Clinical presentation of retinoblastoma in a middle-income country.

The presenting features of retinoblastoma in developing countries and their correlation with disease stage and patient survival are poorly known and they may be useful as background information for planning early diagnosis initiatives. Therefore, we undertook a retrospective review of 508 patients (467 evaluable, 296 unilateral) treated in Argentina from 1988 to 2008. Patients presented at an older age than reported from high-income countries [mean age 24 mo (range, 0 to 165 mo), 31 mo for unilateral (range, 0 to 165 mo), and 13.3 mo (range, 0 to 62 mo) for bilateral disease]. Leukocoria was the most common presenting sign (n=402, 86%). Strabismus was the only complaint in 25 (5.3%) patients. Forty-two patients (9%) presented with an enlarged eyeball and 37 (7.9%) with a red eye. Retinoblastoma was diagnosed in 22 (4.7%) asymptomatic children. These patients and those with strabismus alone were significantly younger and had a significantly better survival. Children presenting with enlarged eyeballs were significantly older and had significantly lower survival. In multivariable analysis older age and presentation with enlarged eyeballs were independently associated to advanced stage and mortality (P<0.001). Retinoblastoma is diagnosed in later stages in our setting and presentation with eye enlargement and increasing age at diagnosis correlate with worse outcome.

Pharmacokinetic analysis of topotecan after intra-vitreal injection. Implications for retinoblastoma treatment.

Topotecan is a promising drug with activity against retinoblastoma, however, attaining therapeutic concentrations in the vitreous humor is still a challenge for the treatment of vitreous seeds in retinoblastoma. Our aim was to characterize topotecan pharmacokinetics in vitreous and aqueous humor, and to assess the systemic exposure after intra-vitreal injection in rabbits as an alternative route for maximizing local drug exposure. Anesthetized rabbits were administered intra-vitreal injections of 5 microg of topotecan. Vitreous, aqueous, and blood samples were collected at pre-defined time points. A validated high-performance liquid chromatography assay was used to quantitate topotecan (lactone and carboxylate) concentrations. Topotecan pharmacokinetic parameters were determined in vitreous, aqueous and plasma using a compartmental analysis. Topotecan lactone concentrations in the vitreous of the injected eye were about 8 ng/mL 48 h after drug administration. The median maximum vitreous, aqueous and plasma total topotecan concentrations (C(max)) were 5.3, 0.68 and 0.21 microg/mL, respectively. The C(max) vitreous/aqueous of treated eyes and the C(max) vitreous/plasma were approximately 8 and 254, respectively. Total topotecan exposure (AUC) in the vitreous of the injected eye was 50 times greater than the total systemic exposure. These findings suggest that intra-vitreal administration of only 5 microg of topotecan reaches significant local levels over an extended period of time while minimizing systemic exposure in the rabbit. Intra-vitreal topotecan administration offers a promising alternative route for enhanced drug exposure in the vitreous humor with potential application for treatment of vitreal seeds in retinoblastoma while avoiding systemic toxicities.