AKT Signaling as a Novel Factor Associated with In Vitro Resistance of Human AML to Gemtuzumab Ozogamicin

Abstract

Gemtuzumab ozogamicin (GO), an immunoconjugate between an anti-CD33 antibody and a calicheamicin-γ1 derivative, induces remissions and improves survival in a subset of patients with acute myeloid leukemia (AML). As the mechanisms underlying GO and calicheamicin-γ1 resistance are incompletely understood, we herein used flow cytometry-based single cell network profiling (SCNP) assays to study cellular responses of primary human AML cells to GO. Our data indicate that the extent of DNA damage is quantitatively impacted by CD33 expression and drug efflux activity. However, although DNA damage is required for GO-induced cytotoxicity, it is not sufficient for effective cell kill, suggesting that downstream anti-apoptotic pathways may function as relevant resistance mechanisms. Supporting this notion, we found activated PI3K/AKT signaling to be associated with GO resistance in vitro in primary AML cells. Consistently, the investigational AKT inhibitor MK-2206 significantly sensitized various human AML cells to GO or free calicheamicin-γ1 with particularly pronounced effects in otherwise GO or free calicheamicin-γ1 -resistant cells. Likewise, MK-2206 also sensitized primary AML cells to calicheamicin-γ1. Together, our findings illustrate the capacity of SCNP assays to discover chemotherapy-related biological pathways and signaling networks relevant to GO-induced genotoxic stress. The identification of AKT signaling as being associated with GO resistance in vitro may provide a novel approach to improve the in vivo efficacy of GO/calicheamicin-γ1 and, by extrapolation, other DNA damage-based therapeutics.

Efficacy and resistance of gemtuzumab ozogamicin for acute myeloid leukemia

“…The activation of survival signaling pathways, such as PI3K/AKT, MEK/ERK and JAK/STAT, is reportedly associated with GO resistance in vitro in AML cells [63]. An AKT inhibitor, MK-2206, restored the resistance of GO and calicheamicin in resistant AML cells.…”

Phospho-Inositol-3-Kinase Activity and Dysregulation in Pediatric Leukemia and Lymphoma

“…A number of other PI3K-AKT-mTOR pathway inhibitors such as deguelin, a naturally occurring compound that inhibits PI3K, the AKT inhibitor MK-2206, and the dual PI3K/mTOR inhibitors PI-103 and NVP-BEZ235 have also been shown to induce apoptosis and enhance chemosensitivity [191][192][193][194][195]. Furthermore, simultaneous inhibition of the anti-apoptotic proteins Bcl-2 and Bcl-xL with ABT-737 enhanced the apoptosis-inducing effects of PI-103 and NVP-BEZ235, as well as the pan-PI3K inhibitor GDC-0941 [196,197].…”

Immunotoxins, Resistance and Cancer Stem Cells: Future Perspective

“…The activation of the AKT signaling pathway has been correlated with failure to therapy in AML. Recently, Rosen et al, [36] noted the association of AKT signaling with GO resistance in vitro using the single cell network profiling (SCNP) assays with the AKT inhibitor, MK-2206, in AML samples.…”