We thank Jun Masuda and colleagues for their interest in the results of the KEYNOTE-355 study.1Cortes J Cescon DW Rugo HS et al.Pembrolizumab plus chemotherapy versus placebo plus chemotherapy for previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer (KEYNOTE-355): a randomised, placebo-controlled, double-blind, phase 3 clinical trial. We examined whether the addition of pembrolizumab would enhance the antitumour activity of chemotherapy, including taxanes or a non-taxane platinum-based regimen, in patients with locally recurrent unresectable or metastatic triple-negative breast cancer.1Cortes J Cescon DW Rugo HS et al.Pembrolizumab plus chemotherapy versus placebo plus chemotherapy for previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer (KEYNOTE-355): a randomised, placebo-controlled, double-blind, phase 3 clinical trial. Pembrolizumab combined with chemotherapy produced a statistically significant and clinically meaningful improvement in progression-free survival as compared with placebo combined with chemotherapy for the first-line treatment of patients with a PD-L1 combined positive score of 10 or more.

In addition to patients with at least a 12-month disease-free interval, our study included patients with early recurrences (between 6 months and 12 months following completion of definitive treatment with curative intent for early disease), a patient population with a high unmet medical need. A pre-specified exploratory analysis was to examine the benefit of pembrolizumab combined with chemotherapy on progression-free survival in predefined subgroups, including those based on disease-free interval at baseline. The results showed a generally consistent benefit of pembrolizumab combined with chemotherapy as compared with chemotherapy alone on progression-free survival, although subgroup analyses are underpowered and should be interpreted with caution.

In response to Masuda and colleagues, we are delighted to share the baseline characteristics and which chemotherapy was chosen as the study treatment for the subgroup of patients with early recurrences. Overall, 176 (20·8%) of 847 patients had a disease-free interval of less than 12 months. The baseline characteristics of this subgroup were as expected and generally well balanced between the two treatment arms (appendix). In this subgroup of 176 patients, 27 (15·3%) received nab-paclitaxel, 12 (6·8%) received paclitaxel, 137 (77·8%) received gemcitabine–carboplatin in the study and 36 (20·5%) had previously received treatment with the same class of neoadjuvant or adjuvant chemotherapy (appendix). We hope that Masuda and colleagues will find this additional information to be useful.A summary of competing interests in available in the appendix.Supplementary MaterialReference1.Cortes J Cescon DW Rugo HS et al.

Pembrolizumab plus chemotherapy versus placebo plus chemotherapy for previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer (KEYNOTE-355): a randomised, placebo-controlled, double-blind, phase 3 clinical trial.

Lancet. 396: 1817-1828Article InfoPublication HistoryIdentification

DOI: https://doi.org/10.1016/S0140-6736(21)00374-3

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