Development of novel methods for non-canonical myeloma protein analysis with an innovative adaptation of immunofixation electrophoresis, native top-down mass spectrometry, and middle-down de novo sequencing.

OBJECTIVES: Multiple myeloma (MM) is a malignant plasma cell neoplasm, requiring the integration of clinical examination, laboratory and radiological investigations for diagnosis. Detection and isotypic identification of the monoclonal protein(s) and measurement of other relevant biomarkers in serum and urine are pivotal analyses. However, occasionally this approach fails to characterize complex protein signatures. Here we describe the development and application of next generation mass spectrometry (MS) techniques, and a novel adaptation of immunofixation, to interrogate non-canonical monoclonal immunoproteins. METHODS: Immunoprecipitation immunofixation (IP-IFE) was performed on a Sebia Hydrasys Scan2. Middle-down de novo sequencing and native MS were performed with multiple instruments (21T FT-ICR, Q Exactive HF, Orbitrap Fusion Lumos, and Orbitrap Eclipse). Post-acquisition data analysis was performed using Xcalibur Qual Browser, ProSight Lite, and TDValidator. RESULTS: We adapted a novel variation of immunofixation electrophoresis (IFE) with an antibody-specific immunosubtraction step, providing insight into the clonal signature of gamma-zone monoclonal immunoglobulin (M-protein) species. We developed and applied advanced mass spectrometric techniques such as middle-down de novo sequencing to attain in-depth characterization of the primary sequence of an M-protein. Quaternary structures of M-proteins were elucidated by native MS, revealing a previously unprecedented non-covalently associated hetero-tetrameric immunoglobulin. CONCLUSIONS: Next generation proteomic solutions offer great potential for characterizing complex protein structures and may eventually replace current electrophoretic approaches for the identification and quantification of M-proteins. They can also contribute to greater understanding of MM pathogenesis, enabling classification of patients into new subtypes, improved risk stratification and the potential to inform decisions on future personalized treatment modalities.

Multiple myeloma with central nervous system relapse.

Central nervous system involvement in multiple myeloma is a rare complication but carries a very poor prognosis. We provide a review of current literature, including presentation, treatment and survival data, and describe our experience in a regional hematologic malignancy diagnosis center where, over a 15-year period, ten cases were identified. Although the median age of onset, frequently between 50-60 years, is comparatively young, those diagnosed usually have a preceding diagnosis of multiple myeloma and often have had several lines of treatment. We discuss putative underlying factors such as prior treatment and associations including possible risk factors and features suggestive of a distinct biology. Central nervous system involvement may be challenging to diagnose in myeloma, displaying heterogeneous symptoms that can be confounded by neurological symptoms caused by the typical features of myeloma or treatment side-effects. We discuss the clinical features, imaging and laboratory methods used in diagnosis, and highlight the importance of considering this rare complication when neurological symptoms occur at presentation or, more commonly, during the disease pathway. In the absence of clinical trial data to inform an evidence-based approach to treatment, we discuss current and novel treatment options. Finally, we propose the establishment of an International Registry of such cases as the best way to collect and subsequently disseminate presentation, diagnostic and treatment outcome data on this rare complication of multiple myeloma.

The role of the laboratory in the diagnosis of an unusual case of Waldenstrom's macroglobulinaemia that lacked the common clinical features: A case report.

Lymphoplasmacytic lymphoma (LPL) is a neoplasm of small B lymphocytes, plasmacytoid lymphocytes and plasma cells usually involving the bone marrow (BM). A subset of LPL which is associated with IgM monoclonal gammopathy is called Waldenstrom's macroglobulinaemia (WM), and usually requires therapeutic intervention when a patient becomes symptomatic (Bone Marrow failure characterised by cytopenia or hyperviscosity syndrome). Here, we report the case of an 80-year-old female with clinically unsuspected WM who initially presented to the Emergency Department (ED) with nausea and vomiting. The patients' gastrointestinal symptoms subsequently settled and was awaiting discharge. Non-specific, borderline size significant lymph nodes on CT chest was the only substantial past medical history. The diagnosis of WM was made after the Biochemistry Biomedical Scientist (BMS) detected the presence of a Type I monoclonal cryoglobulin. A potential cryoprecipitate was suspected when repeated 'clotting' error flags occurred during routine laboratory analyses; the sample aspiration difficulties being attributed to the viscous nature of the sample. The investigation of inaccessible low volume lymphadenopathy in the elderly should include serum protein electrophoresis and immunoglobulins as this may have established an earlier diagnosis in this case. The application of good scientific principles informed the laboratory investigation and resulted in the identification of a large IgM monoclonal cryoglobulin that prompted further appropriate investigations resulting in the diagnosis of WM. This case also highlights the importance of good communication between the laboratory and clinical staff.

IgD multiple myeloma: biology, diagnosis, and treatment.

IgD multiple myeloma is uncommon. Patients generally present at a younger age and have shorter progression free and overall survivals (OSs). Its rarity has inhibited development of a specific risk stratification system or informed best treatment protocols. We present interphase fluorescence in situ hybridization results from a group of 29 cases. These showed evidence of a decreased male to female ratio, decreased OS in patients aged 70 and over, better outcomes in those with kappa light chain restriction, and CD56 positive patients had longer survivals than those lacking CD56. We discuss the biology of IgD multiple myeloma, the need for prospective studies, and challenges for improvements in diagnosis and treatment. We suggest an International Register to accelerate development of best practice guidelines for diagnosis, risk stratification, and treatment.