Durable therapeutic efficacy utilizing combinatorial blockade against IDO, CTLA-4, and PD-L1 in mice with brain tumors

Derek A. Wainwright, Alan L. Chang, Mahua Dey, Irina V. Balyasnikova, Chung Kwon Kim, Alex Tobias, Yu Cheng, Julius W. Kim, Jian Qiao, Lingjiao Zhang, Yu Han, Maciej S. Lesniak

Research output: Contribution to journalArticlepeer-review

424 Scopus citations


Purpose: Glioblastoma (GBM) is the most common form of malignant glioma in adults. Although protected by both the blood-brain and blood-tumor barriers, GBMs are actively infiltrated by T cells. Previous work has shown that IDO, CTLA-4, and PD-L1 are dominant molecular participants in the suppression of GBM immunity. This includes IDO-mediated regulatory T-cell (Treg; CD4+CD25+FoxP3+) accumulation, the interaction of T-cell-expressed, CTLA-4, with dendritic cell-expressed, CD80, as well as the interaction of tumor- and/or macrophage-expressed, PD-L1, with T-cell-expressed, PD-1. The individual inhibition of each pathway has been shown to increase survival in the context of experimental GBM. However, the impact of simultaneously targeting all three pathways in brain tumors has been left unanswered. Experimental Design and Results: In this report, we demonstrate that, when dually challenged, IDO-deficient tumors provide a selectively competitive survival advantage against IDO-competent tumors. Next, we provide novel observations regarding tryptophan catabolic enzyme expression, before showing that the therapeutic inhibition of IDO, CTLA-4, and PD-L1 in a mouse model of well-established glioma maximally decreases tumor-infiltrating Tregs, coincident with a significant increase in T-cell-mediated long-term survival. In fact, 100% of mice bearing intracranial tumors were long-term survivors following triple combination therapy. The expression and/or frequency of T cell expressed CD44, CTLA-4, PD-1, and IFN-γ depended on timing after immunotherapeutic administration. Conclusions: Collectively, these data provide strong preclinical evidence that combinatorially targeting immunosuppression in malignant glioma is a strategy that has high potential value for future clinical trials in patients with GBM.

Original languageEnglish (US)
Pages (from-to)5290-5301
Number of pages12
JournalClinical Cancer Research
Issue number20
StatePublished - Oct 15 2014

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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