Proteasome inhibitors in AL amyloidosis: focus on mechanism of action and clinical activity

Amyloid Neuropathy: From Pathophysiology to Treatment in Light-Chain Amyloidosis and Hereditary Transthyretin Amyloidosis

Amyloid neuropathy is caused by deposition of insoluble β-pleated amyloid sheets in the peripheral nervous system. It is most common in: (1) light-chain amyloidosis, a clonal non-proliferative plasma cell disorder in which fragments of immunoglobulin, light or heavy chain, deposit in tissues, and (2) hereditary transthyretin (ATTRv) amyloidosis, a disorder caused by autosomal dominant mutations in the TTR gene resulting in mutated protein that has a higher tendency to misfold. Amyloid fibrils deposit in the endoneurium of peripheral nerves, often extensive in the dorsal root ganglia and sympathetic ganglia, leading to atrophy of Schwann cells in proximity to amyloid fibrils and blood-nerve barrier disruption. Clinically, amyloid neuropathy is manifested as a length-dependent sensory predominant neuropathy associated with generalized autonomic failure. Small unmyelinated nerves are involved early and prominently in early-onset Val30Met ATTRv, whereas other ATTRv and light-chain amyloidosis often present with large- and small-fiber involvement. Nerve conduction studies, quantitative sudomotor axon testing, and intraepidermal nerve fiber density are useful tools to evaluate denervation. Amyloid deposition can be demonstrated by tissue biopsy of the affected organ or surrogate site, as well as bone-avid radiotracer cardiac imaging. Treatment of light-chain amyloidosis has been revolutionized by monoclonal antibodies and stem cell transplantation with improved 5-year survival up to 77%. Novel gene therapy and transthyretin stabilizers have revolutionized treatment of ATTRv, improving the course of neuropathy (less change in the modified Neuropathy Impairment Score + 7 from baseline) and quality of life. With great progress in amyloidosis therapies, early diagnosis and presymptomatic testing for ATTRv family members has become paramount. ANN NEUROL 2024.

A randomized phase 3 study of ixazomib-dexamethasone versus physician's choice in relapsed or refractory AL amyloidosis

In the first phase 3 study in relapsed/refractory AL amyloidosis (TOURMALINE-AL1 NCT01659658), 168 patients with relapsed/refractory AL amyloidosis after 1-2 prior lines were randomized to ixazomib (4 mg, days 1, 8, 15) plus dexamethasone (20 mg, days 1, 8, 15, 22; n = 85) or physician's choice (dexamethasone ± melphalan, cyclophosphamide, thalidomide, or lenalidomide; n = 83) in 28-day cycles until progression or toxicity. Primary endpoints were hematologic response rate and 2-year vital organ deterioration or mortality rate. Only the first primary endpoint was formally tested at this interim analysis. Best hematologic response rate was 53% with ixazomib-dexamethasone vs 51% with physician's choice (p = 0.76). Complete response rate was 26 vs 18% (p = 0.22). Median time to vital organ deterioration or mortality was 34.8 vs 26.1 months (hazard ratio 0.53; 95% CI, 0.32-0.87; p = 0.01). Median treatment duration was 11.7 vs 5.0 months. Adverse events of clinical importance included diarrhea (34 vs 30%), rash (33 vs 20%), cardiac arrhythmias (26 vs 15%), nausea (24 vs 14%). Despite not meeting the first primary endpoint, all time-to-event data favored ixazomib-dexamethasone. These results are clinically relevant to this relapsed/refractory patient population with no approved treatment options.

Daratumumab for relapsed AL amyloidosis-When cumulative real-world data precedes clinical trials: A multisite study and systematic literature review

OBJECTIVES

Patients with relapsed/refractory AL amyloidosis (RRAL) have poor prognosis, but emerging data shows promising results with the use daratumumab. We evaluated daratumumab treatment in RRAL in real-world setting.

METHODS

A retrospective multisite study of RRAL patients treated with daratumumab alone and in combinations.

RESULTS

Forty-nine patients, diagnosed between 1.1.2008 and 1.2.2018 were included; 27% also had multiple myeloma (MM). Revised Mayo score was ≥ 3 in 67%. Hematologic overall response rate was 81%, 64% achieved very good partial response (VGPR) or better. Concurrent active MM was associated with lower rates of VGPR (OR 0.19, 95% CI 0.04-0.81; P = .03) in a multi-variate analysis. Cardiac and renal responses were 74% and 73%, respectively. Median progression-free survival (PFS) was 28.4 months and median overall survival (OS) was not reached; 2-year PFS and OS were 68.6 ± 7.5% and 90.4 ± 4.6%, respectively. Hematologic response correlated with prolonged PFS and OS. Daratumumab was safe and well tolerated, no patients discontinued therapy due to toxicity. Our data was aligned with outcomes from a systematic literature review, which identified 10 case series (n = 517) and 2 clinical trials (n = 62) meeting prespecified criteria.

CONCLUSIONS

Our data support favorable safety tolerability and efficacy of daratumumab among non-selective RRAL patients in a real-world setting.

Distribution of amyloidosis subtypes based on tissue biopsy site - Consecutive analysis of 729 patients at a single amyloidosis center in Japan

This study was performed to elucidate the distribution of amyloidosis subtypes based on tissue biopsy site. Samples obtained from 729 consecutive patients with amyloidosis were analyzed by immunohistochemical staining (IHC) and supplemental mass spectrometry (MS). The correlations between the type of organs from which samples were obtained and amyloidosis subtypes were investigated retrospectively. Among the patients, 95.1% were diagnosed by IHC and 4.9% were diagnosed by MS. The distribution of amyloidosis subtypes was as follows: AL, 59.1%; ATTR, 32.9%; AA, 4.0%; AH, 1.4%; Aβ2M, 0.8%; and others, 0.9%. AL was the most common subtype in most organs, including the liver, lung, kidney, lower urinary tract, bone marrow, gastrointestinal tract, and skin/subcutaneous tissue. ATTR was the most common subtype in the heart, carpal tunnel, and peripheral nerves. AH was the second most common subtype in renal biopsy. Three or more amyloidosis subtypes were detected in each organ. In conclusion, AL was the most common subtype in most biopsy sites except the heart, carpal tunnel, and peripheral nerve, in which ATTR was more common. Because several types of amyloidogenic protein were detected in each organ, amyloid typing must be pursued, no matter the site from where biopsy was obtained.

Anti-tumor Drug Targets Analysis: Current Insight and Future Prospect

The incidence and mortality of malignant tumors are on the rise, which has become the second leading cause of death in the world. At present, anti-tumor drugs are one of the most common methods for treating cancer. In recent years, with the in-depth study of tumor biology and related disciplines, it has been gradually discovered that the essence of cell carcinogenesis is the infinite proliferation of cells caused by the disorder of cell signal transduction pathways, followed by a major shift in the concept of anti-tumor drugs research and development. The focus of research and development is shifting from traditional cytotoxic drugs to a new generation of anti-tumor drugs targeted at abnormal signaling system targets in tumor cells. In this review, we summarize the targets of anti-tumor drugs and analyse the molecular mechanisms of their effects, which lay a foundation for subsequent treatment, research and development.

Monoclonal antibodies in the treatment of AL amyloidosis: co-targetting the plasma cell clone and amyloid deposits

Immunoglobulin light-chain amyloidosis (AL amyloidosis) is a rare disease in which a small plasma cell clone produces toxic misfolded proteins that deposit in organs and impair their function. Currently, the only available treatment approach is the elimination of clonal plasma cells. However, a rapid strike that halts and possibly reverses organ damage is crucial. The development of agents that facilitate the clearance of pathological fibrillar deposits, therefore reducing the frailty of patients, is the needed supplement to plasma cell-directed therapy. Monoclonal antibodies provide therapy against malignant plasma cells (daratumumab, isatuximab, elotuzumab) but they are also able to target and eliminate the amyloid from organs (NEOD001, CAEL-101, dezamizumab). From the plasma cell-directed group, daratumumab in monotherapy has proved to be extremely efficient in relapsed AL amyloidosis, exceeding its results in multiple myeloma. Compared to other agents, monoclonal antibodies possess the advantage of high selectivity and low toxicity and could potentially become future game-changers in this field. Co-targetting of the plasma cell clone and amyloid deposits shall together be translated in the revolutionary improved outcome of potentially curable AL amyloidosis.

A retrospective analysis of treatment outcomes in 45 patients with cardiac light-chain amyloidosis: a single-center experience in Japan

The prognosis of cardiac light-chain (AL) amyloidosis is considered to be very poor. We studied the treatment efficacy and outcomes by retrospectively analyzing the clinical results of 45 patients with cardiac AL amyloidosis treated at our hospital between September 2008 and March 2016. The group of patients analyzed included 29 males and 16 females with a median age of 68 years. Their baseline median NT-proBNP, cTnT, and dFLC were 3167 pg/ml, 0.080 ng/ml, and 286.17 mg/l, respectively. Twenty-eight patients were in Cardiac Stage (CS) III and 17 patients were in Revised Prognostic Stage (RPS) IV. At the median follow-up of 10 months, the median overall survival (OS) was 16 months and 3-year OS was 35.9%. The patients in CS III showed significantly poorer survival rate than those in CS I or II (3-year OS: 12.2% vs. 65.8%, p = 0.0115) and the patients in RPS IV showed significantly poorer survival rate than those in RPS I, II, or III (3-year OS: 11.0% vs. 53.3%, p = 0.000914). Regardless of the therapeutic approaches, patients who achieved hematological CR or cardiac organ response demonstrated significantly improved prognosis. Therefore, achievement of hematological and organ responses is important in the treatment of cardiac AL amyloidosis.

Recent Advances in the Diagnosis, Risk Stratification, and Management of Systemic Light-Chain Amyloidosis

The term amyloidosis refers to a group of disorders in which protein fibrils accumulate in certain organs, disrupt their tissue architecture, and impair the function of the effected organ. The clinical manifestations and prognosis vary widely depending on the specific type of the affected protein. Immunoglobulin light-chain (AL) amyloidosis is the most common form of systemic amyloidosis, characterized by deposition of a misfolded monoclonal light-chain that is secreted from a plasma cell clone. Demonstrating amyloid deposits in a tissue biopsy stained with Congo red is mandatory for the diagnosis. Novel agents (proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, venetoclax) and autologous stem cell transplantation, used for eliminating the underlying plasma cell clone, have improved the outcome for low- and intermediate-risk patients, but the prognosis for high-risk patients is still grave. Randomized studies evaluating antibodies that target the amyloid deposits (PRONTO, VITAL) were recently stopped due to futility and currently there is an intensive search for novel treatment approaches to AL amyloidosis. Early diagnosis is of paramount importance for effective treatment and prognosis, due to the progressive nature of this disease.

Current applications of multiparameter flow cytometry in plasma cell disorders

Multiparameter flow cytometry (MFC) has become standard in the management of patients with plasma cell (PC) dyscrasias, and could be considered mandatory in specific areas of routine clinical practice. It plays a significant role during the differential diagnostic work-up because of its fast and conclusive readout of PC clonality, and simultaneously provides prognostic information in most monoclonal gammopathies. Recent advances in the treatment and outcomes of multiple myeloma led to the implementation of new response criteria, including minimal residual disease (MRD) status as one of the most relevant clinical endpoints with the potential to act as surrogate for survival. Recent technical progress led to the development of next-generation flow (NGF) cytometry that represents a validated, highly sensitive, cost-effective and widely available technique for standardized MRD evaluation, which also could be used for the detection of circulating tumor cells. Here we review current applications of MFC and NGF in most PC disorders including the less frequent solitary plasmocytoma, light-chain amyloidosis or Waldenström macroglobulinemia.