Validated criteria for early response assessment in AL amyloidosis
| Response criteria . | Definition . |
|---|---|
| Hematologic response* | |
| Complete response | Negative serum and urine immunofixation and normal FLC ratio |
| Very good partial response | dFLC < 40 mg/L |
| Partial response | FLC decrease > 50% compared with baseline |
| No response | All other patients |
| Cardiac response | Decrease of NT-proBNP by > 30% and 300 ng/L (if baseline NT-proBNP > 650 ng/L), or at least 2-point decrease of NYHA class (if baseline NYHA class is III or IV) |
| Renal response | At least 30% decrease in proteinuria or drop below 0.5 g/24 h, in the absence of renal progression defined as a > 25% decrease in eGFR |
| Response criteria . | Definition . |
|---|---|
| Hematologic response* | |
| Complete response | Negative serum and urine immunofixation and normal FLC ratio |
| Very good partial response | dFLC < 40 mg/L |
| Partial response | FLC decrease > 50% compared with baseline |
| No response | All other patients |
| Cardiac response | Decrease of NT-proBNP by > 30% and 300 ng/L (if baseline NT-proBNP > 650 ng/L), or at least 2-point decrease of NYHA class (if baseline NYHA class is III or IV) |
| Renal response | At least 30% decrease in proteinuria or drop below 0.5 g/24 h, in the absence of renal progression defined as a > 25% decrease in eGFR |
Response criteria are validated for use as early as 3 months after treatment initiation.
Treatment with immune modulatory drugs and decreasing glomerular filtration rate increase the concentration of NT-proBNP, preventing the assessment of cardiac response with this biomarker.
The hematologic response criteria were designed and validated using the Freelite assay. Although preliminary data indicate that changes in dFLC measured with the novel N latex FLC assay predict response, the results of the Freelite and N latex FLC assays are not interchangeable, and the current response criteria cannot be used with the N latex FLC test.