Uninvolved immunoglobulins predicting hematological response in newly diagnosed AL amyloidosis

Immunoparesis serves as a marker for elevated risk for progression in plasma cell proliferative disorders. However, the impact of immunoparesis in AL amyloidosis has not been addressed. Immunoparesis was defined qualitatively as any decrease below the low reference levels of the uninvolved immunoglobulins and quantitatively, as the relative difference between the uninvolved immunoglobulins and the lower reference values. Forty-one newly diagnosed AL amyloidosis patients were included. Sixty-six percent of patients had a suppression of the uninvolved immunoglobulins. The median relative difference of the uninvolved immunoglobulins was 18% above the low reference levels [range (-71%)-210%]. Ninety percent of the patients were treated with novel agents-based regimens, mostly bortezomib-containing regimens. Nineteen percent of the patients did not attain response to first line treatment. Patients with relative difference of uninvolved immunoglobulins below -25% of the low reference levels were less likely to respond to first line treatment compared to patients with a relative difference of -25% and above [odds ratio for no response vs. partial response and better 30 [(95% CI 4.1-222.2), P=0.0004]. Patients who failed first line treatment were successfully salvaged with lenalidomide-based treatment. Immunoparesis, if assessed quantitatively, may serve as a predictor of response in AL amyloidosis patients treated with bortezomib-containing regimens.