Dartumumab in Pretreated AL Amyloidosis: A Systematic Review

Background: Amyloidosis is characterized by the deposition of misfolded lambda or kappa light chain (AL) proteins in tissue. It commonly affects the heart, which correlates with poor prognosis. Disease-modifying therapies aim to suppress the production of abnormal light chains. Daratumumab (Dara) use is associated with a reduction in light chain protein production. Dara is a human anti-CD38 monoclonal antibody approved for the treatment of newly diagnosed and Relapsed & Refractory Multiple Myeloma. AL amyloidosis plasma cells express CD38, and therefore, Dara is an attractive alternative in this setting. This review aims to assess the efficacy and safety of daratumumab in pre-treated AL amyloidosis patients.

Methods:

We conducted a comprehensive literature search in PubMed, Embase, Medline using MeSH terms and keywords "AL amyloidosis," "daratumumab", and "darzalex" to incorporate the studies published up to July 2020. We included studies assessing the efficacy and safety of daratumumab alone or in combination with other therapies in pretreated AL amyloidosis. After excluding duplicates, non-relevant, and review articles, we selected four prospective and twelve retrospective studies.

RESULTS:

In our review, data on 482 patients were included. The ages ranged from 35-88 years. The median number of prior therapies was 3 (ranges:2-6), and the most common therapy was bortezomib in 90% of patients followed by immunomodulators in 55% and stem cell transplant in 35%.

A total of 260 (54%) patients received Dara monotherapy, 126 (26%) received Dara plus Dexamethasone (d), and 96 (20%) patients received other Dara containing two or three-drug regimens.

The time from the diagnosis to the start of Dara therapy varied from 1 to 137 months. 71 % of patients had cardiac, and 62 % had renal involvement. There was a greater than 30 % reduction of N-terminal pro-brain natriuretic peptide (NT-proBNP) in cardiac patients responsive to therapy.

1. Daratumumab monotherapy:

Dara monotherapy achieved an overall response rate (ORR) of 76% (191/249), complete response (CR) of 30% (69/224), very good partial response (VGPR) of 41% (79/192) and partial response (PR) of 14% (19/140). The overall survival (OS) ranges from 59-100% at 10-12 months were noted. Table 1.

2. Daratumumab+ Dexamethasone:

Dara plus d achieved ORR of 81% (86/106), CR of 51% (53/102), VGPR of 29% (18/62), PR of 15% (15/102), and OS of 87% at 24 months. Table 1.

3. Daratumumab with combination regimens:

The use of Dara based combination regimens of Dara+pomalidomide (P)+d (36% of patients), Dara+lenalidomide (R)+d (32%) and Dara+bortezomib (V)+d (18%), reported by Abeykoon et al., showed an ORR of 88% (14/16), CR of 19 % (3/16), VGPR of 63% (10/16), PR of 6 %(1/16), OS of 89 % at 10 months and progression-free survival (PFS) of 83% at 10 months. Godara et al. reported an ORR of 100% (9/9) using a combination of Dara and birtamimab. The combination of D+cyclophosphamide (c)+V+d reported by Palladini et al. achieved an ORR of 96 % (27/28), CR of 36 % (11/28), VGPR of 29 % (8/28) and PR of 14 % (4/28).Table 1.

The most reported adverse event was infusion-related reactions; grade 3-4 adverse were less than 10 % and mostly related to the heart (heart failure & atrial fibrillation). The most-reported hematological adverse effects were anemia, thrombocytopenia, neutropenia, infections, and sepsis. The most common non-hematological adverse events were heart failure, bronchitis, pneumonia, fatigue, nausea, and diarrhea. Table 2.

Conclusion:

Dara therapy is associated with promising efficacy with a response rate of more than 70% when used alone and more than 80% when used in combination. These regimens are well tolerated in advanced cardiac disease patients with a tolerable risk of volume overload and infusion-related complications. Additional multicenter randomized, double-blind clinical trials are needed to confirm these results.

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