NERDG 2026
Poster 11 Abstract
Pembrolizumab as an Immune Checkpoint Blockade Therapy
Umang Shah and Kideok Jin
Albany College of Pharmacy and Health Sciences
Presenting Author: Umang Shah
Corresponding Author: Kideok Jin, [email protected]
Abstract
Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by a lack of targeted therapeutic options and poor clinical outcomes. Immune checkpoint blockade targeting the PD-1/PD-L1 axis has emerged as a promising therapeutic approach; however, pembrolizumab’s mechanistic effects in preclinical breast cancer models remain incompletely defined. In this study, we utilized a PD-1/PD-L1 Bio-IC™ reporter system to investigate pembrolizumab-mediated PD-1 activation and its functional consequences in both engineered cell models and TNBC cell lines. PD-L1–overexpressing Raji (RPDL1) cells and PD-1–overexpressing Jurkat (JPD1) cells were first validated by qRT-PCR to confirm robust transgene expression. Using the QUANTI-Luc™ 4 Lucia/Gaussia luminescence assay, we demonstrated that co-cultures of RPDL1 and JPD1 cells exhibited significantly increased luciferase activity in response to pembrolizumab across all tested concentrations, confirming effective PD-1 pathway engagement by the antibody. Extending this system to TNBC models, we showed that pembrolizumab similarly enhanced luciferase activity in co-cultures of JPD1 cells with human TNBC cell lines (MDA-MB-231, MDA-MB-468). In contrast, murine TNBC cell lines (EO771, 4T1) displayed only modest activation, consistent with the known species specificity of pembrolizumab, which binds human PD-1 with high affinity but interacts poorly with murine PD-1 or PD-L1. Importantly, apoptotic assays revealed no significant increase in tumor cell death in any co-culture condition, reflecting the non-cytotoxic nature of Jurkat reporter cells. Collectively, these findings establish the PD-1/PD-L1 Bio-IC™ co-culture system as a sensitive platform for assessing pembrolizumab-mediated PD-1 activation and demonstrate that PD-L1 expressed by TNBC cells is sufficient to drive PD-1 signaling. This reporter-based strategy provides a useful first-stage screening model for evaluating immune checkpoint interactions and may inform future studies incorporating cytotoxic T cells or in vivo models to more fully assess pembrolizumab’s antitumor potential.
Keywords
pembrolizumab, triple negative breast cancer, PD-1, PDL-1
Poster 11 Abstract
Pembrolizumab as an Immune Checkpoint Blockade Therapy
Umang Shah and Kideok Jin
Albany College of Pharmacy and Health Sciences
Presenting Author: Umang Shah
Corresponding Author: Kideok Jin, [email protected]
Abstract
Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by a lack of targeted therapeutic options and poor clinical outcomes. Immune checkpoint blockade targeting the PD-1/PD-L1 axis has emerged as a promising therapeutic approach; however, pembrolizumab’s mechanistic effects in preclinical breast cancer models remain incompletely defined. In this study, we utilized a PD-1/PD-L1 Bio-IC™ reporter system to investigate pembrolizumab-mediated PD-1 activation and its functional consequences in both engineered cell models and TNBC cell lines. PD-L1–overexpressing Raji (RPDL1) cells and PD-1–overexpressing Jurkat (JPD1) cells were first validated by qRT-PCR to confirm robust transgene expression. Using the QUANTI-Luc™ 4 Lucia/Gaussia luminescence assay, we demonstrated that co-cultures of RPDL1 and JPD1 cells exhibited significantly increased luciferase activity in response to pembrolizumab across all tested concentrations, confirming effective PD-1 pathway engagement by the antibody. Extending this system to TNBC models, we showed that pembrolizumab similarly enhanced luciferase activity in co-cultures of JPD1 cells with human TNBC cell lines (MDA-MB-231, MDA-MB-468). In contrast, murine TNBC cell lines (EO771, 4T1) displayed only modest activation, consistent with the known species specificity of pembrolizumab, which binds human PD-1 with high affinity but interacts poorly with murine PD-1 or PD-L1. Importantly, apoptotic assays revealed no significant increase in tumor cell death in any co-culture condition, reflecting the non-cytotoxic nature of Jurkat reporter cells. Collectively, these findings establish the PD-1/PD-L1 Bio-IC™ co-culture system as a sensitive platform for assessing pembrolizumab-mediated PD-1 activation and demonstrate that PD-L1 expressed by TNBC cells is sufficient to drive PD-1 signaling. This reporter-based strategy provides a useful first-stage screening model for evaluating immune checkpoint interactions and may inform future studies incorporating cytotoxic T cells or in vivo models to more fully assess pembrolizumab’s antitumor potential.
Keywords
pembrolizumab, triple negative breast cancer, PD-1, PDL-1
