Abstract B062: CRO67 has therapeutic potential against pancreatic tumor cells and cancer associated fibroblasts
Authors: Netto Keilah Garcia , Chiang Shannon , Kokkinos John , Haghighi Koroush S. , Raina Aparna , Pitiyarachchi Omali , Youkhana Janet , Truong Quach , Wenholz Daniel , Li Xiang , Laczka Olivier , Kumar Naresh , Wilkinson John , Goldstein David , Sharbeen George , Phillips Phoebe A. 
Published: January 2024

Abstract
Background: Pancreatic ductal adenocarcinoma (PDAC) is highly resistant to therapy. Stromal cancer-associated fibroblasts (CAFs) play a key role in promoting tumor progression and chemoresistance, by creating a fibrotic microenvironment that impedes drug access and feeds PDAC cells nutrients and pro-tumor signals. CRO-67 (Patent PCT/AU2023/050505) is a novel drug developed with Noxopharm Ltd using a rational medicinal chemistry design to improve bioavailability of chromans which have potent anti-cancer activity. Using our patient-derived PDAC tumor in a dish model (explants; maintain multicellular architecture and fibrosis) we previously showed that CRO-67 has both anti-tumor and CAF reprogramming capacity in 4 patient explants [Cancer Res (2022) 82 (22_Supplement):C073]. Aims: 1) To expand evaluation of CRO-67 in additional patient-derived PDAC tumor explants given PDAC heterogeneity. 2) Assess the effect of CRO-67 on PDAC cell and CAF function. 3) Validate the therapeutic potential of CRO-67 on PDAC growth in vivo. Methods: 1) PDAC tumor samples collected from 7 patients undergoing pancreatic resection. Tumor explants (1–2mm diameter) were cultured on gelatin sponges, treated with CRO-67 (0–50μg/mL) every 3 days and fixed on day 12. Therapeutic response assessed by immunohistochemistry for cytokeratin (PDAC cells), α-smooth muscle actin (CAFs), bromodeoxyuridine (proliferation) and TUNEL (cell death). 2) PDAC cells (MiaPaCa-2) and patient-derived CAFs were treated with CRO-67 (1.5μM) for 48h before proliferation analysis (IncuCYTE S3) and for 24h before apoptosis (Annexin V/DAPI staining; flow cytometry) and cell cycle (DAPI staining; flow cytometry) analysis. 3) Subcutaneous PDAC (BxPC3 human cells) tumors in mice were treated with CRO-67 (2.5mg/kg Intraperitoneally, twice a day) for 21 days and tumor volume measured (calipers). Results: 1) CRO-67 treatment decreased tumor and CAF cell frequency in 6/6 (no quantifiable tumor in patient 7 explants) and 7/7 patient PDAC explants, respectively. It also decreased explant cell proliferation and increased cell death versus controls. 2) CRO-67 completely abolished proliferation of MiaPaCa-2 and reduced the average growth rate of CAFs by 81.3±8.8% (p=0.0025; n=5), increased apoptosis in MiaPaCa-2 by 455.7±21.4% (p=0.003; n=3) and in CAFs by 172.6±13.1% (p=0.0067; n=5) and increased the fraction of cells in G2/M cell cycle phase by 163.8±12.8% (p&lt;0.0001; n=3) in MiaPaCa-2 and by 74.6±8.6% (p=0.0015; n=5) in CAFs versus controls. 3) CRO-67 reduced PDAC tumors in vivo by 56.7±6.6% (p=0.0013; n=9 mice/group) versus controls. Conclusions: CRO-67: 1) reduced PDAC cells and CAFs in human PDAC explants via reduced proliferation and increased death; 2) reduced proliferation of PDAC cells and CAFs in vitro, increased apoptosis and disrupted cell cycle progression through G2/M phase; 3) reduced PDAC tumor growth in vivo. Implication: We predict CRO-67 is a potential ‘dual cell’ therapy with direct anti-tumor effects and CAF reprogramming capacity, warranting further investigation in vivo.
Citation Format: Keilah Garcia Netto, Shannon Chiang, John Kokkinos, Koroush S. Haghighi, Aparna Raina, Omali Pitiyarachchi, Janet Youkhana, Quach Truong, Daniel Wenholz, Xiang Li, Olivier Laczka, Naresh Kumar, John Wilkinson, David Goldstein, George Sharbeen, Phoebe A. Phillips. CRO67 has therapeutic potential against pancreatic tumor cells and cancer associated fibroblasts [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B062.