Pembrolizumab plus chemotherapy benefits patients with combined positive score ≥10

Combined positive score (CPS) ≥10 is a reasonable cut-off to define patients with metastatic triple-negative breast cancer who benefit from pembrolizumab plus chemotherapy, subgroup analyses of KEYNOTE-355 show.

In the phase 3 KEYNOTE-355 trial (NCT02819518), first-line pembrolizumab combined with chemotherapy showed statistically significant improvements in overall survival (OS) and progression-free survival (PFS) compared with placebo plus chemotherapy in patients with previously untreated, locally recurrent, inoperable, or metastatic TNBC whose tumours expressed PD-L1 with a CPS ≥10 [1]. Additional analyses were done in subgroups of patients by additional CPS cut-offs to the primary results of KEYNOTE-355. Dr Javier Cortés (Vall d'Hebron Institute of Oncology, Spain) presented the results [2].

At the time of the final analysis, the median follow-up was 44 months. Of all patients, 25% had a CPS<1, 37% had a CPS 1–9, 14% had a CPS 10–19, and 24% had a CPS>20. In the primary analyses, the hazard ratios for OS were 0.73 in the CPS≥10 subgroup, 0.86 in the CPS≥1 subgroup, and 0.89 in the intent-to-treat population. Hazard ratios for PFS were 0.66, 0.75, and 0.82, respectively. In the additional analyses, hazard ratios for OS were 0.97 in the CPS<1 subgroup, 1.09 in the CPS 1–9 subgroup, 0.71 in the CPS 10–19 subgroup, 0.72 in the CPS≥20 subgroup, and 0.89 in the intent-to-treat population. Hazard ratios for PFS were 1.09, 0.85, 0.70, 0.62, and 0.82, respectively (see Figure).

Figure: Progression-free survival in PD-L1 patients with combined positive score cut-offs of: <1, 1–9, 10–19, and ≥20 [2].



 

 

 

 

 

CPS, combined positive score; HR, hazard ratio; CI, confidence interval

Based on these results, Dr Cortés concluded that: “CPS≥10 is a reasonable cut-off to define patients with metastatic triple-negative breast cancer who will benefit from pembrolizumab plus chemotherapy.”

1. Rugo HS, et al. LBA16, ESMO Virtual Annual Meeting 2021, 16–21 September.
2. Cortes J, et al. Final results of KEYNOTE-355: Randomized, double-blind, phase 3 study of pembrolizumab + chemotherapy vs placebo + chemotherapy for previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer. GS1-02, SABCS 2021 Virtual Meeting, 7–10 December.

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Posted on 31 January 202225 March 2024