Dr. Cortes on Updated PFS Data From KEYNOTE-355 in PD-L1-High TNBC

Javier Cortes, MD, PhD, head of breast cancer program at IOB Institute of Oncology, Madrid and Barcelona, discusses updated progression-free survival (PFS) data on the phase 3 KEYNOTE-355 study with pembrolizumab plus chemotherapy in previously untreated patients with locally recurrent, inoperable or metastatic triple-negative breast cancer (TNBC).

At the 2020 ASCO Virtual Scientific Program, investigators presented the first co-primary end point of PFS and safety from the KEYNOTE-355 study, says Cortes. Firstly, in patients who are PD-L1—positive with a CPS score of ≥10, the primary end point was met with a hazard ratio (HR) of 0.65, which is both statistically significant and of great clinical importance, adds Cortes. The median PFS was 9.7 months with pembrolizumab and chemotherapy versus 5.6 months with placebo and chemotherapy (range, 0.49-0.86; 95% CI; P = .0012).

Once this primary end point was achieved, investigators looked at the PFS data in patients with a CPS score of ≥1, adds Cortes. The trend was very clear, with a HR of 0.74; however, the P value of 0.0014 did not reach statistical significance. The median PFS was 7.6 months in the pembrolizumab arm and 5.6 months in the placebo arm. The PFS data in the intent-to-treat population was not formally tested. Pembrolizumab plus chemotherapy improved PFS in patients with PD-L1—positive disease and a CPS score of ≥10 or more, concludes Cortes.