Effects of TKIs on viability and CSC enrichment in short term ex vivo culture of resected clinical sarcoma tumors. A. (Left) High power view shows moderately differentiated recurrent renal vein leiomyosarcoma from patient SA-0689. Freshly digested tumor cells were exposed to increasing doses of sorafenib for 16 – 18 hours and then analyzed by flow cytometry for viability and ALDH expression using 7AAD and ALDEFLUOR™, respectively. (Middle) Ex vivo tumor cell viability was significantly inhibited at ≥16 μM of sorafenib. (Right) Significant enrichment of ALDHbright sarcoma cells was observed at sorafenib doses of 8 and 16 μM. B. (Left) High power view shows highly cellular, non-lipogenic dedifferentiated liposarcoma from patient CCS0015-010, confirmed by MDM2 overexpression. (Middle) Sorafenib significantly decreases ex vivo tumor viability at 32 and 64 μM, while simultaneously enriching for ALDHbright sarcoma cells doses ≥64 μM (Right). C. (Left) High power view shows poorly-differentiated high grade leiomyosarcoma from patient CCS0015-012 exposed to sorafenib, regorafenib, and pazopanib. (Middle) Cell viability was significantly inhibited at ≥16 μM of sorafenib and regorafenib, while no significant differences were observed following pazopanib exposure. (Right) Significant enrichment of ALDHbright sarcoma cells was observed following sorafenib and regorafenib exposure, while negligible differences were observed with pazopanib. D. (Left) High power view shows benign leiomyoma from patient SA-0624. No significant effects on cell viability (Middle) nor on ALDHbright CSCs (Right) were observed following exposure to increasing doses of sorafenib. All experiments were performed in triplicate. *P < 0.05, **P < 0.01, and *** P < 0.001 via one-way ANOVA with Tukey’s post-test compared to dose level 0.