In Vivo Antitumour Effect of Combretastatin A-4 Phosphate Added to Fractionated Irradiation

Background: The study aimed at evaluating the potential benefit from a combination of fractionated ionising radiation with the vascular-targeting compound combretastatin A-4 phosphate (CA-4-P). Materials and Methods: Syngenic rat rhabdomyosarcoma (R1), growing subcutaneously, was treated at 2 different sizes: either small (2±0.5 cm 3 ) or large (10.94±0.6 cm 3 ). Localised fractionated irradiation of the tumours (5 x 3 Gy) in 5 days was followed 1 day later by an intraperitoneal CA-4-P treatment (25 mg/kg). Results: The combined treatment of only large tumours resulted in a small additional growth delay when compared with radiotherapy only. Conclusion: The present data indicate a size-dependent increase in tumour growth delay from combining fractionated irradiation with CA-4-P.