Greg M. Delgoffe, PhD
Member, Tumor Microenvironment Center
Hillman Cancer Center, Suite 2.26e
Tumor immunology; regulatory T cells; immunometabolism; cancer immunotherapy
In recent years, the decades-long promise of tumor immunotherapy has finally begun to come to fruition. Checkpoint blockade, for example, represents a critically important intervention for potentiating the antitumor immune response. In these therapies, blockade of T cell intrinsic negative regulators (such as CTLA-4 and PD-1 signaling) releases the brake on effector T cells in the tumor, resulting in substantial, durable antitumor immunity, and clinical responses.
While negative regulators on the effector T cells can be relieved through these interventions, effector T cells still face a variety of cell extrinsic modes of immune suppression, notably through suppression via regulatory T (Treg) cells. Treg cells play critical roles in preventing autoimmune responses to self tissues as well as limiting immunopathology during exuberant immune responses. However, Treg cells represent a major barrier to antitumor immunity. Many tumors recruit, activate, and expand large numbers of Treg cells, which can be specific for any number of normal, self antigens expressed by the tumor. While depletion of total Treg cells can result in autoimmune pathologies, inhibition of Treg cell stability or function has been shown to allow for local inhibition of Treg cell suppression in the tumor, while sparing normal tissues from an autoimmune response.
Thus, finding phenotypic, signaling, or functional parameters that distinguish intratumoral Treg and conventional T (Tconv) cells could shed light on mechanisms by which Treg cells could be targeted to allow for a greater antitumor response. Recent studies have found that Tconv and Treg cells have distinct metabolic requirements. Not unlike cancer cells, conventional T cells undergo aerobic glycolysis (the “Warburg effect”) when undergoing robust expansion. However, regulatory T cells utilize alternative sources of fuel. Our initial findings in the laboratory suggest that not only do intratumoral Treg cells utilize distinct fuel from their conventional brethren, but engage different metabolic pathways from Treg cells in normal tissues and lymphoid organs. This suggests that metabolic pathways, or their downstream targets, could be targeted in order to inhibit intratumoral Treg cells specifically, releasing a crucial cell extrinsic brake on the antitumor immune response. The goal is to provide alternative modalities of therapy that could be utilized alone or in combination with other immunotherapeutic strategies, to allow for robust and durable immune responses for the eradication of cancer.
- Delgoffe GM, Woo SR, Turnis ME, Gravano DM, Guy C, Overacre AE, Bettini ML, Vogel P, Finkelstein D, Bonnevier J, Workman CJ, Vignali DA. Stability and function of regulatory T cells is maintained by a neuropilin-1-semaphorin-4a axis. Nature. 2013 Sep 12;501(7466):252-6. PubMed Link
- Collison LW*, Delgoffe GM*, Guy CS, Vignali KM, Chaturvedi V, Fairweather D, Satoskar AR, Garcia KC, Hunter CA, Drake CG, Murray PJ, Vignali DA. The composition and signaling of the IL-35 receptor are unconventional. Nat Immunol. 2012 Feb 5;13(3):290-9. PubMed Link
- Delgoffe GM, Pollizzi KN, Waickman AT, Heikamp E, Meyers DJ, Horton MR, Xiao B, Worley PF, Powell JD. The kinase mTOR regulates the differentiation of helper T cells through the selective activation of signaling by mTORC1 and mTORC2. Nat Immunol. 2011 Apr;12(4):295-303. PubMed Link
- Zheng Y*, Delgoffe GM*, Meyer CF*, Chan W, Powell JD. Anergic T cells are metabolically anergic. J Immunol. 2009 Nov 15;183(10):6095-101. PubMed Link
- Delgoffe GM, Kole TP, Zheng Y, Zarek PE, Matthews KL, Xiao B, Worley PF, Kozma SC, Powell JD. The mTOR kinase differentially regulates effector and regulatory T cell lineage commitment. Immunity. 2009 Jun 19;30(6):832-44. PubMed Link