Growth Differentiation Factor-15 in Patients with Light Chain (AL) Amyloidosis Has Independent Prognostic Significance and Adds Prognostic Information Related to Risk of Early Death and Renal Outcomes
Authors: Kastritis Efstathios , Papassotiriou Ioannis , Terpos Evangelos , Akalestos Athanassios , Psimenou Erasmia , Apostolakou Filia , Roussou Maria , Gavriatopoulou Maria , Kaldara Elisavet , Eleutherakis-Papaiakovou Evangelos , Kalapanida Despoina , Pamboucas Constantinos , Kostis Evangelos , Kontogiannis Sofoklis , Toumanidis Savvas Th. , Boletis Ioannis , Dimopoulos Meletios A. 
Published: November 2019

Abstract

Growth differentiation factor-15 (GDF-15) is a member of the TGF-beta family, which is involved in several pathological conditions, including inflammation, cancer, cardiovascular, pulmonary and renal diseases. GDF-15 has prognostic value in patients with cardiovascular disorders and adds prognostic information to conventional prognostic factors, such as NT-proBNP and high-sensitivity troponin (hs-TnT). Cardiac involvement is the most important determinant of prognosis in patients with AL amyloidosis and cardiac biomarkers have major prognostic importance in AL. The aim of the study was to explore the value of GDF-15 in patients with AL amyloidosis.
We measured the circulating levels of GDF-15, NT-proBNP and hs-TnT in 77 patients with newly diagnosed AL amyloidosis, before and 3 months post frontline treatment. GDF-15 was measured by a novel pre-commercial immunoassay (Roche Diagnostics).
Patients' median age was 68 years; most patients had cardiac (61%) or renal involvement (74%); 61% had NT-proBNP >1284 pg/ml and 46% had hsTnT>54 ng/ml. Median eGFR was 57 ml/min/1.73m2, 52% had eGFR <60 ml/min/1.73m2, while 12% required dialysis at the time of treatment initiation. All patients received primary therapy with bortezomib- (49%) or lenalidomide-based regimens (51%). Median levels of GDF-15 were 3594 pg/ml (range 626-71,475pg/ml); 95% of patients with AL had GDF-15 levels >1200 pg/ml (the upper limit of normal for individuals without cardiovascular disease). GDF-15 correlated with NT-proBNP (r=0.538, p<0.001), hs-TnT (r=0.447, p=0.02) and eGFR (r=-0.570, p<0.001). Patients with GDF-15 levels within the upper quartile (>7575 pg/ml) had a very poor outcome (median overall survival (OS) 3 months) compared to patients with GDF-15 levels below the upper quartile (p=0.01; see the Figure). Among other cardiac markers, hs-TnT >54 ng/ml (12 vs >48 months, p=0.001) and NT-proBNP >1284 pg/ml (11 vs >48 months, p<0.001) were also associated with shorter OS. Higher cut-off levels for NT-proBNP and hs-TnT did not discriminate patients at high risk for early death more accurately. In a multiple logistic regression model which included GDF-15, NT-proBNP and hs-TnT, only GDF-15 in the upper quartile (HR: 8.427, 95% CI 1.73-41.1, p=0.008) was independently predictive of early death at 3 months. Similar results were obtained when these biomarkers were treated as continuous variables. Regarding OS, GDF-15 had independent prognostic significance in a multivariate model that included both NT-proBNP and hs-TnT.
We also evaluated changes in the levels of GDF-15, NT-proBNP and hs-TnT in patients who received lenalidomide after 3 months of treatment. In these patients NT-proBNP often increases without obvious deterioration of cardiac function, thus complicating the assessment of cardiac response early, during the course of therapy. GDF-15 levels did not change significantly either in patients with hematological response (p=0.998) or those without hematological response (p=0.774). However, NT-proBNP levels increased substantially both in those with hematological response (p=0.05) and in those without hematological responses (p=0.013). Similarly, hs-TnT levels increased in non-responders (p=0.006) and did not change in patients with hematological response (p=0.251).
As GDF-15 reflects heart and renal defects, we further evaluated whether GDF-15 could be associated with the risk of progression to ESRD and need for dialysis. Using ROC analysis, GDF-15 >median was identified to better discriminate patients which had a shorter time to dialysis (29 months vs not reached, p=0.001, see the Figure; with 38% vs. 8% progressing to ESRD, respectively). eGFR< 60 ml/min/m2 was also a strong predictor of ESRD (p=0.004). However, in multivariate analysis which included GDF-15 >median, eGFR <60 ml/min/m2 and proteinuria >5 g/day, only GDF-15 was independently associated with a higher risk of ESRD requiring dialysis (HR: 4.25, 95% CI 1.01-18, p=0.045).
In conclusion, GDF-15 is a novel biomarker with prognostic implications for different outcomes in patients with AL; it is associated with a high risk of early death, with OS and also with renal outcome. More importantly GDF-15 adds prognostic information independent of the traditional cardiac biomarkers and thus, its measurement in larger series of patients is recommended.
Figure 1 Figure 1.

Disclosures
No relevant conflicts of interest to declare.