Targeted interferon therapy with modakafusp alfa for relapsed or refractory multiple myeloma

Interferon alfa has activity against multiple myeloma (MM). Modakafusp alfa is an immunocytokine comprising 2 attenuated interferon alfa-2b molecules and an anti-CD38 immunoglobulin G4 antibody, targeting delivery of interferon alfa to CD38-expressing (CD38⁺) immune and myeloma cells. This phase 1/2 trial enrolled patients with relapsed/refractory multiple myeloma with ≥3 prior lines of treatment and refractory to, or intolerant of, ≥1 proteasome inhibitor and ≥1 immunomodulatory drug. During dose escalation, modakafusp alfa was administered at 10 doses in 4 schedules across 13 cohorts. The primary end point was safety for dose escalation, and overall response rate (ORR) for dose expansion. We enrolled 106 patients who had received a median of 6.5 lines of prior therapy; 84% of patients had myeloma previously refractory to an anti-CD38 antibody. The most feasible dosing schedule was every 4 weeks (Q4W), at which the maximum tolerated dose was 3 mg/kg. Among 30 patients treated at 1.5 mg/kg Q4W, the ORR was 43.3%, with a median duration of response of 15.1 months (95% confidence interval [CI], 7.1-26.1); median progression-free survival was 5.7 months (95% CI, 1.2-14). Grade ≥3 adverse events (AEs) occurred in 28 (93.3%) patients, the most common were neutropenia (66.7%) and thrombocytopenia (46.7%); infections were reported in 8 (26.7%) patients (including grade 3 in 4 [16.7%]). Modakafusp alfa therapy induced upregulation of the type 1 interferon gene signature score, increased CD38 receptor density in CD38⁺ cells, and innate and adaptive immune cell activation. Modakafusp alfa resulted in antitumor activity and immune activation in patients with MM. AEs were primarily hematologic. This trial was registered at www.clinicaltrials.gov as #NCT03215030.