Cell-free targeted therapy of T-cell Acute Lymphoblastic Leukemia
by Jacob Neethling
T-cell Acute Lymphoblastic Leukemia (T-ALL) is a malignancy of immature T-cell lymphoblasts that constitutes approximately 20% of all leukemias and carries a worse prognosis and overall survival at all stages compared to its B-cell counterpart. It has been established that mutations in Notch1 are a key oncogenic driver for T-ALL arising in 60-70% of cases. Despite this knowledge, a targeted therapy has not been developed to treat T-ALL via Notch inhibition. There are potent Notch inhibitors such as gamma-secretase inhibitors (GSIs), yet they fail clinical trials due to systemic side effects namely Goblet cell metaplasia in the gastrointestinal tract leading to devastating secretory diarrhea. To address this, our group has studied Notch1 dependent biology in the context of T-ALL to develop a better, more targeted therapeutic option, and we discovered a potential target with Deltex1 (Dtx1). We identified Dtx1 as a binding partner of Notch1 with Selective Isotope Labeling with Amino Acids in Cell Culture Mass Spectrometry (SILAC-MS) and confirmed these results with a Co-Immunoprecipitation experiment. Of significance, while Dtx1 has not been investigated in the context of T-ALL; it has been shown to act antagonistically towards Notch signaling in multiple cancer context including osteosarcomas via E3 Ubiquitin Ligase activity. With this knowledge in mind, we have preliminarily shown that Dtx1 can inhibit even the most robust Notch signaling in-vitro as well as inhibiting T-ALL cell line growth via Notch1 inhibition. Because of the potential clinical impact of our work, it is pertinent to elucidate the precise mechanism of the Deltex1-Notch1 interaction and how that interaction impacts leukemic cell growth in-vitro and leukemia progression in-vivo. We postulate that removing a negative regulator of Notch1 signaling in T-ALL allows for more robust proliferation and progression of leukemia. Our hypothesis maintains that introduction of Dtx1 will inhibit Notch1 signaling in T-ALL and slow the progression of leukemia. To allow for a translation capacity of our work, we will test our hypothesis by implementing a novel and robust therapeutic paradigm that utilizes targeted fusogenic nanoparticles carrying Dtx1 as a mode of delivery. With this, we predict improved clinical outcomes by targeting the Notch1 signaling axis in leukemic cells and improved overall quality of life as a byproduct of reduced systemic side effects. Through our experiments, we will gain valuable insight into these events in hopes of curtailing or eradicating the progression of T-ALL and improving the overall survival and quality of life of those suffering from this disease. In addition, we believe our findings can be generalized to other cancers harboring Notch mutations.