Effects on Walker 256 tumour of carmustine associated with a cholesterol-rich microemulsion (LDE)

A cholesterol-rich microemulsion that binds to low-density lipoprotein (LDL) receptors (LDE), after injection into the bloodstream, concentrates in neoplastic tissues that over-express those receptors. LDE can thus serve as a vehicle for drug targeting. It was shown that carmustine side effects are pronouncedly reduced when the drug is associated with LDE in cancer patients. In this study, the therapeutic action of LDE associated with carmustine was compared with that of the non-associated drug in rats implanted with Walker 256 tumour. The toxicity and anti-tumour activity in rats treated with either free carmustine or carmustine associated with LDE and in control rats treated with saline solution were determined after a single intraperitoneal injection. The LD90 (90% lethal dose) of LDE-carmustine was 77 mg kg(-1) and of free carmustine was 44 mg kg(-1), indicating that LDE decreases toxicity. LDE-carmustine was able to decrease tumour mass at a lower dose level than free carmustine. Tumour regression time was shorter in LDE-carmustine- than in free carmustine-treated animals. Therefore, this study shows that the association of carmustine with LDE increases the therapeutic index of carmustine.