In Smoldering/Indolent (SMM/IMM) Myeloma Patients Treated with Interleukin-1 Receptor Antagonist (IL-1Ra), Responders Demonstrate a Significantly Increased Time to Progression (TTP) and a Decreased C-Reactive Protein (CRP) Compared with Nonresponders.
Authors: Lust John A. , Lacy Martha Q. , Zeldenrust Steven R. , Dispenzieri Angela , Gertz Morie A. , Greipp Philip R. , Witzig Thomas E. , Geyer Susan M. , Moon-Tasson Laurie L. , Rajkumar S. Vincent , Donovan Kathleen A. 
Published: April 2020

Background: Patients with SMM/IMM are at high risk for progression to active MM and are appropriate candidates for chemoprevention trials. High IL-1beta levels are a useful surrogate marker for progression from SMM/IMM to active myeloma.

Methods: We carried out a Phase II clinical trial of IL-1Ra (Anakinra) in patients with SMM/IMM to determine the biologic activity, progression-free rate, and toxicity of IL-1Ra. Since IL-1beta induces paracrine IL-6, we hypothesized that IL-1Ra would inhibit IL-6 production and myeloma cell growth. Patients that had ≥ 10% bone marrow plasma cells and/or an IgG or IgA M-spike ≥ 3 g/dL and did not require immediate chemotherapy were eligible. Patients received 100 mg of Anakinra (IL-1Ra) SQ qd for a total duration of 6 months. Non-progressors were allowed to continue on therapy with IL-1Ra until they converted to active myeloma. IL-1beta levels were measured in a bioassay with a read out of IL-1 inducible IL-6 production. CRP levels served as a surrogate for IL-6 production.

Results: Thirty-six patients are included for analysis based on intent to treat at diagnosis. At baseline, twenty-nine patients had elevated functional IL-1beta levels consistent with progressive disease and 12 patients had radiologic evidence of disease on bone survey. The median TTP for the entire group was 1 year and 2 patients exhibited a minor response based on M-protein reduction. A proportional hazards analysis was performed and the variables examined were: % bone marrow plasma cells, plasma cell labeling index (PCLI), circulating plasma cells, albumin, M-protein level, IgA subtype, CRP, CRP % reduction ≥ one-third, beta-2 microglobulin, creatinine, calcium, hemoglobin, urine total protein, presence of lytic bone disease, and IL-1 level. Univariate Cox model results showed that % BMPC, PCLI, circulating plasma cells, CRP % reduction, presence of lytic disease, and IL-1 level were all statistically significant (p &lt; .05) variables. However, only the CRP % reduction from baseline remained significant in the multivariate analysis (p &lt; 0.01). The median TTP for patients without (n=18) and with (n=18) a decrease in CRP was 6 months and &gt; 2 years, respectively (p &lt; .0001). Toxicities included injection site reactions during the first month of therapy and asymptomatic neutropenia necessitating a reduction in therapy to every other day. Five patients in whom the CRP decreased and the baseline PCLI was &gt; 0 also demonstrated a parallel decrease in the PCLI. Several of the patients with progressive disease on IL-1Ra alone could later be rescued with the addition of low dose dexamethasone (20 mg once a week) suggesting that the endogenous IL-1beta levels were too high to inhibit with IL-1Ra alone. Conclusion: In summary, IL-1Ra can prolong the TTP to active myeloma in responsive SMM/IMM patients through inhibition of IL-6 production (decrease in CRP) and myeloma cell growth.

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