Multicenter, randomized, double‐blinded, placebo‐controlled study of rabacfosadine in dogs with lymphoma

BACKGROUND: Rabacfosadine (RAB, Tanovea‐CA1) is a novel chemotherapy agent conditionally approved for the treatment of lymphoma in dogs. HYPOTHESIS/OBJECTIVES: To determine the efficacy and safety of RAB in dogs with lymphoma. ANIMALS: One hundred and fifty‐eight client‐owned dogs with naïve or relapsed multicentric lymphoma were prospectively enrolled from January to October 2019. METHODS: Dogs were randomized to receive RAB or placebo at a 3 : 1 ratio. Treatment was given every 21 days for up to 5 treatments. Study endpoints included progression‐free survival (PFS), overall response rate (ORR) at a given visit, best overall response rate (BORR), and percent progression free 1 month after treatment completion. Safety data were also collected. RESULTS: The median PFS was significantly longer in the RAB group compared to placebo (82 vs 21 days; P < .0001, HR 6.265 [95% CI 3.947‐9.945]). The BORR for RAB‐treated dogs was 73.2% (50.9% complete response [CR], 22.3% partial response [PR]) and 5.6% (0% CR, 5.6% PR) for placebo‐treated dogs (P < .0001). One month after the last treatment, 37 RAB‐treated dogs (33%) were progression free compared with no placebo‐treated dogs (P < .0001). The most common adverse events observed in the RAB group were diarrhea (87.5%), decreased appetite (68.3%), and vomiting (68.3%) and were generally low grade and reversible. Serious adverse events were reported in 24 RAB‐treated (20%) and 5 placebo‐treated dogs (13%). CONCLUSIONS AND CLINICAL IMPORTANCE: Rabacfosadine demonstrated statistically significant antitumor efficacy in dogs with lymphoma when administered every 21 days for up to 5 treatments as compared to placebo.