Delineation of the timing of second-line therapy post-autologous stem cell transplant in patients with AL amyloidosis.

Among patients with immunoglobulin light chain (AL) amyloidosis, there is little consensus on when reinstitution of chemotherapy should occur. We conducted a retrospective study to evaluate the patterns of relapse or progression (R/P) and the timing of reinitiating therapy among 235 patients initially treated with autologous stem cell transplant (ASCT) at Mayo Clinic. The median time from ASCT to second-line therapy was 24.3 months. At the time of restarting therapy, median difference of free light chain (dFLC) was 9.9 mg/dL (42% of diagnosis value), 32% had a dFLC <5 mg/dL, and 63% met criteria for organ R/P. The indications for retreatment were (1) clinical suspicion of R/P, 10%; 92) hematologic R/P only, 23%; (3) organ R/P only, 32%; (4) both hematologic and organ R/P, 31%; and (5) suboptimal response to ASCT and second-line therapy as consolidation, 4%. Patients with organ progression at the time of second-line therapy had inferior survival. Although a dFLC of >5 mg/dL at the time of reinstituting therapy was associated with risk, patients relapsing from very good partial response (VGPR) or better had a longer time to develop organ progression after hematologic R/P (24.2 vs 3.2 months, P = .007). These data suggest that the best candidates for clinical trials testing novel plasma cell-directed chemotherapy beyond first line may be those patients who are either relapsing from VGPR or better (dFLC at diagnosis was >5 mg/dL) or having inadequate response to prior therapy. This strategy should allow for hematologic response assessment while avoiding the risk of deleterious organ progression. Implementation of more stringent progression criteria may also be warranted.

Serum immunoglobulin free light-chain measurement in primary amyloidosis: prognostic value and correlations with clinical features.

Immunoglobulin free light chains (FLCs) are the precursors of amyloid fibrils in primary amyloidosis (AL). We studied the relationship between FLC levels and clinical features in 730 patients with newly diagnosed AL. The plasma cell clone was λ in 72% patients, and κ in 28% patients. κ-AL had more GI tract and liver involvement, where as renal involvement was more with λ-AL. While the overall survival (OS) was similar for κ and λ-AL, the median OS for those without an identifiable serum heavy chain was significantly shorter (12.6 vs 29.9 months; P = .02). The OS was shorter among those with a higher dFLC (involved FLC-uninvolved FLC; κ > 29.4 mg/dL or λ > 18.2 mg/dL using median for cutoff); 10.9 vs 37.1 months; P < .001. In multivariate analysis, dFLC was independent of other prognostic factors. The type of light chain impacts the spectrum of organ involvement and the FLC burden correlates with survival in AL.

Prognostic restaging at the time of second-line therapy in patients with AL amyloidosis.

It is well known that staging of patients with AL amyloidosis at diagnosis predicts for survival, but there is a paucity of literature delineating the prognostic value of these systems at relapse. We evaluated the prognostic value of AL staging among 413 patients initiated with second-line therapy between 2000 and 2015. Both the Revised Mayo 2012 and the European revision of Mayo 2004 staging systems were used. The median time from initial treatment to second-line therapy was 11.7 months. The first-line therapy was autologous stem cell transplant (ASCT) in 179 (43%) patients and non-ASCT therapies in 234 patients. Median survival from the institution of second-line therapy was 61 months. Both the Mayo 2004 and 2012 staging systems were of prognostic benefit at second-line therapy with respective risk ratios of 2.78 (95% CI: 2.15, 3.58) and 3.03 (95% CI: 2.33, 3.93) for patients with > stage 2 disease. On multivariate analysis, the predictive value of staging at second-line therapy was independent of stage at diagnosis and prior ASCT as first-line therapy. This study indicates that the Mayo staging systems work well at second-line therapy. Consequently, it is suitable for the stratification of patients in trials for relapsed, refractory AL amyloidosis.

Serum uric acid: novel prognostic factor in primary systemic amyloidosis.

OBJECTIVE: To determine the prognostic value of serum uric acid (UA) in patients with primary systemic (light chain) amyloidosis (AL). PATIENTS AND METHODS: A cohort of 1977 patients with newly diagnosed AL seen at our institution between April 1, 1960, and August 1, 2006, and 293 patients with AL who underwent peripheral blood stem cell transplant between March 1, 1996, and October 1, 2006, were studied retrospectively to examine the value of serum UA. The prognostic value of several variables was examined using Cox proportional hazards models, and the survival time was estimated using Kaplan-Meier analysis; curves were compared using the log-rank test. RESULTS: Patients with UA levels greater than 8 mg/dL had a median overall survival of 9 months from diagnosis compared with 20.3 months for the remaining patients (P less than .001). The prognostic value of UA was independent of the known cardiac prognostic markers cardiac troponin T (cTnT) and N-terminal propeptide of brain-type natriuretic peptide (NTProBNP). Addition of UA to these factors allows us to classify patients into 4 groups with significantly different outcomes. Patients with none, 1, 2, or 3 of these risk factors (UA, greater than 8 mg/dL; cTnT, greater than 0.035 ng/mL; and NTProBNP, greater than 332 pg/mL) had a median overall survival of 36.6, 29.2, 11.1, and 3.6 months, respectively (P less than .001). Similarly, UA levels helped predict overall survival in patients undergoing peripheral blood stem cell transplant for AL and added to the value of cTnT and NTProBNP. CONCLUSION: The data confirm the prognostic utility of cTnT and NTProBNP in a large group of patients and highlight the value of serum UA in allowing better forecasting of probable outcomes for patients with AL.

Urinary albumin excretion patterns of patients with cast nephropathy and other monoclonal gammopathy-related kidney diseases.

BACKGROUND AND OBJECTIVES: Multiple myeloma is responsible for a wide variety of renal pathologies. Urinary protein and monoclonal spike cannot be used to diagnose cast nephropathy (CN). Because albuminuria is a hallmark of glomerular disease, this study evaluated the percentage of urinary albumin excretion (%UAE) as a tool to differentiate CN from Ig light chain amyloidosis (AL), light chain deposition disease (LCDD), and acute tubular necrosis (ATN). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Patients were selected from the Renal Biopsy Database and the Dysproteinemia Database. Participants were excluded if laboratory data were missing within 1 week of the renal biopsy. The %UAE was obtained from urine protein electrophoresis. RESULTS: From 1992 to 2011, 260 patients were biopsied (177 with AL, 28 with LCDD, 43 with CN, and 12 with ATN). The %UAE for CN patients was significantly lower (7%) than for ATN (25%), LCDD (55%), and AL (70%) patients (P<0.001). Significant differences were also found in serum creatinine, serum albumin, free light chain ratio, total urine protein, and urine monoclonal spike; only the %UAE remained independently associated with CN in a logistic regression model (P<0.001). The area under the curve for the receiver operator characteristic curve for %UAE was 0.99. At <25%, the %UAE had a sensitivity of 0.98, specificity of 0.94, positive predictive value of 0.75, and negative predictive value of 0.99. CONCLUSIONS: This study showed that %UAE was significantly less in CN than the other three renal lesions and %UAE may thus be helpful in diagnosis of CN.

Revised prognostic staging system for light chain amyloidosis incorporating cardiac biomarkers and serum free light chain measurements.

PURPOSE: Cardiac involvement predicts poor prognosis in light chain (AL) amyloidosis, and the current prognostic classification is based on cardiac biomarkers troponin-T (cTnT) and N-terminal pro-B-type natriuretic peptide (NT-ProBNP). However, long-term outcome is dependent on the underlying plasma cell clone, and incorporation of clonal characteristics may allow for better risk stratification. PATIENTS AND METHODS: We developed a prognostic model based on 810 patients with newly diagnosed AL amyloidosis, which was further examined in two other datasets: 303 patients undergoing stem-cell transplantation, and 103 patients enrolled onto different clinical trials. RESULTS: We examined the prognostic value of plasma cell-related characteristics (ie, difference between involved and uninvolved light chain [FLC-diff], marrow plasma cell percentage, circulating plasma cells, plasma cell labeling index, and ß(2) microglobulin). In a multivariate model that included these characteristics as well as cTnT and NT-ProBNP, only FLC-diff, cTnT, and NT-ProBNP were independently prognostic for overall survival (OS). Patients were assigned a score of 1 for each of FLC-diff ≥ 18 mg/dL, cTnT ≥ 0.025 ng/mL, and NT-ProBNP ≥ 1,800 pg/mL, creating stages I to IV with scores of 0 to 3 points, respectively. The proportions of patients with stages I, II, III and IV disease were 189 (25%), 206 (27%), 186 (25%) and 177 (23%), and their median OS from diagnosis was 94.1, 40.3, 14, and 5.8 months, respectively (P < .001). This classification system was validated in the other datasets. CONCLUSION: Incorporation of serum FLC-diff into the current staging system improves risk stratification for patients with AL amyloidosis and will help develop risk-adapted therapies for AL amyloidosis.

Isolation and biochemical characterization of plasma monoclonal free light chains in amyloidosis and multiple myeloma: a pilot study of intact and truncated forms of light chains and their charge properties.

BACKGROUND: The presence of monoclonal immunoglobulin free light chains (FLC) in the serum is commonly associated with the gammopathies, including multiple myeloma, systemic light chain amyloidosis and non-amyloid light chain deposition disease. Although a sensitive nephelometry-based assay is used for quantification of serum FLC and patient follow-up, this method does not provide information regarding the biochemical properties of these proteins. The present study focused on the development of the procedure for isolation and biochemical characterization of monoclonal FLC in small plasma specimens from patients with these disorders. METHODS: Methods used in this study were ultrafiltration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), protein elution from gel and support membranes, dialysis, lyophilization, isoelectric focusing (IEF) and Western blotting. RESULTS: The isolation, concentration and partial purification of FLC was based on micro-preparative SDS-PAGE employing analytical scale gels. For the determination of the isoelectric point of FLC, the developed protocol included consecutive IEF, electrotransfer of IEF-separated proteins onto and elution from support membranes, and their analysis by SDS-PAGE-based Western blotting. The procedures, which require only 20-50 microL of starting plasma, allow biochemical characterization of the monomeric, dimeric and truncated forms of FLC, including their charge properties. CONCLUSIONS: The developed procedure may be applied to reveal distinguishing chemical features of FLC in serum, which could be important in predicting the pathologic form of disease, and in yielding information to better understand the mechanism(s) involved in the deposition of light chains in tissues.