Genetically Defined, Syngeneic Organoid Platform for Developing Combination Therapies for Ovarian Cancer

SUMMARY The paucity of genetically informed, immune-competent tumor models impedes evaluation of conventional, targeted, and immune therapies. By engineering mouse fallopian tube (FT) organoids using lentiviral gene transduction and/or CRISPR/Cas9 mutagenesis, we generated multiple high grade serous ovarian carcinoma (HGSOC) models exhibiting mutational combinations seen in patients. Detailed analysis of homologous recombination (HR)-proficient ( Tp53 -/- ; Ccne1 OE ; Akt2 OE ; Kras OE ), HR-deficient ( Tp53 -/- ; Brca1 -/- ; Myc OE ) and unclassified ( Tp53 -/- ; Pten -/- ; Nf1 -/- ) organoids revealed differences in in vitro properties and tumorigenicity. Tumorigenic organoids had variable sensitivity to HGSOC chemotherapeutics and evoked distinct immune microenvironments. These findings enabled development of a chemotherapy/immunotherapy regimen that yielded durable, T-cell dependent responses in Tp53 -/- ; Ccne1 OE ; Akt2 OE ; Kras HGSOC; by contrast, Tp53 -/- ; Pten -/- ; Nf1 -/- tumors failed to respond. Genotype-informed, syngeneic organoid models could provide an improved platform for rapid evaluation of tumor biology and therapeutics. HIGHLIGHTS Orthotopic injection of genetically defined fallopian tube organoids yield HGSOC. Ovarian tumors with different genotypes evoke distinct immune microenvironments Combining Gemcitabine, anti-PD-L1, and anti-CTLA-4 result in complete responses in Tp53 -/- ; Ccne1 OE ; Akt2 OE ; Kras OE organoid-derived HGSOC Therapeutic response is tumor genotype-specific