The MAGIC algorithm probability predicts treatment response and long-term outcomes to second-line therapy for acute GVHD

• The MAGIC algorithm probability measured at initiation of second-line therapy for acute GVHD predicts NRM and OS.

• The higher D28 response rates and survival observed with ruxolitinib compared to other therapies was limited to patients with low MAP.

The significance of biomarkers at second-line treatment for acute graft-versus-host disease (GVHD) is not well characterized. We analyzed clinical data and serum samples at initiation of second-line systemic treatment of acute GVHD from 167 patients from 17 centers of the Mount Sinai Acute GVHD International Consortium (MAGIC) between 2016 and 2021. Sixty-two patients received ruxolitinib-based therapy while 102 received other systemic agents. In agreement with prospective trials, ruxolitinib resulted in higher day 28 (D28) ORR compared to non-ruxolitinib therapies (55% vs 31%, P=0.003) and patients who received ruxolitinib had significantly lower non-relapse mortality (NRM) than those who received non-ruxolitinib therapies (point estimates at 2-year: 35% vs 61%, p=0.002). Biomarker analyses demonstrated that the benefit from ruxolitinib was observed only in patients with low MAGIC algorithm probabilities (MAPs) at the start of second-line treatment. Among patients with a low MAP, those who received ruxolitinib experienced significantly lower NRM than those who received non-ruxolitinib therapies (point estimates at 2-year: 12% vs 41%, p=0.016). However, patients with a high MAP experienced high NRM regardless of treatment with ruxolitinib or non-ruxolitinib therapies (point estimates at 2-year: 67% vs 80%, p=0.65). A landmark analysis demonstrated that the relationship between D28 response and NRM largely depends on the MAP level at initiation of second-line therapy. In conclusion, the MAP measured at second-line systemic treatment for acute GVHD predicts treatment response and NRM. Outcomes of patients with high MAP are poor, regardless of treatment choice, and ruxolitinib appears to primarily benefit patients with low MAP.