Response to anti-PD-1 and anti-LAG-3 immune checkpoint blockade is associated with induction of pro-inflammatory Tregs.

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Publication Date


Publication Title

AAI Annual Meeting; May 6-11; Portland, OR. 2022


oregon; chiles


  1. Only a subset of patients exhibits durable clinical responses to aPD-1 and/or aCTLA-4 immunotherapies, thus, developing new therapeutic agents to increase the proportion of

responding patients is a priority. Combining aPD-1 with aLAG-3 has shown promising results;

however, lack of mechanistic understanding of aPD-1/aLAG-3 synergy remains a barrier for its

  • optimal clinical use. Here, we examined the mechanism of aPD-1/aLAG-3 synergy in multiple mouse models using flow cytometry and single cell RNA sequencing. Combined aPD-1/aLAG-3

immunotherapy significantly improved the survival of CT26 (BALB/c; colon carcinoma) and MCA-205 (C57BL/6; sarcoma) tumor-bearing mice compared to monotherapy. Regulatory T cells (Tregs) suppressed response to this therapy, as in the absence of CD4+ T cells, 100% of

mice responded. To understand how responders overcome Treg suppression, we performed an

in-depth analysis of tumor-infiltrating lymphocytes (TIL) comparing mice that responded to

treatment (decreased tumor size post-treatment) to non-responders (same tumor growth

trajectory as control). Responders had reduced Foxp3+ CD4+ Tregs in comparison to nonresponders and, in addition, those Tregs had a ‘fragile’ phenotype, including a pro-inflammatory cytokine profile (TNF-a; IFN-g), increased LAG-3, and decreased NRP1 expression. Within responders, CD8+ TIL exhibited increased frequency, effector cytokine production (TNF-a; IFNg), and LAG-3 expression as compared to non-responders. Together, these data suggest that aPD-1/aLAG-3 can reduce Treg frequency and function leading to expansion of active tumor specific CD8+ T cells capable of supporting tumor regression and improved survival

Clinical Institute



Earle A. Chiles Research Institute




Rolig AS, Sturgill ER, Mick C, Rose D, Kaufmann J, Yanamandran N, Griffin S, Smothers J, Redmond WL. AAI Annual Meeting; May 6-11; Portland, OR. 2022: P933.

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