01 December, 2019

#amyloidosisjc 12-1-19: MRD and AL #amyloidosis

Here is a synopsis of the article we will be discussing in the December 1st, 2019 session of #amyloidosisJC, an online journal club focusing on all things amyloidosis.  The synopsis was prepared by two recipients of the Don Brockman ASH 2019 Trainee Travel Grants supported by the Amyloidosis Foundation, Dr Suresh Balasubramanian (@malignantheme, Karmanos Cancer Institute) and Dr Holly Lee (@holly_dldumls, University of Calgary), with the help of Dr Naresh Bumma (@NB191186, Ohio State University), the faculty co-moderator for the session. 


In this round of #AmyloidosisJC, we will be discussing a clinical paper that discusses the role of minimal (measurable) residual disease (MRD) in the management of AL amyloidosis.

In this retrospective observation study, the authors presented updated results with extended follow up of the AL amyloidosis patients who underwent end of treatment (EOT) MRD assessment by multiparametric flow cytometry (MFC)  described in a previous publication in 2017.

Study objective: 

To establish whether clearance of clonal plasma cells at EOT using sensitive and uniform MFC is associated with improved OS

Patient population: 

Of the original 173 patients with newly diagnosed AL amyloidosis patients (from their 2017 study), 82 patients who had MRD testing at EOT using sensitive and uniform MFC
 were included in this follow up publication.

84% of the patients underwent autologous stem cell transplant as first line therapy (relevance: consider inherent selection bias to include primarily transplant eligible patients who are generally fit and do not have extensive baseline organ involvement


For MFC testing, reported sensitivity was 1x10-4 to 2x10-5, depending on the number of analyzed events, phenotype and DNA index

A total of 500,000 live cellular events were set as a target per exam (median gated events achieved 489,922, 25–75% IQR 469,765–493,662)


MRD and hematologic response: 29% (24) had negative MRD, and 71% (58) had positive MRD at EOT. 19.5% (16) had CR, 46.3% (38) had VGPR, and 28 (34.1%) had less than VGPR

Patient outcomes (median 4.6 year follow up)

Among VGPR patients, MRD- was associated with improved PFS compared to patients with MRD+ (3-year PFS 88% vs. 46%, p=0.003), particularly among patients who achieved a complete response (3-year PFS 100% vs. 33%, p=0.001). In contrast, this difference in PFS advantage in VGPR/MRD- compared to those who achieved VGPR/MRD+ did not reach statistical significance (p=0.14)

OS difference was not seen between MRD- and MRD+ groups (3-year OS 96% vs. 84%, p=0.17)

MRD- compared with MRD+ among deep responders was associated with lower level of involved light chain (involved free light chain, median 1.1 vs. 1.7mg/dL; p=0.02) and higher frequency of renal response (100% vs. 68%; p=0.005)
. When assessing independent organ function, this difference was not evident in cardiac response


  • Conclusion 1. Despite the retrospective nature of this study with the inherent selection bias to include primarily transplant eligible patients, this work aims at offering novel, robust surrogate endpoint for the design of clinical trials, as well as for optimizing individual patients’ treatment
  • Conclusion 2. There may be value in bone marrow biopsy/aspirate at end of therapy in AL amyloidosis patients who achieve VGPR/CR. Presence of MRD is associated with reduced PFS in this group of patients.
  • Conclusion 3. The sensitivity of the current standard assay for serum free light chain detection does not discern between MRD positive vs negative among VGPR/CR patients.
  • Conclusion 4. This study is notable for presenting one of the largest patient cohorts for end of treatment MRD assessment and applying uniform flow cytometric techniques.


MRD assessment in AL amyloidosis is not yet standardized. Of interest, a study using next generation flow for MRD assessment found that 5 out of 12 MRD positive cases had very low residual tumor burden (<3x10-5), which would have not been detected with lower sensitivity assays (Kastritis et al. 2018). This paper assessed 20 AL patients with hemCR. 8 out of 20 patients were MRD(-).   2 out of 8 patients who had ASCT as primary therapy achieved MRD(-) status, versus 6/12 (50%) patients who did not have ASCT as primary therapy (p = 0.264). In two cases aberrant cells were detected at levels between 10−5 and 10−6  Their reported median sensitivity level of next gen flow was 2.3 x 10−6 (range: 2 × 10−6–3.1 × 10-6)

This is not surprising, as in the myeloma literature, 25% of MRD neg cases by conventional MFC were found to be MRD positive by next gen flow (Flores-Monteroet al. 2017)

We do not have studies that inform us how best to manage/ monitor patients deep hematological response based on their MRD status

  • How does MRD status guide frequency of follow up of patients after therapy?
  • If a patient initially achieves MRD neg CR but then progresses to MRD positive CR on repeat follow up, does this indicate progression/ requirement for treatment?
  • What is the role of transplant in achieving MRD negative status? The impact of daratumumab in achieving MRD negative status? As per our discussion from last week, looking forward to upcoming ISA abstract from @vsanchorawala regarding role of transplant in this topic!
  • Does time to MRD achievement matter and if so, what is the optimal time to assess MRD in AL amyloidosis? Interesting report by Muchtar et al. 2019 in Leukemia journal, looked at not only the depth of response (in this case nadir iFLC <2mg/dL) but also the impact of time to nadir iFLC on patient outcomes. Patients whose nadir iFLC occurred after 12 months from EOT had significantly longer PFS and OS compared to patients who reached nadir before 12 months. This raises the question as to whether there a role for MRD assessment not only at EOT but also further out from EOT.
Obviously, there are many questions related to the utility and usage of MRD testing in AL amyloidosis - looking forward to the journal club where we can explore this further! -J.Zonder,MD

UPDATE 12/1/19 @ 10:19 pm: link to transcript of tonight's twitter discussion CLICK HERE

19 June, 2019

#amyloidosisJC 6/19/19: light chain stabilization and AL #amyloidosis

In this round of #AmyloidosisJC, we will be discussing a basic science paper that describes small molecules that stabilize light chain proteins in vitro. The following summary was written by Gareth Morgan (@wittyremarkhere), the first author. He will lead the discussion for this session of #amyloidosisJC.

Here is a link to the original paper: 

This work was carried out at Scripps Research by the group of Dr. Jeff Kelly. 

Dr. Kelly’s group invented tafamidis, a molecule that stabilizes transthyretin that was recently FDA approved (link: https://www.pfizer.com/news/press-release/press-release-detail/u_s_fda_approves_vyndaqel_and_vyndamax_for_use_in_patients_with_transthyretin_amyloid_cardiomyopathy_a_rare_and_fatal_disease) for treatment of ATTR amyloidosis. 

Amyloidosis is caused by aggregation of normally-soluble proteins. In inherited diseases such as familial ATTR amyloidosis, aggregation is linked to destabilization of the precursor protein by mutation. In AL amyloidosis this connection is less well understood, because each patient has a unique amyloid-forming antibody light chain, secreted by monoclonal plasma cells. However, several lines of evidence show that unstable light chains are associated with amyloidosis:

2. Blancas-Mejia et al, 2014 https://www.ncbi.nlm.nih.gov/pubmed/24157440

Since stabilization of precursor proteins has been shown to have clinical benefit for ATTR patients, the authors looked for stabilizers of light chains.

Key points from the paper:

1. The authors developed a method to measure light chain stability by high throughput screening. This was important because light chains do not have any known natural ligands that could be modified to make a drug. Instead, screening a large number of molecules was required.

2. From a starting set of 650,000 molecules, 16 molecules in four chemical classes could stabilize light chains when tested in several assays.

3. The paper focuses on one compound, which is a commercially available dye called “coumarin 1”. This molecule becomes fluorescent when it binds to light chains, which makes it useful as a tool for other experiments.

4. The crystal structure of coumarin 1 bound to light chains shows that the small molecule binds between the two variable domains in the dimer, at an interface that is made up of highly conserved residues (Figure D in the image seen at this link: F3.large.jpg). This site is likely to be present in most patient’s involved light chains. However, the molecules do not bind to the normal antibody heavy chain:light chain dimer interface.

5. The authors intend to develop molecules that bind more tightly and more specifically to light chains. These molecules could become drug candidates.

Clinical points for discussion:
1. These molecules are not drugs. There is a lot of work to be done before they can be tested in patients.

2. Stabilization may be most effective in when combined with anti plasma-cell therapies. One potentially promising use would be in maintenance for patients who have a hematological response to therapy but are at risk of relapse. Another would be for patients who are too sick to tolerate cytotoxic drugs.

3. Doxycycline, which has shown some efficacy for AL in Phase 2 trials, does not stabilize light chains in this assay – whatever it’s doing is probably different. https://www.ncbi.nlm.nih.gov/pubmed/28338670

4. Tafamidis is beneficial in ATTR patients. Would a light chain stabilizer have similar properties? We don’t know what the consequences of stabilizing light chains in patients will be. Many individuals with other plasma cell dycrasias (e.g., MGUS, smoldering myeloma, multiple myeloma) tolerate elevated levels of a monoclonal light chain without direct organ damage. However, light chains are cleared by the kidneys and several renal syndromes other than amyloidosis are associated with light chains. Altering light chain metabolism may cause problems in the kidney or elsewhere.

5. if stabilizers alter light chain clearance, they may interfere with free light chain measurements, currently considered key in the management and monitoring of AL amyloidosis.

6. It may be possible to measure the inherent stability of light chains in blood, thereby potentially identifying patients who might benefit from light chains  stabilization by small molecules.