Identification of Novel Therapeutic Agent Candidates Through High Throughput Screening With Chemical Library Based on Molecular Subclassification in Canine Histiocytic Sarcoma Cell Lines.

Effective chemotherapy for canine histiocytic sarcoma (CHS) has yet to be established. In our previous study, CHS cell lines were subclassified into two groups based on their gene expression profiles: Group A and Group B. This study aimed to identify novel therapeutic agents that are effective against each CHS subgroup, and we performed high throughput screening, which examined the effects of 1824 chemical compounds on the 10 CHS cell lines. Among the compounds examined, 73 compounds were identified as candidates to show antiproliferative effects in all CHS cell lines examined, and the median IC50 values of 5-fluorouracil and sunitinib were 7.49 μM and 608 nM, respectively, across all CHS cell lines. While there was no compound that was specifically effective for Group B CHS cell lines, duvelisib was identified as a selective antitumor agent for CHS cell lines in Group A (median IC50 = 287 nM), with minimal effects on the other group (median IC50 > 5 μM) and normal peripheral blood mononuclear cells (IC50 = 7.46 μM). The amount of phosphorylated Akt protein decreased following duvelisib treatment in all eight CHS cell lines in Group A, but not in cell lines in Group B. Furthermore, duvelisib induced cell cycle arrest and increased cell death in a subset of Group A cell lines. These findings demonstrated that duvelisib exerted antiproliferative effects through inhibition of the Akt pathway in a subset of CHS cell lines while causing minimal cytotoxicity to normal cells.