Retrospective evaluation of the use of the International Myeloma Working Group response criteria in dogs with secretory multiple myeloma

Abstract

Background Current recommendations for monitoring disease progression and response to treatment in humans with multiple myeloma include evaluation of serum paraprotein (M‐protein) concentration. Densitometry, species‐specific radial immunodiffusion (RID) and ELISA methods can be used to quantify M‐proteins. Objective Retrospectively evaluate use of the International Myeloma Working Group (IMWG) response criteria for humans in dogs with multiple myeloma. Animals Sixteen dogs with a diagnosis of multiple myeloma, M‐protein documented by serum protein electrophoresis (SPE) and immunofixation (IF) in an initial sample and subsequent electrophoretic evaluation of serial samples. Methods Retrospectively, densitometric M‐proteins, RID and globulins were measured and characterized according to IMWG criteria. Available clinical history was reviewed. Overall survival time (OST) was calculated from initial electrophoretic evaluation to death or last contact. Results All cases received some form of nonstandardized chemotherapy. Complete response (CR), a lack of detectable M‐protein by SPE and IF, was documented in 1 case. Median survival was longer for dogs that attained ≥90% densitometric M‐protein reduction (630 days) than for those that did not attain at least 50% reduction in densitometric M‐protein (284 days; log rank P = .006). Five dogs were defined as having progressive disease (M‐protein increase of >25% and at least 0.5 g/dL from nadir), which correlated with concurrent or subsequent clinical deterioration. Response criteria categorized by serum globulins or RID was not correlated with OST or clinical findings. Conclusions and Clinical Importance Densitometric M‐protein characterized using IMWG response criteria correlated with OST and clinical findings. Densitometric M‐protein detection should be used to monitor dogs with multiple myeloma.

Diagnostic performance of routine electrophoresis and immunofixation for the detection of immunoglobulin paraproteins (M‐Proteins) in dogs with multiple myeloma and related disorders: Part 1 – Current performance

“…1 Detection of the immunoglobulin paraproteins produced by these neoplasms (M-proteins) allows the diagnosis and monitoring of MRD. 2 Serum immunoglobulin concentration and composition can be affected by several processes including infection, inflammation, and non-immunoglobulin secreting neoplasms. Some of these non-MRD related changes can complicate the diagnosis of M-proteins.…”

Method comparison for serum protein electrophoretic M‐protein quantification: Agarose gel electrophoresis and capillary zone electrophoresis in canine and feline sera

“…The CV I for M-protein in the dog or cat is unknown, but the human-based response criteria appear to be clinically applicable in dogs with multiple myeloma. 21 Nonetheless, using the current TEa estimate and available data, there appears to be a clinically significant difference between the methods, especially at lower concentrations, and these methods should not be used interchangeably.…”

Bite-size introduction to canine hematologic malignancies

“…Presenting clinical signs and clinicopathologic abnormalities in dogs with MM are ascribed either to direct tissue infiltration by neoplastic cells or associated paraneoplastic syndromes. Historically the diagnosis of MM is established by documenting the presence of at least two of the following: neoplastic marrow/organ/nodal infiltration, lytic skeletal lesions, and monoclonal gammopathy (M proteins) in the serum or urine 81 . Although one small series of dogs presenting with monoclonal gammopathy revealed MM to be the most frequent cause, other diseases including leishmaniasis and ehrlichiosis should be excluded 80 .…”