Treatment options for advanced intra-abdominal pediatric rhabdomyosarcoma (RMS) with peritoneal sarcomatosis (PS) include cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). However, optimal dosages and combination regimens of drugs used for HIPEC are underexplored. We aimed to evaluate the efficacy of HIPEC with cisplatin, doxorubicin, and their combination in vivo. We established PS/RMS mouse model by intraperitoneally injecting RH30 cells into NOD/LtSz-scid IL2Rγ-null mice. Two weeks post xenotransplantation, mice underwent a single HIPEC procedure at 42°C for 60minutes. Treatment groups received cisplatin (50, 100, and 150mg/m2) and doxorubicin (30, 45, and 60mg/m2), administered alone or combined. The control group underwent an intraperitoneal lavage with isotonic saline. Peritoneal cancer index (PCI) was used to quantify the extent of peritoneal tumor spread. Tissue samples were evaluated regarding proliferation (Ki-67) and apoptosis (caspase 3). Mice treated with cisplatin at 100mg/m2 (PCI of 3.875, p=.007) and 150mg/m2 (PCI of 4.556, p=.026), and doxorubicin at 30mg/m2 (PCI of 2.875, p<.001) and 45mg/m2 (PCI of 4.143, p=.021) showed reduced PCI, with the combination of cisplatin 50mg/m2 and doxorubicin 30mg/m2 showing the most prominent effect (PCI of 3.333, p<.001) compared to the control group (PCI of 8.615). Histologically, there was no difference in Ki-67 or caspase 3 expression among the groups. The cisplatin- and doxorubicin-based HIPEC significantly reduces peritoneal tumor dissemination in vivo. Further investigations are needed to explore the underlying molecular responses to optimize therapeutic strategies.
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