Abstract
Artemisinin from Artemisia annua L. and its derivatives are well‑known antimalarial drugs. In addition, in vitro studies, in vivo studies and clinical trials have demonstrated that these drugs exhibit anticancer activity in human patients with cancer. Therefore, the aim of the present study was to investigate whether a phytotherapeutic A. annua preparation exerts anticancer activity in veterinary tumors of small pets. Dogs and cats with spontaneous cancer (n=20) were treated with standard therapy plus a commercial A. annua preparation (Luparte®) and compared with a control group treated with standard therapy alone (n=11). Immunohistochemical analyses were performed with formalin‑fixed paraffin‑embedded tumor biopsies to analyze the expression of transferrin receptor (TfR) and the proliferation marker Ki‑67 as possible biomarkers to assess treatment response of tumors to A. annua. Finally, the expression levels of TfR and Ki‑67 were compared with the IC50 values towards artemisinin in two dog tumor cells lines (DH82 and DGBM) and a panel of 54 human tumor cell lines. Retrospectively, the present study assessed the survival times of small animals treated by standard therapy with or without A. annua. A. annua treatment was associated with a significantly higher number of animals surviving >18 months compared with animals without A. annua treatment (P=0.0331). Using a second set of small pet tumors, a significant correlation was identified between TfR and Ki‑67 expression by immunohistochemistry (P=0.025). To further assess the association of transferrin and Ki‑67 expression with cellular response to artemisinin, the present study compared the expression of these two biomarkers and the IC50 values for artemisinin in National Cancer Institute tumor cell lines in vitro. Both markers were inversely associated with artemisinin response (P<0.05), and the expression levels of TfR and Ki‑67 were significantly correlated (P=0.008). In conclusion, the promising results of the present retrospective study warrant further confirmation by prospective studies in the future.