08 May, 2019

#AmyloidosisJC 5/8/19: ASCT in AL patients with impaired renal function

In this installment of #amyloidosisJC we will be discussing outcomes of Autologous Stem Cell Transplant (ASCT) in AL amyloidosis patients who have impaired renal function, written by Dr. M. Hasib Sadiqi and colleagues at the Mayo Clinic's Amyloidosis Program. 

Here is a link to the article: https://www.nature.com/articles/s41409-019-0524-2

For those of you who either do not have access to the full article or didn't have time to read it (or couldn't make the live journal club discussion taking place at 9 pm EST on 5/8/19), here is a synopsis of the paper, including key findings:

  • This is a retrospective review of all patients with AL amyloidosis transplanted at Mayo between May 1999 and September 2017. Of 696 pts, 41 were excluded for various reasons (including ALREADY BEING ON DIALYSIS AT TIME OF ASCT IN 29 PATIENTS).  The remaining 655 pts were divided into "Normal Renal Function" (NRF; eGFR >45 mL/min; n=568) and "Impaired Renal Function" (IRF; eGFR <45 mL/min; n=87)
  • Since this wasn't a randomized prospective study, the groups were predictably not balanced for all clinical characteristics. The NRF grp was less likely to have gotten pre-ASCT chemotherapy (41% vs 53%) and more likely to have been treated with a full dose of melphalan as ASCT conditioning (79% vs 29%). Also, the IRF grp had higher cardiac biomarkers (though no statistical difference in Mayo Cardiac Stage distribution) and more patients with advanced Amyloid Renal Stage (0% renal stage 1, compared with 63% in the NRF grp).  Cardiac and Renal staging have both been covered in previous #amyloidosisJC sessions.
  • 100-day mortality was greater in the IRF grp (14% vs 5%). Risk of progression to ESRD and hemodialysis was also higher in the IRF grp (16% vs 6%). These differences did not have to do with differences in control of the underlying amyloidosis, as the hematologic response rates (88-89%) and complete hematologic response (CR) rates (42-44%) were essentially identical in each grp, though NRF pts who got less than 200 mg/m2 of melphalan had lower CR rates than other patient subsets. There was a higher rate of hospitalizations, a longer duration of hospitalizations, and a higher incidence of culture-confirmed episodes of bacteremia in the IRF group, though causes of death within the first 100 days post-ASCT were not elaborated upon in the article. 
  • Median Overall Survival (140 mos) and Progression Free Survival (49 mos) were not statistically different between the NRF and IRF gaps. 
  • The authors provided a thoughtful discussion regarding the limitations and quirks of the trial. 
    • The period over which patients were treated was long, and eligibility criteria for ASCT evolved over that time. A disproportionate number of pts in the IRF grp were treated in the earlier part of the analyzed period. 
    • It was difficult to determine whether any of the differences in survival were due to an imbalance of cardiac involvement, because cardiac markers (used to assign Cardiac Stage) are affected by renal clearance
    • The definition of "NRF" was not really "N" (that is, a significant number of patients had an eGFR of less than 60 mL/min, though it is not clear exactly how many. The definition of "Renal Stage I" assures us that at least 63% of the NRF pts had an eGFR of at least 50 mL/min). 
Looking forward to a lively discussion at #amyloidosisJC! 

24 March, 2019

#amyloidosisJC 3/27/19: BU Cardiac Staging System for AL Using BNP


This week we will be discussing cardiac staging of AL (light chain) amyloidosis. As mentioned in this post from February 4th, 2018, we are used to the idea of staging AL amyloidosis on the basis of baseline cardiac biomarker measurements. The most widely used system is the European modification of the original 3-stage Mayo 2004 system which uses Troponin T or I and NT-pro-BNP to divide patients into Stages 1, 2, 3a and 3b. The Mayo 2012 system, which incorporates serum free light chain levels, is another 4-stage variation on this theme. Finally, there is a British cardiac staging system for transthyretin (ATTR) amyloidosis which was the subject of a prior #amyloidosisJC discussion. What all of these publications have in common is the use of NT-pro-BNP as a key cardiac biomarker. What all medical centers don't have in common is the ability to order this test without having to send out a blood sample. Many centers use BNP as an alternative. In this installment of #amyloidosisJC, we examine a new 4-stage cardiac staging system for AL amyloidosis devised by researchers at Boston University which incorporates BNP rather than NT-pro-BNP (and we will be lucky enough to have them lead the Twitter discussion!)


Here is a Visual Abstract from the journal Blood summarizing the article:

Visual Abstract for Lilleness B, et al


Key Details of the article we will be reviewing: 
  • A 250-patient derivation cohort from 2016 was used to establish an optimal BNP cut-off to identify cardiac involvement by amyloidosis and also to establish the optimal BNP value to incorporate into a prognostic staging system that corresponded well with the Mayo 2004 system. All the patients in this cohort (except 1) had both BNP and NT-pro-BNP measured. The authors then validated the new staging system with a 1073-patient validation cohort (patients seen between 2004 and 2014, of whom 592 had both BNP and TnI measured at baseline). A Receiver Operating Characteristic (ROC) analysis of 1-yr survival was done to establish a BNP cut-off for BU Cardiac Stage 3b (corresponding to European Cardiac Stage 3b).
  • The presence of cardiac involvement was determined by the following criteria, in order of preference: endomyocardial biopsy or cardiac MRI consistent with cardiac amyloidosis, intraventricular septal end-diastole (IVSd) thickness of at least 12 mm obtained on transthoracic echocardiography without other cause of wall thickening (consistent with established consensus criteria), and IVSd at least 11 mm in men or at least 10 mm in women with no history of hypertension or valvular disease (consistent with current reference ranges, as established by the American Society of Echocardiography).
  • Based on the ECHO/MRI criteria outlined above, 47% of pts in the derivation cohort had cardiac involvement. Only 22 out of the 116 pts identified as having cardiac involvement (19%) had an endomyocardial biopsy confirming cardiac amyloidosis. 
  • In deriving the new cardiac staging system, the authors elected to use the same Troponin I (TnI) cut-off of 0.1 ng/mL used in the Mayo 2004 system, and then determine the best BNP cut-off to use with that. The value they found was 81 pg/mL (𝛋 = 0.854 with Mayo 2004 system). 81 pg/mL also turned out to be an optimal value for predicting the presence of cardiac amyloidosis (except for pts with advanced Chronic Kidney Disease, defined as eGFR <30, in whom the BNP and NT-pro-BNP cut-offs were higher). 
Concordance between he BU and Mayo AL cardiac staging systems
  • Of 592 patients with both BNP and TnI levels measured in the validation cohort, 151 patients (25.5%) were assigned to stage I, 259 patients (43.6%) were assigned to stage II, and 182 patients (30.7%) were assigned to stage III. To create a stage IIIb, a BNP threshold of 700 pg/mL was derived by ROC analysis for survival at 1 yr among the 182 pts with stage III disease (AUC, 0.73; 95% CI, 0.66-0.81). 
  • The median OS from the time of diagnosis was 1.0 year for stage IIIb, 4.3 years for stage III, 9.4 years for stage II, and not reached for stage I patients (Figure 3; HR, 2.6; 95% CI, 1.7-3.9; P , .001). 43.6% of patients with stage IIIb disease died within 6 months.

  • The authors comment on the fact that about half of cardiac stage 3 patients die within the first year, after which time the survival curve for this group flattens out. This is similar to what has been noted previously by the Mayo investigators, and it remains a major challenge in the management of AL amyloidosis. 
  • A BNP-based staging system was hypothesized to be superior to the NT-pro-BNP-based one (since NT-pro-BNP is affected by renal clearance) but this was not confirmed in this work.
Please join us at 9 pm on Wednesday, March 27th, 2019 on Twitter (find us at #amyloidosisJC) for a full and spirited discussion of this article, as well as the other AL cardiac staging papers cited above! 

20 January, 2019

#amyloidosisJC 1/23/19: LECT2 Amyloidosis

#amyloidosisJC resumes this week on a new night: Wednesday night (Jan 23, 2019 at 8 pm EST). 

Short notice and a short but important article describing a series of patients with a relatively recently recognized subtype of amyloidosis: ALect2. 

Here is a link to the full text of the article: 

http://www.bloodjournal.org/content/bloodjournal/123/10/1479.full.pdf

For anyone unable to access the article via that link, email me at zonderj@gmail.com and I can send you the pdf. 

The article we are reviewing this week discusses a series of 130 patients with hepatic #amyloidosis analyzed with tandem mass spectrometry at the Mayo Clinic. 

Key Points:


  • The most common form of hepatic amyloidosis was AL (light chain) subtype. Alect2 also commonly affects the kidneys. 
  • Leukocyte cell-derived chemotaxin 2 associated amyloidosis (ALect2) was next most common (25% of analyzed cases).
  • No definite amyloid-associated LECT2 gene mutation has been identified, but 10 of 10 sequenced patients in another report were homozygous for the G nucleotide in a non-synonymous SNP amongst people of Mexican heritage. 


We'll talk about Alect2 and other forms of hepatic and renal amyloidosis this Wednesday - join us!