A 73-year-old man was diagnosed as having multiple myeloma (MM), with serum protein electrophoresis (SPEP) and immunofixation (IF) showing a monoclonal (M) IgA κ at 0.3 g/dL and serum free κ/λ ratio skewed at 257. A computed tomographic scan showed lytic lesions, and bone marrow biopsy findings revealed 30% κ-restricted plasma cells. He was assigned to the bortezimib-lenalidomide-dexamethasone–elotuzumab (VRD-E) arm of a phase 3 trial. Three weeks after therapy initiation, follow-up SPEP-IF demonstrated an M-IgA κ at 0.1 g/dL. Two months later, SPEP-IF demonstrated a new M-IgG κ band in the same electrophoretic position as the M-IgA κ, with the 2 distinguishable only by IF and measured at 0.1 g/dL. Three months later, SPEP-IF demonstrated only the M-IgG κ, with the original M-IgA κ not detected. Over the next 8 months, the patient received maintenance therapy with VRD-E, and monthly SPEP-IF consistently showed M-IgG κ at 0.1 g/dL, with the original M-IgA κ consistently not detected. The serum free κ/λ ratio gradually decreased to 4.86 one year later. The Table summarizes assay data.

一名73岁的男子被诊断患有多发性骨髓瘤（MM），血清蛋白电泳（SPEP）和免疫固定（IF）显示单克隆（M）IgAκ浓度为0.3 g / dL，无血清κ/λ比值偏高在257。计算机断层扫描显示溶胞性病变，骨髓活检发现30％的κ受限浆细胞。他被分配到一项3期试验的硼替佐米-来那度胺-地塞米松-依洛珠单抗（VRD-E）组中。治疗开始三周后，随访SPEP-IF显示M-IgAκ为0.1 g / dL。两个月后，SPEP-IF在与M-IgAκ相同的电泳位置显示了一条新的M-IgGκ带，其中2条仅可通过IF区分，测量值为0.1 g / dL。三个月后，SPEP-IF仅显示了M-IgGκ，而未检测到原始M-IgAκ。在接下来的8个月里，患者接受了VRD-E维持治疗，并且每月SPEP-IF始终显示0.1 g / dL的M-IgGκ，始终未检测到原始M-IgAκ。一年后，血清游离κ/λ比逐渐降低至4.86。该表总结了测定数据。