Subcutaneous delivery of nanoconjugated doxorubicin and cisplatin for locally advanced breast cancer demonstrates improved efficacy and decreased toxicity at lower doses than standard systemic combination therapy in vivo.

BACKGROUND

Combination cytotoxic agents in breast cancer carry dose-limiting toxicities. The aim of this study was to test the hypothesis that nanocarrier-conjugated doxorubicin and cisplatin would have improved tumor efficacy with decreased systemic toxicity over standard drugs, even at lower doses.

METHODS

Female Nu/Nu mice were injected in the breast with human MDA-MB-468LN cells and treated with either standard or nanocarrier-conjugated combination therapy (doxorubicin plus cisplatin) at 50% or 75% maximum tolerated dose (MTD) and monitored for efficacy and toxicity over 12 weeks.

RESULTS

Efficacy results for mice treated with hyaluronan-conjugated doxorubicin and cisplatin at 50% MTD were as follows: 5 complete responses, 2 partial responses, and 1 case of stable disease. For hyaluronan-conjugated doxorubicin and cisplatin at 75% MTD, efficacy results were as follows: 7 complete responses, 1 partial response. All complete responses were confirmed histologically. In comparison, mice given standard doxorubicin and cisplatin at 50% MTD demonstrated progressive disease in 6, stable disease in 1, and partial response in 1. For standard doxorubicin and cisplatin at 75% MTD, there were 5 cases of progressive disease and 3 of stable disease (P < .0001 on multivariate analysis of variance). At 75% MTD, standard drug-treated mice had significant weight loss compared to nanocarrier drug-treated mice (P < .001).

CONCLUSIONS

Subcutaneous nanocarrier delivery of doxorubicin and cisplatin demonstrated significantly improved efficacy with decreased toxicity compared with standard agent combination therapy at all doses tested, achieving complete pathologic tumor response.