KEYNOTE-355: A Randomized, double-blind, phase III study of pembrolizumab plus chemotherapy vs. placebo plus chemotherapy for previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer
Author, Company: Javier Cortes, MD, PhD
Abstract Number: 1000
Indications: Triple Negative Breast Cancer
Interventions: Pembrolizumab plus chemotherapy
Background and objectives:
- KEYNOTE-355, a randomized, double blind, Phase III trial, studied the comparison of pembro + chemo vs. placebo + chemo for previously untreated locally recurrent inoperable or metastatic TNBC.
- Dual primary outcome measures were PFS and OS by tumor PD-L1 expression (CPS ≥10 and ≥1) as well as ITT. Secondary end points were ORR, disease control rate, duration of response, and safety.
Results and observations:
|Regimen||n Size||mFollow up||mPFS||Grade 3-5 AEs|
|CPS ≥10||CPS ≥1||ITT|
|Pembro +Chemo vs Pbo+Chemo||566
|26.1||9.7 vs 5.6
|7.6 vs 5.6
|7.5 vs 5.6
|68.1% vs 66.9%|
- Pembro + chemo was not able to show any meaningful results in mPFS in
patients with CPS ≥ 1, and therefore, formal testing in ITT was not performed
- IMPassion130 which was a randomized, placebo, phase III trial that assessed efficacy and safety of atezolizumab + nab-paclitaxel in patients with mTNBC.
|IMPassion130||KN – 355|
|Reduction in risk progression||40%||35%|
|Median PFS||7.5 mo. vs. 5.0 mo. (atezo + chemo) vs. pbo+chemo);
|9.7 mo vs 5.6 mo. (pembro + chemo vs. pbo+chemo)
- According to KN-355, pembro + chemo showed a significant relevant improvement in PFS vs. placebo + chemo in patients with metastatic Triple Negative Breast Cancer whose tumors expressed PD-L1 (CPS >=10). The combination was well tolerated and had no new safety concerns.
- The study highlighted that addition of Immunotherapy could significantly lead to a paradigm shift in the overall treatment of metastatic triple-negative breast cancer.
- These results also indicate routine testing for PD-L1+ status in newly diagnosed patients with metastatic triple-negative breast cancer to determine if they could benefit from these combinations