Systemic Immunoglobulin Light-Chain Amyloidosis

Amyloid-like aggregates of short self-assembly peptide selectively induce melanoma cell apoptosis

With the rising global incidence of melanoma, new anti-melanoma drugs with low-inducing drug resistance and high selectivity are in urgent need. Inspired by the physiological events in which fibrillar aggregates formed by amyloid proteins are toxic to normal tissues, we here rationally design a tyrosinase responsive peptide, I₄K₂Y* (Ac-IIIIKKDopa-NH₂). Such peptide self-assembled into long nanofibers outside the cells, while it was catalyzed into amyloid-like aggregates by tyrosinase which was rich in melanoma cells. The newly formed aggregates concentrated around the nucleus of melanoma cells, blocking the exchange of biomolecules between the nucleus and cytoplasm and finally leading to cell apoptosis via the S phase arrest in cell cycle distribution and dysfunction of mitochondria. Furthermore, I₄K₂Y* effectively inhibited B16 melanoma growth in a mouse model but with minimal side effects. We believe that the strategy of combining the usage of toxic amyloid-like aggregates and in-situ enzymatic reactions by specific enzymes in tumor cells will bring profound implications for designing new anti-tumor drugs with high selectivity.

Autologous stem cell transplant is an effective therapy for carefully selected patients with AL amyloidosis: experience of a single institution

Autologous stem-cell transplant has been widely used to treat patients with AL amyloidosis. However, transplant-related mortality rates are high, and a recent randomized trial suggested that non-transplant regimens produced comparable results with less toxicity. In order to define the role of patient selection in stem cell transplantation, we evaluated 78 consecutive AL amyloidosis patients transplanted at our centre. Transplant-related mortality occurred in 11·5%. Complete haematological response and organ response were achieved in 56% and 60%. Median overall survival was significantly lower for patients with brain-type natriuretic peptide (BNP) >300 pg/ml (17·5 months vs. not-reached) (P = 0·0004), troponin-I >0·07 ng/ml (13·5 months vs. not-reached) (P = 0·00001) and those not achieving a complete haematological response (88 months vs. not-reached) (P = 0·0345); high BNP and troponin-I were the most important predictive factors in a multivariate analysis. Based on this study, patients with BNP <300 pg/ml and/or normal levels of troponin-I should be considered transplant candidates.

A kinetic aggregation assay allowing selective and sensitive amyloid-β quantification in cells and tissues

The process of amyloid-β (Aβ) fibril formation is genetically and pathologically linked to Alzheimer's disease (AD). Thus, a selective and sensitive method for quantifying Aβ fibrils in complex biological samples allows a variety of hypotheses to be tested. Herein, we report the basis for a quantitative in vitro kinetic aggregation assay that detects seeding-competent Aβ aggregates in mammalian cell culture media, in Caenorhabditis elegans lysate, and in mouse brain homogenate. Sonicated, proteinase K-treated Aβ fibril-containing tissue homogenates or cell culture media were added to an initially monomeric Aβ(1-40) reporter peptide to seed an in vitro nucleated aggregation reaction. The reduction in the half-time (t(50)) of the amyloid growth phase is proportional to the quantity of seeding-competent Aβ aggregates present in the biological sample. An ion-exchange resin amyloid isolation strategy from complex biological samples is demonstrated as an alternative for improving the sensitivity and linearity of the kinetic aggregation assay.

Treatment of immunoglobulin light chain amyloidosis

No therapy is uniformly effective in the management of immunoglobulin light chain amyloidosis (AL amyloidosis). Despite the common generalization, therapy is highly effective. Options available to patients with AL amyloidosis include high-dose therapy, but this is applicable to only about one fourth of patients. Therapies shown to be effective are based on alkylators, dexamethasone, or combinations of an alkylator and steroids. In the past 5 years, novel agents previously shown to be effective in multiple myeloma (eg, thalidomide, lenalidomide, and bortezomib) have been shown to have efficacy in the management of AL amyloidosis. Predictors of outcome include the serum brain natriuretic peptide, the number of organs involved, and the severity of cardiac involvement detected by echocardiography. Virtually all patients are candidates for a trial of therapy, and it is possible to find a nontoxic regimen that can be administered to virtually any patient.

Amyloidosis and POEMS syndrome

IMPORTANCE OF THE FIELD

Treatment options for amyloidosis and polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes (POEMS) syndrome have rapidly increased in the past years, but many patients are diagnosed late in the disease course and do not receive state-of-the art therapy.

AREAS COVERED IN THIS REVIEW

Stem-cell transplantation and novel agents have widened the chemotherapy alternatives available in these disorders and combinations of novel agents with high-dose therapy further improve treatment options. This review covers the main areas of debate in the optimal treatment amyloidosis and POEMS patients, focusing on the implications for everyday clinical practice and management strategies published in the past 36 months.

WHAT THE READER WILL GAIN

Insights into treatment strategies are provided in the review. Keys to early recognition of the syndromes are reviewed.

TAKE-HOME MESSAGE

With early diagnosis most patients are therapy candidates. New agents and new application of stem-cell transplantation have dramatically improved outcomes for these previously uniformly poor prognosis disorders.

Troponin T level as an exclusion criterion for stem cell transplantation in light-chain amyloidosis

The efficacy of stem cell transplantation in amyloidosis largely is determined by treatment-related mortality rates (range, 11-25%). Appropriate patient selection is essential to avoid this high mortality rate. Among 271 patients undergoing stem cell transplantation, troponin T was a powerful predictor of treatment-related mortality. Patients with troponin T levels of 0.06 microg/L or higher had a day-100 all-cause mortality rate of 28%. Patients with troponin T levels less than 0.06 microg/L had a day-100 all-cause mortality rate of 7% (P < 0.001). Troponin T levels should be measured in all patients before transplantation. Those with troponin T levels exceeding 0.06 microg/L should be considered for less toxic therapies until the clinically optimal use of stem cell transplantation is better defined by randomized clinical trials.

Deposition-associated diseases related with a monoclonal compound

Up to 3% of adults over 50 years of age show a monoclonal peak values in blood or urine. Findings and prognosis will be distinct in view of the nature of this factor. In B-cell neoplasias (multiple myeloma, Waldeström macroglobulinaemia, chronic myeloid leukaemia and non-Hodgkin lymphoma) the clinical pattern is dominated by the systemic effects produced by the expansion of the malign clone; the monoclonal protein may result in hyperviscosity syndrome or renal damage. On the other hand, there are other less frequent processes called diseases associated to monoclonal components, where the main clinical manifestations and prognosis depend of the biological effects of the monoclonal protein. With reference to this last group, which is the objective of this revision, no bone lesions, anaemia or a greater tendency to infections usually occur when compared with the first group. Even so, there are some cases of interposition between both groups: for instance, type IgM immunoglobulin present in Waldeström macroglobulinaemia may have cold agglutinin activity, and in the case of multiple myeloma, the clone may secrete amyloidogenic light chains.