Free
taxol and
liposome-encapsulated
taxol were compared for their antitumoral activities on two human
brain tumors serially grafted into female athymic mice in the scapular region. In the first experiment, a human
glioblastoma (15th and 16th passages) was studied. In the second experiment, a fast growing human
gliosarcoma (19th passage) was used. Free
taxol and liposomal
taxol were administered intraperitoneally, at the same dose; 12.5 mg/kg (i.e. 1/15 of the evaluated LD 50 value). In the first experiment, the treatment was performed for four consecutive days, with four courses separated by three rest periods of three days in between. Both free
taxol and encapsulated
taxol produced a statistically significant delay in
tumor growth, and at the end of the experiment some total
tumor regressions were obtained. However,
liposomes were observed to be more effective in their action on the two consecutive passages of the
glioblastoma, giving a marked increase of the number of total
tumor regressions. In the second experiment another schedule of treatment was chosen because of the fast growth pattern of the xenografted human
gliosarcoma: free
taxol and
liposome-encapsulated
taxol were administered for five consecutive days and three courses of treatment were performed with two rest periods of two days. The two forms of
taxol had a significant inhibitory effect on
gliosarcoma tumor growth; as before encapsulation in
liposomes was found to increase the anti-tumoral activity of
taxol, although, in this case no
tumor regression was observed.