Whole Genome Sequencing of Leiomyosarcoma to Identify Therapeutic Opportunities
Leiomyosarcoma (LMS) encompasses a genetically heterogeneous group of malignant neoplasms differentiating along smooth muscle lines. LMS is a common adult sarcoma whose outcome is limited by metastatic failure (Ann Surg Oncol. 2013, PMID: 23354568, Link here). Currently, treatment is not informed by molecular subtyping and is associated with highly variable survival rates. While disease site represents an important prognostic factor, the contribution of genetic factors remains mostly unknown.
Thus, the overall goal of our LMS program is to perform comprehensive whole genome sequencing (WGS) and transcriptomic profiles to identify and validate actionable targets/pathways in primary and metastatic LMS. Our genomics approach, in collaboration with Dr. Adam Shlien at the Hospital for Sick Children, is focused on understanding the molecular signatures of primary tumors compared to their matched metastasis to determine what the common and disparate mechanisms are. This knowledge will be used to determine the clonal evolution and architecture of LMS.
Previously, we have performed drug screen to identify NVP-BEZ235 as an effective compound in combating LMS. “PI3K/AKT/mTOR inhibition in combination with doxorubicin is an effective therapy for Leiomyosarcoma” (Journal of Translational Medicine, 2016, PMID: 26952093, Link here).
Metabolic Reprogramming in Sarcoma
Undifferentiated pleomorphic sarcoma (UPS) is one of the most common adult soft tissue sarcoma subtypes that is derived from an unknown lineage. Unfortunately, UPS often metastasizes and there are currently no effective system therapeutic options. We performed a comprehensive drug screen (>3,300 compounds) in UPS to identify a new novel therapy. We validated and triaged several compounds, in particular simvastatin – an anti-cholesterol agent that inhibits the rate limiting enzyme in the mevalonate (MVA) pathway. Simvastatin appears to be highly effective in UPS and other high-grade sarcomas, such as LMS. Our group and others have documented that PI3K/mTOR signaling is dysregulated in LMS. Dysregulation of proliferative pathways is involved in metabolic reprogramming, an emerging hallmark of cancer that occurs when cellular metabolism is altered to provide the energy and the essential building blocks that are required to maintain the aberrant survival and growth that is seen in cancer.
We are working on determining if dysregulation of the PI3K/mTOR pathway and/or the MVA pathway render certain high-grade sarcomas sensitive to simvastatin.
Functional-Omics in pediatric sarcoma: translating mechanism into novel therapies / Epigenetic chemical screens to identify novel therapeutic strategies for rhabdomyosarcoma
Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children and adolescents. Despite treatment with chemotherapy, radiation and/or surgery, >70% of high-risk patients have poor outcome, with little improvement over the past decade. The two most common histological RMS subtypes are embryonal (ERMS) and alveolar (ARMS), the latter of which is defined by PAX3-FOXO1 or PAX7-FOXO1 gene fusions.
Although the genomic landscape of RMS is well characterized, epigenetic vulnerability is emerging as a novel potential therapeutic target. We are currently validating epigenetic compounds for RMS.
RMS Murine Models
We have established novel murine models of RMS using mosaicism, whereby the cell of origin is isolated, lentivirally transduced with specific genes and injected into host mice to assess sarcoma formation. Our initial models generated high-grade sarcomas by activating RAS signaling (Oncotarget, 2015, PMID: 25992772 Link here). Specifically, we validated that FGFR4 mutations are oncogenic in RMS and went on to use this system to identify novel treatment agents (Oncogene, 2018 Pubmed link: 29487419 Link here).
Magnetic resonance imaging (MRI) guided high intensity focused ultrasound-controlled hyperthermia to activate thermosensitive liposomal doxorubicin to treat rhabdomyosarcoma (RMS) in mouse models.
In cases of relapsed or metastatic RMS chemotherapies include doxorubicin, which is cardiotoxic. An alternate form of doxorubicin has been developed that is encapsulated in a thermosensitive liposome (TLD). Magnetic resonance guided high intensity focused ultrasound (MRgHIFU) is an emerging therapy that combines visualization using MRI and computational control of the ultrasound, which generates localized hyperthermia.
We are currently pursuing this as a possible treatment for RMS through testing on our mouse models. We are evaluating the effectiveness of the treatment compared to vincristine, the first line standard of care chemotherapy, and doxorubicin. This project is in collaboration with the Center for Image Guided Innovation and Therapeutic Intervention at SickKids, the Spatio-Temporal Targeting and Amplification of Radiation Response Program at UHN, the Leslie Dan Department of Pharmacy at the University of Toronto and the University of Calgary. Our multidisciplinary team engages expertise from engineering, computer programming, imaging, pre-clinical RMS mouse models, pharmacy, and medical oncology.
The Gladdy lab is involved with the management and execution of ongoing clinical trials and research projects through the Toronto Sarcoma clinical research group. Dr. Gladdy and her team connect the patient experience to the laboratory through patient consent for research, collection of clinical specimens and annotation of all specimens collected within the Toronto Sarcoma Clinical Database. Through this, Dr. Gladdy and her team have established many multi-institutional projects involving clinically annotated cell lines and tumor samples throughout the international sarcoma community.
The Toronto Sarcoma Clinical Research Group is actively involved with projects through the Transatlantic Australasia Retroperitoneal Sarcoma Group and the Canadian Sarcoma Research and Clinical Collaboration.