Belumosudil for Chronic Graft-Versus-Host Disease: Analysis of Long-Term Results from the KD025-208 and ROCKstar Studies

Belumosudil is an oral selective rho-associated coiled-coil-containing protein kinase-2 (ROCK2) inhibitor approved for the treatment of chronic graft-versus-host disease (cGVHD) following an allogeneic hematopoietic cell transplant in patients aged ≥12 years after failure of ≥2 prior systemic lines of therapy. The KD025-208 (NCT02841995) and KD025-213 (ROCKstar; NCT03640481) studies demonstrated that belumosudil was well tolerated, with clinically meaningful responses in patients with cGVHD. KD025-217 (NCT05305989) is a follow-up study that evaluated extended treatment with belumosudil in patients enrolled in the parent studies, KD025-208 and ROCKstar. This pooled analysis reports the long-term follow-up (overall median follow-up duration of 31.4 months) results from these studies in patients with cGVHD. The study included a total of 208 patients across 3 cohorts. Cohort 1 (n = 95) received belumosudil 200 mg once daily, cohort 2 (n = 92) received belumosudil 200 mg twice daily, and cohort 3 (n = 21) received belumosudil 400 mg once daily. The primary endpoint was best overall response rate (ORR). Duration of response (DOR), failure-free survival (FFS), and time to next treatment (TTNT) were also evaluated in this analysis. The best ORR in the modified intent-to-treat (mITT) population was 72%. The median DOR for the responder population was 62.3 weeks (range, 36.1 to 82.6 weeks). The median FFS in the mITT population was 15.1 months (range, 11.3 to 20.6 months). The 1- and 2-year FFS rates were 56% and 40%, respectively. The median TTNT was 22.1 months (range, 15.2 to 40.3 months), where 47% of patients received a new systemic therapy for cGVHD by 36 months. When compared with the published data, the long-term results from this pooled analysis of these two phase 2 studies demonstrated belumosudil was associated with durable responses, and it remained well tolerated with no new safety concerns.