PTPN2 inhibition restores STING signaling, sensitizing anti-PD-1 refractory HNSCC to STING agonism

The cGAS-STING signaling pathway is crucial for promoting antitumor immunity, yet its activity is often suppressed in various cancer subtypes, leading to resistance against immune checkpoint blockade (ICB) therapies. Despite the potential, clinical trials for direct STING agonists have largely failed, highlighting a critical need for precision approaches that restore tumor cell STING expression. This study addresses this gap by investigating a mechanism of STING suppression in head and neck squamous cell cancer (HNSCC), aiming to identify strategies to re-sensitize these tumors to STING agonism and enhance immune responses.

Researchers investigated the role of protein tyrosine phosphatase non-receptor type 2 (PTPN2) in STING suppression within HNSCC tumor cells. They utilized anti-PD-1 refractory syngeneic HNSCC mouse tumor models, specifically in female mice, to evaluate the therapeutic potential of PTPN2 inhibition (PTPN2i) in combination with STING agonism. The study aimed to determine if PTPN2i could restore STING expression and subsequently enhance the antitumor effects of STING agonists. Key assays likely included qPCR for STING mRNA levels, western blot for STING protein, and flow cytometry to assess natural killer (NK) cell activation, with tumor growth suppression as a primary endpoint.

The study identified that HNSCC exhibits a mechanism of STING suppression linked to the upregulation of protein tyrosine phosphatase non-receptor type 2 (PTPN2), a finding also observed in other cancer types. > PTPN2 inhibition (PTPN2i) significantly increased HNSCC tumor cell STING by restoring IFNγ-STAT1-mediated induction of STING mRNA. This restoration of STING expression subsequently re-established sensitivity to STING agonism. Furthermore, the combination therapy led to enhanced natural killer cell activation. Crucially, this combined approach suppressed tumor growth in an immune cell-dependent manner in anti-PD-1 refractory syngeneic HNSCC mouse tumor models. While specific numerical data such as percentages or p-values were not provided in the abstract, the findings strongly indicate a robust and synergistic effect of PTPN2i and STING agonism.