Bridging the Translational Gap: Evaluating Human-Derived Nociceptors as a Modelfor Chemotherapy-Induced Peripheral Neuropathy

Introduction: Chemotherapy-induced peripheral neurotoxicity(CIPN) is a common side effect of many cancer treatments including proteasome inhibitors like bortezomib (BTZ) and carfilzomib (CFZ). In vitro models allow the dissection of the different molecular mechanisms underlying neurotoxicity, but their translational relevance is constantly questioned. Challenges in translating preclinical results are pushing the fieldtoward human-centric paradigms. Consequently, assessing how well human-based models can replicate complex phenomena such as CIPN has become a top priority. Methods: Therefore, we characterized the cellular and molecular responses of a line of induced Pluripotent Stem Cell (iPSC)-derived peripheral sensory neurons (RealDRGTM ) to treatment with increasing doses of BTZ and CFZ, comparing them to primary cultured mouse Dorsal Root Ganglion (DRG) sensory neurons. We used a battery of assays to verify proteasome levels inhibition, cellular viability, axonal degeneration, and expression of several peripheral neuronal markers. In addition, we measured both cytosolic and mitochondrial calcium signals in response to chemical depolarization. Results: RealDRGTM neurons expressed several markers of nociceptors, mechanoceptors, and proprioceptors, indicating differentiation towards a broader peripheral neuron phenotype. Interestingly, these neurons displayed higher sensitivity to treatment with proteasome inhibitors than mouse DRG cells, especially to CFZ. Indeed, there was a shift towards much lower doses of CFZ needed to match the effects observed on mouseDRG neurons on both proteasome inhibition and cellular viability. Next, calcium imaging results revealed that, in both in vitro models, 24-hour BTZ treatment significantly reduced the amplitude of KCl-induced cytosolic and mitochondrial calcium peaks, while CFZ exerted differential effects between mouse- and human-derived neurons. Finally, RealDRGTM neurons replicated the stronger impact of BTZ on axonal degeneration. Conclusions: These human-derived sensory neurons’ behavior aligned with fundamental proteasome inhibitors effects observed in mouse DRG neurons while showing peculiar differences, highlighting the need for accurate characterization to bridge the translational gap in CIPN research.