Genome-scale CRISPR/Cas9 screen determines factors modulating sensitivity to ProTide NUC-1031

Area of Science:

• Oncology
• Cancer Therapeutics
• Drug Development

Background:

• Gemcitabine, a key chemotherapy, has limited efficacy in pancreatic cancer due to resistance.
• Intrinsic and acquired resistance mechanisms reduce gemcitabine's impact on patient survival.
• NUC-1031 (Acelarin) is a novel phosphoramidate prodrug of gemcitabine, designed to overcome resistance.

Purpose of the Study:

• To investigate the in vitro cytotoxicity differences between gemcitabine and NUC-1031.
• To identify genetic factors influencing cancer cell sensitivity to NUC-1031 using CRISPR/Cas9 screening.
• To evaluate the prognostic significance of deoxycytidine kinase (dCK) expression in patients treated with gemcitabine versus NUC-1031.

Main Methods:

• In vitro cytotoxicity assays comparing gemcitabine and NUC-1031.
• Genome-wide CRISPR/Cas9 genetic screening to identify sensitivity modifiers.
• Immunohistochemical analysis of deoxycytidine kinase expression in patient tumor biopsies.
• Correlation analysis of dCK expression with patient prognosis in gemcitabine and NUC-1031 treated cohorts.

Main Results:

• NUC-1031 exhibits distinct in vitro cytotoxicity compared to gemcitabine.
• Pyrimidine metabolism pathway was identified as a key determinant of NUC-1031 sensitivity via CRISPR/Cas9 screening.
• Low deoxycytidine kinase expression correlates with poor prognosis in gemcitabine-treated patients.
• No correlation between deoxycytidine kinase expression and prognosis was observed in NUC-1031-treated patients.

Conclusions:

• NUC-1031 demonstrates differential sensitivity and resistance mechanisms compared to gemcitabine.
• The pyrimidine metabolism pathway is crucial for NUC-1031's anti-cancer activity.
• Deoxycytidine kinase expression may serve as a predictive biomarker for gemcitabine but not for NUC-1031 therapy.