NOV-002, a glutathione disulfide mimetic, is a pleiotropic modulator of cellular redox balance

Abstract

NOV-002 is a novel formulation of oxidized glutathione (GSSG) currently in a pivotal Phase 3 clinical trial in advanced non-small cell lung cancer. In clinical trials conducted to date, NOV-002 administered in combination with standard chemotherapeutic regimens has resulted in increased efficacy (survival, tumor response) and improved toleration (e.g. hematological recovery, immune stimulation). The studies reported here were aimed at further elucidating its cellular and in vivo pharmacologic profile. The effects of NOV-002 were assessed on a range of cellular and in vivo endpoints reflecting its proposed key pharmacological action – modulation of redox balance. NOV-002 treatment of the pre-myeloid cell line HL60 resulted in mild and transient timeand concentration-dependent oxidative signals at the cell surface (reduction in protein thiols) and intracellularly (altered GSSG and GSH levels and ratio). These oxidative signals were associated with an increase in S-glutathionylation of cell proteins, particularly actin, with a concomitant decrease in focal adhesions as detected by fluorescence microscopy. Intravenous administration of NOV-002 to mice also resulted in a fingerprint of glutathionylated serum proteins which could represent a useful pharmacodynamic biomarker. Commensurate with the above in vitro effects, NOV-002 treatment of HL60 cells resulted in increases in activated (phosphorylated) forms of the signaling kinases p38, JNK and ERK and caused a dose-dependent increase in phosphorylation of three proteins that have previously been linked with hematopoiesis, AKT, JAK2 and STAT5. The effect of NOV002 on enzymes involved in glutathione metabolism was evaluated. These multiple redox-associated cell-signaling actions occurred in the context of increased HL-60 cell proliferation after treatment with NOV002. We conclude that the pleiotropic pharmacological effects of NOV002 can be attributed to the GSSG component of the drug, and that modulation of cellular redox balance is a feature central to NOV-002’s mechanism of action. Such modulation may underlie its clinical actions, including hematological recovery and immunostimulation in the face of chemosuppression.