The efficacy and adverse event profile of dexamethasone, melphalan, actinomycin D, and cytosine arabinoside (DMAC) chemotherapy in relapsed canine lymphoma

In this retrospective study, a chemotherapy protocol using dexamethasone, melphalan, actinomycin D, and cytosine arabinoside (DMAC) was evaluated for efficacy and adverse event profile as a first line rescue protocol in 86 client-owned dogs previously treated with a CHOP-based protocol. Forty-three dogs (43%) achieved remission (16% complete remission, 27% partial remission), and 57% were non-responders. The median overall progression-free survival (PFS) was 24 days. Adverse events included thrombocytopenia in 41% of dogs, neutropenia in 17% of dogs, and gastrointestinal toxicity in 13% of dogs. Overall, 16% (13/79) dogs experienced grade III to IV thrombocytopenia, 8% (6/74) dogs grade III to IV neutropenia and 1% (1/79) dogs grade III to IV gastrointestinal toxicity. The efficacy of the DMAC protocol is similar to that of other rescue protocols in dogs with relapsed lymphoma but is associated with shorter PFS. The main toxicity is thrombocytopenia, which may limit treatment.