Background: Retinoblastoma is the most common primary malignant intraocular neoplasm of childhood. The poor outcomes of patients with metastatic retinoblastoma have encouraged the search for new therapies. In the current study, the efficacy of combination therapy with calcitriol and cisplatin in athymic mice with subcutaneous Y-79 human retinoblastoma tumors was assessed.
Methods: 60 athymic mice were subcutaneously injected with human Y79 retinoblastoma cells. Animals were randomized into four groups: group 1 - 50 µg of cisplatin; group 2 - 0.05 µg of calcitriol; group 3 - 0.05µg of calcitriol and 50 µg of cisplatin; group 4 - control.The cisplatin was administered once a week, and the calcitriol was given 5 times a week.
Results: There was a significant inhibition of tumor growth in animals treated with the combination therapy of calcitriol and cisplatin as compared to controls and cisplatin alone (p=0.0001 and p=0.0041 respectively). In terms of toxicity, serum calcium levels were increased, but there was no mortality and minimal nephrotoxicity in any of the groups.
Conclusion: The present study shows that cisplatin given in combination with calcitriol may be a viable multidrug therapy option in the treatment of high risk retinoblastoma.