Developing a real-world database for oncology: a descriptive analysis of breast cancer in Argentina.

Introduction: Registries based on Real-World Data (RWD) are those obtained outside of systematised and randomised clinical trials. They allow the collection of information from a large number of patients and enable the participation of a significant number of professionals. PrecisaXperta is a web platform developed for this purpose with more than 2 years of operation, parameterised for oncology. Its design allows the construction of an epidemiological database in real time and exportable for processing. Objective: To describe the characteristics and operation of this online data recording tool, explain how it was developed and analyse the quality of the information recorded, taking as an example the data obtained for breast cancer. Materials and methods: Physicians, computer scientists and data science analysts participated in the development. Patient data, history, educational level, diagnosis, staging, molecular markers, quality of life, types of treatments, progression and response, imaging, complications, adverse events are some of the fields included. Data treatment in terms of encryption, anonymisation, protection and validation is also explained. The selected breast cancer data for description were processed with medium-level statistical programmes, since the number required to apply Big Data engines is not yet available. Results: From a total of 6,892 solid tumours, 1,892 were breast cancer and 1,654 were selected that complied with a data set minimum elaborated ad hoc. Cases from 13 provinces showed a geolocation bias according to the place of practice of the professionals in the collaborative network. The predominant lack of data was detected in molecular markers (ki67) and correlativity in some lines of treatment. Inconsistencies in dates and therapeutic schemes were also detected. Data curation made it possible to exclude them. The age of the patients was 55.3 ± 11.88 years. At the time of diagnosis, the predominance was in stage I: 36.48% and II 30.06%, with positive hormone receptors in 1,424 (89.96%) cases. The predominant treatments were hormonal (61.54%) and target directed with 30.85% for HER2(+) and 39.14% for HER2(-) accompanied in most cases (85.9%) by some period of chemotherapy. Immunotherapy was much less represented (0.36%). Data were processed, homogenised, pooled and presented and made accessible in a form suitable for application to RWD analyses. Conclusions: PrecisaXperta fulfils this purpose of systematising the information to facilitate its loading with its simple and intuitive interface. From the analysis of the data obtained in breast cancer, it is clear that some fields should be mandatory in order to improve the quality of the information. The results describing the registered breast cancers give us a surface view of the affected population and prepare us to design future studies when we have local Big Data. This type of development, with continuous improvements and online results, will allow with its dissemination, that the participating professionals have information of what happens in the real world, having available in a democratic way, the epidemiology to be able to study, publish and investigate with these data.

Principios de estadística Bayesiana y su relación con la farmacocinética aplicada / Principles of Bayesian statistics and its relationship with applied pharmacokinetics

La metodología estadística Bayesiana permite, si se conoce la probabilidad poblacional de que un suceso ocurra, modificar su valor cuando se dispone de nueva información individual. Aunque las metodologías Bayesiana y frecuentista (clásica) tienen idénticos campos de aplicación, la primera se aplica cada vez más en investigación científica y análisis de big data. En la farmacoterapia moderna, la farmacocinética clínica ha sido responsable de la expansión de la monitorización, facilitada por desarrollos técnico-analíticos y matemático-estadísticos. La farmacocinética poblacional ha permitido identificar y cuantificar las características fisiopatológicas y de tratamiento en una población de pacientes determinada, en particular en pediatría y neonatología, y otros grupos vulnerables, explicando la variabilidad farmacocinética interindividual. Asimismo, la estimación Bayesiana resulta importante como herramienta estadística aplicada en programas informáticos de optimización farmacoterapéutica cuando la monitorización farmacológica se basa en la interpretación farmacocinética clínica. Aunque con ventajas y limitaciones, la optimización farmacoterapéutica basada en la estimación Bayesiana es cada vez más usada en la actualidad, siendo el método de referencia. Esto es particularmente conveniente para la práctica clínica de rutina debido al limitado número de muestras requeridas por parte del paciente, y a la flexibilidad en cuanto a los tiempos de muestreo de sangre para cuantificación de fármacos. Así, la aplicación de los principios Bayesianos a la práctica de la farmacocinética clínica resulta en la mejora de la atención farmacoterapéutica.

If one knows the probability of an event occurring in a population, Bayesian statistics allows mo difying its value when there is new individual information available. Although the Bayesian and frequentist (classical) methodologies have identical fields of application, the first one is increasin gly applied in scientific research and big data analysis. In modern pharmacotherapy, clinical phar macokinetics has been used for the expansion of monitoring, facilitated by technical-analytical and mathematical-statistical developments. Population pharmacokinetics has allowed the identification and quantification of pathophysiological and treatment characteristics in a specific patient popu lation, especially in the pediatric and neonatal population and other vulnerable groups, explaining interindividual variability. Likewise, Bayesian estimation is important as a statistical tool applied in pharmacotherapy optimization software when pharmacological monitoring is based on clinical phar macokinetic interpretation. With its advantages and despite its limitations, pharmacotherapeutic op timization based on Bayesian estimation is increasingly used, becoming the reference method today. This characteristic is particularly convenient for routine clinical practice due to the limited number of samples required from the patient and the flexibility it shows regarding blood sampling times for drug quantification. Therefore, the application of Bayesian principles to the practice of clinical phar macokinetics has led to the improvement of pharmacotherapeutic care.

Frequency of CYP3A5 Genetic Polymorphisms and Tacrolimus Pharmacokinetics in Pediatric Liver Transplantation.

The evidence available in the pediatric population is limited for making clinical decisions regarding the optimization of tacrolimus (TAC) in pharmacotherapy. The objective of this study was to estimate the frequency of CYP3A5 genetic polymorphisms and their relationship with tacrolimus requirements in the pediatric population. This was a longitudinal cohort study with a two-year follow-up of 77 patients under 18 years old who underwent a liver transplant during the period 2009-2012 at the J.P. Garrahan Pediatric Hospital. Tacrolimus levels from day five up to two years after the transplant were obtained from hospital records of routine therapeutic drug monitoring. The genotyping of CYP3A5 (CYP3A5*1/*3 or *3/*3) was performed in liver biopsies from both the donor and the recipient. The frequency of CYP3A5*1 expression for recipients was 37.1% and 32.2% for donors. Patients who received an expresser organ showed lower Co/dose, especially following 90 days after the surgery. The role of each polymorphism is different according to the number of days after the transplant, and it must be taken into account to optimize the benefits of TAC therapy during the post-transplant induction and maintenance phases.

[Principles of Bayesian statistics and its relationship with applied pharmacokinetics]. / Principios de estadística Bayesiana y su relación con la farmacocinética aplicada.

If one knows the probability of an event occurring in a population, Bayesian statistics allows mo difying its value when there is new individual information available. Although the Bayesian and frequentist (classical) methodologies have identical fields of application, the first one is increasin gly applied in scientific research and big data analysis. In modern pharmacotherapy, clinical phar macokinetics has been used for the expansion of monitoring, facilitated by technical-analytical and mathematical-statistical developments. Population pharmacokinetics has allowed the identification and quantification of pathophysiological and treatment characteristics in a specific patient popu lation, especially in the pediatric and neonatal population and other vulnerable groups, explaining interindividual variability. Likewise, Bayesian estimation is important as a statistical tool applied in pharmacotherapy optimization software when pharmacological monitoring is based on clinical phar macokinetic interpretation. With its advantages and despite its limitations, pharmacotherapeutic op timization based on Bayesian estimation is increasingly used, becoming the reference method today. This characteristic is particularly convenient for routine clinical practice due to the limited number of samples required from the patient and the flexibility it shows regarding blood sampling times for drug quantification. Therefore, the application of Bayesian principles to the practice of clinical phar macokinetics has led to the improvement of pharmacotherapeutic care.

Molecular Epidemiology of ALK Rearrangements in Advanced Lung Adenocarcinoma in Latin America.

OBJECTIVE: Latin American countries are heterogeneous in terms of lung cancer incidence and exposure to potential carcinogens. We evaluated the frequency and clinical characteristics of ALK rearrangements (ALKr) in Latin America. METHODS: A total of 5,130 lung cancer patients from 10 Latin American countries were screened for inclusion. ALKr detection was performed by fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), and real-time reverse transcriptase-polymerase chain reaction (RT-PCR) to assess method variability. Demographic and clinicopathologic characteristics were analyzed. RESULTS: Among the 5,130 patients screened, 8.4% (n = 433) had nonevaluable FISH tests. Evaluable FISH analyses revealed positive ALKr in 6.8% (320/4,697) of the study population, which included patients from 9 countries. ALKr distribution for each country was: Mexico 7.6% (79/1,034), Colombia 4.1% (10/242), Argentina 6.0% (153/2,534), Costa Rica 9.5% (13/137), Panama 4.4% (5/114), Uruguay 5.4% (2/37), Chile 8.6% (16/185), Venezuela 8.9% (13/146), and Peru 10.8% (29/268). RT-PCR showed high positive (83.6%) and negative (99.7%) predictive values when compared to the gold standard FISH. In contrast, IHC only showed a high negative predictive value (94.6%). CONCLUSIONS: Although there is a clear country and continental variability in terms of ALKr frequency, this difference is not significant and the overall incidence of ALKr in Latin America does not differ from the rest of the world.

High incidence of persistent subtherapeutic levels of the most common AEDs in children with epilepsy receiving polytherapy.

BACKGROUND: Low levels of AEDs can be secondary drug-drug interactions or related to irregular intake due to poor treatment adherence. This latter behavior is highly suspected in ambulatory pediatric epileptic patients when controls of AEDs are subtherapeutic. However, it cannot be considered for inpatients during long periods of hospitalization. A few isolated case reports have documented persistent low levels (PLL) of AEDs in hospitalized epileptic children, but no population study has currently been reported. OBJECTIVE: The aim of this study was to document the incidence of PLL of the most common AEDs - phenytoin (PHT), phenobarbital (PHB), valproic acid (VA), and carbamazepine (CBZ) - in pediatric epileptic in- and outpatients (PEP). METHODS: 21,040 plasma levels of the aforementioned AEDs from 3279 PEP were retrospectively analyzed. Plasma levels of AEDs were measured by an automated method using trademarked commercial kits with their corresponding quality control programs. Randomized samples were also controlled by HPLC methods. Only cases with more than 3 controls were included in the study. RESULTS: A high rate of PLL of PHT was detected in in- (71.7%) and outpatients (74.1%), while PLL of PHB, VA, and CBZ were detected in a lower proportion. Rates of PLL of PHT were similar in in- and outpatients. PLL of PHB was more commonly observed in outpatients while PLL of VA and CBZ were more frequently seen in inpatients. In some hospitalized patients receiving polytherapy, PLL of at least one AED were documented during a long time. DISCUSSION: Treatment non-adherence could be present in part of the outpatients, but cannot explain the PLL observed in a group of inpatients as described here. The recently described "pharmacokinetic hypothesis" of pharmaco-resistant epilepsy should be addressed in cases with AEDs-PLL, particularly in hospitalized cases. Perhaps, instead of stopping the subtherapeutic medication, the increasing doses of this AED and/or administration of inhibitors of CYP and P-glycoprotein, could help to achieve its therapeutic range, allowing a better pharmacologic effect and avoiding the development of more severe complications, such as status epilepticus or SUDEP.

Increased delivery of chemotherapy to the vitreous by inhibition of the blood-retinal barrier.

Treatment of retinoblastoma -a pediatric cancer of the developing retina- might benefit from strategies to inhibit the blood-retinal barrier (BRB). The potent anticancer agent topotecan is a substrate of efflux transporters BCRP and P-gp, which are expressed at the BRB to restrict vitreous and retinal distribution of xenobiotics. In this work we have studied vitreous and retinal distribution, tumor accumulation and antitumor activity of topotecan, using pantoprazole as inhibitor of BCRP and P-gp. We used rabbit and mouse eyes as BRB models and patient-derived xenografts as retinoblastoma models. To validate the rabbit BRB model we stained BCRP and P-gp in the retinal vessels. Using intravitreous microdialysis we showed that the penetration of the rabbit vitreous by lactone topotecan increased significantly upon concomitant administration of pantoprazole (P=0.0285). Pantoprazole also increased topotecan penetration of the mouse vitreous, measured as the vitreous-to-plasma topotecan concentration ratio at the steady state (P=0.0246). Pantoprazole increased topotecan antitumor efficacy and intracellular penetration in retinoblastoma in vitro, but did not enhance intratumor drug distribution and survival in mice bearing the intraocular human tumor HSJD-RBT-2. Anatomical differences with the clinical setting likely limited our in vivo study, since xenografts were poorly vascularized masses that loaded most of the vitreous compartment. We conclude that pharmacological modulation of the BRB is feasible, enhances anticancer drug distribution into the vitreous and might have clinical implications in retinoblastoma. CHEMICAL COMPOUNDS INCLUDED IN THIS MANUSCRIPT: Topotecan (PubChem CID: 60700) Pantoprazole sodium (PubChem CID: 15008962).

Sobreexpresión de C-MET en carcinoma de vesícula y del tracto biliar: prevalencia y correlación clínico-molecular / Overexpression of C-MET in gallbladder and biliary tract carcinoma: prevalence and clinical-molecular correlation

El objetivo fue determinar la sobreexpresión de c-MET en pacientes con cáncer biliar y analizar asociaciones con parámetros clínicos. Este es un estudio descriptivo, longitudinal, retrospectivo y prospectivo. Se determinó la sobreexpresión por inmunohistoquímica en 58 pacientes con resultados: positivo fuerte, positivo débil y negativo. Se construyeron curvas de supervivencia global con el método de KaplanMeier en todos los pacientes y en subgrupos según estadío, género, origen tumoral y grado de diferenciación histológica. La diferencia en supervivencia global entre subgrupos se analizó por el método log-rank. La asociación entre sobreexpresión y grado de diferenciación se estudió por el método chi cuadrado. Las pruebas estadísticas se realizaron a dos colas con un valor de p 0.05. Veintinueve muestras (50%) fueron negativas, 24 (41%) positivas débiles y 5 (9%) positivas fuertes. La mediana de supervivencia fue 18.2, 11.3 y 11.7 meses en pacientes con sobreexpresión negativa, positiva débil y positiva fuerte, respectivamente. Sin embargo, la diferencia en supervivencia global entre pacientes c-MET negativos y positivos (fuerte y débil) no alcanzó significancia estadística (p 0.068). En los subgrupos los resultados fueron similares. La sobreexpresión se asoció al grado de diferenciación (p 0.015), mostrando una relación inversa; y no se correlacionó con tasa de respuesta a la quimioterapia y tiempo a la progresión. La sobreexpresión de c-MET es frecuente en cáncer biliar, se asocia al grado de diferenciación tumoral y podría tener valor pronóstico. Si la vía c-MET es importante, los fármacos inhibidores tendrían impacto en la supervivencia global (AU)

The objective was to determine the overexpression of c-MET in patients with biliary cancer and to analyze associations with clinical parameters. This is a descriptive, longitudinal, retrospective and prospective study. Overexpression was obtained by immunohistochemistry in 58 patients, with the following results: strong positive, weak positive and negative. Overall survival curves were constructed using the Kaplan-Meier method in all patients and in subgroups according to stage, gender, tumor origin and grade of histological differentiation. The difference in overall survival between groups was analyzed by the log-rank test. The association between overexpression and grade of differentiation was studied using the chisquare method. Statistical tests were two-tailed with a p value 0.05. Twenty nine samples (50%) were negative, 24 (41%) weak positive and 5 (9%) strong positive. Median survival was 18.2, 11.3 and 11.7 months in patients with negative, weak positive and strong positive overexpression, respectively. However, the difference in overall survival between negative and positive (strong and weak together) c-MET patients did not reach statistical significance (p 0.068). In the subgroup analyses the results were similar. Overexpression correlated with tumor grade (p 0.015), showing an inverse association; and was not associated neither with chemotherapy response rate nor with time to progression. Overexpression of c-MET is common in biliary cancer, is associated with grade of tumor differentiation and could have prognostic value. If the c-MET pathway is important, the inhibitory drugs would have an impact on overall survival (AU)

Pharmacokinetics of Immediate and Sustained Release Cephalexin Administered by Different Routes to Llamas (Lama glama).

We investigate the pharmacokinetics of two different cephalexin formulations administered to llamas by the intravenous (IV), intramuscular (IM), and subcutaneous (SC) routes, the minimum inhibitory concentration (MIC) of cephalexin against some Escherichia coli and staphylococci isolated from llamas, and we apply the PK/PD modelling approach, so that effective dosage recommendations for this species could be made. Six llamas received immediate (10 mg/kg, IV, IM, and SC) and sustained (8 mg/kg IM, SC) release cephalexin. Pharmacokinetic parameters were calculated by noncompartmental approach. Immediate release SC administration produced a significantly longer elimination half-life as compared with the IV and IM administration (1.3 ± 0.2 versus 0.6 ± 0.1 and 0.6 ± 0.1 h, resp.) and higher mean absorption time as compared with the IM administration (1.7 ± 0.5 versus 0.6 ± 0.4 h). Absolute bioavailability was in the range of 72-89% for both formulations and routes of administration. Cephalexin MIC90 values against staphylococci and E. coli were 1.0 and 8.0 µg/mL, respectively. Our results show that the immediate release formulation (10 mg/kg) would be effective for treating staphylococcal infections administered every 8 h (IM) or 12 h (SC), whereas the sustained release formulation (8 mg/kg) would require the IM or SC administration every 12 or 24 h, respectively.

Twenty-One Novel EGFR Kinase Domain variants in Patients with Nonsmall Cell Lung Cancer.

Somatic sequence variants in the epidermal growth factor receptor (EGFR) kinase domain are associated with sensitivity to tyrosine kinase inhibitors (TKIs) in patients with nonsmall cell lung cancer (NSCLC). Patients exhibiting sequence variants in this domain that produce kinase activity enhancement, are more likely to benefit from TKIs than patients with EGFR wild-type disease. Although most NSCLC EGFR-related alleles are concentrated in a few positions, established protocols recommend sequencing EGFR exons 18-21. In this study, 21 novel somatic variants belonging to such exons in adult Argentinean patients affected with NSCLC are reported. Of these, 18 were single amino acid substitutions (SASs), occurring alone or in combination with another genetic alteration (complex cases), one was a short deletion, one was a short deletion-short insertion combination, and one was a duplication. New variants and different combinations of previously reported variants were also found. Moreover, two of the reported SASs occurred in previously unreported positions of the EGFR kinase domain. In order to characterize the new sequence variants, physicochemical, sequence and conformational analyses were also performed. A better understanding of sequence variants in NSCLC may facilitate the most appropriate treatment choice for this complex disease.

Combinational Effect of CYP3A5 and MDR-1 Polymorphisms on Tacrolimus Pharmacokinetics in Liver Transplant Patients.

OBJECTIVES: Previous studies have reported reduced tacrolimus dose-adjusted exposure in individuals expressing the CYP3A5*1 allele (reference single nucleotide polymorphism identification number 776746). However, results on patients from South America are scarce. The objective of this study was to investigate the influence of CYP3A5 and MDR1 allelic variants and their correlation on the pharmacokinetics of tacrolimus and a modified release formulation of tacrolimus in stable patients with liver transplant. MATERIALS AND METHODS: This was a prospective, single center, open-label study. Included patients were ≥ 18 years old and receiving a stable dose of tacrolimus for at least 6 months. Patients receiving stable treatment of twice daily tacrolimus were switched to a once-daily dose of modified release tacrolimus, on a milligram-to-milligram basis, with the modified release formulation administered for at least 4 weeks. Blood levels of tacrolimus were obtained before and 1 month after treatment was switched to the modified release formulation. RESULTS: The frequency of the intron 3 allelic variant of the CYP3A5 isoform (G-to-A substitution at nucleotide 6986) in recipients was 16.6% and 25% in donors. Dose levels of tacrolimus and the modified formulation were significantly higher in donors and recipients who expressed CYP3A5 versus donors and recipients who did not express this allele. In addition, patients who received a liver from a donor expressing CYP3A5 had significantly lower trough concentrations of tacrolimus and the modified formulation. CYP3A5 expression in the donor liver affected tacrolimus (40.46%, P = .001) and modified formulation (37.56%, P = .001) variability. No association was found between the ABCB1 genotype and levels of tacrolimus or its modified formulation. CONCLUSIONS: Our data suggest that CYP3A5*1 in either the donor or recipient resulted in higher mean daily doses of tacrolimus or its modified formulation to achieve target drug exposure in liver transplant patients.

Tetronic® 904-containing polymeric micelles overcome the overexpression of ABCG2 in the blood-brain barrier of rats and boost the penetration of the antiretroviral efavirenz into the CNS.

AIM: To assess the involvement of ABCG2 in the pharmacokinetics of efavirenz in the blood-brain barrier (BBB) and investigate a nanotechnology strategy to overcome its overexpression under a model of chronic oral administration. Materials & methods A model of chronic efavirenz (EFV) administration was established in male Sprague-Dawley rats treated with a daily oral dose over 5 days. Then, different treatments were conducted and drug concentrations in plasma and brain measured. RESULTS: Chronic treatment with oral EFV led to the overexpression of ABCG2 in the BBB that was reverted after a brief washout period. Moreover, gefitinib and the polymeric amphiphile Tetronic(®) 904 significantly inhibited the activity of the pump and potentiated the accumulation of EFV in CNS. The same effect was observed when the drug was administered within mixed micelles containing TetronicT904 as the main component. CONCLUSION: Tetronic 904-containing polymeric micelles overcame the overexpression of ABCG2 in the BBB caused by chronic administration of EFV then boosting its penetration into the CNS.

Updated Frequency of EGFR and KRAS Mutations in NonSmall-Cell Lung Cancer in Latin America: The Latin-American Consortium for the Investigation of Lung Cancer (CLICaP).

INTRODUCTION: Previously, we reported the frequency of epidermal growth factor receptor (EGFR) and KRAS mutations in nonsmall-cell lung cancer (NSCLC) patients in Latin America. The EGFR mutation frequency was found between Asian (40%) and Caucasian (15%) populations. Here, we report the updated distribution of NSCLC mutations. METHODS: A total of 5738 samples from NSCLC patients from Argentina (1713), Mexico (1417), Colombia (1939), Peru (393), Panama (174), and Costa Rica (102) were genotyped for EGFR and KRAS. RESULTS: The median patient age was 62.2 ± 12.3 years; 53.5% were women, 46.7% had a history of smoking, and 95.2% had adenocarcinoma histology. The frequency of EGFR mutations was 26.0% (95% confidence interval [CI], 24.9-27.1; Argentina, 14.4% [12.8-15.6]; México, 34.3% [31.9-36.7]; Colombia, 24.7% [22.8-26.6]; Peru, 51.1% [46.2-55.9]; Panamá, 27.3 [20.7-33.9]; and Costa Rica, 31.4% [22.4-40.4]). The frequency of KRAS mutations was 14.0% (9.1-18.9). In patients with adenocarcinoma, EGFR mutations were independently associated with gender (30.7% females vs. 18.4% males; p < 0.001), nonsmoker status (27.4% vs. 17.1%, p < 0.001), ethnicity (mestizo/indigenous, 35.3% vs. Caucasian, 13.7%, p < 0.001), and the absence of KRAS mutation (38.1% vs. 4.7%; p < 0.001). The overall response rate to EGFR tyrosine kinase inhibitors was 60.6% (95% CI, 52-69), with a median progression-free survival and overall survival of 15.9 (95% CI, 12.420.6) and 32 months (95% CI, 26.5-37.6), respectively. CONCLUSION: Our findings support the genetic heterogeneity of NSCLC in Latin America, confirming that the frequency of EGFR mutations is intermediate between that observed in the Asian and Caucasian populations.

Ocular pharmacology of topotecan and its activity in retinoblastoma.

PURPOSE: To review the ocular pharmacology and antitumor activity of topotecan for the treatment of retinoblastoma by an evaluation of different routes of administration. METHODS: Systematic review of studies available at PubMed using the keywords retinoblastoma, topotecan, and camptothecins, including preclinical data such as cell lines and animal models, as well as clinical studies in patients with retinoblastoma. RESULTS: Forty-two available studies were reviewed. Evidence of antitumor activity against retinoblastoma as a single agent is based on data on cell lines and a limited number of affected patients with intraocular and extraocular disease when given in a protracted schedule. Evidence of additive or synergistic activity in combination with other agents such as carboplatin, melphalan, and vincristine was reported in preclinical and clinical models. In animal models, pharmacokinetic evaluation of topotecan administered by the periocular route shows that most of the drug reaches the vitreous through the systemic circulation. Topotecan administered by intravitreal injection shows high and sustained vitreal concentrations with limited systemic exposure and lack of retinal toxicity at a dose of up to 5 µg. Topotecan administered intraophthalmic artery shows higher passage to the vitreous compared with periocular administration in a swine model. CONCLUSION: Topotecan alone or in combination is active against retinoblastoma. It shows a favorable passage to the vitreous when given intravenously and intraarterially, and ocular toxicity is minimal by all routes of administration. However, its clinical role, optimal dose, and route of administration for the treatment of retinoblastoma are to be determined.

Effects of combinational CYP3A5 6986A>G polymorphism in graft liver and native intestine on the pharmacokinetics of tacrolimus in liver transplant patients: a meta-analysis.

BACKGROUND: Many studies have reported reduced tacrolimus dose-adjusted exposure in individuals expressing the CYP3A5*1 allele. A meta-analyses of the current data may help characterize the extent of impact this polymorphism has on tacrolimus pharmacokinetics in adult liver transplant recipients and whether donor or recipient genotype is the most influential factor. METHODS: Structured searches, of studies that evaluated the association between CYP3A5*1 allele and tacrolimus pharmacokinetics in adult liver transplant recipients, were conducted using Embase and Medline. A meta-analysis comparing tacrolimus daily dose, trough concentrations (C0), and dose-adjusted trough concentrations (C0/dose) across the donor and recipient genotype pairs was conducted using a random effects model. RESULTS: Eight studies, involving a total of 694 adult liver transplant recipients, were included. Dose-adjusted tacrolimus trough concentrations were significantly lower in those in whom the donor or recipient expressed a *1 allele compared with those in whom neither the donor nor recipient expressed this allele at 7 days and 2, 3, 6, and 12 months after transplant [standardized mean differences between expressers and nonexpressers of -1.98, -2.12, -2.39, -3.68, and -3.26 (ng/mL)/(mg·kg·d), respectively]. CONCLUSIONS: Results of the meta-analysis demonstrated that, in adult liver transplant patients, CYP3A5 expression in either the donor or recipient resulted in a need for a higher mean tacrolimus daily dose to achieve the target drug exposure. In the immediate posttransplant period, recipient expression of a CYP3A5*1 allele seemed to have the greatest influence on tacrolimus pharmacokinetics with donor expression of a CYP3A5*1 allelle possibly becoming more important with increasing time after transplant.

Influence of MDR1 C1236T polymorphism on lopinavir plasma concentration and virological response in HIV-1-infected children.

BACKGROUND: Variability in MDR1 and PXR has been associated with differences in drug plasma levels and response to antiretroviral therapy. We investigated whether polymorphisms in MDR1 (T-129C, C1236T and C3435T) and PXR (C63396T) affect lopinavir plasma concentration and the virological or immunological response to HAART in HIV-1-infected children. METHODS: Genotypes were identified in 100 blood donors and 38 HIV-1-infected children. All children received HAART with lopinavir boosted with ritonavir (LPV/r) at the time of LPV plasma level quantification, before (Ctrough) and between 1 and 2h after (Cpost-dose) the administration of the next dose of drug. CD4(+) T-cell counts and plasma viral load were analyzed before and after the initiation of LPV/r. RESULTS: MDR1 1236T, MDR1 3435T and PXR 63396T alleles showed a frequency of ~50% while the MDR1 -129C allele only reached 5%. Children heterozygotes 1236CT showed a significantly lower LPV Cpost-dose than homozygotes 1236TT (median Cpost-dose=3.04 µg/ml and 6.50 µg/ml, respectively; p=0.016). Children heterozygotes 1236CT also had a lower decrease of viral load after 36 weeks of LPV/r exposure compared with homozygotes 1236CC (median viral load changes=-0.50 log 10 copies/ml and -2.08 log 10 copies/ml, respectively; p=0.047). No effect on the immunological response was observed for polymorphisms of MDR1 or PXR. CONCLUSIONS: Our results suggest that the MDR1 C1236T SNP significantly reduces LPV plasma concentration affecting the virological response to HAART. Heterozygotes 1236CT might have an altered level of P-gp expression/activity in enterocytes and CD4(+) T lymphocytes that limits the absorption of LPV leading to an impaired virological suppression.

Ocular and systemic toxicity of intravitreal topotecan in rabbits for potential treatment of retinoblastoma.

Treatment of intraocular retinoblastoma with vitreous seeding is a challenge. Different routes of chemotherapy administration have been explored in order to attaining pharmacological concentrations into the posterior chamber. Intravitreal drug injection is a promissing route for maximum bioavailability to the vitreous but it requires a well defined dose for achieving tumor control while limited toxicity to the retina. Topotecan proved to be a promising agent for retinoblastoma treatment due to its pharmacological activity and limited toxicity. High and prolonged concentrations were achieved in the rabbit vitreous after 5 µg of intravitreal topotecan. However, whether a lower dose could achieve potentially therapeutic levels remained to be determined. Thus, we here study the pharmacokinetics of topotecan after 0.5 µg and the toxicity profile of intravitreal topotecan in the rabbit eye as a potential treatment of retinoblastoma. A cohort of rabbits was used to study topotecan disposition in the vitreous after a single dose of 0.5 µg of intravitreal topotecan. In addition, an independent cohort of non-tumor bearing rabbits was employed to evaluate the clinical and retinal toxicity after four weekly injections of two different doses of intravitreal topotecan (Group A, 5 µg/dose; Group B, 0.5 µg/dose) to the right eye of each animal. The same volume (0.1 ml) of normal saline was administered to the left eye as control. A third group of rabbits (Group C) served as double control (both eyes injected with normal saline). Animals were weekly evaluated for clinical and hematologic values and ocular evaluations were performed with an inverse ophthalmoscope to establish potential topotecan toxicity. Weekly controls included topotecan quantitation in plasma of all rabbits. Electroretinograms (ERGs) were recorded before and after topotecan doses. One week after the last injection, topotecan concentrations were measured in vitreous of all eyes and samples for retinal histology were obtained. Our results indicate that topotecan shows non linear pharmacokinetics after a single intravitreal dose in the range of 0.5-5 µg in the rabbit. Vitreous concentration of lactone topotecan was close to the concentration assumed to be therapeutically active after 5 h of 0.5 µg intravitreal administration. Eyes injected with four weekly doses of topotecan (0.5 or 5 µg/dose) showed no significant differences in their ERG wave amplitudes and implicit times in comparison with control (p > 0.05). Animals showed no weight, hair loss or significant changes in hematologic values during the study period. There were no significant histologic damage of the retinas exposed to topotecan treatments. After intravitreal administration no topotecan could be detected in plasma during the follow-up period nor in the vitreous of treated and control animals after 1 week of the last injection. The present data shows that four weekly intravitreal injection of 5 µg of topotecan is safe for the rabbit eye. Despite multiple injections of 0.5 µg of topotecan are also safe to the rabbit eye, lactone topotecan vitreous concentrations were potentially active only after 5 h of the administration. We postulate promising translation to clinics for retinoblastoma treatment.

Pharmacokinetic analysis of melphalan after superselective ophthalmic artery infusion in preclinical models and retinoblastoma patients.

PURPOSE: To characterize melphalan pharmacokinetics after superselective ophthalmic artery infusion (SSOAI) in animals and children with retinoblastoma. METHODS: Vitreous and plasma samples of five Landrace pigs were obtained over a 4-hour period after SSOAI of melphalan (7 mg). Melphalan cytotoxicity was evaluated in retinoblastoma cell lines with and without topotecan. Plasma samples were obtained from 17 retinoblastoma patients after SSOAI of 3 to 6 mg of melphalan to one (n=14) or two eyes (n=3). Correlation between plasma pharmacokinetics and age, dosage, and systemic toxicity was studied in patients. RESULTS: In animals, melphalan peak vitreous levels were greater than its IC50 and resulted in 3-fold vitreous-to-plasma exposure. In patients, a large variability in pharmacokinetic parameters was observed and it was explained mainly by body weight (P<0.05). A significantly higher systemic area under the curve was obtained in children receiving more than 0.48 mg/kg for bilateral tandem infusions (P<0.05). These children had 50% probability of grades 3-4 neutropenia. Plasma concentrations after 2 and 4 hours of SSOAI were significantly higher in these children (P<0.05). A synergistic cytotoxic effect of melphalan and topotecan was evident in cell lines. CONCLUSIONS: Potentially active levels of melphalan after SSOAI were achieved in the vitreous of animals. Low systemic exposure was found in animals and children. Doses greater than 0.48 mg/kg, given for bilateral tandem infusions, were associated with significantly higher plasma levels and increased risk of neutropenia. Synergistic in vitro cytotoxicity between melphalan and topotecan favors combination treatment.

Pharmacokinetic analysis of topotecan after superselective ophthalmic artery infusion and periocular administration in a porcine model.

PURPOSE: To characterize the vitreous and plasma pharmacokinetics of topotecan after ophthalmic artery infusion (OAI) subsequent to superselective artery catheterization and to compare it with periocular injection (POI). METHODS: The ophthalmic artery of 4 pigs was catheterized and 1 mg of topotecan infused over a period of 30 minutes. The contralateral eye was subsequently used for administering topotecan by POI. Serial vitreous specimens were obtained by microdialysis and plasma samples collected and assayed for total and lactone topotecan. RESULTS: Maximum total topotecan concentration in the vitreous (median, range) was significantly higher after OAI compared with POI (131.8 ng/mL [112.9-138.7] vs. 13.6 ng/mL [5.5-15.3], respectively; P < 0.005). Median vitreous exposure calculated as area under the curve for total topotecan attained after OAI was significantly higher than after POI (299.8 ng·hour/mL [247.6-347.2] and 48.9 ng·hour/mL [11.8-63.4], respectively; P < 0.05). The vitreous to plasma exposure ratio was 29 after OAI and 3.4 after POI. Systemic exposure for total topotecan was low after both modalities of administration, with a trend to be lower after OAI compared with POI (10.6 ng·hour/mL [6.8-13.4] vs. 18.7 ng·hour/mL [6.3-21.7]; P = 0.54). CONCLUSION: Superselective OAI resulted in significantly higher vitreous concentrations and exposure and a trend toward lower systemic exposure than POI.

Genotyping non-small cell lung cancer (NSCLC) in Latin America.

INTRODUCTION: Frequency of mutations in EGFR and KRAS in non-small cell lung cancer (NSCLC) is different between ethnic groups; however, there is no information in Latin-American population. METHODS: A total of 1150 biopsies of NSCLC patients from Latin America (Argentina, Colombia, Peru, and Mexico) were used extracting genomic DNA to perform direct sequencing of EGFR gene (exons 18 and 21) and KRAS gene in 650 samples. In Mexico, Scorpions ARMS was also used to obtain a genetic profile. RESULTS: We report the frequency of mutations in EGFR and KRAS genes in four Latin-American countries (n = 1150). Frequency of EGFR mutations in NSCLC was 33.2% (95% confidence interval [CI] 30.5-35.9) (Argentina 19.3%, Colombia 24.8%, Mexico 31.2%, and Peru 67%). The frequency of KRAS mutations was 16.6% (95% CI 13.8-19.4). EGFR mutations were independently associated with adenocarcinoma histology, older age, nonsmokers, and absence of KRAS mutations. Overall response rate to tyrosine kinase inhibitors in EGFR-mutated patients (n = 56) was 62.5% (95% CI 50-75) with a median overall survival of 16.5 months (95% CI 12.4-20.6). CONCLUSIONS: Our findings suggest that the frequency of EGFR mutations in Latin America lies between that of Asian and Caucasian populations and therefore support the genetic heterogeneity of NSCLC around the world.