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Phase 3 Trial of Pertuzumab Retreatment in HER2-Positive, Locally Advanced/Metastatic Breast Cancer Patients Previously Treated with Pertuzumab, Trastuzumab, and Chemotherapy

Conference Correspondent

Few therapeutic options are available for human epidermal growth factor receptor 2 (HER2)-positive locally advanced/metastatic breast cancer patients who had been previously treated with pertuzumab-based regimens. The efficacy of pretreatment combined with trastuzumab plus chemotherapy as third- or fourth-line chemotherapy was analyzed in this patient population by Yutaka Yamamoto of the Kumamoto University, Kumamoto, Japan, and colleagues.

In this study, previously treated patients who had received pertuzumab-containing regimens as first- or second-line therapy for locally advanced/metastatic breast cancer were randomized 1:1 to receive either pertuzumab plus trastuzumab plus chemotherapy based on physician’s choice, and trastuzumab plus chemotherapy.

Progression-free survival was the primary end point. Progression-free survival in patients treated with trastuzumab emtansine as the latest regimen (progression-free survival after trastuzumab emtansine), overall survival, objective response rate, health-related quality of life, and safety were considered secondary end points.

Of the 219 patients enrolled, 217 were included in the study, of which 108 received pertuzumab + trastuzumab + chemotherapy, and 109 received trastuzumab plus chemotherapy.

Progression-free survival and overall survival were 84.8% and 38.7%, correspondingly. The median follow-up time was 14.2 months, with progression-free survival significantly better in the physicians’ choice group (median progression-free survival, 5.3 vs 4.2 months; hazard ratio [HR], 0.755).

After trastuzumab emtansine treatment, median progression-free survival was 5.3 months compared with 4.2 months (HR, 0.801) and overall survival was 28.8 months compared with 23.4 months (HR, 0.713). Further assessment is needed, despite preliminary evidence suggesting that the physicians’ choice group tended to be longer.

There was no appreciable difference detected between groups for the objective response rate in patients with measurable disease, in the physician’s choice group was 18.9% compared with 19.6% in the trastuzumab plus chemotherapy group. The treatment groups were comparable in terms of the rate of serious adverse events and time to deterioration quality-of-life measurement. Finally, no new safety signals were detected.

The investigators concluded that retreatment with pertuzumab as either third- or fourth-line chemotherapy was both effective and reasonable. For patients with HER2-positive locally advanced/metastatic breast cancer who previously received treatment with pertuzumab, retreatment can be considered a standard treatment practice.

Source: Yamamoto Y, Iwata H, Naruto T, et al. A randomized, open-label, phase III trial of pertuzumab re-treatment in HER2-positive, locally advanced/metastatic breast cancer patients previously treated with pertuzumab, trastuzumab, and chemotherapy: the Japan Breast Cancer Research Group-M05 (PRECIOUS) study. Presented at: 2020 San Antonio Breast Cancer Symposium, December 8-11, 2020. Abstract PD3-11.

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