Droxidopa for Treatment of Refractory Orthostatic Hypotension in Patients with AL Amyloidosis: A Case Series

Background Orthostatic hypotension due to autonomic dysfunction is a well-known complication of light chain (AL) amyloidosis, which can become progressively debilitating and difficult to manage. Treatment of the underlying plasma cell dyscrasia will eventually decrease further amyloid deposition. Management of orthostatic hypotension secondary to AL amyloidosis improves quality of life and facilitates delivery of plasma cell therapy. Pharmacologic interventions include fludrocortisone, sympathomimetic agents such as midodrine, droxidopa, the acetylcholinesterase inhibitor pyridostigmine or the norepinephrine transporter (NET) inhibitor atomoxetine. Fludrocortisone is often poorly tolerated in amyloid patients because it may exacerbate edema. Droxidopa is a synthetic amino acid analog that is directly metabolized to norepinephrine by dopa-decarboxylase, which increases blood pressure (BP) by inducing peripheral arterial and venous vasoconstriction. Aims To assess the effectiveness of droxidopa in patients with AL amyloidosis with severe orthostatic hypotension refractory to midodrine. Also, to describe effective dose of droxidopa, duration of therapy, adverse effects and reasons for discontinuation. Methods A regional retrospective study was done in patients with AL amyloidosis with severe, refractory orthostatic hypotension who received droxidopa. Retrospective data was reviewed from 2018 to 2021 at a single academic center in the United States. Results Five patients with AL amyloidosis were included in the study; three patients had lambda-restricted plasma cell dyscrasia and two had multiple myeloma (MM) associated AL amyloidosis (both kappa light chain restricted). Of the five patients, all had cardiac, renal, autonomic nervous system and peripheral nervous system involvement and two of the five had gastrointestinal involvement as well. Given their poor performance status and advanced organ involvement, none of the patients were eligible for high-dose intravenous melphalan with autologous peripheral blood stem cell transplantation (HDM/SCT), and thus were treated with cyclophosphamide, bortezomib and dexamethasone (CyBorD). All patients achieved very good partial response to complete hematologic response. The main findings are summarized in table 1. All patients had severe, symptomatic orthostatic hypotension that was objectively defined as a decrease in systolic blood pressure by 20 millimeters of mercury (mmHg) or a decrease in diastolic blood pressure