Nimustine Treatment of 11 Cases of Canine Histiocytic Sarcoma

Serum level of apoptosis inhibitor of macrophage in dogs with histiocytic sarcoma and its association with the disease

Histiocytic sarcoma (HS) is a rare neoplasm of macrophages or dendritic cells with a poor prognosis in dogs. As the apoptosis inhibitor of macrophage (AIM) is characteristically expressed in canine macrophages, we hypothesised that AIM is involved in the development or progression of HS in dogs. In this study, AIM expression in the tumour region and serum AIM levels in dogs with HS was assessed. Additionally, the effects of AIM overexpression on HS cell viability were investigated using a HS cell line that was selected from five validated HS cell lines. Immunohistochemistry showed that AIM expression was observed in the cytoplasm of the HS cells. CD36, a candidate AIM receptor, was also observed on the cell membrane of HS cells. When the serum AIM level was detected in 36 dogs with HS and 10 healthy dogs via western blot analysis, the AIM levels in the HS dogs were significantly higher than those in the controls. AIM mRNA expression in the 5 HS cell lines varied but was higher than that in the other tumour-derived lines. Among the five HS cell lines, DH82 originally had lower AIM and the highest CD36 expression. When AIM was overexpressed in DH82, therein cell growth speed and invasion, apoptosis inhibition and phagocytic activity were strongly upregulated. These data suggest that elevated intra-tumour expression of AIM could induce the progression of HS cells in dogs. Moreover, elevated serum AIM levels in dogs with HS could serve as a biomarker of HS.

Retrospective evaluation of nimustine use in the treatment of feline lymphoma

Background

Nimustine, similar to lomustine, is an alkylating agent from the nitrosourea family. There have been some reports regarding lomustine treatment for tumour‐bearing cats. However, information regarding nimustine treatment for tumour‐bearing cats is limited.

Objectives

To retrospectively evaluate adverse events and clinical outcomes in tumour‐bearing cats receiving nimustine.

Methods

Information regarding diagnosis, treatment condition, adverse events, and clinical outcomes was collected in tumour‐bearing cats receiving nimustine through reviews of medical records.

Results

Nine cats with lymphoma were treated with nimustine in the primary therapy (n = 2) and in the rescue therapy (n = 7). Median starting dose of nimustine was 25 mg/m² (range: 20–30 mg/m²) with dosing interval of three weeks and 1–11 administrations. Adverse events were mild gastrointestinal toxicity (grade 1) including diarrhoea (n = 2) and vomiting (n = 2) and mild myelosuppression (grade 1 or 2) including thrombocytopenia (n = 3) and neutropenia (n = 1). No severe adverse events were observed. Progression‐free survival durations among cats receiving nimustine in the primary therapy and in the rescue therapy were 274–688 days (median: 481 days) and 9–671 days (median: 102 days), respectively. Overall survival durations among cats receiving nimustine in the primary therapy and in the rescue therapy were 275–745 days (median: 510 days) and 14–671 days (median: 109 days), respectively.

Conclusions

Nimustine was well tolerated and showed clinical outcomes similar to lomustine in cats with lymphoma. These findings suggest that nimustine might be an alternative to lomustine in the treatment of feline lymphoma.