Comparison of two melphalan protocols and evaluation of outcome and prognostic factors in multiple myeloma in dogs

BACKGROUND: Multiple myeloma (MM) in dogs typically is treated with melphalan. A daily melphalan dosing schedule reportedly is well tolerated and associated with favorable outcome. Although anecdotally a pulse dose regimen has resulted in successful responses, little long‐term outcome and safety data is available regarding this dosing regimen for dogs with MM. HYPOTHESIS/OBJECTIVES: (1) To compare outcome and adverse event profiles between pulse dose and daily dose melphalan schedules and (2) to report prognostic factors in dogs with MM treated with melphalan. We hypothesized that both protocols would have similar outcomes and tolerability. ANIMALS: Thirty‐eight client‐owned dogs diagnosed with MM receiving pulse dose (n = 17) or daily dose (n = 21) melphalan. METHODS: Retrospective cohort study assessing outcome and adverse events in dogs receiving either protocol. Risk factors were evaluated for their prognostic relevance. RESULTS: Both regimens were well tolerated and similarly effective, with an overall median survival time of 930 days. Renal disease and neutrophil‐to‐lymphocyte ratio (NLR) were negative prognostic factors, whereas hypercalcemia and osteolytic lesions were not prognostic factors in this study population. CONCLUSIONS AND CLINICAL IMPORTANCE: Positive results support the use of either dosing regimen for the treatment of dogs with MM, and renal disease and NLR were negative prognostic factors. Prospective, controlled, and randomized studies are warranted to confirm these findings.