AL Amyloidosis — Staging and Risk Stratification
Definition
Survival in AL amyloidosis is dominated by the severity of cardiac involvement at diagnosis. Multiple staging systems using cardiac, renal, and hematologic biomarkers have been developed to predict early death, late survival, and organ-specific outcomes.
Key Concepts
Mayo Clinic 2004 Staging (Cardiac)
- Uses: NT-proBNP and cardiac troponin T/I.
- Stage I (both normal) → Stage II (one elevated) → Stage III (both elevated).
- Most widely used system; best for predicting early death (within months of diagnosis). (sources/lc-amyloidosis-nejm-2024, rating: very high)
- European modification (Wechalekar et al. 2013): adds NT-proBNP >8500 pg/mL cutoff to create stage IIIb = very high risk. Mayo 2004 + European modification = best for predicting early death. (sources/lc-amyloidosis-nejm-2024, rating: very high)
Mayo Clinic 2012 Staging
- Adds dFLC (difference between involved and uninvolved serum free light chain; cutoff 180 mg/L) to Mayo 2004 cardiac biomarkers.
- Predicts late survival more accurately than Mayo 2004. (sources/lc-amyloidosis-nejm-2024, rating: very high)
- dFLC as a prognostic tool is increasingly less predictive in the modern daratumumab-based treatment era — staging system may need revision. (sources/lc-amyloidosis-nejm-2024, rating: very high)
- Very low dFLC (<50 mg/L) at diagnosis confers substantially better outcomes irrespective of cardiac stage. (sources/lc-amyloidosis-nejm-2024, rating: very high)
Boston University Staging
- Uses BNP and troponin I (as opposed to NT-proBNP and troponin T/I in Mayo systems); also predicts survival. (sources/lc-amyloidosis-nejm-2024, rating: very high)
Renal Staging System
- Uses: 24-hour urinary protein excretion + estimated glomerular filtration rate.
- Predicts risk of progression to dialysis at 2 years (annual risk).
- Stage I → Stage III based on combination of proteinuria/eGFR thresholds. (sources/lc-amyloidosis-nejm-2024, rating: very high)
Emerging Biomarkers (Not Yet in Staging Systems)
- Von Willebrand factor — predicts survival.
- D-dimer — predicts survival.
- Growth differentiation factor-15 (GDF-15) — predicts survival and renal outcomes.
- MRD (measurable residual disease): Next-generation flow cytometry and blood mass spectrometry detect residual disease more sensitively than immunofixation — may predict organ dysfunction despite deep hematologic response. (sources/lc-amyloidosis-nejm-2024, rating: very high)
Treatment Response Criteria
- Hematologic response graded and monitored monthly:
- CR: Negative serum AND urine immunofixation + normal FLC ratio
- VGPR: dFLC <40 mg/L
- PR: dFLC decrease >50%
- iFLC <20 mg/L + dFLC <10 mg/L predict longer survival
- Organ response now graded (not binary) — grading predicts survival and long-term outcomes. (sources/lc-amyloidosis-nejm-2024, rating: very high)
- Time to best organ response: cardiac 24 months, renal 29 months, hepatic 35 months — clinicians must maintain patience before declaring treatment failure. (sources/lc-amyloidosis-nejm-2024, rating: very high)
Contradictions / Open Questions
- dFLC less prognostic in modern era: The dFLC component of Mayo 2012 is losing predictive value as daratumumab-CyBorD drives rapid, deep hematologic responses in most patients; all four staging systems were validated in earlier treatment eras. (sources/lc-amyloidosis-nejm-2024, rating: very high)
- No single optimal staging system: Mayo 2004 + European modification best for early death; Mayo 2012 best for late survival. Which to use as a primary decision tool is not standardised across centres.
- MRD not incorporated in staging: MRD negativity predicts organ response improvement and may matter most for deciding maintenance therapy, but no validated staging system incorporates it. (sources/lc-amyloidosis-nejm-2024, rating: very high)
Connections
- Related to entities/AL-Amyloidosis — clinical context and treatment decisions informed by staging
- Related to entities/ATTR-Amyloidosis — distinct staging; ATTR uses NYHA/6MWT rather than dFLC
- Related to concepts/Cardiac-Amyloidosis-Imaging — imaging parameters that correlate with cardiac staging