medwireNews: Older women with metastatic, HER2-positive breast cancer derive a progression-free survival (PFS) benefit from the addition of metronomic chemotherapy to the anti-HER2 agents pertuzumab and trastuzumab, indicate results from the EORTC 75111-10114 trial.
Median PFS in the phase II study was 12.7 months for the 41 patients (≥70 years or 60–69 years with functional restrictions) who were randomly allocated to receive cyclophosphamide 50 mg/day alongside trastuzumab plus pertuzumab and 5.6 months for their 39 counterparts given just the HER2 inhibitors.
The estimated 6-month PFS rates were 73.4% and 46.2%, respectively, with the between-group difference of 27.2% exceeding the protocol-specified difference threshold of 10.0%.
Grade 3 lymphopenia occurred more often in the chemotherapy than in the dual HER2-blockade group, at 37% versus 3%, but on the whole both regimens had a favorable adverse event profile, which Hans Wildiers (KU Leuven in Belgium) and co-investigators believe is “a major asset” for this population of older and frail patients.
Writing in The Lancet Oncology, they conclude: “The results of this study indicate that the benefit of avoiding the side-effects of chemotherapy with the use of dual anti-HER2 blockade alone does not compensate for the substantial loss of activity in the metastatic breast cancer setting.”
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