Chemo-free anti-ERBB2 therapy viable in ERBB2-positive MBC

In the treatment of ERBB2-positive metastatic breast cancer (MBC), the use of pertuzumab plus trastuzumab alone in the first-line setting and delaying chemotherapy may be a reasonable option for some patients, with the treatment strategy not compromising overall survival (OS) despite a much shorter progression-free survival (PFS), as shown in a study.

For the study, researchers conducted a secondary analysis of a multicentre, open-label, phase II trial, wherein patients with MBC were randomly assigned to receive first-line pertuzumab (840 mg intravenously [IV], then 420 mg IV every 3 weeks) plus trastuzumab (8 mg/kg IV, then 6 mg/kg IV every 3 weeks) alone (group A) or with chemotherapy (group B) followed by trastuzumab and emtansine at progression.

The chemotherapy used in group B was either paclitaxel (90 mg/m² for days 1, 8, and 15, then every 4 weeks for ≥4 months) or vinorelbine tartrate (25 mg/m² for first administration, followed by 30 mg/m² on days 1 and 8 and every 3 weeks for ≥4 months).

The current analysis included 210 patients (median age 58 years) with centrally confirmed ERBB2-positive MBC. At 24 months, OS rates did not significantly differ between groups A and B (79.0 percent, 90 percent confidence interval [CI], 71.4–85.4 vs 78.1 percent, 90 percent CI, 70.4–84.5, respectively).

However, the median PFS was significantly shorter in group A with only 8.4 months relative to 23.3 months in group B.

Of note, OS and PFS showed no significant difference between populations with ERBB2-enriched and ERBB2-nonenriched cancer.

In terms of safety, adverse events were less frequent in group A, with quality of life improving slightly from baseline in group A and remaining stable in group B.