A phase 1/2 study of the oral proteasome inhibitor ixazomib in relapsed or refractory AL amyloidosis.

This phase 1/2 study assessed the safety, tolerability, and preliminary efficacy of the oral proteasome inhibitor (PI) ixazomib in patients with relapsed/refractory immunoglobulin light chain (AL) amyloidosis. Ixazomib was administered to adult patients with relapsed/refractory AL amyloidosis after 1 or more prior lines of therapy (including bortezomib) on days 1, 8, and 15 of 28-day cycles, for up to 12 cycles. Patients with less than partial response after 3 cycles received oral dexamethasone (40 mg, days 1-4) from cycle 4. A 3+3 dose-escalation phase was followed by 2 expansion cohorts (PI-naive and PI-exposed patients) at the maximum tolerated dose (MTD). Twenty-seven patients were enrolled: 11 during dose escalation (6 at 4.0 mg and 5 at 5.5 mg) and 16 during dose expansion (4.0 mg). Three patients experienced dose-limiting toxicities: 1 at 4.0 mg and 2 at 5.5 mg; the MTD was determined as 4.0 mg. Most common adverse events (AEs) included nausea, skin and subcutaneous tissue disorders (SSTD), diarrhea, and fatigue; grade 3 or higher AEs included dyspnea, fatigue, and SSTD. Overall, the hematologic response rate was 52% in patients treated at the MTD (n = 21). Organ responses were seen in 56% of patients (5 cardiac, 5 renal). Median hematologic progression-free survival was 14.8 months; 1-year progression-free and overall survival rates were 60% and 85%, respectively (median follow-up, 16.9 months). Weekly oral ixazomib appears to be active in patients with relapsed/refractory AL amyloidosis, with a generally manageable safety profile. The study was registered at clinicaltrials.gov as #NCT01318902 A phase 3 study is ongoing (#NCT01659658).

Pomalidomide and dexamethasone in the treatment of AL amyloidosis: results of a phase 1 and 2 trial.

The objectives of a phase 1/2 trial of pomalidomide with dexamethasone for the treatment of light chain (AL) amyloidosis were to determine the safety, tolerability, maximum tolerated dose (MTD), recommended phase 2 dose, and hematologic and clinical response. A 3+3 dose-escalation phase (15 patients) was followed by an expansion cohort (12 patients) enrolled at the MTD. Pomalidomide was administered at 2 and 3 mg on days 1 to 28 (cohorts 1 and 2) and 4 mg on days 1 to 21 (cohort 3) every 28 days, with weekly dexamethasone at a dose of 20 mg. Twenty-seven patients with previously treated AL were enrolled, 15 during dose escalation (6 at 2 mg, 3 at 3 mg, and 6 at 4 mg) and 12 during dose expansion (all at 4 mg). One patient experienced dose-limiting toxicity at 4 mg; the MTD was determined as 4 mg. The most common grade ≥3 drug-related adverse events included myelosuppression and fatigue. Overall, hematologic response (HR) was 50% in 24 evaluable patients. The median time to best HR was 3 cycles, and median duration of HR was 15 months. Median overall survival has not yet been reached, with a median follow-up of 17.1 months and median event-free survival of 17.8 months. This trial was registered at www.clinicaltrials.gov as #NCT01570387.

Heart Failure Resulting From Age-Related Cardiac Amyloid Disease Associated With Wild-Type Transthyretin: A Prospective, Observational Cohort Study.

BACKGROUND: Heart failure caused by wild-type transthyretin amyloidosis (ATTRwt) is an underappreciated cause of morbidity and mortality in the aging population. The aims of this study were to examine features of disease and to characterize outcomes in a large ATTRwt cohort. METHODS AND RESULTS: Over 20 years, 121 patients with ATTRwt were enrolled in a prospective, observational study. Median age at enrollment was 75.6 years (range, 62.6-87.8 years); 97% of patients were white. The median survival, measured from biopsy diagnosis, was 46.69 months (95% confidence interval, 41.95-56.77); 78% of deaths were attributable to cardiac causes. By Kaplan-Meier analysis, 5-year survival was 35.7% (95% confidence interval, 25-46). Impaired functional capacity (mean Vo2max, 13.5 mL·kg(-1)·min(-1)) and atrial fibrillation (67%) were common clinical features. Multivariate predictors of reduced survival were elevated serum brain natriuretic peptide (482 ± 337 pg/mL) and uric acid (8.2 ± 2.6 mg/dL), decreased left ventricular ejection fraction (50% median; range, 10%-70%), and increased relative wall thickness (0.75 ± 0.19). CONCLUSIONS: In this series of patients with biopsy-proven ATTRwt, poor functional capacity and atrial arrhythmias were common clinical features. Elevated brain natriuretic peptide and uric acid, decreased left ventricular ejection fraction, and increased relative wall thickness were associated with limited survival of only 35.7% at 5 years for the group as a whole. These data establish the natural history of ATTRwt, provide statistical basis for the design of future interventional clinical trials, and highlight the need for more sensitive diagnostic tests and disease-specific treatments for this disease.

The role of the aryl hydrocarbon receptor in the development of cells with the molecular and functional characteristics of cancer stem-like cells.

BACKGROUND: Self-renewing, chemoresistant breast cancer stem cells are believed to contribute significantly to cancer invasion, migration and patient relapse. Therefore, the identification of signaling pathways that regulate the acquisition of stem-like qualities is an important step towards understanding why patients relapse and towards development of novel therapeutics that specifically target cancer stem cell vulnerabilities. Recent studies identified a role for the aryl hydrocarbon receptor (AHR), an environmental carcinogen receptor implicated in cancer initiation, in normal tissue-specific stem cell self-renewal. These studies inspired the hypothesis that the AHR plays a role in the acquisition of cancer stem cell-like qualities. RESULTS: To test this hypothesis, AHR activity in Hs578T triple negative and SUM149 inflammatory breast cancer cells were modulated with AHR ligands, shRNA or AHR-specific inhibitors, and phenotypic, genomic and functional stem cell-associated characteristics were evaluated. The data demonstrate that (1) ALDH(high) cells express elevated levels of Ahr and Cyp1b1 and Cyp1a1, AHR-driven genes, (2) AHR knockdown reduces ALDH activity by 80%, (3) AHR hyper-activation with several ligands, including environmental ligands, significantly increases ALDH1 activity, expression of stem cell- and invasion/migration-associated genes, and accelerates cell migration, (4) a significant correlation between Ahr or Cyp1b1 expression (as a surrogate marker for AHR activity) and expression of stem cell- and invasion/migration-associated gene sets is seen with genomic data obtained from 79 human breast cancer cell lines and over 1,850 primary human breast cancers, (5) the AHR interacts directly with Sox2, a master regulator of self-renewal; AHR ligands increase this interaction and nuclear SOX2 translocation, (6) AHR knockdown inhibits tumorsphere formation in low adherence conditions, (7) AHR inhibition blocks the rapid migration of ALDH(high) cells and reduces ALDH(high) cell chemoresistance, (8) ALDH(high) cells are highly efficient at initiating tumors in orthotopic xenografts, and (9) AHR knockdown inhibits tumor initiation and reduces tumor Aldh1a1, Sox2, and Cyp1b1 expression in vivo. CONCLUSIONS: These data suggest that the AHR plays an important role in development of cells with cancer stem cell-like qualities and that environmental AHR ligands may exacerbate breast cancer by enhancing expression of these properties.

Risk factors for venous thromboembolism in immunoglobulin light chain amyloidosis.

Patients with immunoglobulin light chain amyloidosis are at risk for both thrombotic and bleeding complications. While the hemostatic defects have been extensively studied, less is known about thrombotic complications in this disease. This retrospective study examined the frequency of venous thromboembolism in 929 patients with immunoglobulin light chain amyloidosis presenting to a single referral center, correlated risk of venous thromboembolism with clinical and laboratory factors, and examined complications of anticoagulation in this population. Sixty-five patients (7%) were documented as having at least one venous thromboembolic event. Eighty percent of these patients had events within one year prior to or following diagnosis. Lower serum albumin was associated with increased risk of VTE, with a hazard ratio of 4.30 (CI 1.60-11.55; P=0.0038) for serum albumin less than 3 g/dL compared to serum albumin greater than 4 g/dL. Severe bleeding complications were observed in 5 out of 57 patients with venous thromboembolism undergoing treatment with anticoagulation. Prospective investigation should be undertaken to better risk stratify these patients and to determine the optimal strategies for prophylaxis against and management of venous thromboembolism.

Cooperative stabilization of transthyretin by clusterin and diflunisal.

The circulating protein transthyretin (TTR) can unfold, oligomerize, and form highly structured amyloid fibrils that are deposited in tissues, causing organ damage and disease. This pathogenic process is caused by a heritable TTR point mutation in cases of familial TTR-related amyloidosis or wild-type TTR in cases of age-associated amyloidosis (previously called senile systemic amyloidosis). The TTR amyloid cascade is hypothesized to begin with the dissociation of the TTR native tetrameric structure into folded but unstable monomeric TTR subunits. Unfolding of monomeric TTR initiates an oligomerization process leading to aggregation and fibril formation. Numerous proteostatic mechanisms for regulating the TTR amyloid cascade exist. Extracellular chaperones provide an innate defense against misfolded proteins. Clusterin (CLU), a plasma protein, has the capacity to recognize exposed hydrophobic regions of misfolded proteins, shielding them from aggregation. We have previously demonstrated that CLU is associated with the amyloid fibrils in cardiac tissues from patients with TTR amyloidosis. In this study, we have used tetrameric and monomeric TTR structural variants to determine the ability of CLU to inhibit TTR amyloid fibril formation. Using circular dichroism spectroscopy, we determined that CLU preferentially stabilizes monomeric TTR and generates increasingly stable conformations under acid stress. Moreover, studies using surface plasmon resonance showed a direct interaction of CLU with high-molecular weight TTR oligomers. The interactions of CLU with monomeric and aggregated TTR proceed in a cooperative manner in the presence of diflunisal, a small molecule drug used to stabilize TTR tetramers.

Induction Therapy with Bortezomib Followed by Bortezomib-High Dose Melphalan and Stem Cell Transplantation for Light Chain Amyloidosis: Results of a Prospective Clinical Trial.

The depth of hematologic response has been shown to correlate with survival and organ responses for patients with light chain (AL) amyloidosis. We conducted a prospective trial of 2 cycles of induction with bortezomib and dexamethasone on a twice a week schedule followed by conditioning with bortezomib and high-dose melphalan (HDM) and autologous stem cell transplantation (SCT). The objectives were hematologic responses, tolerability, and survival. Thirty-five patients were enrolled from 2010 to 2013. Of these, 30 proceeded with SCT, whereas 5 did not because of clinical deterioration during induction (n = 3) or complications after stem cell collection (n = 2). Two patients developed features of an autologous graft-versus-host disease-like syndrome post-SCT, which responded to steroids; no other unusual complications were seen. Treatment-related mortality occurred in 8.5% (3/35). Hematologic responses were achieved by 100% of the 27 assessable patients (63% complete response, 37% very good partial response [VGPR]) who completed the planned treatment. By intention-to-treat, hematologic responses occurred in 77% of patients (49% complete response, 29% VGPR). With a median follow-up of 36 months, the median overall survival and progression-free survival were not reached. In conclusion, incorporating bortezomib into induction and conditioning yielded a high rate of hematologic responses after HDM/SCT in patients with AL amyloidosis.

Genetic variation of the transthyretin gene in wild-type transthyretin amyloidosis (ATTRwt).

Wild-type transthyretin amyloidosis (ATTRwt), typically diagnosed as congestive heart failure in elderly Caucasian men, features myocardial amyloid deposits of wild-type plasma protein transthyretin (TTR). ATTRwt is sporadic, its pathogenesis is poorly understood, and currently there are no biomarkers for diagnosis or prognosis. Genetic studies of variant-associated transthyretin amyloidosis have suggested that non-coding TTR gene variants modulate disease. We hypothesized that cis-acting regulatory elements in the TTR gene non-coding regions may modify expression, affecting ATTRwt onset and progression. We studied an ATTRwt cohort consisting of 108 Caucasian males ranging in age from 59 to 87 years with cardiomyopathy due to wild-type TTR deposition; results were compared to 118 anonymous controls matched by age, sex, and race. Four predicted non-coding regulatory regions and all exons in the TTR gene were sequenced using the Sanger method. Eleven common variants were identified; three variants were significantly associated with ATTRwt (p < 0.05), though only one, rs72922940, remained near significance (p corrected = 0.083) after multiple testing correction. Exon analyses demonstrated the occurrence of the p.G26S (G6S) polymorphism in 7 % of ATTRwt subjects and 12 % of controls; this variant was predicted to be a protective factor (p = 0.051). Four variants were significantly associated with age at onset and survival. In this first genetic study of a large, well-characterized cohort of ATTRwt, non-coding and coding variants associated with disease, age at onset, and survival were identified. Further investigation is warranted to determine the prevalence of these variants in ATTRwt, their regulatory function, and potential role in assessing disease risk.

Amyloidomics comes of age.

Potentially effective and life-saving treatment for patients with systemic amyloidosis relies on the astute clinician recognizing the signs and symptoms, histochemical identification of fibrils, and accurate diagnosis of amyloid type. In this issue of Blood, Brambilla et al report a new methodology for accomplishing the key third step in this process.

Single agent lenalidomide three times a week induces hematologic responses in AL amyloidosis patients on dialysis.

The combination of lenalidomide and dexamethasone can produce hematologic responses in previously treated patients with AL amyloidosis. Because lenalidomide is primarily excreted unchanged by the kidney, adjustments to the starting dose of lenalidomide are recommended to provide appropriate drug exposure in patients with moderate or severe renal impairment and in patients on dialysis. Here, we report on a study of patients with AL amyloidosis on dialysis treated with lenalidomide at a dose of 10 mg orally three times a week. Seven patients were enrolled. All patients had received prior treatment, with 57% receiving prior high-dose melphalan and stem cell transplantation. Two patients died before evaluation of response. The most common adverse event was infection; no thromboembolic complications were seen. One patient required dose-modification. Hematologic responses were obtained by four of the five evaluable patients. Median overall survival was 18 months. In conclusion, adjusted dose lenalidomide was reasonably tolerated and induced sustained hematologic responses in previously treated patients with AL amyloidosis on dialysis.

Human amyloidogenic light chain proteins result in cardiac dysfunction, cell death, and early mortality in zebrafish.

Systemic amyloid light-chain (AL) amyloidosis is associated with rapidly progressive and fatal cardiomyopathy resulting from the direct cardiotoxic effects of circulating AL light chain (AL-LC) proteins and the indirect effects of AL fibril tissue infiltration. Cardiac amyloidosis is resistant to standard heart failure therapies, and, to date, there are limited treatment options for these patients. The mechanisms underlying the development of cardiac amyloidosis and AL-LC cardiotoxicity are largely unknown, and their study has been limited by the lack of a suitable in vivo model system. Here, we establish an in vivo zebrafish model of human AL-LC-induced cardiotoxicity. AL-LC isolated from AL cardiomyopathy patients or control nonamyloidogenic LC protein isolated from multiple myeloma patients (Con-LC) was directly injected into the circulation of zebrafish at 48 h postfertilization. AL-LC injection resulted in impaired cardiac function, pericardial edema, and increased cell death relative to Con-LC, culminating in compromised survival with 100% mortality within 2 wk, independent of AL fibril deposition. Prior work has implicated noncanonical p38 MAPK activation in the pathogenesis of AL-LC-induced cardiotoxicity, and p38 MAPK inhibition via SB-203580 rescued AL-LC-induced cardiac dysfunction and cell death and attenuated mortality in zebrafish. This in vivo zebrafish model of AL-LC cardiotoxicity demonstrates that antagonism of p38 MAPK within the AL-LC cardiotoxic signaling response may serve to improve cardiac function and mortality in AL cardiomyopathy. Furthermore, this in vivo model system will allow for further study of the molecular underpinnings of AL cardiotoxicity and identification of novel therapeutic strategies.

Stanniocalcin1 is a key mediator of amyloidogenic light chain induced cardiotoxicity.

Immunoglobulin light chain (LC) amyloidosis (AL) results from overproduction of circulating amyloidogenic LC proteins and subsequent amyloid fibril deposition in organs. Mortality in AL amyloidosis patients is highly associated with a rapidly progressive AL cardiomyopathy, marked by profound impairment of diastolic and systolic cardiac function and significant early mortality. While myocardial fibril deposition contributes to the severe diastolic dysfunction seen in AL cardiomyopathy patients, the degree of fibril deposition has not been found to correlate with prognosis. Previously, we and others showed a direct cardiotoxic effect of amyloidogenic LC proteins (AL-LC), which may contribute to the pathophysiology and mortality observed in AL cardiomyopathy patients. However, the mechanisms underlying AL-LC related cardiotoxicity remain unknown. Mammalian stanniocalcin1 (STC1) is associated with a number of cellular processes including oxidative stress and cell death. Herein, we find that STC1 expression is elevated in cardiac tissue from AL cardiomyopathy patients, and is induced in isolated cardiomyocytes in response to AL-LC, but not non-amyloidogenic LC. STC1 overexpression in vitro recapitulates the pathophysiology of AL-LC mediated cardiotoxicity, with increased ROS production, contractile dysfunction and cell death. Overexpression of STC1 in vivo results in significant cardiac dysfunction and cell death. Genetic silencing of STC1 prevents AL-LC induced cardiotoxicity in cardiomyocytes and protects against AL-LC induced cell death and early mortality in zebrafish. The cardiotoxic effects of STC1 appears to be mediated via mitochondrial dysfunction as indicated by loss of mitochondrial membrane potential, ROS production and increased mitochondrial calcium levels. Collectively, this work identifies STC1 as a critical determinant of AL-LC cardiotoxicity.

Outcome of AL amyloidosis after high-dose melphalan and autologous stem cell transplantation: long-term results in a series of 421 patients.

Previous studies have suggested that, in patients with AL amyloidosis treated with high-dose melphalan and autologous stem-cell transplantation (HDM/SCT), the greatest benefit is seen in those patients achieving a hematologic complete response (CR). We analyzed a series of 421 consecutive patients treated with HDM/SCT at a single referral center and compared outcomes for patients with and without CR. Treatment-related mortality was 11.4% overall (5.6% in the last 5 years). By intention-to-treat analysis, the CR rate was 34% and the median event-free survival (EFS) and overall survival (OS) were 2.6 and 6.3 years, respectively. Eighty-one patients died within the first year after HDM/SCT and were not evaluable for hematologic and organ response. Of 340 evaluable patients, 43% achieved CR and 78% of them experienced an organ response. For CR patients, median EFS and OS were 8.3 and 13.2 years, respectively. Among the 195 patients who did not obtain CR, 52% achieved an organ response, and their median EFS and OS were 2 and 5.9 years, respectively. Thus, treatment of selected AL patients with HDM/SCT resulted in a high organ response rate and long OS, even for those patients who did not achieve CR.

Doxycycline reduces fibril formation in a transgenic mouse model of AL amyloidosis.

Systemic AL amyloidosis results from the aggregation of an amyloidogenic immunoglobulin (Ig) light chain (LC) usually produced by a plasma cell clone in the bone marrow. AL is the most rapidly fatal of the systemic amyloidoses, as amyloid fibrils can rapidly accumulate in tissues including the heart, kidneys, autonomic or peripheral nervous systems, gastrointestinal tract, and liver. Chemotherapy is used to eradicate the cellular source of the amyloidogenic precursor. Currently, there are no therapies that target the process of LC aggregation, fibril formation, or organ damage. We developed transgenic mice expressing an amyloidogenic λ6 LC using the cytomegalovirus (CMV) promoter to circumvent the disruption of B cell development by premature expression of recombined LC. The CMV-λ6 transgenic mice develop neurologic dysfunction and Congophilic amyloid deposits in the stomach. Amyloid deposition was inhibited in vivo by the antibiotic doxycycline. In vitro studies demonstrated that doxycycline directly disrupted the formation of recombinant LC fibrils. Furthermore, treatment of ex vivo LC amyloid fibrils with doxycycline reduced the number of intact fibrils and led to the formation of large disordered aggregates. The CMV-λ6 transgenic model replicates the process of AL amyloidosis and is useful for testing the antifibril potential of orally available agents.

Amyloidosis of the gastrointestinal tract: a 13-year, single-center, referral experience.

Amyloidosis of the gastrointestinal tract, with biopsy-proven disease, is rare. We reviewed a series of patients who presented with biopsy-proven gastrointestinal amyloidosis and report their clinical characteristics, treatments, and survival. This is a retrospective review of data prospectively collected from January 1998 to December 2011 in a tertiary referral center; 2,334 patients with all types of amyloidosis were evaluated during this period. Seventy-six patients (3.2%) had biopsy-proven amyloid involvement of the gastrointestinal tract. Their median age was 61 years (range, 34-79). Systemic amyloidosis with dominant gastrointestinal involvement was present in 60 (79%) patients, whereas the other 16 (21%) patients had amyloidosis localized to the gastrointestinal tract without evidence of an associated plasma cell dyscrasia or other organ involvement. Of the 60 systemic cases, 50 (83%) had immunoglobulin light-chain, five (8%) had familial lysozyme, three (5%) had wild-type transthyretin, and two (3%) had mutant transthyretin amyloidosis. The most frequent symptoms for all patients were weight loss in 33 (45%) and gastrointestinal bleeding in 27 (36%). Incidental identification of amyloidosis on routine endoscopic surveillance played a role in the diagnosis of seven patients with systemic immunoglobulin light-chain, and four patients with immunoglobulin light-chain localized to the gastrointestinal tract. Amyloid protein subtyping was performed in 12 of the cases of localized disease, and all had lambda light chain disease. Of the 50 patients with systemic immunoglobulin light-chain amyloidosis, 45 were treated with anti-plasma cell therapy. The median survival has not been reached for this group. For the 16 patients with localized gastrointestinal amyloidosis, supportive care was the mainstay of treatment; none received anti-plasma cell therapy. All 16 are alive at a median follow-up of 36 months (range, 1-143). Patients with biopsy-proven gastrointestinal amyloidosis often present with weight loss and bleeding. In localized cases, all that underwent typing were due to lambda light chain amyloidosis and none progressed to systemic disease during the period of follow-up. Most patients with systemic disease had immunoglobulin light-chain, and their tolerance of therapy and median survival were excellent. Although a rare manifestation of amyloidosis, staining for amyloid should be considered in patients undergoing gastrointestinal biopsy who have unexplained chronic gastrointestinal symptoms.

Melphalan, lenalidomide and dexamethasone for the treatment of immunoglobulin light chain amyloidosis: results of a phase II trial.

We report results of a phase II trial of combination of melphalan, lenalidomide, and dexamethasone for the treatment of immunoglobulin light chain (AL) amyloidosis. The primary objectives were tolerability and hematologic response rate; secondary objectives were organ responses and survival. Treatment protocol consisted of melphalan 5 mg/m(2)/day for four days, lenalidomide 10 mg/day for 21 days and dexamethasone 20-40 mg once a week every 28 days for a total of 12 cycles. Sixteen subjects were enrolled of whom 14 completed at least 3 cycles and were evaluable for response. Grade 3/4 toxicities were experienced by 88% (n=14), the most common being myelosuppression (n=7). Dose reductions occurred in 85% (n=12 of 14) of subjects. Hematologic partial and complete responses were achieved by 43% (n=6 of 14) and 7% (n=1 of 14), respectively. The median overall survival has not been reached and median progression-free survival is 24 months. In conclusion, this combination is associated with significant myelosuppression leading to dose modifications and producing minor hematologic responses in AL amyloidosis. http://clinicaltrials.gov/ct2/show/NCT00679367.

Foxk1 recruits the Sds3 complex and represses gene expression in myogenic progenitors.

Previous studies have established that Foxk1 (forkhead box k1) plays an important role in skeletal muscle regeneration. Foxk1 regulates the cell-cycle progression of myogenic progenitors by repressing the cell-cycle inhibitor gene p21. However, the underlying mechanism is not well understood. In the present study, we report the identification of Sds3 (suppressor of defective silencing 3) as an adaptor protein that recruits the Sin3 [SWI (switch)-independent 3]-HDAC (histone deacetylase) repression complex and binds Foxk1. Using GST (glutathione transferase) pull-down assays, we defined the interaction between the Foxk1 FHA (forkhead-associated domain) domain and phospho-Thr(49) in Sds3. We demonstrated that the transcriptional repression of Foxk1 is dependent on the Sin3-Sds3 repression complex, and knockdown of Sds3 results in cell-cycle arrest. We further identified the protein kinase CK2 as the protein kinase for Sds3 Thr(49) and demonstrated that the protein kinase activity of CK2 is required for proper cell-cycle progression. Analysis of CK2 mutant mice reveals perturbation of skeletal muscle regeneration due to the dysregulation of cell-cycle kinetics. Overall, these studies define a CK2-Sds3-Foxk1 cascade that modulates gene expression and regulates skeletal muscle regeneration.

Amyloidogenic light chains induce cardiomyocyte contractile dysfunction and apoptosis via a non-canonical p38alpha MAPK pathway.

Patients with primary (AL) cardiac amyloidosis suffer from progressive cardiomyopathy with a median survival of less than 8 months and a 5-year survival of <10%. Contributing to this poor prognosis is the fact that these patients generally do not tolerate standard heart failure therapies. The molecular mechanisms underlying this deadly form of heart disease remain unclear. Although interstitial amyloid fibril deposition of Ig light chain proteins is a major cause of cardiac dysfunction in AL cardiac amyloidosis, we have previously shown that amyloid precursor proteins directly impair cardiac function at the cellular and isolated organ levels, independent of fibril formation. In this study, we report that amyloidogenic light chain (AL-LC) proteins provoke oxidative stress, cellular dysfunction, and apoptosis in isolated adult cardiomyocytes through activation of p38 mitogen-activated protein kinase (MAPK). AL-LC-induced p38 activation was found to be independent of the upstream MAPK kinase, MKK3/6, and instead depends upon transforming growth factor-beta-activated protein kinase-1 binding protein-1 (TAB1)-mediated p38alpha MAPK autophosphorylation. Treatment of cardiomyocytes with SB203580, a selective p38 MAPK inhibitor, significantly attenuated AL-LC-induced oxidative stress, cellular dysfunction, and apoptosis. Our data provide a unique mechanistic insight into the pathogenesis of AL-LC cardiac toxicity and suggest that TAB1-mediated p38alpha MAPK autophosphorylation may serve as an important event leading to cardiac dysfunction and subsequent heart failure.

Repurposing diflunisal for familial amyloid polyneuropathy: a randomized clinical trial.

IMPORTANCE: Familial amyloid polyneuropathy, a lethal genetic disease caused by aggregation of variant transthyretin, induces progressive peripheral nerve deficits and disability. Diflunisal, a nonsteroidal anti-inflammatory agent, stabilizes transthyretin tetramers and prevents amyloid fibril formation in vitro. OBJECTIVE: To determine the effect of diflunisal on polyneuropathy progression in patients with familial amyloid polyneuropathy. DESIGN, SETTING, AND PARTICIPANTS: International randomized, double-blind, placebo-controlled study conducted among 130 patients with familial amyloid polyneuropathy exhibiting clinically detectable peripheral or autonomic neuropathy at amyloid centers in Sweden (Umeå), Italy (Pavia), Japan (Matsumoto and Kumamoto), England (London), and the United States (Boston, Massachusetts; New York, New York; and Rochester, Minnesota) from 2006 through 2012. INTERVENTION: Participants were randomly assigned to receive diflunisal, 250 mg (n=64), or placebo (n=66) twice daily for 2 years. MAIN OUTCOMES AND MEASURES: The primary end point, the difference in polyneuropathy progression between treatments, was measured by the Neuropathy Impairment Score plus 7 nerve tests (NIS+7) which ranges from 0 (no neurological deficits) to 270 points (no detectable peripheral nerve function). Secondary outcomes included a quality-of-life questionnaire (36-Item Short-Form Health Survey [SF-36]) and modified body mass index. Because of attrition, we used likelihood-based modeling and multiple imputation analysis of baseline to 2-year data. RESULTS: By multiple imputation, the NIS+7 score increased by 25.0 (95% CI, 18.4-31.6) points in the placebo group and by 8.7 (95% CI, 3.3-14.1) points in the diflunisal group, a difference of 16.3 points (95% CI, 8.1-24.5 points; P < .001). Mean SF-36 physical scores decreased by 4.9 (95% CI, -7.6 to -2.2) points in the placebo group and increased by 1.5 (95% CI, -0.8 to 3.7) points in the diflunisal group (P < .001). Mean SF-36 mental scores declined by 1.1 (95% CI, -4.3 to 2.0) points in the placebo group while increasing by 3.7 (95% CI, 1.0-6.4) points in the diflunisal group (P = .02). By responder analysis, 29.7% of the diflunisal group and 9.4% of the placebo group exhibited neurological stability at 2 years (<2-point increase in NIS+7 score; P = .007). CONCLUSIONS AND RELEVANCE: Among patients with familial amyloid polyneuropathy, the use of diflunisal compared with placebo for 2 years reduced the rate of progression of neurological impairment and preserved quality of life. Although longer-term follow-up studies are needed, these findings suggest benefit of this treatment for familial amyloid polyneuropathy. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00294671.