Abstract LB267: Evaluating the therapeutic potential of novel TrkA agonists in targeting glioblastoma stem cells (GSCs)

Abstract Background: Glioblastoma multiforme (GBM) is the most frequent malignant central nervous system tumor in adults, with an average survival rate of approximately 15 months. In children, high grade gliomas, such as diffuse intrinsic pontine glioma (DIPG), are equally aggressive and present unique challenges due to developmental differences in the brain and the limited treatment options available. One model for studying high grade gliomas lies within a population of stem-like cells, known as glioblastoma stem cells (GSCs). GSCs exhibit self-renewal capabilities, resistance to conventional therapies, and the ability to drive tumor recurrence and progression. Understanding and targeting GSCs is necessary for developing therapies that can improve treatment outcomes in both adult and pediatric patients suffering from high grade gliomas. A family of neurotrophin receptors known as the tropomyosin receptor kinases (TRKs), including TrkA, TrkB, and TrkC, encoded by the NTRK1, NTRK2, and NTRK3 genes respectively, are critical for normal neuronal development and survival. In brain tumors, the canonical signaling of these receptors is often corrupted through gene fusions or overexpression, leading to abnormal activation of signaling pathways that promote tumor cell survival, self-renewal, and resistance to treatment. Here, we investigate the use of novel agonists 231 and 237, developed by our team, to specifically target TrkA, in effort to better understand its role in GSC biology, with the goal of finding ways to inhibit tumor growth and improve therapeutic outcomes in high grade glioma models. GSC lines 448T and 559T were cultured under standard conditions to investigate the effects of novel TrkA agonists (231 and 237) on proliferation, differentiation, and TrkA/TrkB expression. Synergy with targeted therapies, including Abemaciclib (a CDK4/6 inhibitor) and Altiratinib (a multi-kinase inhibitor targeting MET, VEGFR2, and Trk pathways), was also evaluated. For proliferation and Western blot analysis, cells were treated with PBS (control), 231, or 237 for 72 hours, followed by cell counting and lysate preparation. Differentiation was assessed using neurite outgrowth assays with Incucyte Live-Cell Imaging and Neurotrack software, measuring neurite length, branch points, and neurite-bearing cells. Western blot analysis demonstrated a reduction in TrkA expression in 559T glioblastoma stem cell lines treated with novel TrkA-specific agonists 231 and 237 compared to the PBS control. This decrease suggests potential downregulation of TrkA or feedback inhibition in response to agonist treatment. Ongoing studies aim to further elucidate the mechanisms underlying TrkA modulation and its role in maintaining GSCs in vitro. Additionally, investigations are exploring the potential synergistic effects of TrkA-specific agonists with targeted therapies to enhance GSC susceptibility to treatment. Citation Format: Taylor Simone Jackson, David E. Johnson, Hawa L. Jagana, Leyre Merino-Galan, Siobhan S. Pattwell, Thomas Schlichthaerle, Natasha Edman, David Baker. Evaluating the therapeutic potential of novel TrkA agonists in targeting glioblastoma stem cells (GSCs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB267.