Project 2: Perineural Invasion

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal malignancies, with a five-year survival rate of 13%. PDAC is characterized by early metastasis and intrinsic therapy resistance. Combination chemotherapy with FOLFIRINOX (5-fluorouracil, leucovorin, irinotecan, and oxaliplatin) or gemcitabine plus albumin-bound (nab-) paclitaxel represents the standard first-line treatment, while gemcitabine plus nab-paclitaxel is frequently employed in patients who are unable to tolerate FOLFIRINOX. The tumor microenvironment (TME) of PDAC is defined by a dense desmoplastic stroma dominated by cancer-associated fibroblasts (CAFs), which markedly increase intratumoral pressure, resulting in vascular compression and vessel collapse. In parallel, the TME is profoundly immunosuppressive, enriched in regulatory T-cells, tumor-associated macrophages and myeloid-derived suppressor cells, promoting immune evasion and therapy resistance. In addition to stromal and immune components, nerves constitute a functionally relevant component of the TME. They contribute to perineural invasion (PNI), a pathological hallmark of PDAC histopathologically found in nearly 100% of cases. PNI is characterized by tumor cell invasion of neural structures along the epineural, perineural and endoneural layers, which creates a tumor-neural niche within the TME. PNI is strongly associated with cancer-associated pain driven by neuroinflammation and nerve injury. Moreover, PNI correlates with a higher risk of local recurrence after surgical resection. Clinically, PNI is an important prognostic factor correlating with reduced overall and disease-free survival. Increasing evidence suggests that PNI is a neurobiologically driven process in which tumor cells promote nerve growth within the TME. Conversely, nerves recruit tumor cells via chemotactic signaling. These bidirectional interactions shape a distinct tumor-neural niche that sustains PNI. However, the precise mechanisms remain incompletely understood.

We assess the functional consequences of tumor invasiveness within the tumor-neural niche. To this end, a co-culture invasion model composed of primary Schwann cells and pancreatic cancer cells was employed, and a significant increased number of invaded pancreatic cancer cells in the co-culture was observed. Furthermore, we demonstrated pronounced axon-guided tumor invasion by co-culturing pancreatic cancer spheroids and iPSC-derived sensory neurons. By leveraging the first 3D PNI model, this model provides a robust platform for sequencing and transcriptomic analyses, thereby enabling comprehensive molecular interrogation of tumor–nerve interactions.