Phenotypic small-molecule screening identifies JAK inhibitors as pharmacologic modulators of T cell exhaustion

The Journal of Immunology, vol. 204, pp. 246.26

Abstract

Abstract Immune checkpoint blockade (ICB) therapy has emerged as viable first-line treatment for cancers such as melanoma. Despite the striking long-term clinical benefits that were previously unattainable, the effectiveness of ICB therapy remains limited in a majority of patients and cancer types. This is due in part to insufficient activation and/or restoration of anti-tumor T cell responses. Thus, understanding the signaling pathways that potentiate T cell exhaustion is essential for developing pharmacologic drugs that reactivate T cells and overcome the limitations of current ICB therapy. To this end, we developed a biologically relevant phenotypic screening system using the LCMV-CL13 infection model coupled with high-throughput flow cytometry to identify small-molecules that resurrect hypofunctional T cells. We discovered 19 hits following a screen of a manually curated collection of 12,000 repurposed drugs. Among the lead compounds identified were janus kinase (JAK) inhibitors including the anti-myelofibrosis drug ruxolitinib. Phenotypic rescue of exhausted T cells in vitro following ruxolitinib treatment resulted in a unique transcriptional signature that diverged from anti-PD-L1 treatment. Lineage-defining genes known to preserve precursor exhausted CD8+ T cells, including transcription factor 7 (Tcf7), were significantly upregulated following exposure to ruxolitinib. Mechanistically, ruxolitinib attenuated the cumulative pSTAT signaling signature within resurrected cells to enhance their survival. Collectively, these results demonstrate a disease-relevant framework for identifying small-molecule modulators of dysfunctional T cells and suggest that JAKs are viable targets for cancer immunotherapy.

Authors 6

1. Brett S. Marro

   Scripps Research Institute

   Affiliation as printed

   1The Scripps Research Institute

2. Jaroslav Žák

   Scripps Research Institute

   Affiliation as printed

   1The Scripps Research Institute

3. Isaraphorn Pratumchai Aachen 2Leiden Univ. Med. Ctr

   Leiden University Medical Center · Scripps Research Institute

   Affiliation as printed

   1The Scripps Research Institute

   2Leiden Univ. Med. Ctr., Netherlands

4. Luke L. Lairson

   Scripps Research Institute

   Affiliation as printed

   1The Scripps Research Institute

5. Michael B. A. Oldstone

   Scripps Research Institute

   Affiliation as printed

   1The Scripps Research Institute

6. John Ross Teijaro

   Scripps Research Institute

   Affiliation as printed

   1The Scripps Research Institute