Combined Treatment of Metastatic Breast Cancer (MBC) by High-dose Chemotherapy (HDCT) and Bispecific Antibodies: A Pilot Study

Abstract

This pilot study analyzed the efficacy and toxicity of high-dose chemotherapy (HDCT), autologous stem-cell transplantation (ASCT) and subsequent immunotherapy with T-cell reinfusion and trifunctional antibodies (trAbs) in chemotherapy-sensitive patients with metastatic breast cancer (MBC). Patients and Methods: After leukapheresis and cryopreservation of T-cells, patients received 2 cycles of induction chemotherapy ET (epirubicin/paclitaxel) and 1 cycle of EI (epirubicin/ifosfamide), followed by G-CSF and stem-cell harvest. After a final cycle of ET, responders (CR/PR) underwent HDCT (thiotepa 600 mg/m²/melphalan 140-180 mg/m²) and ASCT. Once reconstitution was achieved, T-cells were reinfused, followed by application of trifunctional antibodies with specificities anti-EpCAM X anti-CD3 and anti-Her2/neu X anti-CD3. Results: Thirty-three patients were recruited into the study and 19, who had responded to initial chemotherapy, underwent HDCT and ASCT (4 CR, 15 PR, OR=57.6%; 95%CI: 40-75%). Two early deaths were observed (1 toxic, 1 early progression). T-cell reinfusion and trAbs were given to 17 patients. TrAbs treatment resulted in intermittent fever, chills and elevated liver enzymes, which were seen in all patients. The median overall survival was 27.7 months (range: 5.9-82.6+). Patients who received 3 trAbs doses showed a trend towards an improved overall survival (47.2 vs. 22.4 months, p=0.08 log rank). Conclusion: This pilot study has shown the feasibility of combining HDCT with immunotherapy in MBC. Further investigation of this approach is indicated.