18.4.2. HLC assays to monitor oligosecretory patients

Chapter 18

The 2016 IMWG consensus criteria for response and minimal residual disease assessment in multiple myeloma recognise that HLC assays can offer an additional means of monitoring oligosecretory patients (Section 25.3.5) [905]. This is based on a number of studies, which are discussed below.

In a study of 156 MM patients by Ludwig et al. [37], an abnormal HLC ratio was identified at presentation in all 18 oligosecretory patients (7 IgG and 11 IgA). Similar findings were reported by Boyle et al. [406]. In a study by Young and colleagues [405] IgG and IgA HLC analysis was performed on serial samples from 8 oligosecretory patients (5 IgA, 3 IgG) with sFLC <100 mg/L. In all 8 patients, the HLC ratio was abnormal at presentation and changes in the HLC ratio were in concordance with clinical assessment during follow-up. An example of an IgAκ oligosecretory MM patient is shown in Figure 18.13. Although the patient initially responded to therapy (indicated by a fall in the IgAκ/IgAλ HLC ratio), the HLC ratio remained abnormal. A subsequent increase in the HLC ratio suggested disease progression 445 days before a clinical relapse was confirmed.