Two-year overall survival (OS) is not reduced by omitting chemotherapy from the first-line treatment of patients with HER2-positive metastatic breast cancer (MBC) who receive dual anti-HER2 therapy followed by trastuzumab emtansine (T-DM1). That is the finding of a study presented at the inaugural ESMO Breast Cancer congress last week in Germany.
The phase 2 PERNETTA trial randomly allocated 210 patients with HER2+ MBC to receive either pertuzumab (P) plus trastuzumab (T) alone (arm A) or P+T combined with weekly paclitaxel or vinorelbine (arm B), followed by maintenance treatment with P+T until progression. After progression, T-DM1 was given as a second-line therapy in both arms.
Progression-free survival (PFS) after the first-line therapy was 8.4 months with antibodies alone and 23.3 months with antibodies plus chemotherapy. However, OS at two years was similar in both treatment arms, both 76.2 per cent.
Side effects were less frequently seen in the chemotherapy-free arm, although the quality of life (QoL) was similar during first-line in both arms.
In the first-line setting, changes from baseline showed small improvements in QoL (NFBSI-16 summary scores) in arm A, while QoL scores remained stable in arm B. Patients in arm B reported more treatment burden during the first six months but not thereafter.