In the treatment of canine histiocytic sarcoma (CHS), a nitrosourea agent lomustine (CCNU) is often used. CCNU is a potent myelosuppressive agent and can cause cumulative dose-related irreversible hepatotoxicity, indicating a need of accurate dose adjustment. However, CCNU is an oral capsule drug, and thus, a fine dose adjustment is difficult. Nimustine (ACNU), the same nitrosourea agent, is an intravenous injection drug and its safety in dogs has been demonstrated in a phase I study. ACNU is therefore an attractive agent for the treatment of CHS. In this study, we thus examined the therapeutic potential of ACNU in the cases of CHS.
Nine CHS cases (with gross disease, n = 4; in the adjuvant setting, n = 5) were treated with ACNU (20-30 mg/m2) for 1-527 days. The therapeutic effects were evaluated by overall survival (OS) and progression-free interval (PFI). Tumor responses to ACNU were evaluated by c-RESIST v.1.0 criteria and/or by improvement of tumor-associated symptoms.
Median OS and median PFI were 256 days (range, 6 to >1286 days) and 131 days (range, 1 to >1286 days), respectively. Tumor responses of two cases with measurable disease were CR or SD. Of the five cases with tumor-associated symptoms, three were improved the symptoms.
In this study, median OS/PFI appeared similar to those reported in CHS treated with CCNU. Moreover, tumor regression and/or improvement of tumor-associated symptoms were observed in three dogs. ACNU could be potential therapeutic agent for CHS. Our results warrant further investigation of ACNU in larger clinical studies.
Nippon Veterinary and Life Science University
Thursday, June 14
5:15 PM – 5:30 PM
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