What is Leiomyosarcoma?
Leiomyosarcoma (LMS) is a type of soft-tissue sarcoma, referred to as a malignant smooth muscle tumor, which can arise in several locations within the body.1 Soft-tissue sarcomas are heterogeneous comprising more than 70 histologic subtypes.2 Leiomyosarcoma accounts for approximately 5-10% of all soft tissue sarcomas and affects a variety of organ systems, including the abdomen, retroperitoneum, large blood vessels, gastrointestinal tract and uterus.1,3
Leiomyosarcoma often presents as enlarging masses. Symptoms are typically non-specific, caused by displacement of structures in specific parts of the body where the tumor and its metastases are located.4 In retroperitoneal leiomyosarcoma, which accounts for about 50% of all leiomyosarcomas, symptoms may include swelling, pain, weight loss, nausea and vomiting.5
Leiomyosarcoma typically develops when the patient is in their 50s or 60s, although it can be present in children.3,6 Leiomyosarcoma is highly unpredictable and resistant to treatment and can recur in later stages of life.1
How Common is LMS?
LMS is a rare disease with 1.2 cases per 100,000 person-years.7 Approximately 4,000 patients are diagnosed each year in the U.S.8 Women are at a higher risk for leiomyosarcoma with 2:1 incidence in females compared to males.3
How is PTC Working to Treat LMS?
PTC596 is an orally bioavailable small molecule tubulin inhibitor that arrests tumor cells, including cancer stem cells, in the G2/M cell cycle phase, through the action of inhibiting tubulin polymerization.9
PTC is currently recruiting for a leiomyosarcoma clinical trial called SunriseLMS.
 Singh Z. J Cancer Res Pract 2018;5(1):1–8.
 Pankova, Valeriya et al. The Extracellular Matrix in Soft Tissue Sarcomas: Pathobiology and Cellular Signalling. Frontiers in cell and developmental biology 2021; 9 763640 doi:10.3389/fcell.2021.763640.
 Saluja TS, Iyer J, Singh SK. Leiomyosarcoma: Prognostic outline of a rare head and neck malignancy. In: Ferris R, ed. Oral Oncology. Philadelphia: Elsevier;2019:100–105.
 George S, Serrano C, Hensley ML, et al. J Clin Oncol 2018;10;36(2):144–150.
 Golden T, Stout AP. Smooth muscle tumors of the gastrointestinal tract and retroperitoneal tissues. Surg Gynecol Obstet 73:784, 1941.
 De Saint Aubain Somerhausen N, Fletcher C. Leiomyosarcoma of Soft Tissue in Children: Clinicopathologic analysis of 20 cases. Am J Surg Pathol, 23(7):755, 1999.
 Toro JR, Travis LB, Wu HJ, et al. Int J Cancer 2006 15;119(12):2922–2930.
 Ries LAG, Young JL, Keel GE, Eisner MP, Lin YD, Horner M-J (editors). SEER Survival Monograph: Cancer Survival Among Adults: U.S. SEER Program, 1988–2001, Patient and Tumor Characteristics. National Cancer Institute, SEER Program, NIH Pub. No. 07-6215, Bethesda, MD, 2007.
 Jernigan F, et al. Preclinical and Early Clinical Development of PTC596, a Novel Small-Molecule Tubulin-Binding Agent. Molecular Cancer Therapeutics. 2021;20:1846-1857. Published OnlineFirst July 26, 2021; DOI: 10.1158/1535-7163.MCT-20-0774.