Abstract 1624: eIF4E allosteric regulators cause rapid commitment to apoptosis in cancer cells while sparing immune cells
Authors: Sturla Lisa-Marie , Zhang Xuemei , Bowdish Katherine , Alters Susan E. , VanDeusen Christopher 
Published: April 2023

Advanced or metastatic breast cancers represents a large patient population. Targeted therapies following hormonal or chemotherapeutic approaches offer some benefit. Subsequently, molecular profiling has identified over 100 mutations that render inhibitor resistance, creating challenges for physicians, patients, and the healthcare system broadly. While advances in therapeutic options have improved treatment outcomes by prolonging PFS with better QOL, long-term solutions remain a challenge for the majority of patients. The aim of our work is to drive strong mechanistic responses in this large patient population by developing targeted therapies to a key fundamental mechanism at the convergence of many oncogenic signaling pathways through which resistance arises. Our work in established cell lines and primary patient derived organoids demonstrated potent and complete responses in breast cancers that represent patient populations where unmet needs remain high including ER positive, TNBC, PTEN and RB null molecular profiles. The regulation of CAP dependent protein translation is a central element in oncogenesis. One of a family of CAP binding proteins, eIF4E serves to anchor the m7GTP CAP of RNA into several protein complexes and regulates multiple aspects of mRNA processing such as nuclear export and ribosomal translation. Previous communications revealed our eIF4E regulators potently cause cell death in primary breast cancer organoid models differentially to models derived from healthy tissue. We have expanded our efforts following our observations of both rapid apoptosis and differential sensitivity of healthy cells. In vitro, in breast cancer cells we observed stable responses in mechanistic markers of pharmacodynamic response, including phospho-Rb, with short term drug incubation. In vivo, in a ZR-75-1 breast CDX model, intermittent dosing (QW) of our lead compound resulted in strong tumor growth inhibition (&gt;95%). Consistent with growth impacts, we observed stable pharmacodynamic marker (p-Rb) changes in tumor tissue at 24 and 48 hours. To understand the impact on immune cells, we evaluated our regulators against primary cells including PBMCs, CD4+ T cells, and bone marrow mononuclear cells. Our eIF4E regulators did not impair survival of these cells up to a maximum tested dose of 25 micromolar. Primary CD4+ T cells were also functional in the presence of eIF4E regulators up to 5 micromolar, which included assessments of CD3/CD28 stimulated cytokine production and proliferative responses. Our findings suggest that allosteric modulation of eIF4E provides a unique and efficient way to address multiple resistance mechanisms while sparing normal immune cellular function. Thus, our allosteric eIF4E regulators represent a potential beneficial therapeutic approach to address multiple resistant cancer patient populations and fulfill the promise of this elusive target.

Citation Format: Lisa-Marie Sturla, Xuemei Zhang, Katherine Bowdish, Susan E. Alters, Christopher VanDeusen. eIF4E allosteric regulators cause rapid commitment to apoptosis in cancer cells while sparing immune cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1624.