The subject of the invention is a liposomal formulation of doxorubicin and compounds from the group of isothiocyanates, showing increased antitumor properties compared with the properties of the individual components of the composition. The key finding in this approach is that the active agents are encapsulated within lipid nanocarriers, which considerably enhances their antitumor action. To demonstrate the anticancer properties of the formulation, several in vitro studies were conducted. MTT and CVDE cytotoxicity tests were performed on MCF-7 and MDA-MB-231 breast cancer cell lines. It was shown that the concurrent action of the cytostatic agent (doxorubicin) and isothiocyanates reveals considerable synergy as concluded based on a Chou-Talalay analysis. On the other hand, in vitro studies on normal cells (CRL-1790) showed reduced toxicity of the formulation (antagonistic effect).