Emerging drugs for the treatment of light chain amyloidosis

Safety and Efficacy of Subcutaneous Daratumumab in Systemic AL Amyloidosis

Introduction

Systemic AL amyloidosis, a plasma cell dyscrasia, is characterized by the production of misfolded immunoglobulin light chain. These misfolded proteins aggregate into amyloid fibrils and deposit throughout the body, resulting in widespread organ dysfunction and ultimately death. Achieving rapid and maximal elimination of the plasma cell clone is crucial to long-term survival. Daratumumab, an anti-CD38 monoclonal antibody delivered intravenously, has been swiftly incorporated into standard first-line treatment regimens. A novel formulation of daratumumab has been developed that can be injected subcutaneously.

Areas Covered

As a retrospective qualitative review of prior publications involving daratumumab, this work briefly summarizes the existing data regarding the safety and efficacy of subcutaneous (SC) daratumumab, compared to intravenous (IV) daratumumab. SC daratumumab appears to deliver the same disease benefit as IV daratumumab to patients with decreased infusion-related reactions (IRRs), decreased time for administration, and similar rates of adverse events (AEs) intrinsically related to daratumumab.

Expert Opinion

SC daratumumab is preferred over IV daratumumab, but the clinical situation ultimately should determine route of administration. Further investigation into cost-effectiveness benefit is warranted.

Producing amyloid fibrils in vitro: A tool for studying AL amyloidosis

Amyloid light-chain (AL) amyloidosis is the second most common form of systemic amyloidosis which is characterized by a high level of mortality and no effective treatment to remove fibril deposition. This disorder is caused by malfunctioning of B-cells resulting in production of abnormal protein fibrils composed of immunoglobulin light chain fragments that tend to deposit on various organs and tissues. AL amyloidosis is set apart from other forms of amyloidosis in that no specific sequences have been identified in the immunoglobulin light chains that are amyloid fibril formation causative and patient specific. This unusual feature hinders the therapeutic progress and requires either direct access to patient samples (which is not always possible) or a source of in vitro produced fibrils. While isolated reports of successful AL amyloid fibril formation from various patient-specific protein sequences can be found in literature, no systematic research on this topic was performed since 1999. In the present study we have developed a generalized approach to in vitro fibril production from various types of previously reported [[1], [2], [3]] amyloidogenic immunoglobulin light chains and their fragments. We describe the procedure from selection and generation of starting material, through finding of optimal assay conditions, to applying a panel of methods to confirm successful fibril formation. Procedure details are discussed in the light of the most recent findings and theories on amyloid fibril formation. The reported protocol produces high quality AL amyloid fibrils that can subsequently be used in the development of the much-needed amyloid-targeting diagnostic and therapeutic approaches.

Antibodies gone bad - the molecular mechanism of light chain amyloidosis

Light chain amyloidosis (AL) is a systemic disease in which abnormally proliferating plasma cells secrete large amounts of mutated antibody light chains (LCs) that eventually form fibrils. The fibrils are deposited in various organs, most often in the heart and kidney, and impair their function. The prognosis for patients diagnosed with AL is generally poor. The disease is set apart from other amyloidoses by the huge number of patient-specific mutations in the disease-causing and fibril-forming protein. The molecular mechanisms that drive the aggregation of mutated LCs into fibrils have been enigmatic, which hindered the development of efficient diagnostics and therapies. In this review, we summarize our current knowledge on AL amyloidosis and discuss open issues.

AL Amyloidosis for Cardiologists: Awareness, Diagnosis, and Future Prospects: JACC: CardioOncology State-of-the-Art Review

Amyloid light chain (AL) amyloidosis is a rare, debilitating, often fatal disease. Symptoms of cardiomyopathy are common presenting features, and patients often are referred to cardiologists. Cardiac amyloid infiltration is the leading predictor of death. However, the variable presentation and perceived rarity of the disease frequently lead to delay in suspecting amyloidosis as a cause of heart failure, leading to misdiagnoses and a marked delay in diagnosis, with devastating consequences for the patient. A median time from symptom onset to correct diagnosis of about 2 years is often too long when median survival from diagnosis for patients with AL amyloidosis and cardiomyopathy is 4 months to 2 years. The authors highlight the challenges to diagnosis, identify gaps in the current knowledge, and summarize novel treatments on the horizon to raise awareness about the critical need for early recognition of symptoms and diagnosis of AL amyloidosis aimed at accelerating treatment and improving outcomes for patients.

Recent guidelines for high dose chemotherapy and autologous stem cell transplant for systemic AL amyloidosis: a practitioner's perspective

INTRODUCTION

High dose melphalan followed by autologous stem cell transplant (ASCT) has been transformative in treating AL amyloidosis since the early nineties. Recently, the European Haematology Association (EHA) and International Society of Amyloidosis (ISA) have developed a combined guideline for the management of patients undergoing an ASCT for AL amyloidosis.

AREAS COVERED

In this practitioner's perspective, we review the guideline, focussing on 6 major areas and offer practical advice for its application. We provide a perspective on the optimal use of ASCT and its potential application in the future.

EXPERT OPINION

The EHA-ISA guideline comprehensively outlines the practicalities of performing an ASCT in AL amyloidosis. The critical aspect is careful patient selection. Vigilant fluid balance assessments are crucial as associated complications are common and dangerous.The role of ASCT is changing with improving haematological responses associated with novel agents. Evidence is limited for the use of ASCT in patients who achieve a complete haematological response (CR). Therefore, ASCT should be considered for those who only achieve a very good partial response (VGPR)/partial response (PR) and fulfil the strict selection criteria. Future research identifying the cohort who would benefit most from ASCT in the era of novel therapies is warranted.

The Peptide–Drug Conjugate Melflufen Modulates the Unfolded Protein Response of Multiple Myeloma and Amyloidogenic Plasma Cells and Induces Cell Death

Immunoglobulin light-chain (AL) amyloidosis is a rare disease caused by clonal plasma cell secretion of misfolded light chains that assemble as toxic amyloid fibrils, depositing in vital organs including the heart and kidneys, causing organ dysfunction. Plasma cell–directed therapeutics are expected to reduce production of toxic light chain by eliminating amyloidogenic cells in bone marrow, thereby diminishing amyloid fibril deposition and providing the potential for organ recovery. Melphalan flufenamide (melflufen) is a first-in-class peptide–drug conjugate that targets aminopeptidases and rapidly releases alkylating agents inside tumor cells. Melflufen is highly lipophilic, permitting rapid uptake by cells, where it is enzymatically hydrolyzed by aminopeptidases, resulting in intracellular accumulation of the alkylating agents, including melphalan. Previous data demonstrating sensitivity of myeloma cells to melflufen suggest that the drug might be useful in AL amyloidosis. We describe the effects of melflufen on amyloidogenic plasma cells in vitro and ex vivo, demonstrating enhanced cytotoxic effects in comparison to melphalan, as well as novel mechanisms of action through the unfolded protein response (UPR) pathway. These findings provide evidence that melflufen-mediated cytotoxicity extends to amyloidogenic plasma cells, and support the rationale for the evaluation of melflufen in patients with AL amyloidosis.

Daratumumab Monotherapy in Severe Patients with AL Amyloidosis and Biopsy-Proven Renal Involvement: A Real Life Experience

OBJECTIVES

This paper aims to describe the clinical experience with Daratumumab (DARA), a first-in-class anti-CD38 human monoclonal IgG1κ antibody monotherapy, in severe patients with AL and biopsy-proven renal involvement. Immunoglobulin light chain (AL) amyloidosis with multi-organ involvement is characterized by short survival. Novel powerful drugs are expanding the therapeutic options. Current treatment of AL amyloidosis, which has been adopted from multiple myeloma (MM), is based on chemotherapy targeting the underlying plasma cell clone. DARA is effective in treating MM. The clinical activity and toxicity profile of DARA as a single agent in the treatment of AL amyloidosis is currently under evaluation.

PATIENTS AND METHODS

DARA was administered in a series of patients with severe AL amyloidosis and biopsy-proven renal involvement. Five patients(mean age 64.2 years) were treated. One patient was refractory and one intolerant to conventional bortezomib-based therapy, two were treated with DARA for relapsing disease, and one was treated front-line.

RESULTS

Data showed that DARA monotherapy resulted in good clinical results, with the disappearance of M-proteins in four out of five patients and with serum free light chains (sFLC) ratio normalization in three out of four and a remarkable amelioration in the remaining patient. The four patients with still preserved renal function at baseline also showed serum creatinine stabilization or improvement and a decrease in proteinuria. These data were paralleled by the reduction of the N-terminal prohormone of brain natriuretic peptide (NT pro-BNP)values.

CONCLUSIONS

Our data show that monotherapy with DARA had significant clinical efficacy in pretreated/naïve patients with severe AL amyloidosis and biopsy-proven renal involvement.