Abstract 2152: Optimizing therapies for drug-resistant ovarian cancer stem cells using aCAM-PDX model
Authors: Contreras Altagracia , Shahin Sophia Allaf , Ratliff Laura E. , Simargi Shirleen I. , Wang Ruining , Vu Binh , Dellinger Thanh H. , Zink Jeffrey I. , Tamanoi Fuyuhiko , Unternaehrer-Hamm Julia , Glackin Carlotta A. 
Published: August 2018

Purpose: To develop rapidly operational CAM-PDX (chorioallantoic membrane-patient derived xenograft) tumor models that morphologically resemble human tumors in order to perform therapeutic/efficacy studies targeting TWIST, a transcription factor expressed in cancer stem cells critical to embryonic development, and aberrantly activated in many cancers. This CAM-PDX model was used to optimize mesoporous silica nanoparticle with hyaluronic acid (MSN-HA) and siTWIST in combination with cisplatin, as well as screen other drug therapies (e.g., doxorubicin) that will benefit ovarian cancer patients.

Experimental Procedures: Fertilized eggs were obtained from AA Lab Eggs, Inc. The eggs were incubated for 10 days at 100°F and 60% humidity. At day 10, a small window was opened on the surface of the egg and the CAM was dropped. A teflon ring was inserted, 50µg/µL of cancer cells (1 million cells) were deposited, and the window was covered with transparent film dressing and replaced in the incubator. 120µL of siTWIST (with MSN-HA) and/or 100µL of cisplatin were administered intravenously (day 13 and 14, respectively). On day 17, the eggs were imaged using Leica microscope. The CAM-PDX models were developed first with standard EOC cell lines and second using primary cells from patient tissues transfected with eGFP/ffluc for imaging growth, histology, and tumor biodistribution studies. Toxicity studies were performed by administering doxorubicin at varying doses and with different nanoparticle delivery methods.

Results: The study showed that we were able to grow patient-derived tumors in the egg CAM model. Moreove,r a histologic comparison of CAM tumors and ovarian patient tumors reveals highly similar morphology. Furthermore, when treated with chemotherapy, the tumor regressed, as it does in patients. Our toxicity study demonstrates that surrounding organs, as well as the embryo, were spared from detrimental off-target effects of doxorubicin when the drug was delivered inside nanoparticles, as opposed to free-drug, as demonstrated by final egg survivability count. Images show free-drug administration of doxorubicin damaged organs in the peritoneal cavity while nanoparticle administration of doxorubicin resulted in a clean cavity and sound organs. Our study also shows that our siTWIST MSN-HA sensitized drug-resistant cancer stem cells to cisplatin. Finally, our results also show that the optimal treatment for tumor dissemination in the PDX-CAM system is the combination of siTWIST MSN-HA and cisplatin compared to cisplatin alone.

Conclusions: This study provides a much-needed, cost-effective means to grow PDX lines from patient tissues. The CAM-PDX system provides a faster means of collecting information on the efficacy of novel MSNs for the delivery of siRNA and drugs than expensive mouse models. Thus, the CAM-PDX model is beneficial toward moving us closer to translation and application in other cancers.

Citation Format: Altagracia Contreras, Sophia Allaf Shahin, Laura E. Ratliff, Shirleen I. Simargi, Ruining Wang, Binh Vu, Thanh H. Dellinger, Jeffrey I. Zink, Fuyuhiko Tamanoi, Julia Unternaehrer-Hamm, Carlotta A. Glackin. Optimizing therapies for drug-resistant ovarian cancer stem cells using aCAM-PDX model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2152.