Pembrolizumab (MK-3475) is a highly selective humanized monoclonal antibody that antagonizes PD-1. It can block the PD-1 protein on T cells and prevent their interaction with PD-L1 on cancer cells.

T cells:0.535 µg/mL, PD-1:0.6 nM

METHODS: Peripheral blood mononuclear cells (PBMC) from healthy donors (HD) and primary breast cancer (PBC) were cultured for 24 hours (with plate-bound anti-CD3 and anti-CD28 antibodies for activated cells) and treated with 2 μg/ul Pembrolizumab (MK-3475) treatment (for treated cells) stains intracellular expression of CD4, PD-1 surface marker, and CTLA-4.
RESULTS In CD4 T cells, PD-1 expression was significantly higher in PBC patients compared with steady-state HD. Pembrolizumab treatment significantly reduced PD-1 expression in CD4 T cells in both cohorts of non-activated and activated PBMC. [3]
METHODS: After HCCLM3 and SK-HEP.1 cells were lysed, 10 ng/mL TNF-α and 10 ng/mL IL-1β were added to the medium of DC and incubated for 48 hours. Finally, DCs were co-cultured with CIK cells at a ratio of 1:10 for 2 days, and on day 12, pembrolizumab 20 ug/mL was added to DC-CIK cells to mediate PD-1 blockade.
RESULTS pembrolizumab treatment increased DC-CIK cell proliferation, indicating that pembrolizumab enhanced DC-CIK cell cytotoxicity against HCC cell lines.[4]

METHODS: In the open-label, international, multicenter extension cohort of the phase 1 KEYNOTE-001 trial, patients with advanced melanoma who progressed after 2 or more doses of ipilimumab were randomly assigned to receive 2 mg/kg every 3 weeks or Treatment with Pembrolizumab (MK-3475)10 mg/kg.
RESULTS Among the 173 patients treated (2 mg/kg, N = 89; 10 mg/kg, N = 84), the ORR was nearly identical at 26% for both doses, 73% and 68%, respectively. of patients showed reduction in target lesion size. [1]
METHODS: Patients were randomly assigned to intravenous pembrolizumab 200 mg every 3 weeks for ≤35 cycles of pembrolizumab or until disease progression, unacceptable toxicity, or discontinuation. Imaging was performed at week 9, then every 6 weeks until year 1, and every 9 weeks thereafter.
RESULTS The median OS of pembrolizumab was 14.9 months (95% CI, 11.5-20.6), and it could improve OS in the PD-L1 CPS ≥ 20 and CPS ≥ populations, and the DOR was also significantly longer. [2]