Receiver operator curve relating percentage reduction of dFLC* after 2 months of therapy to overall ECOG response. A total of 40% reduction → sensitivity 77% and specificity 68%; 45% reduction → sensitivity 75% and specificity 69%; and 50% reduction → sensitivity 69% and specificity 70%. FLC was expressed as difference between involved and uninvolved FLC, but the results were similar if absolute FLC used in place of the difference.