Targeting The Glucagon Receptor Signaling Pathway As A Novel Strategy To Counteract Pi3k Inhibitor Induced Hyperglycemia While Sustaining Tumor Pi3k Inhibition

Pathologic activation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is an oncogenic driver for many malignancies, including lymphomas1. Although validated as a therapeutic oncologic target, the PI3K signaling pathway is also implicated in normal glucose homeostasis. Specifically, since the PI3K subunit p110α is chiefly responsible for downstream insulin receptor (INSR) signaling, PI3K signaling inhibition that includes p110α leads to severe hyperglycemia. Both compensatory endogenous insulin release as well as treatment of hyperglycemia with exogenous insulin/insulin mimetics activate INSR-associated PI3K signaling, ultimately limiting blockade of tumor associated PI3K signaling2. Aggressive lymphomas driven by pathologic PI3K signaling respond to combined PI3Kα and δ/γ inhibition, but this is likely submaximal due to endogenous insulin feedback, and more intense dosing is difficult to achieve safely due to severe hyperglycemia3. Therefore, a novel strategy to maintain blockade of tumor associated PI3K signaling while reducing hyperglycemia is needed. We hypothesized that inhibition of glucagon receptor (GCGR) signaling, a pathway that does not depend on PI3K, may normalize PI3K inhibitor induced hyperglycemia without disrupting antitumor PI3K blockade. GCGR blockade with a GCGR specific monoclonal antibody (REMD-477, a human anti-GCGR antibody, or REMD2.59c, a murine equivalent) may allow for the safer use of more potent PI3K inhibitors or more intensive dosing schedules in the treatment of aggressive lymphomas.