Immunomodulatory effects of PI3Kδ inhibition in solid tumors – evaluation in a randomized phase II trial

Ottensmeier, Christian ORCID: 0000-0003-3619-1657, Eschweiler, Simon, Suastegui, Ciro Ramirez, King, Emma, Chudley, Lindsey, Thomas, Jaya, Oliver, Wood, Jeffrey, Danielle, McCann, Katy, Simon, Hayley
et al (show 28 more authors) (2021) Immunomodulatory effects of PI3Kδ inhibition in solid tumors – evaluation in a randomized phase II trial. [Preprint]

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Phosphoinositide 3-kinase δ (PI3Kδ) plays a key role in lymphocytes and inhibitors targeting this PI3K have been approved for hematological malignancies. While studies in hematological and solid tumor models in mice have demonstrated that PI3Kδ inhibitors (PI3Kδi) can induce anti-tumor immunity, the impact of PI3Kδi on solid tumors in humans remains unclear. Here, we assessed the effects of the PI3Kδi AMG319 in patients with resectable head and neck cancer in a neoadjuvant, double-blind, placebo-controlled randomised phase-II trial. We find that PI3Kδ inhibition decreases tumor-infiltrating immunosuppressive TREG cells and causes heightened cytotoxic potential of tumor-infiltrating CD8+ and CD4+ T cells. Loss of intratumoral TREG cells and an increase in the frequency of activated TREG cells in the blood post-treatment are indicative of systemic effects on TREG tissue retention and maintenance. At the tested AMG319 doses, immune-related adverse events caused treatment discontinuation in 12/21 of AMG319-treated patients, further suggestive of systemic effects on TREG cells. Consistent with this notion, in a murine syngeneic tumor model, PI3Kδi decreased TREG cells in both tumor and non-malignant tissues and affected TREG subtype composition, maintenance and functionality. Our data demonstrate the cancer-immunotherapy potential of PI3Kδ inhibition in humans, but its modulation will need to be carefully balanced to harness its anti-tumor capacity while minimizing immune related toxicity.

Item Type: Preprint
Uncontrolled Keywords: Adrian von Witzleben2, Gavin Halbert8
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User: Symplectic Admin
Date Deposited: 23 Dec 2021 08:03
Last Modified: 18 Jan 2023 21:18
DOI: 10.21203/
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