Abstract 2415: Chloroquine disruption of autophagy: A new treatment for DCIS. (2013)

Abstract Background: Survival of intraductal, pre-invasive proliferating cells under stress may promote genetic instability and the selection of invasive carcinoma cells. Our analysis of the mechanisms used by DCIS cells to survive in the hypoxic, nutrient deprived intraductal niche has revealed autophagy as a therapeutic target. We hypothesize that the intraductal pre-neoplastic cellular niche will be preferentially sensitive to a short term, anti-autophagy based prevention therapy which targets survival pathways used by pre-invasive carcinomas. Our unique trial design offers a means to functionally screen investigational agents that kill premalignant breast lesions.Methods: DCIS spheroid forming cells have been isolated and propagated from fresh human DCIS lesions. We characterized the DCIS cells by organ culture, xenograft transplantation, molecular cytogenetics (300,000 SNPs) and 59 signal pathway profiling endpoints (Reverse Phase Protein Microarray (RPMA)). Results: Autophagy is a means for intraductal neoplastic cells, accumulating in the duct, to digest intracellular contents and generate energy to survive in the face of severe metabolic, oxidative, and hypoxic stress. DCIS spheroid forming cells were tumorigenic in xenograft models. Autophagy is up-regulated in: human DCIS lesions, DCIS spheroid-forming cells, and the xenograft tumors they generate. Suppression of autophagy by chloroquine kills human DCIS spheroid forming cells in culture and prevents them from forming tumors in xenografts (p&lt;.0003). Based on these preclinical insights our neoadjuvant therapy trial for DCIS patients with any stage/grade DCIS (NCT01023477 PINC Trial), examines the safety and effectiveness of oral chloroquine for 30 days. At the conclusion of treatment, all patients receive standard of care surgical therapy. MRI is performed before and after the treatment period. Endpoints compared before, versus after, therapy are: lesion shrinkage, pathologic regression, disruption of lesion autophagy and proliferation (PCNA), induction of apoptosis, and suppression of xenograft tumorigenicity. Each patient serves as her own control because effectiveness is judged by comparing the patient's DCIS lesion before and after therapy. Conclusions: We have identified the autophagy pathway as a therapeutic target for DCIS. Chloroquine, an inhibitor of autophagy, suppresses the growth and survival of DCIS progenitor, stem-like cells. Autophagy is necessary for survival of intra-ductal DCIS cells and provides justification for this PINC trial. Our initial PINC clinical trial results provide strong evidence that anti-autophagy therapy can generate a measurable reduction in DCIS proliferation index (PCNA) within 4 weeks. In addition to justifying the trial design, these data suggest that at least a subset of DCIS cases may respond to oral chloroquine. Citation Format: Virginia A. Espina, Kirsten Edmiston, Emil Kamar, Geetha Menezes, Hassan Nayer, Lance A. Liotta. Chloroquine disruption of autophagy: A new treatment for DCIS. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2415. doi:10.1158/1538-7445.AM2013-2415