Alternating rabacfosadine and doxorubicin for treatment of naïve canine lymphoma.

The current standard of care treatment for canine lymphoma is a multi-agent, CHOP-based chemotherapy protocol. Single agent doxorubicin (DOX) is less burdensome; however, multi-agent chemotherapy protocols are often superior. The recently approved drug rabacfosadine (RAB, Tanovea) provides an attractive option for combination therapy with DOX, as both drugs demonstrate efficacy against lymphoma and possess different mechanisms of action. A previous study evaluating alternating RAB/DOX reported an overall response rate (ORR) of 84%, with a median progression-free survival time (PFS) of 194 days. The aim of this prospective trial was to evaluate the same protocol in an additional population of dogs. Fifty-nine dogs with treatment naïve lymphoma were enrolled. RAB (1.0 mg/kg IV) was alternated with DOX (30 mg/m2 IV) every 21 days for up to six total treatments (3 cycles). Response assessment and adverse event (AE) evaluation were performed every 21 days using VCOG criteria. The ORR was 93% (79% CR, 14% PR). The median time to maximal response was 21.5 days; median PFS was 199 days. T cell immunophenotype and lack of treatment response were predictive of inferior outcomes. AEs were mostly gastrointestinal. Six dogs developed presumed or confirmed pulmonary fibrosis; four were grade 5. One dog experienced grade 3 extravasation injury with RAB that resolved with supportive treatment. These data mirror those of the previously reported RAB/DOX study, and support the finding that alternating RAB/DOX is a reasonable treatment option for canine lymphoma.