Pilot study of immunotherapy with interleukin-2 after autologous stem cell transplantation in advanced breast cancers

Median survival for advanced breast cancer does not exceed 2 years. Immunotherapy following Hihg Dose Chemotherapy (HDC) and autologous stem cell transplantation (ASCT) is a procedure that could hypothetically decrease relapse rate. The mechanism implicated is induction of immune modulation and a possible Graft Versus Tumor effect (GVHT). Tolerance and feasibility of rIL-2 administered after HDC with ASCT was analyzed in twenty one advanced breast cancer patients. The patients were treated either with intra-venous high-dose rIL-2 (9 patients) or subcutaneous low dose (12 patients). With intra-venous high-dose rIL-2, 50% of the scheduled dose was administered and 100% of the scheduled dose was administered at a lower dose in the subcutaneous route. rIL-2 was administered safely after HDC and ASCT, particularly in the subcutaneous low dose arm. However no clinical beneficial effect was documented for these advanced heavily pretreated breast cancers. Immune modulation with rIL-2 earlier requires further investigation.