Daratumumab Therapy for Patients With Refractory or Relapsed AL Amyloidosis

Systemic AL amyloidosis is a rare disease caused by the deposition of misfolded monoclonal immunoglobulin free light chains (FLC) in various tissues and organs. It is usually associated with a clonal plasma cell dyscrasia with a low tumour burden. Treatment of AL amyloidosis relies mainly on chemotherapy aimed at suppressing the underlying plasma cell clone secreting monoclonal FLC. The organ responses and the survival are greatly influenced by the degree of hematological response evaluated by the decrease in serum FLC that has been the principal endpoint in recent trials in AL amyloidosis. The goal of treatment is to reach at least a very good partial response (VGPR) defined as a difference between the involved FLC and the normal \<40 mg/l.

Over the last 2 years, Daratumumab, a novel, high-affinity, therapeutic, human monoclonal antibodies (mAb) that specifically recognizes the CD38 epitope has emerged as a breakthrough targeted therapy for patients with myeloma. Taking into account that, in 90% of AL patients, the monoclonal cells producing amyloidogenic FLC are Cluster of Differentiation 38 (CD38) expressing plasma cells Daratumumab should be a promising treatment in AL amyloidosis.

The study will consist of 4 steps:

• A 21 day screening period This period start with screening visit which may occurs up to 21 days before the first study drug administration. After signature of the informed consent form, procedures will be performed to ensure patient meet all inclusion/exclusion criteria and document health status to receive study treatment. These assessments will include quality of life questionnaires
• A treatment period Patient eligible to enter the study will receive 6 cycles of 28 days of intra venous Daratumumab. During cycles 1 and 2, Daratumumab will be administered weekly at days 1, 8, 15, and 22 then from cycles 3 to 6, Daratumumab will be administered every two weeks at days 1 and 15. Patient will have assessments at the ignition of a new cycle to document haematological and organs response and intra cycle to watch for toxicities.
• An end of study visit (when PD or unacceptable adverse events occurs, or planned end of study visit). Study procedures will be performed at 28 days (± 15) after the last dose of study medication for all patients, including early termination patients.
• Followup period After treatment discontinuation, followup will be made to the patient every 3 months for at least 1 year to inquire about the patient's hematological and organ status, general health, and information on any new medical events.

DOSING REGIMEN

Daratumumab. Six 28-day cycles, 16 mg/kg administered by IV route, During cycle 1 and 2, Daratumumab will be administered weekly at days 1, 8, 15, and 22

For cycles 3 to 6, Daratumumab will be administered every other week at days 1 and 15