Chapter 32

Preliminary evidence suggests that IgM HLC may be useful for monitoring response to treatment in WM [681][720]. Manier et al. [681] compared the IgM response rate using SPE, IgM nephelometry and IgM HLC, for 10 WM patients who were treated as part of a Phase 3 trial. After 14 months, the proportion of patients achieving a partial response or better, vs. those who had stable disease, was similar across the three techniques. The median time to response and time to progression was also similar.

Koulieris et al. [720] monitored nine WM patients with IgM HLC. The involved HLC concentration and the IgMκ/IgMλ HLC ratio mostly followed disease fluctuations. During the study period patients only achieved a partial remission, and consistent with this, the IgM HLC ratio never normalised. Boyle et al. [901] compared HLC, SPE and total IgM results from 25 patients during follow-up. A proportion of patients could not be monitored using standard techniques (due to non-quantifiable bands on SPE [4/25] or oligosecretory disease [<10 g/L, 4/25]), but all 25 patients had abnormal HLC ratios at presentation and could be subsequently monitored using HLC assays. A comparison of the responses assigned using SPE or total IgM with the iHLC concentration, indicated an almost perfect agreement between the assays (weighted Kappa 0.84 and 0.86, respectively). Similar results were reported by Alvi et al. [721] Boyle et al. [901] noted however, that using standard assessments, 6/21 patients achieved a complete response, but in each case the HLC ratio indicated residual disease. In addition, 10/21 patients progressed and in each case the changes in the HLC ratio were consistent with the clinical findings.

An update of the consensus panel criteria for the assessment of clinical response in WM stated that further prospective evaluation of the use of HLC to assess response in WM is encouraged [703].