Expanding Horizons in Precision Oncology: Ex vivo microtissues from PDX to predict in vivo drug response of Malignant Peripheral Nerve Sheath Tumors

Introduction: Malignant Peripheral Nerve Sheath Tumors (MPNST) is a rare yet incredibly serious and aggressive sarcoma developing along the peripheral nerve sheaths. Generally, MPNST metastasizes quickly, leaving patients to face a daunting 5-year survival rate of 23-69%. Despite the severity of MPNST, there is a notable scarcity of models exploring the complex landscape of MPNST. To address the significant need for therapeutics in this space, we aim to create an ex vivo platform utilizing 3D microtissues to accurately capture genomic diversities in MPNST. With the use of genetically matched in vivo and ex vivo cells, we aim to provide a model that accurately reflects the disease while remaining relevant, offering a superior platform for studying MPNST and advancing drug development. Through, this process we can discover the distinctive qualities of MPNST and what makes them incredibly difficult to treat in a clinic.

Materials and

Methods: To address the limitations of current preclinical studies, our platform utilizes a medium throughput layout for drug screening (trabectedin, olaparib, and mirdametinib) and in vivo validation using patient-derived xenografts (PDX), selected post-genomic analysis. Within our model, we can create 3D microtissues utilizing a microfluidic device that provides us with the advantages of being able to rapidly perform cost-effective drug studies while also maintaining the ability to evaluate drug effectiveness while maintaining the MPNST tumor heterogeneity and recapitulating the tumor microenvironment.

Within this study, cell viability in 3D microtissues was assessed using Zeiss Axio Observer. In PDX drug studies, tumor volume was measured biweekly. Additionally, bulk RNA sequencing was performed to identify enriched pathways, providing insights into MPNST biology and potential therapeutic targets.

Results, Conclusions, and Discussions: Throughout this study, PDX was successfully generated into 3D microtissues and categorized based on viability: robust (>90% at 48h), good (>50%), and unusable ( < 50%). We evaluated drug responses in robust or good microtissues, revealing a correlation between ex vivo and in vivo drug responses, with enhanced effects observed in select models.

Additionally, we established 13 NF1-associated MPNST PDX models and identified structural abnormalities in NF1 (100%), SUZ12 (85%), EED (15%), TP53 (15%), CDKN2A (85%), and chromosome 8 gain (77%).

Data from this study conclude the fact that MPNST PDX can be established in a 3D microtissue environment and can be utilized for testing candidate drugs in MPNST. This will expand the horizons of precision oncology by being an innovative platform that allows researchers to complete comprehensive drug panel studies and understand the biological aspects of the tumor in a more physiologically relevant system. Future studies aim to explore new drug combinations and to clarify components of the tumor microenvironment that effectively condition drug response.

Currently, the pre-clinical platforms utilized for MPNST have relied heavily upon genetically engineered mouse models. With these models, however, there is a lack of representation of the full heterogeneity of genomic alterations that are present in-patient tumors. This limits the ability to translate findings into a clinical setting. To bridge the gap, we have created a PDX-based ex vivo 3D microtissue platform. Utilizing this system offers many advantages, including the opportunity to perform rapid, cost-effective drug studies, validate the effectiveness of drugs, and optimize the tumor microenvironment. This approach opens doors to the path of precision oncology. All of which can be achieved while maintaining the MPNST tumor heterogeneity.

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