The CD73 immune checkpoint promotes tumor cell metabolic fitness

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    eLife assessment

    This important study demonstrates a non-canonical, cancer-cell intrinsic role of the ectonucleotidase CD73 in the regulation of cancer cell metabolism. The evidence supporting the claims is solid, although further experimental details and conditions would strengthen the evidence provided.

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Abstract

CD73 is an ectonucleotidase overexpressed on tumor cells that suppresses anti-tumor immunity. Accordingly, several CD73 inhibitors are currently being evaluated in the clinic, including in large randomized clinical trials. Yet, the tumor cell-intrinsic impact of CD73 remain largely uncharacterized. Using metabolomics, we discovered that CD73 significantly enhances tumor cell mitochondrial respiration and aspartate biosynthesis. Importantly, rescuing aspartate biosynthesis was sufficient to restore proliferation of CD73-deficient tumors in immune deficient mice. Seahorse analysis of a large panel of mouse and human tumor cells demonstrated that CD73 enhanced oxidative phosphorylation (OXPHOS) and glycolytic reserve. Targeting CD73 decreased tumor cell metabolic fitness, increased genomic instability and suppressed poly ADP ribose polymerase (PARP) activity. Our study thus uncovered an important immune-independent function for CD73 in promoting tumor cell metabolism, and provides the rationale for previously unforeseen combination therapies incorporating CD73 inhibition.

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  1. eLife assessment

    This important study demonstrates a non-canonical, cancer-cell intrinsic role of the ectonucleotidase CD73 in the regulation of cancer cell metabolism. The evidence supporting the claims is solid, although further experimental details and conditions would strengthen the evidence provided.

  2. Reviewer #1 (Public Review):

    CD73 is a promising biomarker in cancer and has been characterized as having an immunosuppressive role in the tumor microenvironment. However, many cancer cell-intrinsic roles of CD73 are still under investigation. In this work, the authors explore the immune-independent roles of CD73 in cancer and demonstrate a function in maintaining metabolic fitness in cancer cells. The authors utilize genetic and pharmacological inhibition of CD73 to characterize metabolic changes in a panel of cancer cell lines and assess tumor growth in vivo. Furthermore, the authors demonstrate that the impaired metabolic fitness due to CD73 inhibition rendered cancer cells more susceptible to DNA-damaging agents. Overall, this work demonstrates the new roles of CD73 in cancer and provides a rationale for combination therapies including CD73 inhibition.

  3. Reviewer #2 (Public Review):

    This manuscript describes the involvement of CD73 in tumor cell metabolism by inhibiting CD73 expression in a CD73-positive tumor cell line. The authors demonstrated that CD73 deletion decreases aspartate synthesis via the alteration of mitochondrial respiration. The study is well-designed and the data are convincing.