Ocular topotecan pharmacokinetics following topical administration to rabbits for diffused anterior retinoblastoma.

OBJECTIVES: We characterized and compared the in-vivo absorption of topotecan into the aqueous humor after instillation of aqueous and ointment formulations. METHODS: A lanolin/petrolatum ointment was used. New Zealand rabbits were instilled with topotecan solution (6 µg, group A), a single 10 µg dose of topotecan ointment (group B) or with five 10 µg doses of topotecan ointment (group C). Aqueous humor samples were collected at different times. Corneal samples were collected only for group A. Topotecan was quantified using HPLC, and pharmacokinetic parameters were calculated. Acute corneal epithelial toxicity was assessed after multiple instillations of topotecan ointment. KEY FINDINGS: Total topotecan maximum aqueous humor concentration (Cmax ) was 16.1, 69.9 and 287 ng/ml in group A, B and C, respectively. A single dose of topotecan ointment increased threefold and sevenfold the aqueous humor Cmax , and exposure compared to the aqueous formulation. Aqueous humor concentrations from group C eyes were substantially above the cytotoxic concentration for retinoblastoma cells. No corneal toxicity was evident after ointment instillation. CONCLUSIONS: Topotecan penetrated into the aqueous humor of the rabbit eye after multiple doses of an ointment in concentrations pharmacologically active against retinoblastoma cells without eliciting acute toxicity. Topotecan ointment may translate to the clinical treatment of anterior segment disseminated retinoblastoma.

[Current status and regulation of bioanalytical laboratories engaged in quantifying immunosuppressants for transplant patients in Argentina]. / Estado de situación y regulación de laboratorios bioanalíticos que cuantifican inmunosupresores para trasplantes en Argentina.

Objective Determine the status of analytical laboratories that quantify immunosuppressants in transplant patients who are under therapeutic drug monitoring (TDM) for these drugs in Argentina in order to identify potential perfectible areas for action. Methods A survey of the clinical and analytical TDM centers in Argentina was conducted between September 2013 and November 2014 under the direction of the Garrahan Hospital Clinical Pharmacokinetics Unit and the National Unified Central Institute for Ablation and Implant Coordination. Results A nationally representative sample of 27 clinical and analytical centers was identified, of which 45% were public hospitals. Most of these centers (95%) monitor ciclosporin and tacrolimus, and to a lesser extent, sirolimus and everolimus; a small number of them also monitor mycophenolic acid. The median number of samples of these five drugs analyzed per month was 251 (range: 10-2024). Nearly 60% of the samples were analyzed in private institutions. Only four of the respondents (17%) reported values within the therapeutic margin. Of all the centers, 92% use immunoassay as the analytical methodology. Of the bioanalytical installations that have their own facilities, 68% reported that they also have their own quality assurance program. Conclusions TDM of immunosuppressants is a recommended practice for transplant patients in Argentina. Initiatives need to be taken at the national level to develop uniform guidelines for analytical laboratories that include TDM-related quality assurance processes with regulatory force. There is also a need to train technical and professional personnel and to invite the participation of public and private organizations in the regulatory, public health, and research areas.

Sustained-release hydrogels of topotecan for retinoblastoma.

Treatment of retinoblastoma, the most common primary ocular malignancy in children, has greatly improved over the last decade. Still, new devices for chemotherapy are needed to achieve better tumor control. The aim of this project was to develop an ocular drug delivery system for topotecan (TPT) loaded in biocompatible hydrogels of poly(ε-caprolactone)-poly(ethyleneglycol)-poly(ε-caprolactone) block copolymers (PCL-PEG-PCL) for sustained TPT release in the vitreous humor. Hydrogels were prepared from TPT and synthesized PCL-PEG-PCL copolymers. Rheological properties and in vitro and in vivo TPT release were studied. Hydrogel cytotoxicity was evaluated in retinoblastoma cells as a surrogate for efficacy and TPT vitreous pharmacokinetics and systemic as well as ocular toxicity were evaluated in rabbits. The pseudoplastic behavior of the hydrogels makes them suitable for intraocular administration. In vitro release profiles showed a sustained release of TPT from PCL-PEG-PCL up to 7days and drug loading did not affect the release pattern. Blank hydrogels did not affect retinoblastoma cell viability but 0.4% (w/w) TPT-loaded hydrogel was highly cytotoxic for at least 7days. After intravitreal injection, TPT vitreous concentrations were sustained above the pharmacologically active concentration. One month after injection, animals with blank or TPT-loaded hydrogels showed no systemic toxicity or retinal impairment on fundus examination, electroretinographic, and histopathological assessments. These novel TPT-hydrogels can deliver sustained concentrations of active drug into the vitreous with excellent biocompatibility in vivo and pronounced cytotoxic activity in retinoblastoma cells and may become an additional strategy for intraocular retinoblastoma treatment.

Topotecan Delivery to the Optic Nerve after Ophthalmic Artery Chemosurgery.

Extraocular retinoblastoma is a major challenge worldwide, especially in developing countries. Current treatment involves the administration of systemic chemotherapy combined with radiation, but there is a clear need for improvement of chemotherapy bioavailability in the optic nerve. Our aim was to study the ophthalmic artery chemosurgery (OAC) local route for drug delivery assessing ocular and optic nerve exposure to chemotherapy and to compare it to exposure after intravenous infusion (IV) of the same dose in an animal model. Topotecan was used as a prototype drug that is active in retinoblastoma and based on the extensive knowledge of its pharmacokinetics in preclinical and clinical settings. Five Landrace pigs received 4mg of topotecan via OAC as performed in retinoblastoma patients. At the end of the infusion, the eyes were enucleated, the optic nerve and retina were dissected, and the vitreous and plasma were separated. After recovery and a wash-out period, the animals received a 30-min IV infusion of topotecan (4 mg). The remaining eye was enucleated and tissues and fluids were separated. All samples were stored until quantitation using HPLC. A significantly higher concentration of topotecan in the optic nerve, vitreous, and retina was obtained in eyes after OAC compared to IV infusion (p<0.05). The median (range) ratio between topotecan concentration attained after OAC to IV infusion in the optic nerve, retina and vitreous was 84(54-668), 143(49-200) and 246(56-687), respectively. However, topotecan systemic exposure after OAC and IV infusion remained comparable (p>0.05). The median optic nerve-to-plasma ratio after OAC and IV was 44 and 0.35, respectively. Topotecan OAC delivery attained an 80-fold higher concentration in the optic nerve compared to the systemic infusion of the same dose with similar plasma concentrations in a swine model. Patients with retinoblastoma extension into the optic nerve may benefit from OAC for tumor burden by increased chemotherapy bioavailability in the optic nerve without increasing systemic exposure or toxicity.

Estado de situación y regulación de laboratorios bioanalíticos que cuantifican inmunosupresores para trasplantes en Argentina / Current status and regulation of bioanalytical laboratories engaged in quantifying immunosuppressants for transplant patients in Argentina

Objetivo. Establecer el estado de situación de los laboratorios analíticos que cuantifican inmunosupresores en pacientes con trasplantes que se encuentran bajo monitoreo terapéutico de drogas (TDM) de estos fármacos en Argentina, para establecer potenciales áreas de actuación perfectibles. Métodos. Se realizó una encuesta en centros clínicos y analíticos de TDM de Argentina, coordinada por la Unidad de Farmacocinética Clínica del Hospital Garrahan y el Instituto Nacional Central Único Coordinador de Ablación e Implante, desde setiembre de 2013 hasta noviembre de 2014. Resultados. Se incluyeron 27 centros clínicos y analíticos (muestra representativa nacional). El 45% fueron hospitales públicos. La mayoría (95%) monitorizan ciclosporina y tacrolimús; en menor medida, sirolimús y everolimús, y muy pocos el ácido micofenólico. La cantidad (mediana, rango) de muestras analizadas por mes para estos cinco fármacos fue de 251 (10 - 2024). Casi 60% de las muestras se analizaron en instituciones privadas. Solo cuatro (17%) de los encuestados informan valores del margen terapéutico. El 92% usa inmunoensayos como metodología analítica. El 68% de los encuestados que contaban con instalaciones bioanalíticas propias informaron poseer algún programa de garantía de calidad. Conclusiones. El TDM de inmunosupresores es una práctica recomendada para pacientes con trasplante en Argentina. Se requiere generar iniciativas nacionales que desarrollen guías armonizadas para laboratorios analíticos que incluyan procesos de garantía de calidad con alcance regulatorio relacionados con el TDM. Por otra parte, también es necesario capacitar al personal técnico y profesional, e invitar a participar a organizaciones públicas y privadas del ámbito regulatorio, sanitario y de la investigación.

Objective. Determine the status of analytical laboratories that quantify immunosuppressants in transplant patients who are under therapeutic drug monitoring (TDM) for these drugs in Argentina in order to identify potential perfectible areas for action. Methods. A survey of the clinical and analytical TDM centers in Argentina was conducted between September 2013 and November 2014 under the direction of the Garrahan Hospital Clinical Pharmacokinetics Unit and the National Unified Central Institute for Ablation and Implant Coordination. Results. A nationally representative sample of 27 clinical and analytical centers was identified, of which 45% were public hospitals. Most of these centers (95%) monitor ciclosporin and tacrolimus, and to a lesser extent, sirolimus and everolimus; a small number of them also monitor mycophenolic acid. The median number of samples of these five drugs analyzed per month was 251 (range: 10-2024). Nearly 60% of the samples were analyzed in private institutions. Only four of the respondents (17%) reported values within the therapeutic margin. Of all the centers, 92% use immunoassay as the analytical methodology. Of the bioanalytical installations that have their own facilities, 68% reported that they also have their own quality assurance program. Conclusions. TDM of immunosuppressants is a recommended practice for transplant patients in Argentina. Initiatives need to be taken at the national level to develop uniform guidelines for analytical laboratories that include TDM-related quality assurance processes with regulatory force. There is also a need to train technical and professional personnel and to invite the participation of public and private organizations in the regulatory, public health, and research areas.

Estado de situación y regulación de laboratorios bioanalíticos que cuantifican inmunosupresores para trasplantes en Argentina / Current status and regulation of bioanalytical laboratories engaged in quantifying immunosuppressants for transplant patients in Argentina

RESUMEN Objetivo Establecer el estado de situación de los laboratorios analíticos que cuantifican inmunosupresores en pacientes con trasplantes que se encuentran bajo monitoreo terapéutico de drogas (TDM) de estos fármacos en Argentina, para establecer potenciales áreas de actuación perfectibles. Métodos Se realizó una encuesta en centros clínicos y analíticos de TDM de Argentina, coordinada por la Unidad de Farmacocinética Clínica del Hospital Garrahan y el Instituto Nacional Central Único Coordinador de Ablación e Implante, desde setiembre de 2013 hasta noviembre de 2014. Resultados Se incluyeron 27 centros clínicos y analíticos (muestra representativa nacional). El 45% fueron hospitales públicos. La mayoría (95%) monitorizan ciclosporina y tacrolimús; en menor medida, sirolimús y everolimús, y muy pocos el ácido micofenólico. La cantidad (mediana, rango) de muestras analizadas por mes para estos cinco fármacos fue de 251 (10 - 2024). Casi 60% de las muestras se analizaron en instituciones privadas. Solo cuatro (17%) de los encuestados informan valores del margen terapéutico. El 92% usa inmunoensayos como metodología analítica. El 68% de los encuestados que contaban con instalaciones bioanalíticas propias informaron poseer algún programa de garantía de calidad. Conclusiones El TDM de inmunosupresores es una práctica recomendada para pacientes con trasplante en Argentina. Se requiere generar iniciativas nacionales que desarrollen guías armonizadas para laboratorios analíticos que incluyan procesos de garantía de calidad con alcance regulatorio relacionados con el TDM. Por otra parte, también es necesario capacitar al personal técnico y profesional, e invitar a participar a organizaciones públicas y privadas del ámbito regulatorio, sanitario y de la investigación.

ABSTRACT Objective Determine the status of analytical laboratories that quantify immunosuppressants in transplant patients who are under therapeutic drug monitoring (TDM) for these drugs in Argentina in order to identify potential perfectible areas for action. Methods A survey of the clinical and analytical TDM centers in Argentina was conducted between September 2013 and November 2014 under the direction of the Garrahan Hospital Clinical Pharmacokinetics Unit and the National Unified Central Institute for Ablation and Implant Coordination. Results A nationally representative sample of 27 clinical and analytical centers was identified, of which 45% were public hospitals. Most of these centers (95%) monitor ciclosporin and tacrolimus, and to a lesser extent, sirolimus and everolimus; a small number of them also monitor mycophenolic acid. The median number of samples of these five drugs analyzed per month was 251 (range: 10-2024). Nearly 60% of the samples were analyzed in private institutions. Only four of the respondents (17%) reported values within the therapeutic margin. Of all the centers, 92% use immunoassay as the analytical methodology. Of the bioanalytical installations that have their own facilities, 68% reported that they also have their own quality assurance program. Conclusions TDM of immunosuppressants is a recommended practice for transplant patients in Argentina. Initiatives need to be taken at the national level to develop uniform guidelines for analytical laboratories that include TDM-related quality assurance processes with regulatory force. There is also a need to train technical and professional personnel and to invite the participation of public and private organizations in the regulatory, public health, and research areas.

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.

Clinical pharmacokinetics of intra-arterial melphalan and topotecan combination in patients with retinoblastoma.

PURPOSE: To assess the antitumor activity, toxicity, and plasma pharmacokinetics of the combination of melphalan and topotecan for superselective ophthalmic artery infusion (SSOAI) treatment of children with retinoblastoma. DESIGN: Single-center, prospective, clinical pharmacokinetic study. PARTICIPANTS: Twenty-six patients (27 eyes) with intraocular retinoblastoma. METHODS: Patients with an indication for SSOAI received melphalan (3-6 mg) and topotecan (0.5-1 mg; doses calculated by age and weight). Plasma samples were obtained for pharmacokinetic studies, and a population approach via nonlinear mixed effects modeling was used. Safety and efficacy were assessed and compared with historical cohorts of patients treated with melphalan single-agent SSOAI. MAIN OUTCOME MEASURES: Melphalan and topotecan pharmacokinetic parameters and efficacy and safety parameters. RESULTS: Twenty-seven eyes from 26 consecutive patients received 66 cycles of SSOAI melphalan and topotecan in combination. All 5 eyes treated as primary therapy responded to the combination chemotherapy and were preserved. Sixteen of the 22 eyes with relapsed or resistant tumors responded, but 3 of them ultimately underwent enucleation at a median of 8 months (range, 7.9-9.1 months). The incidence of grade III and IV neutropenia was 10.6% and 1.5%, respectively, which was comparable with historical controls of single-agent SSOAI melphalan. No episode of fever neutropenia was observed, and no patient required transfusion of blood products. The large variability in melphalan pharmacokinetics was explained by body weight (P <0.05). Concomitant topotecan administration did not influence melphalan pharmacokinetic parameters. There was no effect of the sequence of melphalan and topotecan administration in plasma pharmacokinetics. CONCLUSIONS: A regimen combining melphalan and topotecan for SSOAI treatment of retinoblastoma is active and well tolerated. This combination chemotherapy previously showed synergistic pharmacologic activity, and we herein provide evidence of not increasing the hematologic toxicity compared with single-agent melphalan.

Intra-arterial chemotherapy is more effective than sequential periocular and intravenous chemotherapy as salvage treatment for relapsed retinoblastoma.

BACKGROUND: Treatment of eyes with retinoblastoma failing systemic chemoreduction and external beam radiotherapy is seldom efficacious. This study compares the efficacy and toxicity of intra-arterial ophthalmic artery chemotherapy (IAO) to our historical cohort of sequential periocular and systemic chemotherapy in such patients. PATIENTS AND METHODS: Eighteen eyes (15 consecutive patients) were retrospectively evaluated. Eight eyes received IAO for a median of four cycles (range: 2-9) including melphalan alone (n = 3) or after topotecan and carboplatin (n = 4) or topotecan and carboplatin without melphalan (n = 1). Ten eyes received a median of two cycles (range: 1-3) of periocular topotecan (n = 9) or carboplatin (n = 1) followed by intravenous topotecan and cyclophosphamide in three patients if at least stable disease was achieved. Both groups were comparable for disease extension and prior therapy. RESULTS: No extraocular dissemination or second malignancy occurred and all patients are alive. The probability of enucleation-free eye survival at 12 months was 0.87 (95% CI: 0.42-0.97) for the IAO group, compared to 0.1 (95% CI: 0.06-0.35) for the periocular group (P < 0.01). Ocular toxicity was mild and similar in both groups (mostly mild orbital edema). Systemic toxicity was low for IAO and periocular injection, but children who received sequentially intravenous chemotherapy (n = 12 cycles) had five episodes of grade 4 neutropenia, three of which resulted in hospitalizations. No case in the IAO group presented these complications. CONCLUSIONS: IAO is significantly superior to sequential periocular-intravenous topotecan-containing regimens in eyes with relapsed intraocular retinoblastoma with a more favorable toxicity profile.

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.