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Updated: Jul 27, 2026
A Fluorescence-based Lymphocyte Assay Suitable for High-throughput Screening of Small Molecules
Published on: March 10, 2017
Exploratory high-throughput screening of repurposed drugs for canine lymphoid malignancies
Moe Nishida1, Hiroki Sakuma2, Misaki Ishida1
1Laboratory of Laboratory Animal Science, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuou-ku, Sagamihara, 252-5201, Kanagawa, Japan.
Background:
Lymphoid malignancies are common in dogs. However, the limitations of existing chemotherapy highlight the need for alternative therapies. Drug repositioning is a promising approach for discovering new therapies using existing drugs. In this study, we conducted high-throughput screening (HTS) of clinically used drugs to identify candidates with antiproliferative activity against canine lymphoid tumor cells in vitro.
Methods:
A total of 1,824 compounds were screened at 5 µM through HTS using a water-soluble tetrazolium assay in three canine lymphoid tumor cell lines (GL-1, UL-1, CLBL-1) and one non-tumorigenic epithelial cell line (MDCK). Compounds that selectively inhibited tumor cells while sparing the MDCK cells were retained as primary screening candidates. Compounds unsuitable for drug repositioning for cancer treatment, such as anticancer agents or topical formulations, were excluded from the study. The remaining compounds were reviewed based on literature-derived pharmacodynamic or clinical evidence and pharmacokinetic data in dogs. Selected candidates were subjected to secondary screening in which dose-dependent antiproliferative effects were evaluated. Half-maximal inhibitory concentration (IC₅₀) values were determined and compared with reported maximum plasma concentrations (Cmax) in dogs to assess the potential for achieving pharmacologically active concentrations in vivo.
Results:
Forty-five compounds were identified in a primary screening that showed tumor-selective inhibitory activity against lymphoid tumor cells. Based on the literature, five compounds (artesunate, niclosamide, pentamidine, itraconazole, and dronedarone) were selected for secondary screening. All the five compounds exhibited dose-dependent antiproliferative effects, and their IC₅₀ values were comparable to or below the reported Cmax in dogs.
Conclusions:
This exploratory screening study identified clinically approved drugs with available pharmacokinetic data as candidate therapeutic agents for the treatment of canine lymphoid malignancies. Based on this study, further studies are warranted to validate the in vivo efficacy and elucidate the underlying mechanisms of candidate drugs in canine lymphoid malignancies.
Insights
This study screened 1,824 drugs to find new cancer therapies for dogs. Five existing drugs showed promise in inhibiting canine lymphoid tumor cells, offering potential new treatments for canine lymphoid malignancies.
Area of Science:
- Veterinary Oncology
- Pharmacology
- Drug Discovery
Background:
- Canine lymphoid malignancies are prevalent, and current chemotherapy options have limitations.
- Drug repositioning offers a viable strategy for identifying novel therapeutic agents for canine cancers.
- High-throughput screening (HTS) enables the rapid evaluation of numerous compounds for antiproliferative activity.
Purpose of the Study:
- To identify existing, clinically approved drugs with antiproliferative activity against canine lymphoid tumor cells.
- To evaluate the potential of drug repositioning for developing new treatments for canine lymphoid malignancies.
- To assess the in vitro efficacy of selected drug candidates in canine lymphoid tumor cell lines.
Main Methods:
- A high-throughput screen of 1,824 compounds was performed on canine lymphoid tumor cell lines and a non-tumorigenic cell line.
- Compounds showing selective tumor cell inhibition were prioritized, excluding anticancer agents and topical formulations.
- Selected candidates underwent secondary screening to determine dose-dependent antiproliferative effects and IC₅₀ values.
Main Results:
- Forty-five compounds demonstrated selective inhibitory activity against canine lymphoid tumor cells in primary screening.
- Five compounds—artesunate, niclosamide, pentamidine, itraconazole, and dronedarone—were selected for secondary screening.
- All five compounds exhibited dose-dependent antiproliferative effects with IC₅₀ values comparable to or below reported canine Cmax.
Conclusions:
- This study identified clinically approved drugs as potential therapeutic agents for canine lymphoid malignancies.
- The identified drugs possess available pharmacokinetic data, facilitating further investigation in canine models.
- Further research is necessary to validate the in vivo efficacy and mechanisms of action of these candidate drugs.
