received a standard triple immunosuppression regimen. Patients were assigned to the group I (n = 12) additionally receiving omeprazole (20 mg) or the group II (n = 12) receiving famotidine (20 mg). At the time of qualification and during follow-up visits, tacrolimus blood concentration and selected laboratory tests were performed. Statistical analysis was performed using the MedCalc system. The value of tacrolimus concentration in the blood increased after a year in the group I (7.27 ± 2.33 vs 9.20 ± 2.46 ng/mL, p = 0.0478). A reduction in tacrolimus dosage was observed after three years in the group I (3.56 ± 1.75 vs 2.78 ± 1.00 mg, p = 0.0440) and in the group II (2.72 ± 0.84 vs 2.10 ± 0.48 mg, p = 0.0051). There was significant difference in the percentage changes of glomerular filtration rate between the groups after 3 years of the study (− 5.56% vs 9.13%, p = 0.0343). Omeprazole significantly change the concentration of tacrolimus in the blood when administered together with tacrolimus after one year of observation. There was no effect of famotidine or omeprazole on the function of the kidney transplant. ClinicalTrials.gov identifier: NCT05061303.

Rapamycin and FK506 are macrocyclic natural products with an extraordinary mode of action, in which they form binary complexes with FK506-binding protein (FKBP) through a shared FKBP-binding domain before forming ternary complexes with their respective targets, mechanistic target of rapamycin (mTOR) and calcineurin, respectively. Inspired by this, we sought to build a rapamycin-like macromolecule library to target new cellular proteins by replacing the effector domain of rapamycin with a combinatorial library of oligopeptides. We developed a robust macrocyclization method using ring-closing metathesis and synthesized a 45,000-compound library of hybrid macrocycles (named rapafucins) using optimized FKBP-binding domains. Screening of the rapafucin library in human cells led to the discovery of rapadocin, an inhibitor of nucleoside uptake. Rapadocin is a potent, isoform-specific and FKBP-dependent inhibitor of the equilibrative nucleoside transporter 1 and is efficacious in an animal model of kidney ischaemia reperfusion injury. Together, these results demonstrate that rapafucins are a new class of chemical probes and drug leads that can expand the repertoire of protein targets well beyond mTOR and calcineurin. Rapamycin and FK506 are macrocycles that contain an FKBP-binding domain and an effector domain responsible for interacting with their respective targets, mTOR and calcineurin. Now, a 45,000-compound macrocycle library has been synthesized by fusing oligopeptides with synthetic FKBP-binding domains. Screening and subsequent optimization yielded a highly potent FKBP-dependent inhibitor of hENT1.

PurposeTacrolimus is distributed mainly in red blood cells (RBCs) after transfer into blood. This study aimed to evaluate the effect of FK506-binding proteins (FKBPs) on RBC distribution of tacrolimus in a physiological environment.MethodsHuman RBCs were isolated from fresh blood samples from healthy volunteers. The effect of FKBPs on each process of the RBC distribution of tacrolimus was evaluated in vitro. Effect of intracellular FKBPs was assessed by inhibition experiment with rapamycin, which competitively inhibits the binding of tacrolimus to FKBPs. Effect of extracellular FKBPs was examined by pre-exposure of RBCs to FKBP and preincubation of tacrolimus with FKBP.ResultsPretreatment with rapamycin significantly reduced the rate of tacrolimus distribution in RBCs in a concentration-dependent manner. Pre-exposure of RBCs to FKBP12 followed by exposure to tacrolimus significantly decreased tacrolimus distribution in RBCs in a concentration-dependent manner. In addition, preincubation of tacrolimus with FKBP12 significantly reduced the rate of tacrolimus distribution in RBCs.ConclusionsFKBP played an important role in the distribution of tacrolimus in RBCs. The effect of intracellular and extracellular FKBPs on RBC distribution of tacrolimus in circulating blood was substantial. FKBP was shown as a potential biomarker for predicting the pharmacokinetics and pharmacodynamics of tacrolimus.

Calcineurin is important for fungal virulence and a potential antifungal target, but compounds targeting calcineurin, such as FK506, are immunosuppressive. Here we report the crystal structures of calcineurin catalytic (CnA) and regulatory (CnB) subunits complexed with FK506 and the FK506-binding protein (FKBP12) from human fungal pathogens ( Aspergillus fumigatus , Candida albicans , Cryptococcus neoformans and Coccidioides immitis ). Fungal calcineurin complexes are similar to the mammalian complex, but comparison of fungal and human FKBP12 (hFKBP12) reveals conformational differences in the 40s and 80s loops. NMR analysis, molecular dynamic simulations, and mutations of the A. fumigatus CnA/CnB-FK506-FKBP12-complex identify a Phe88 residue, not conserved in hFKBP12, as critical for binding and inhibition of fungal calcineurin. These differences enable us to develop a less immunosuppressive FK506 analog, APX879, with an acetohydrazine substitution of the C22-carbonyl of FK506. APX879 exhibits reduced immunosuppressive activity and retains broad-spectrum antifungal activity and efficacy in a murine model of invasive fungal infection. FK506 is a potential antifungal compound that inhibits calcineurin, but it also has immunosuppressive activity. Here, Juvvadi et al. report the structure of FK506 in complex with the FK506-binding protein FKPB12 and calcineurin, and design a less immunosuppresive FK506 analog with antifungal activity in mice.

We investigated whether life cycle pharma (LCP)-tacrolimus compared to extended-release (ER)-tacrolimus results in a difference in severity of tremors and HRQoL. In this multi-center, open-label, randomized, controlled trial, 108 patients were randomized in a 1:1 ratio to either LCP-tacrolimus regimen or ER-tacrolimus regimen after transplantation. HRQoL was assessed with the EQ-5D-5L and SF-36 questionnaire (two generic HRQoL instruments) and the quality of life in essential tremor (QUEST) questionnaire (domain specific HRQoL instrument). The EQ-5D-5L scores were translated to the societal values. We examined the HRQoL over the course of the study by fitting generalized mixed effect models. In total, 105 patients were included, 53 to the LCP- and 52 to the ER-tacrolimus regimen. Baseline questionnaires were available for every LT recipient. At 12 months 25% [10/40], 95% confidence interval (CI) 14.2%–40.2% of the LT recipients in the LCP-tacrolimus regimen group experienced tremors compared to 30.4% [14/46], 95%-CI 19.1%–44.8% of the LT recipients in the ER-tacrolimus regimen group; risk difference: 0.054; 95%-CI −0.151–0.249; p = 0.63. No statistically significant differences in HRQoL were seen between the two regimens. We could not demonstrate differences in the HRQoL or occurrence of tremors between LCP-tacrolimus and ER-tacrolimus regimens

This study demonstrates that switching from calcineurin inhibitors to sirolimus had an antitumoral effect in kidney-transplant recipients with cutaneous squamous-cell carcinomas and may have implications concerning immunosuppressive treatment of such patients. Skin cancers affect more than half of organ-transplant recipients during their long-term course. 1 Several studies have shown that after a first cutaneous squamous-cell carcinoma, multiple subsequent skin cancers develop in 60 to 80% of kidney-transplant recipients within 3 years. 2 , 3 Transplant recipients share common risk factors with the nonimmunosuppressed population, 4 but the specific tumor burden of such patients is linked to the immunosuppressive medications used. 5 , 6 A decrease in cutaneous carcinogenesis after the reduction of immunosuppression has been reported. 7 Consequently, changes in immunosuppression are frequently made in patients with skin cancer, although there is currently no consensus on the level . . .

Titrating tacrolimus concentration in liver transplantation recipients remains a challenge in the early post-transplant period. This multicenter retrospective cohort study aimed to develop and validate a machine-learning algorithm to predict tacrolimus concentration. Data from 443 patients undergoing liver transplantation between 2017 and 2020 at an academic hospital in South Korea were collected to train machine-learning models. Long short-term memory (LSTM) and gradient-boosted regression tree (GBRT) models were developed using time-series doses and concentrations of tacrolimus with covariates of age, sex, weight, height, liver enzymes, total bilirubin, international normalized ratio, albumin, serum creatinine, and hematocrit. We conducted performance comparisons with linear regression and populational pharmacokinetic models, followed by external validation using the eICU Collaborative Research Database collected in the United States between 2014 and 2015. In the external validation, the LSTM outperformed the GBRT, linear regression, and populational pharmacokinetic models with median performance error (8.8%, 25.3%, 13.9%, and − 11.4%, respectively; P  < 0.001) and median absolute performance error (22.3%, 33.1%, 26.8%, and 23.4%, respectively; P  < 0.001). Dosing based on the LSTM model’s suggestions achieved therapeutic concentrations more frequently on the chi-square test ( P  < 0.001). Patients who received doses outside the suggested range were associated with longer ICU stays by an average of 2.5 days ( P  = 0.042). In conclusion, machine learning models showed excellent performance in predicting tacrolimus concentration in liver transplantation recipients and can be useful for concentration titration in these patients.

Background and aims: Immunosuppressive therapy with intravenous ciclosporin is an alternative treatment option to total colectomy for patients with ulcerative colitis (UC), while the benefits of oral administration of tacrolimus are not well defined and are based on reports of several uncontrolled studies. Methods: Patients with refractory active UC were randomly assigned to a high trough concentration (10–15 ng/ml) group (HT group) (n = 21), low trough concentration (5–10 ng/ml) group (LT group) (n = 22), or placebo group (n = 20). Patients received an initial oral dose of 0.05 mg/kg tacrolimus or placebo twice daily. Efficacy was evaluated in 60 patients based on a disease activity index (DAI) score. Fifty eight patients had additional treatment with tacrolimus and were evaluated for efficacy in a 10 week open label extension. Results: An improvement in DAI score (⩾4 points, all categories improved) was observed for 68.4% of cases in the HT group compared with 10.0% in the placebo group (p<0.001). In the HT group, 20.0% of patients had clinical remission and 78.9% had mucosal healing. In the open label extension, 55.2% of all patients had an improved DAI score at week 10. Mean dose of prednisolone was reduced from 19.7 mg/day at study entry to 7.8 mg/day at week 10. The incidence of side effects in the HT group was significantly higher than that of the placebo group (p = 0.043). The most common event was mild finger tremor. Conclusions: Our findings demonstrate dose dependent efficacy and safety of oral tacrolimus for remission-induction therapy of refractory UC. The optimal target range appears to be 10–15 ng/ml in terms of efficacy with two week therapy.

ObjectiveTo compare the efficacy of tacrolimus (TAC) and mycophenolate mofetil (MMF) for the initial therapy of lupus nephritis (LN).Study designThis is an open randomised controlled parallel group study.MethodsAdult patients with biopsy-confirmed active LN (class III/IV/V) were randomised to receive prednisolone (0.6 mg/kg/day for 6 weeks and tapered) in combination with either TAC (0.06–0.1 mg/kg/day) or MMF (2–3 g/day) for 6 months. Good responders were shifted to azathioprine for maintenance. The primary outcome was the rate of complete renal response (CR) at 6 months and the secondary outcomes included partial renal response, renal flares and decline of renal function over time.Results150 patients (92% women; aged 35.5±12.8 years; 81% class III/IV) were randomised (76 MMF, 74 TAC). At month 6, the rate of CR was 59% in the MMF and 62% in the TAC group (treatment difference: 3.0% (−12%, 18%); p=0.71). Major infective episodes occurred in 9.2% patients treated with MMF and in 5.4% patients treated with TAC (p=0.53). Maintenance therapy with azathioprine was given to 79% patients. After 60.8±26 months, proteinuric and nephritic renal flares developed in 24% and 18% of patients in the MMF group and 35% (p=0.12) and 27% (p=0.21) in the TAC group, respectively. The cumulative incidence of a composite outcome of decline of creatinine clearance by ≥30%, development of chronic kidney disease stage 4/5 or death was 21% in the MMF and 22% in the TAC group of patients (p=0.35).ConclusionsTAC is non-inferior to MMF, when combined with prednisolone, for induction therapy of active LN. With azathioprine maintenance for 5 years, a non-significant trend of higher incidence of renal flares and renal function decline is observed with the TAC regimen.Trial registration numberHospital Authority Research Ethics Committee Clinical Trial Registry (HARECCTR0500018; Hong Kong) and US ClinicalTrials.gov (NCT00371319).