Serum Free Light Chain Assessment Early After Stem Cell Transplantation as a Prognostic Factor in Multiple Myeloma

Multiple myeloma is an incurable cancer commonly treated with stem cell transplantation (SCT). Response is traditionally evaluated 100 days after SCT, both to allow for hematopoietic reconstitution and due to immunoglobulins' long half-lives. Free light chains (FLC) have significantly shorter half-lives and may provide evidence of response or treatment failure earlier after SCT.

We retrospectively studied 83 consecutive patients with multiple myeloma who underwent SCT and found 69 who had FLC measured 30 or 60 days after SCT. Using conventional FLC response criteria, we considered a patient to be at high risk for early relapse if he or she failed to experience a partial response by day 30 or 60.

After a median overall follow-up of only 335 days, these high-risk patients had significantly shorter progression-free survival (median, 98 vs. 335 days, P = .001) and overall survival (366 days vs. median not reached, P = .016).

Early FLC assessment either 1 or 2 months after SCT using standard FLC response criteria was able to identify a subset of patients at high risk of early relapse, and these patients may benefit from earlier interventions.