Tan, Tow Shung

Abstract Introduction: Currently, the most extensively tested treatments for immunoglobulin light chain amyloidosis (AL) are high dose melphalan followed by autologous stem cell transplantation (ASCT) and melphalan and dexamethasone (MDex). A recent randomized controlled trial comparing the two regimens showed MDex is at least equivalent if not superior to ASCT. Most patients with symptomatic systemic AL have a low plasma cell load; however, approximately 30% have bone marrow plasmacytosis greater than 20% but do not meet criteria for multiple myeloma with significant anemia or lytic bone disease. This leads to the speculation that the plasma cell biology (and therefore outcomes) might differ between low and high plasma cell burden AL. We undertook this study to address whether these two standard regimens are equally effective in AL patients with low and high plasma cell burden. Methods: Patients with confirmed AL treated with MDex were recruited for this study. Some of the patients treated were not ASCT candidates while others were eligible but favored MDex. Hematologic response was defined as 50% reduction in serum M-protein or 90% reduction in urine M-protein if one was present, otherwise a 50% reduction in serum free light chain levels was used. Organ involvement was defined according to the Consensus Opinion from the 10th International Symposium on Amyloid and Amyloidosis. Patients were separated into a high and a low marrow plasma cells (PC) group based on their percentage of bone marrow plasma cells. Cutoff for the bone marrow plasmacytosis was calculated using receiver-operator characteristic (ROC) curve. Overall survival (OS) and progression free survival (PFS) were compared using Kaplan-Meier method. OS was also calculated for 342 AL patients treated with ASCT for comparison. Results: Seventy-three patients with AL received MDex between 05/01 and 05/07. Median follow-up was 16.8 months. At the time of the study, 42.5% had died. Calculating for OS and PFS, the best cutoff for bone marrow plasmacytosis was found to be 20%. In our cohort, 28.8% had >20% bone marrow plasmacytosis. Age (64.8 yr vs 61.0 yr, p = 0.61) and sex (81% male vs 63.4% male, p = 0.13) were similarly distributed between patients with high and low PC. Cardiac troponin T (cTnT) was also comparable between the 2 groups (0.03 ng/ml (high) vs 0.06 ng/ml (low), p = 0.41). Cardiac involvement were similar between high and low PC groups (78.9% vs 85.7% respectively, p = 0.49) but renal involvement was less common in the high PC group (70.6% vs 38.1%, p = 0.01). No differences were noted in the gastrointestinal and neurological involvement. Patients with high PC received a median of 4 cycles of MDex vs 5 in the low PC group (p = 0.68). Hematologic response was achieved in 75% of patients with high PC and 54.9% of the low’s (p = 0.11). A significant difference was noted in the PFS and OS between the 2 groups. The PFS and OS were 13.5m and 15.3m, respectively for patients with high PC but neither was reached in those with < 20% plasmacytosis (p=0.02 and p = 0.03 respectively). In the multivariate analysis, hematologic response, cardiac involvement and plasmacytosis >20% were independent predictors of PFS and OS. To determine if plasmacytosis had the same affect on survival of ASCT treated patients, 342 patients were analyzed. No relationship between OS and % of plasmacytosis was found. Conclusion: Our study suggests that ASCT and MDex may not be equivalent for all AL patients. Even though hematologic response rates were similar, patients with plasmacytosis >20% had a worse OS and PFS when treated with MDex. This disparity in survival was not evident in patients treated with ASCT. This effect was independent of cardiac involvement. If confirmed, this could have a significant impact on the choice of therapy for AL patients. The best therapy may be determined by the extent of marrow plasmacytosis, with higher plasma cells favoring high dose therapy.

Abstract Background: Primary systemic amyloidosis (AL) is an incurable plasma cell disorder associated with varying degree of organ infiltration with light chain derived amyloid protein and consequent organ dysfunction. Various acquired coagulopathies, predominantly Factor X (FX) deficiency have been previously described in AL. The factor deficiencies are thought to be due to the direct binding of blood coagulation proteins to amyloid fibrils. Little is known regarding the prognostic significance of abnormal coagulation parameters in AL patients (pts). Methods: After Institutional Review Board approval, we performed a retrospective review of the medical records of 625 consecutive pts who had presented within 3 months of a diagnosis of AL to be evaluated at Mayo Clinic from June 2001 to June 2006. 540 pts had coagulation studies performed within 2 months of presentation. 51 of those pts were on oral anticoagulation and were excluded from the analysis. Results: Of the 489 pts included in the analysis, the median age was 62 years and 61% were male. The median overall survival (OS) of the entire cohort was 26.8 months. Table 1 lists the prevalence of abnormal coagulation tests in the remaining 489 patients. Prothrombin time (PT) was available in the majority of pts. 61 pts (12.6%) had elevated PT, and 63 pts (20.4%) had a decreased FX. 37 of the 61 pts with elevated PT had available FX levels, of which 31 (84%) of those had a decreased FX, suggesting that the cause of elevated PT was mostly due to a low FX. Indicators of hepatic involvement such as alkaline phosphatase and bilirubin levels were higher among the patients with prolonged PT and low FX. An elevated PT (more than 12.4 seconds) was strongly predictive of an adverse outcome, with a median OS of 8.7 months compared to a median OS of 29 months (p<0.0001) in pts with normal PT (Figure 1). Similarly, pts with decreased FX (less than 60% activity), was associated with significantly worse outcomes with a median OS of 14.9 months versus a median OS of 33 months (p<0.0001) in pts with normal FX (Figure 2). In a Cox proportional hazards model containing cardiac troponin (cTnT), NT-Pro BNP, serum alkaline phosphatase, and free light chain difference (involved minus uninvolved), prolonged PT or FX deficiency were independently prognostic for overall survival. Conclusion: Abnormalities of PT and FX are seen in a sizable proportion of pts with newly diagnosed AL. An elevated PT and or FX deficiency appear to adversely affect the outcome of these patients. It is likely that the elevated PT in these patients relate to FX deficiency in the majority which in turn may reflect the amyloid ‘burden’. The effect of other organ involvement like the hepatic involvement may also have an impact on FX and PT. Table 1. Prevalence of abnormal coagulation testing in patients with newly diagnosed primary systemic amyloidosis. Coagulation study N (Test results available) N of abnormal results (%) Elevated prothrombin time 486 61 12.6 Elevated activated partial thromboplastin time 312 48 15.4 Elevated thrombin time 315 84 26.7 Elevated fibrinogen 140 118 84.3 Decreased Factor II activity 62 26 41.9 Decreased Factor V activity 63 9 14.3 Decreased Factor VII activity 63 17 27 Decreased Factor X activity 309 63 20.4 Elevated D-dimer 130 72 55.4 Figure 1. Survival grouped by normal versus elevated Prothrombin time. Figure 1. Survival grouped by normal versus elevated Prothrombin time. Figure 2. Survival grouped by normal versus low Factor X levels. Figure 2. Survival grouped by normal versus low Factor X levels.