The present invention describes the new use in the oncologic field of bioconjugates as differentiating agents obtained by the conjugation between hyaluronic acid (HA) and a chemotherapeutic product (identified hereafter with the trade-name ONCOFID®) among which, in particular, Irinotecan, Doxorubicin, Paclitaxel, Cis-platinum and 5-Fluorouracyl (5-FU) for treating primary tumors and metastasis. In particular, the biological behavior is described in terms of action mechanism, efficacy and tolerability of pharmaceutical preparations of derivative of ONCOFID® soluble in water. More specifically, the invention relates to the surprising biological and pharmacological effect demonstrated by formulations based on ONCOFID-S (HA-SN38 conjugates) and ONCOFID-D (HA-Doxorubicin conjugates) in promoting the differentiation of tumoral cells towards a untransformed phenotype, compared with the reference drug Irinotecan (or CPT11 whose active form is represented by SN38) and Doxorubicin.
