Organ Biomarker Responses in Patients with Light Chain Amyloidosis Treated with NEOD001 Are Independent of Previous Hematologic Response

Introduction:In amyloid light chain (AL) amyloidosis, the most common form of systemic amyloidosis, misfolded light chain (LC) or a fragment of an LC produced by clonal plasma cells accumulates in tissue, resulting in the dysfunction of vital organs and systems (eg, heart, kidneys, nervous system). Current therapies used to treat AL amyloidosis limit LC production but do not directly target deposits underlying multiorgan failure. Approximately 75% of patients do not achieve organ responses and have persistent organ dysfunction. Amyloid-directed therapies may stabilize and potentially reverse organ damage by specifically targeting existing LC aggregates. NEOD001, a monoclonal antibody, targets misfolded LC and is thought to neutralize circulating LC aggregates and to clear insoluble deposits. We have previously reported that monthly infusions of NEOD001 were safe and well tolerated. In addition, NEOD001 was associated with renal and cardiac responses. Here we analyzed the association between organ response and depth and time since last plasma cell-directed (PCD) treatment in the entire cohort of 69 patients enrolled in both the dose-escalation and the expansion phases of the phase 1/2 study.

Methods: Inclusion criteria for this trial were that patients complete ≥1 PCD treatment before enrollment, attain partial hematologic response (HR) or better to any previous therapy, and have persistent organ dysfunction. NEOD001 was administered intravenously every 28 days. During the dose-escalation phase, 27 patients received NEOD001 at 0.5, 1, 2, 4, 8, 16, or 24 mg/kg in a 3+3 study design. An additional 42 patients with renal, cardiac, or nerve involvement were enrolled and treated (24 mg/kg) in the expansion phase. We assessed cardiac and renal responses based on consensus criteria and neuropathy responses using the Neuropathy Impairment Score-Lower Limb (NIS-LL). For this analysis, we focused on the relationship between organ response after treatment with NEOD001 to the time since last or best HR and the depth of best and last HR.

Results: A total of 69 patients were enrolled, 27 in the dose-escalation and 42 in the expansion cohorts. The entire population included 36 cardiac-evaluable patients, 35 renal-evaluable patients, and 11 patients evaluated for peripheral neuropathy; 39% were women, and the median age was 60 years. Time since diagnosis was 2.8 (0.4-12.8; median, range) years, and 45% of patients had undergone ≥3 previous PCD regimens. Of the patients evaluable for organ response, best response rates indicating organ response were observed in 53% of cardiac-evaluable patients (n = 19/36) and 63% of renal-evaluable patients (n = 22/35). NIS-LL scores indicated that 82% (n = 9/11) of patients met criteria for a peripheral neuropathy response to NEOD001. Cardiac and renal response rates for NEOD001-treated patients could not be attributed to previous PCD treatment regimens. For example, 37% of the NEOD001 cardiac responders and 35% of nonresponders received cyclophosphamide-bortezomib-dexamethasone. Similarly, for NEOD001 renal responders vs nonresponders, 27% vs 25% were treated with autologous stem cell transplantation and 27% vs 31% were treated with bortezomib-dexamethasone. There was no relationship between NEOD001 cardiac, renal, or peripheral nerve organ response and time since last chemotherapy, time since last or best HR, or depth of last or best HR. Finally, an equivalent percentage of evaluable patients experienced renal or cardiac response regardless of whether they had received their most recent PCD treatment ≤6 months or >6 months before NEOD001 initiation. The median time since last PCD treatment to the start of NEOD001 intervention for all patients was 6.5 (range, 0.6-85.8) months and the median time to first cardiac response after NEOD001 treatment for all cardiac responders was 2 months. NEOD001 treatment was safe and well tolerated.

Conclusions: Patients treated with monthly NEOD001 infusions had high organ response rates that were independent of time since previous chemotherapy, depth of hematologic response, or predominant type of PCD treatment. Ongoing studies of NEOD001 include VITAL (phase 3 in patients with newly diagnosed AL amyloidosis) and PRONTO (phase 2b in previously treated AL amyloidosis patients with persistent cardiac dysfunction).