Identification of cytokines associated with response and cytokine release syndrome: Analysis of MagnetisMM-3 cohort A.

Abstract

8044 Background: MagnetisMM-3 (NCT04649359) is a phase 2 study of elranatamab monotherapy in patients with multiple myeloma refractory to at least 1 proteasome inhibitor, 1 immunomodulatory drug, and 1 anti-CD38 antibody. Promising efficacy and safety have been observed in patients who were naïve to B-cell maturation antigen (BCMA)-directed therapy (Cohort A) in MagnetisMM-3 (Bahlis et al., ASH 2022). Methods: In MagnetisMM-3, patients received subcutaneous elranatamab in 28-day cycles with step-up doses of 12 mg on C1D1 and 32 mg on C1D4 followed by 76 mg QW beginning C1D8. Serum samples were collected on C1D1 prior to first priming dose, and on C1D2, pre-dose C1D4, C1D5, pre-dose C1D8, C1D15, and C1D22. Levels of 45 peripheral cytokines were analyzed by proximity extension assay and a longitudinal mixed effects model was applied to each cytokine separately. Cytokines with a significant 2-fold differential expression (responders [defined as patients with best overall response of very good partial response or better] vs non-responders [defined as patients with best overall response of partial response or worse]; cytokine release syndrome [CRS] vs no CRS) at any timepoint are reported. Clinical data cutoff was in Oct 2022 with median follow up of 10.4 months. Results: Baseline levels of IL-6 (2.6-fold), IL-17C (2.0-fold), and MIP-1α (2.1-fold) were lower in patients who achieved a response. After the first priming dose, 13 cytokines in the panel, including CCL8, IFN-γ, IL-2, and IL-27, were differentially expressed in responders vs non-responders. At baseline, no cytokines were found to predict CRS. After the first priming dose, 18 cytokines in the panel, including CCL8, IFN-γ, IL-10, IL-2, IL-27, IL-6, and IL-17A, were differentially expressed in patients with CRS vs no CRS. The maximal differential expression for 17/18 cytokines occurred at C1D2, ~24 hours post the first priming dose. Conclusions: Lower baseline levels of IL-6, IL-17C, and MIP-1α correlated with a response of VGPR or better in BCMA-naïve patients from MagnetisMM-3, suggesting that lower levels of these cytokines might reflect a favorable immune environment. Many cytokines were differentially expressed at higher levels in patients who experienced CRS vs those who did not; the most prominent cytokines included CCL-8, IFN-γ, and IL-10. The timing of induction of CCL-8, IFN-γ, and IL-10 occurred by C1D2 suggesting a potential contribution of these cytokines in driving CRS. Clinical trial information: NCT04649359 .