Combination therapies of porcupine inhibition with ruxolitinib, ibrutinib or belumosudil in murine sclerodermatous GvHD

Chronic graft-versus-host disease (cGvHD) is a frequent complication of allogeneic hematopoietic stem cell transplantation (alloSCT) and is associated with high morbidity and mortality. First drugs have been recently approved for the treatment of cGvHD, but the response rates are suboptimal and treatment discontinuation due to side effects remains frequent. Here, we evaluated the efficacy and safety profile of porcupine inhibition by Wnt-C59 in monotherapy or in combination with ruxolitinib, ibrutinib or belumosudil in experimental sclerodermatous GvHD (sclGvHD). Treatment was well tolerated in all groups with improvements in clinical and histological features. Of these, ruxolitinib in monotherapy, and the combination therapies demonstrated the highest efficacy. The combination therapies of Wnt-C59 with ibrutinib or belumosudil showed additive antifibrotic effects in skin and lungs compared to the respective monotherapies. Our study may have direct translational relevance, since: 1) core signaling pathways targeted by these drugs were enriched in both human and murine sclGvHD, and 2) ruxolitinib, ibrutinib and belumosudil are already approved for the treatment of cGvHD, and porcupine inhibitors are in clinical trials for other fibrotic diseases. Thus, simultaneous targeting of different pathogenetically relevant pathways might be a safe and effective therapeutic approach in sclGvHD. Allogeneic transplanted mice (cGVHD model) and syngeneic transplanted control mice (Syn) received daily oral gavage of 0.4% methylcellulose (vehicle) starting on day 21 after allogeneic or syngeneic bone marrow transplantation (alloBMT). Treatment groups included Wnt-C59 monotherapy (5 mg/kg daily, orally) and a combination of Wnt-C59 (5 mg/kg daily, orally) and belumosudil (150 mg/kg daily, orally). All mice were sacrificed seven weeks post-alloBMT.