Tuberous Sclerosis Complex and the kidneys: what nephrologists need to know / Complexo da Esclerose Tuberosa e rins: o que os nefrologistas devem saber

Abstract Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by the development of hamartomas in the central nervous system, heart, skin, lungs, and kidneys and other manifestations including seizures, cortical tubers, radial migration lines, autism and cognitive disability. The disease is associated with pathogenic variants in the TSC1 or TSC2 genes, resulting in the hyperactivation of the mTOR pathway, a key regulator of cell growth and metabolism. Consequently, the hyperactivation of the mTOR pathway leads to abnormal tissue proliferation and the development of solid tumors. Kidney involvement in TSC is characterized by the development of cystic lesions, renal cell carcinoma and renal angiomyolipomas, which may progress and cause pain, bleeding, and loss of kidney function. Over the past years, there has been a notable shift in the therapeutic approach to TSC, particularly in addressing renal manifestations. mTOR inhibitors have emerged as the primary therapeutic option, whereas surgical interventions like nephrectomy and embolization being reserved primarily for complications unresponsive to clinical treatment, such as severe renal hemorrhage. This review focuses on the main clinical characteristics of TSC, the mechanisms underlying kidney involvement, the recent advances in therapy for kidney lesions, and the future perspectives.

Resumo O complexo da esclerose tuberosa (CET) é uma doença autossômica dominante caracterizada pelo desenvolvimento de hamartomas no sistema nervoso central, coração, pele, pulmões e rins e outras manifestações, incluindo convulsões, tubérculos corticais, linhas de migração radial, autismo e deficiência cognitiva. A doença está associada a variantes patogênicas nos genes TSC1 ou TSC2, resultando na hiperativação da via mTOR, um importante regulador do crescimento e metabolismo celular. Consequentemente, a hiperativação da via mTOR leva à proliferação anormal do tecido e ao desenvolvimento de tumores sólidos. O envolvimento renal no CET é caracterizado pelo desenvolvimento de lesões císticas, carcinoma de células renais e angiomiolipomas renais, que podem progredir e causar dor, sangramento e perda da função renal. Nos últimos anos, houve uma mudança notável na abordagem terapêutica do CET, especialmente no tratamento das manifestações renais. Os inibidores de mTOR surgiram como a principal opção terapêutica, enquanto intervenções cirúrgicas como nefrectomia e embolização são reservadas principalmente para complicações que não respondem ao tratamento clínico, como hemorragia renal grave. Esta revisão se concentra nas principais características clínicas do CET, nos mecanismos subjacentes ao envolvimento renal, nos recentes avanços na terapia para lesões renais e nas perspectivas futuras.

Impact of immunosuppression regimen on COVID-19 mortality in kidney transplant recipients: Analysis from a Colombian transplantation centers registry.

BACKGROUND: The impact of immunosuppression in solid organ transplant recipients with SARS-CoV-2 infection is unknown. The knowledge about the behavior of different immunosuppression schemes in clinical outcomes is scarce. This study aimed to determine the risk of death in kidney transplant recipients with COVID-19 under two different schemes of immunosuppression. METHODS: We describe our experience in kidney transplant recipients with SARS-CoV-2 infection in seven transplant centers during the first year of the pandemic before starting the vaccination programs in the city of Bogotá. Demographic characteristics, clinical presentation, immunosuppression schemes at presentation, and global treatment strategies were compared between recovered and dead patients; survival analysis was carried out between calcineurin inhibitors based regimen and free calcineurin inhibitors regimen. RESULTS: Among 165 confirmed cases, 28 died (17%); the risk factors for mortality identified in univariate analysis were age older than 60 years (p=.003) diabetes (p=.001), immunosuppression based on calcineurin inhibitors (CNI) (p=.025) and patients receiving steroids (p=.041). In multivariable analysis, hypoxemia (p=.000) and calcineurin inhibitors regimen (p=.002) were predictors of death. Survival analysis showed increased mortality risk in patients receiving CNI based immunosuppression regimen vs. CNI free regimens mortality rates were, respectively, 21.7% and 8.5% (p=.036). CONCLUSIONS: Our results suggest that the calcineurin inhibitors probably do not provide greater protection compared to calcineurin inhibitor free schemes being necessary to carry out analyzes that allow us to evaluate the outcomes with different immunosuppression schemes in solid organ transplant recipients with SARS-CoV-2 infection.

Sarcoma de Kaposi en orofaringe en paciente postrasplante renal y manejo con inhibidor de señal de coestimulación e inhibidor de mTOR

Introducción: el sarcoma de Kaposi en pacientes de postrasplante renal es poco frecuente y está asociado usualmente a infección por herpes 8 y a dosis altas de inmunosupresión. Objetivo: descripción reporte de caso de Sarcoma de Kaposi en orofaringe en paciente postrasplante renal manejo con inhibidor de señal de coestimulación e inhibidor mTOR. Presentación del caso: en este artículo se describe el caso de una paciente, con antecedente de trasplante renal, con diagnóstico de sarcoma de Kaposi en una localización muy poco frecuente: a nivel orofaríngeo. Se realiza una revisión de los factores de riesgo, patogenia y un acercamiento en el manejo. De igual manera, se realiza un seguimiento y manejo con inhibidor de señal de coestimulación (belatacept) e inhibidor de mTOR. Discusión y conclusión: el sarcoma de Kaposi es una de las neoplasias postrasplante con mayor incidencia comparativamente con la población no trasplantada, donde el papel de la reactivación de la infección viral, más el papel de la inmunosupresión, son puntos fundamentales en la génesis de la neoplasia. La determinación del estatus serológico IgG para HHV8 podría ser una estrategia de determinación del riesgo en el pretrasplante.

Introduction: Kaposi sarcoma in post-renal transplantation patients is a rare entity, usually associated with herpes 8 infection and high doses of immunosupresion. Purpose: Case report description of Kaposi's sarcoma in the oropharynx in a post-renal transplant patient managed with co-stimulation signal inhibitor and mTOR inhibitor. Case presentation: This article describes the case of a patient, with a history of renal transplant, with a diagnosis of Kaposi's sarcoma in a very rare location: oropharyngeal level. A review of the risk factors, pathogenesis and a management approach is made. Likewise, a follow-up and management with co-stimulation signal inhibitor (belatacept) and mTOR inhibitor is performed. Discussion and conclusion: Kaposi's sarcoma is one of the post-transplant neoplasms with the highest incidence compared to the non-transplanted population, where the role of viral infection reactivation, plus the role of immunosuppression, are fundamental points in the genesis of the neoplasm. The determination of IgG serological status for HHV8 could be a strategy to determine risk in pretransplantation.

Virtual screening and molecular dynamic study of potential new binders to mTOR.

In the present work, a library of 239 frentizole derivatives formerly synthesized by our research group were virtually screened on the FRB domain of mTOR in a search of potential binders for further experimental evaluation. 39 compounds from this library were virtually selected and classified in 7 groups according to their structural features. 9 representative compounds of these 7 groups were further submitted to rounds of MD simulation and MM-PBSA calculations. Analysis of our results pointed to the most promising among these groups as binders to the FRB domain of mTOR. We believe that they structurally represent a priority portion of the original library for further experimental evaluation.

[Tuberous sclerosis complex: diagnosis and current treatment]. / Complejo de esclerosis tuberosa: diagnóstico y tratamiento actual.

Tuberous sclerosis complex is an autosomal dominant genetic multisystemic disorder caused primarily by mutations in one of the two tumor suppressor genes TSC1 or TSC2, resulting in increased activation of the mTOR pathway. Regarding clinical manifestations, a wide range of phenotypic variability exists, with symptoms constellations that may differ in affected organs (brain, skin, heart, eyes, kidneys, lungs), age of presentation and severity, but usually with great impact in biopsychosocial aspects of health and in quality of life. Main clinical neurological features are epilepsy (frequently, antiepileptic drug-resistant epilepsy), neuropsychiatric disorders, and subependymal giant cell astrocytomas. Recently, many therapeutic strategies have developed, including preventive treatment of epilepsy, new options for treatment of epilepsy as cannabidiol, mTOR inhibitors, ketogenic diet, and a more precise epilepsy surgery. Subependymal giant cell astrocytomas may require surgical procedures or mTOR inhibitors treatment. mTOR inhibitors may also be useful for other comorbidities. To improve quality of life of patients with tuberous sclerosis complex, it is essential to be able to deliver an integrated approach by specialized multidisciplinary teams, coordinated with primary care physicians and health professionals, that include access to treatments, attention of psychosocial aspects, and an adequate health care transition from pediatric to adult care.

El complejo de esclerosis tuberosa es un trastorno genético autosómico dominante multisistémico, causado primariamente por mutaciones en uno de los genes supresores de tumores TSC1 o TSC2, que generan una sobre-activación de la vía mTOR. En relación a las manifestaciones clínicas, existe una gran variabilidad fenotípica, con constelaciones de síntomas que pueden diferir tanto en los órganos afectados (encéfalo, piel, corazón, ojos, riñones, pulmones), como en la edad de presentación y la gravedad, pero que generalmente impactan fuertemente en los aspectos biopsicosociales y en la calidad de vida. Las principales manifestaciones clínicas neurológicas incluyen la epilepsia (con frecuencia, fármaco-resistente), los trastornos neuropsiquiátricos y los síntomas relacionados a los astrocitomas de células gigantes. En los últimos años han surgido nuevos abordajes terapéuticos, incluyendo el tratamiento preventivo de la epilepsia, nuevas opciones de tratamiento para la epilepsia como el uso de cannabidiol, de inhibidores de mTOR, la terapia cetogénica y cirugía de epilepsia. Los astrocitomas de células gigantes pueden requerir tratamientos quirúrgicos o con inhibidores de mTOR. Estos últimos también pueden utilizarse para el tratamiento de otras comorbilidades. Para mejorar la calidad de atención de los pacientes con esclerosis tuberosa, el desafío es poder brindar un abordaje integral por equipos interdisciplinarios especializados, en coordinación con sus médicos de cabecera y los equipos de salud del primer nivel de atención, que incluya el acceso a los tratamientos, la atención de los aspectos psicosociales, y una adecuada transición desde la atención pediátrica a la de adultos.

The impact of mTOR inhibitors in the regression of left ventricular hypertrophy in elderly kidney transplant recipients.

End-stage kidney disease is frequently associated with left ventricular hypertrophy (LVH), a condition more prevalent in the elderly, that may increase mortality after renal transplantation (RTx). Previous studies suggested that mTOR inhibitors (mTORi) can improve LVH, but this has never been tested in elderly kidney transplant recipients. In this prospective randomized clinical trial, we analyzed the impact of Everolimus (EVL) on the reversal of LVH after RTx in elderly recipients (≥60 years) submitted to different immunosuppressive regimens: EVL/lowTacrolimus (EVL group, n = 53) or mycophenolate sodium/regularTacrolimus (MPS group, n = 47). Patients performed echocardiograms (Echo) up to 3 months after RTx and then annually. At baseline, mean age was 65±3 years in both groups and LVH was observed in 63.6% of patients in EVL group and in 61.8% of MPS group. Last Echo was performed at mean time of 47 and 49 months after RTx in EVL and MPS groups, respectively (P = .34). LVH regression was observed in 23.8% (EVL group) and 19% (MPS group) of patients (P = 1.00). Mean eGFR, blood pressure, and use of RAS blockers were similar between groups throughout follow-up. EVL did not improve LVH in this cohort, and this lack of benefit may be attributed to concomitant use of TAC, senescence, or both.

Comparison of effects of m-TOR inhibitors and calcineurin inhibitor on SUPAR and ox-LDL levels in renal transplant recipients / Comparación de los efectos de los inhibidores de m-TOR y el inhibidor de calcineurina sobre los niveles de SUPAR y ox-LDL en receptores de trasplante renal

ABSTRACT Introduction: We aimed to investigate the effect of different immunosuppressive regimens on SUPAR and ox-LDL levels which are early markers of inflammation in renal transplant recipients. Methods: A total number of 83 patients were enrolled in our study. While fourty- eight of those were received mTORi, thirty five patients were been receiving CNI. According to the immunosuppressive regimen patients were divided into CNI and m-TORi receving groups and serum SUPAR and ox-LDL levels were measured. Results: Log-SUPAR values were lower in the group receiving m-TORi (3.40 ± 0.1 vs 3.48 ± 0.4, p=0.010). OxLDL / LDL levels were higher (0.0168± 005 vs 0.0132 ±004, p=0.009) in the CNI group. In linear regression analysis, a statistically significant relationship was detected between the use of m-TORi and log-SUPAR (β = -0.052, 95% CI [-0.224, -0.012], p = 0.041) . A negative and independent relationship was found between HT and log-SUPAR (β = -0.60, 95% CI--0.112, -0.018], p=0.0024) and ox-LDL (β = -0.169 [-0.330, -0.008], p=0.040). Very strong correlation (r=1.0, p=<0.001) and independent relationship (β=0.321 [0.313,0.330], p=<0.001) was detected between ox-LDL and SUPAR. Conclusion: As a result, when compared immunsuppression between m-TORi and CNI, the former was associated with lower SUPAR and oxLDL levels.

RESUMEN Introducción: Nuestro objetivo fue investigar el efecto de diferentes regímenes inmunosupresores sobre los niveles de SUPAR y ox-LDL, que son marcadores tempranos de inflamación en receptores de trasplante renal. Material y métodos: Un total de 83 pacientes se inscribieron en nuestro estudio. Mientras que cuarenta y ocho de ellos recibieron mTORi, treinta y cinco pacientes recibieron CNI. De acuerdo con el régimen inmunosupresor, los pacientes se dividieron en grupos receptores de CNI y m-TORi y se midieron los niveles séricos de SUPAR y ox-LDL. Resultados: Los valores de Log-SUPAR fueron menores en el grupo que recibió m-TORi (3,40 ± 0,1 vs 3,48 ± 0,4, p = 0,010). Los niveles de OxLDL/LDL fueron mayores (0,0168± 005 vs 0,0132 ±004, p=0,009) en el grupo CNI. En el análisis de regresión lineal, se detectó una relación estadísticamente significativa entre el uso de m-TORi y log-SUPAR (β = -0,052, IC del 95% [-0,224, -0,012], p = 0,041). Se encontró una relación negativa e independiente entre HT y log-SUPAR (β = -0.60, 95% IC--0.112, -0.018], p = 0.0024) y ox-LDL (β = -0.169 [-0.330, -0.008], p = 0,040). Se detectó una correlación muy fuerte (r = 1,0, p <0,001) y una relación independiente (β = 0,321 [0,313, 0,330], p <0,001) entre ox-LDL y SUPAR. Conclusión: Como resultado, cuando se comparó la inmunosupresión entre m-TORi y CNI, la primera se asoció con niveles más bajos de SUPAR y oxLDL.

Expert consensus to optimize the treatment of elderly patients with luminal metastatic breast cancer.

Most patients diagnosed with luminal metastatic breast cancer (MBC) who are seen in oncology consultations are elderly. MBC in elderly patients is characterized by a higher percentage of hormone receptor (HR) expression and a lower expression of human epidermal growth factor receptor 2 (HER2). The decision regarding which treatment to administer to these patients is complex due to the lack of solid evidence to support the decision-making process. The objective of this paper is to review the scientific evidence on the treatment of elderly patients with luminal MBC. For this purpose, the Oncogeriatrics Section of the Spanish Society of Medical Oncology (SEOM), the Spanish Breast Cancer Research Group (GEICAM) and the SOLTI Group appointed a group of experts who have worked together to establish consensus recommendations to optimize the treatment of this population. It was concluded that the chronological age of the patient alone should not guide therapeutic decisions and that a Comprehensive Geriatric Assessment (CGA) should be performed whenever possible before establishing treatment. Treatment selection for the elderly population should consider the patient's baseline status, the expected benefit and toxicity of each treatment, and the impact of treatment toxicity on the patient's quality of life and functionality.

In silico development of new PET radiopharmaceuticals from mTOR inhibitors.

Rapamycin (or sirolimus) is a macrolide that has shown to be useful as an immunosuppressant and that was studied in metabolic, neurological, or genetic disorders. Rapamycin is a specific natural inhibitor of the mechanistic target of rapamycin (mTOR) that is a kinase protein playing a pivotal role in cell growth and proliferation by activation of several metabolic processes. This work aimed to evaluate the utility of several compounds obtained from rapamycin and its semi-synthetic analogs everolimus and temsirolimus as possible radiopharmaceuticals oriented to this protein. Density Functional Theory calculations of these molecules were made and further analysis of the dual descriptor, charges populations, and of the electrostatic potential surfaces were performed. Molecular docking simulations were used to evaluate the interactions of the rapamycin with the studied candidates. They allowed us to propose two strategies for the synthesis of novel compounds based on electrophilic reactions. Molecular docking results also helped us to eliminate molecules that did not interact correctly with the target. Finally, we found for the first time, that the novel compounds synthesized through the electrophilic addition reaction that employed 18F-selectfluor, should maintain the biological activity of original compounds and could be suitable as Positron Emission Tomography radiopharmaceuticals targeting mTOR Complex1 system.

Use of mTOR inhibitor as prophylaxis for cytomegalovirus disease after kidney transplantation: A natural experiment.

OBJECTIVES: To describe the incidence of cytomegalovirus (CMV) infection/disease in kidney transplant recipients receiving an mTOR-inhibitor-containing immunosuppressive regimen without prophylactic CMV treatment. METHODS: This single-center retrospective cohort analysis included all de novo kidney transplant recipients (09/15/2015-07/31/2017) receiving 3 mg/kg single dose of rabbit antithymocyte globulin induction, tacrolimus, everolimus, and prednisone. Preemptive therapy was initiated only in patients deemed at higher risk for CMV infection: (a) D+/R- CMV patients; (b) after treatment for acute rejection (ARt); and (c) after everolimus discontinuation (EVRd). RESULTS: Of 230 patients, there were no episodes of CMV disease among 217 (94%) without criteria to initiate preemptive therapy. Of 77 (33.5%) patients initiating preemptive therapy, 13 were D+/R-, 30 were ARt, and 34 were EVRd. The overall incidence of first CMV infection/disease was 6% (46.1% in D+/R-, 13.3% ARt [all patients had also discontinued everolimus], and 11.8% after early [<90 days] EVRd). The incidence of biopsy-proven acute rejection was 5.6%, and median glomerular filtration rate at month 12 was 47 mL/min/1.73m2 . One-year patient and death-censored graft survivals were 97.4% and 98.1%. CONCLUSION: This study suggests that everolimus-containing immunosuppressive regimen reduces the need for preventive strategies for CMV infection in the majority of kidney transplant recipients, reducing antiviral drug-associated toxicities and healthcare-related expenditures.

Clinical management of cutaneous adverse events in patients on targeted anticancer therapies and immunotherapies: a national consensus statement by the Spanish Academy of Dermatology and Venereology and the Spanish Society of Medical Oncology.

Progress in the understanding of many tumors has enabled the development of new therapies, such as those targeted at specific molecules involved in cell growth (targeted therapies) or intended to modulate the immune system (immunotherapy). However, along with the clinical benefit provided by these new treatments, new adverse effects have also appeared. Dermatological toxicities such as papulopustular eruptions, xerosis, and pruritus are common with EGFR inhibitors. Other adverse effects have also been described with PDGFR, BCR-ABL, and MAPK tyrosine kinase inhibitors, antiangiogenic drugs, and inhibitors at immune checkpoints such as CTLA-4 and PD-1/PD-L1. Onset of these adverse effects often causes dose reductions and/or delays in administering the prescribed therapy, which can affect patient survival and quality of life. It is, therefore, important to prevent the occurrence of these adverse effects, or to treat unavoidable ones as soon as possible. This requires cooperation between medical oncologists and dermatologists. This article reviews the various dermatological toxicities associated with targeted therapies and immunotherapies, along with their diagnosis and therapeutic management.

The impact of everolimus in reducing cytomegalovirus events in kidney transplant recipients on steroid-avoidance strategy: 3-year follow-up of a randomized clinical trial.

There is no evidence of whether everolimus (EVR) reduces cytomegalovirus (CMV) events in patients receiving steroid-free regimens. Besides, studies evaluating a tacrolimus (TAC) and EVR regimen are limited to 1-year follow-up. In this single-center prospective randomized trial, the incidence of CMV and 3-year efficacy and safety outcomes of EVR were compared to those of mycophenolate sodium (MPS) in a steroid-free regimen based on low-exposure TAC. Both groups received rabbit anti-thymocyte globulin (r-ATG) induction (6 mg/kg) and the steroids were withdrawn at day 7. Maintenance immunosuppression consisted of TAC (4-7 ng/ml until month 3 and 2-4 ng/ml thereafter) plus EVR (3-8 ng/ml) in the EVR group (n = 59); and TAC (4-7 ng/ml during all follow-up) plus MPS (1440 mg) in the MPS group (n = 56). The EVR group presented with a lower incidence of CMV events (18.6% vs. 50%, P = 0.001). No differences were observed in biopsy-proven acute rejection (6.8% vs. 3.6%, P = 0.680),graft loss (0.0% vs. 1.8%, P = 0.487),death (6.8% vs. 1.8%, P = 0.365), or estimated glomerular filtration rate at 36 months (61.1 ± 25.4 vs. 66.3 ± 24 ml/min/1.73 m2 , P = 0.369). A higher proportion of patients discontinued MPS treatment (8.5% vs. 26.8%, P = 0.013) for safety issues. In conclusion, EVR was associated with lower rates of CMV events in patients induced with standard dose r-ATG and a maintenance steroid-free regimen based on TAC. This regimen effectively prevented acute rejection and demonstrated a more favorable safety profile. (ClinicalTrials.gov:NCT02084446).

The influence of mTOR inhibitors on the incidence of CMV infection in high-risk donor positive-recipient negative (D+/R-) kidney transplant recipients.

INTRODUCTION: Several studies and meta-analysis suggest the mTOR inhibitors are associated with reduced incidence of CMV infection after kidney transplantation, although their effects on the high-risk population have not been investigated thoroughly. OBJECTIVE: This retrospective cohort study investigates the association between immunosuppression and CMV infection in D+/R- kidney transplant recipients receiving preemptive therapy. METHODS: All patients received rabbit anti-thymocyte globulin, tacrolimus, prednisone and azathioprine (AZA), mycophenolate (MPA) or everolimus (EVR). RESULTS: Among 89 D+R-, the overall incidence of CMV infection was 76%, with no difference among the groups AZA vs MPA vs EVR (73 vs 83 vs 74%, P = 0.643). CMV infection occurred later (31 in AZA vs 31 in MPA vs 43 days in EVR group, P < 0.001) and showed a lower trend of recurrences (57% in AZA vs 79% in MPA vs 48% in EVR group, P = 0.058) in the everolimus group. There were no differences in the IgG seroconversion rate (82% in AZA vs 76% in MPA vs 72% in EVR group, P = 0.983). There were no differences in the incidence of biopsy-proven acute rejection (10% in AZA vs 8% in MPA vs 6% in EVR group, P = 0.811) and renal function at 12 months (53.6 in AZA vs 60.3 in MPA vs. 55.4 mL/min/1.73 m2 in EVR group). CONCLUSION: In this cohort of high-risk CMV D+/R- kidney transplant recipients receiving rATG induction and tacrolimus, the use of mTOR inhibitors could only show a tendency towards but not a significant difference on the incidence of CMV events, when compared to antimetabolites.

Breast cancer patients have increased risk of developing mTOR inhibitor-associated stomatitis.

A total of 115 patients who used everolimus were evaluated. The mean age was 57 (±13.3) years old, and 87 patients were women (75.6%). mTOR inhibitor-associated stomatitis (mIAS) was observed in 36 patients (31.3%). The lesions ranged from 0.5 cm to 1.5 cm, and the tongue was the main site affected. In addition, 21 patients (58.3%) required a dose reduction of everolimus due to mIAS. Patients who had breast cancer presented 2.29-fold higher risk for developing mIAS when compared to patients with kidney or neuroendocrine tumors. This study emphasizes the high prevalence of mIAS in patients using everolimus, in particular, in patients with breast cancer.

Prognostic and predictive role of the PI3K-AKT-mTOR pathway in neuroendocrine neoplasms.

Neuroendocrine neoplasms (NENs) are considered a heterogeneous and rare entity. Its natural history is influenced by multiple clinicopathological characteristics, which guide the management of these patients. The development of molecular biology reveals that the PI3K-AKT-mTOR pathway plays a relevant role in tumorigenesis and progression of NENs. Mammalian target of rapamycin (mTOR) inhibitors, targeted agents that block this pathway, has improved outcomes in neuroendocrine tumors (NETs). Different therapeutic approaches, such as somatostatin analogs, chemotherapy, peptide receptor radionuclide therapy, and targeted agents, have shown benefits in the treatment of NETs. However, there are not any established prognostic or predictive biomarkers to select the best therapy option to individualize treatment. Although a relation between alterations in the PI3K-AKT-mTOR pathway and clinical outcomes has not been found, these anomalies are considered attractive biomarkers. Additional molecular analysis should be integrated in future clinical trials' design to identify potential predictive or prognostic biomarkers.

Generic immunosuppressants.

Immunosuppressive drugs for solid organ transplantation are critical dose drugs with a narrow therapeutic index. Many of the most commonly used innovator drugs are off patent and have been replicated by generic counterparts, often at substantial cost-savings to the patient. However, serious adverse events caused by the transition from innovator to generic medications, specifically in pediatric solid organ transplant recipients, have questioned these autosubstitutions. The purpose of this review is to summarize the criteria set forth by the regulatory bodies, and to examine how major immunosuppressive drugs conform to these recommendations. Regulatory bodies have established inconsistent criteria to demonstrate bioequivalence between innovator and generic medications, causing approved generic variations to have varying levels of equivalence with the innovator drugs. In order to minimize the risk for under-immunosuppression, the following recommendations have been concluded. Brand prescribing of cyclosporine and tacrolimus are recommended due to evidence of adverse events after conversion to generic formulations and differences in dissolution parameters. Mycophenolate mofetil (MMF) shows better bioequivalence between innovator and generic formulations, however caution should be advised when switching between formulations. The institution of 'innovator only' policies may be appropriate at this time in order to minimize the risk of under-immunosuppressing patients until the evidence of more stringent bioequivalence has been established.

mTOR inhibitors in pancreas transplant: adverse effects and drug-drug interactions.

INTRODUCTION: Patient and pancreas allograft survival improved following reductions in surgical complications, tighter donor selection and optimization in immunosuppressive protocols. However, long-term survival of pancreas allografts is adversely affected by rejection and immunosuppressive regimen toxicity. Areas covered: This article reviews the existing literature and knowledge of mammalian target of rapamycin inhibitors (mTORi). Some clinically relevant drug-drug interactions are highlighted. We summarize the nephrotoxic and diabetogenic mechanisms of mTORi after pancreas transplant, the alternatives to minimize these effects, and report on other adverse events. Expert opinion: Calcineurin inhibitor (CNI)-based regimens remain the mainstay treatment after pancreas-kidney transplant. However, long-term use of CNIs may be associated with nephrotoxicity. Switching from CNIs to mTORi (sirolimus/SRL and everolimus/EVR) may preserve kidney function, mainly EVR conversion. However, mTORi promote an imbalance of mTOR signaling during long-term follow-up and may ultimately contribute to proteinuria and hyperglycemia. These drugs disrupt autophagy, inhibit cell proliferation, and downregulate VEGF. Therefore, it is important to comprehend and interpret the experimental data. It is equally important to critically analyze clinical studies. Of importance, minimization of side effects, based on safe approaches, can prolong kidney allograft survival. Additional randomized-controlled studies are required to assess the impact of mTORi on pancreas allograft survival.

Rapamycin and WYE-354 suppress human gallbladder cancer xenografts in mice.

Gallbladder cancer (GBC) is a highly malignant tumor characterized by a poor response to chemotherapy and radiotherapy. We evaluated the in vitro and in vivo antitumor efficacy of mTOR inhibitors, rapamycin and WYE-354. In vitro assays showed WYE-354 significantly reduced cell viability, migration and invasion and phospho-P70S6K expression in GBC cells. Mice harboring subcutaneous gallbladder tumors, treated with WYE-354 or rapamycin, exhibited a significant reduction in tumor mass. A short-term treatment with a higher dose of WYE-354 decreased the tumor size by 68.6% and 52.4%, in mice harboring G-415 or TGBC-2TKB tumors, respectively, compared to the control group. By contrast, treatment with a prolonged-low-dose regime of rapamycin almost abrogated tumor growth, exhibiting 92.7% and 97.1% reduction in tumor size, respectively, compared to control mice. These results were accompanied by a greater decrease in the phosphorylation status of P70S6K and a lower cell proliferation Ki67 index, compared to WYE-354 treated mice, suggesting a more effective mTOR pathway inhibition. These findings provide a proof of concept for the use of rapamycin or WYE-354 as potentially good candidates to be studied in clinical trials in GBC patients.