E179: Patient-Derived Organoids Reveal Intrapatient Drug Response Heterogeneity in Pancreatic Neuroendocrine Liver Metastases

Pancreatic neuroendocrine tumors (PNETs) often present at diagnosis with extensive bilobar liver metastases. We sought to evaluate drug response heterogeneity in multi-focal PNET liver metastases using patient-derived organoids (PDOs).

Methods:

Liver metastasis tissue biopsies were obtained from patients with multifocal metastatic PNETs. Tumor cells were suspended in an extracellular matrix gel for long-term PDO culture and pharmacologic treatment testing. Immunohistochemistry (IHC) demonstrated expression of PNET markers in PDOs, correlating with patient matched tissues. Drug sensitivity testing was completed with FDA-approved drugs or drugs in current clinical trials for PNETs including everolimus, capecitabine:temozolomide (CAPTEM), cabozantinib, sunitinib, and carfilzomib. PDOs were treated for 96-hours. Drug response was measured by post-treatment viability using CellTiter-Glo. Qualitative analysis post-treatment was completed via fluorescent imaging assessing for viability.

Results:

Establishment rate for PNET liver metastasis organoids was 72.7% (8/11). Intra-patient heterogeneity to drug was demonstrated with identification of at least one out of four liver lesions that was relatively resistant. For Patient A, liver lesion 3 (LL3) had a 3 to 20-fold decreased drug response to everolimus (IC₅₀=24.0µM) and a 2 to 3-fold decreased response to CAPTEM (IC₅₀=29.3µM) compared to other liver lesions. However, liver lesion 1 (LL1) demonstrated a 20 to 100-fold superior drug sensitivity with everolimus (IC₅₀=36nM). For Patient B, liver lesion 4 (LL4) demonstrated no drug response to CAPTEM and a 2-fold decreased sensitivity to everolimus (IC₅₀=24.0µM). Conversely, liver lesion 3 (LL3) in Patient B showed a 100-fold increased drug sensitivity to everolimus (IC₅₀=9.9nM) and a 10-fold increased drug sensitivity to sunitinib (IC₅₀=30nM). Despite heterogenous response with other antitumoral agents, carfilzomib demonstrated drug response efficacy in all metastatic liver tumors (IC₅₀=0.88-3.40nM for Patient A, IC₅₀=4.23-13.7nM for Patient B).

Conclusions:

Patient-derived organoids of patients presenting with advanced PNET liver metastases demonstrate intra-patient tumor heterogeneity as measured by drug sensitivity. This data carries implications for the use of PDOs to select personalized therapies.