Activity of Indatuximab Ravtansine against Triple-Negative Breast Cancer in Preclinical Tumor Models

PURPOSE: Triple-negative breast cancer (TNBC) is related with a poor prognosis as patients do hardly benefit from approved therapies. CD138 (Syndecan-1) is upregulated on human breast cancers. Indatuximab ravtansine (BT062) is an antibody-drug-conjugate that specifically targets CD138-expressing cells and has previously shown clinical activity in multiple myeloma. Here we show indatuximab ravtansine as a potential mono- and combination therapy for TNBC. METHODS: The effects of indatuximab ravtansine were assessed in vitro in SK-BR-3 and T47D breast cancer cell lines. The in vivo effects of indatuximab ravtansine alone and in combination with docetaxel or paclitaxel were assessed in MAXF401, MAXF1384 and MAXF1322 xenograft TNBC models. RESULTS: CD138(+) SK-BR-3 and T47D cells were highly sensitive to indatuximab ravtansine. The high CD138-expressing MAXF401 xenograft model demonstrated strong inhibition of tumor growth with 4 mg/kg indatuximab ravtansine. High doses of indatuximab ravtansine (8 mg/kg), docetaxel and the combination of both led to complete remission. In the low CD138-expressing MAXF1384 xenograft model, only combination of indatuximab ravtansine and docetaxel demonstrated a significant efficacy. In the MAXF1322 xenograft model, indatuximab ravtansine alone and in combination with paclitaxel elicited complete remission. CONCLUSIONS: These data demonstrate potential use of indatuximab ravtansine in combination with docetaxel or paclitaxel for CD138-positive TNBC.