Death agonist antibody against TRAILR2/DR5/TNFRSF10B enhances birinapant anti-tumor activity in HPV-positive head and neck squamous cell carcinomas

Abstract

Head and neck squamous cell carcinomas (HNSCC) induced by human papillomavirus (HPV) have increased recently in the US. However, the distinct alterations of molecules involved in the death pathways and drug effects targeting inhibitor of apoptosis proteins (IAPs) have not been extensively characterized in HPV(+) HNSCC cells. In this study, we observed the distinct genomic and expression alterations of nine genes involved in cell death in 55% HNSCC tissues, which were associated with HPV status, tumor staging, and anatomic locations. Expression of four genes was statistically correlated with copy number variation. A panel of HPV(+) HNSCC lines showed abundant TRAILR2 and IAP1 protein expression, but were not sensitive to IAP inhibitor birinapant alone, while combinatory treatment with TNFα or especially TRAIL enhanced this drug sensitivity. The death agonistic TRAILR2 antibody alone showed no cell inhibitory effects, whereas its combination with birinapant and/or TRAIL protein demonstrated additive or synergistic effects. We observed predominantly late apoptosis mode of cell death after combinatorial treatments, and pan-caspase (ZVAD) and caspase-8 (ZIETD) inhibitors attenuated treatment-induced cell death. Our genomic and expression data-driven study provides a framework for identifying relevant combinatorial therapies targeting death pathways in HPV(+) HNSCC and other squamous cancer types.

The expanding role of IAP antagonists for the treatment of head and neck cancer

“…In some cell lines, SMAC mimetics by themselves induced cell death in the form of apoptosis or necroptosis 19,20 . However, in most cases, IAPi sensitized the cell lines to extrinsic TNF‐α or TNF‐related apoptosis‐inducing ligand (TRAIL), often with synergistic activity when both TNF/TRAIL and a SMAC mimetic were added 15,19–26 . Several studies by multiple independent research groups have shown synergistic activity of SMAC mimetics when combined with radiation in mice inoculated with xenografts of human HNSCC cell lines, including HPV‐positive/negative models and four different IAPi (birinapant, xevinapant, tolinapant, and LCL161).…”

“… 19 , 20 However, in most cases, IAPi sensitized the cell lines to extrinsic TNF‐α or TNF‐related apoptosis‐inducing ligand (TRAIL), often with synergistic activity when both TNF/TRAIL and a SMAC mimetic were added. 15 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 Several studies by multiple independent research groups have shown synergistic activity of SMAC mimetics when combined with radiation in mice inoculated with xenografts of human HNSCC cell lines, including HPV‐positive/negative models and four different IAPi (birinapant, xevinapant, tolinapant, and LCL161). The anti‐tumor activity of these combinations was remarkable in these aggressive xenograft models, resulting in the cure of most tumor‐bearing mice.…”