Belumosudil for cGVHD: 200mg with Food, Pregnancy Contraception, Liver Monitoring, Drug Interactions

　　1.Profile and Mechanism

　　Belumosudil is a selective ROCK2 inhibitor for cGVHD after failure of at least two prior lines of systemic therapy in adults and children aged 12 years or older.It modulates inflammatory and profibrotic signaling across skin,mouth,liver,gastrointestinal tract,lung,and other organs.It is not a substitute for overall post-transplant management,infection prophylaxis,or immunotherapy adjustment decided by the transplant team.

　　2.Dosing

　　Standard:200mg orally once daily,approximately the same time,with a meal;swallow whole,do not cut,crush,or chew.

　　Duration:continue until cGVHD progresses to require new systemic therapy or unacceptable toxicity occurs;do not self-increase or stop.

　　Missed dose:take the same day when remembered and resume the regular schedule;if near the next dose,skip and do not double.Some local materials advise taking the next scheduled dose if more than 12 hours late.

　　Population:aged 12 years and older;safety is not established under 12.Older adults need no routine dose change but require assessment for hepatic,renal,infection,and polypharmacy risks.

　　3.Pregnancy,Fertility,and Lactation

　　Embryo-fetal risk:animal studies in rats and rabbits during organogenesis showed embryo-fetal death,growth changes,and malformations;human data are lacking,so fetal harm is assumed possible.

　　Contraception:verify pregnancy before starting in people of childbearing potential;such individuals and males with partners of childbearing potential use effective contraception during treatment and for at least 1 week after the last dose.

　　Lactation:presence in human milk is unknown,but serious infant risk is possible;avoid breastfeeding during treatment and for at least 1 week after the last dose.

　　Pregnant,planning pregnancy,or with fertility concerns should be evaluated by transplant and reproductive counseling before starting.

　　4.Drug Interactions

　　Strong CYP3A inducers such as rifampin,carbamazepine,or phenytoin lower belumosudil exposure and may reduce efficacy;increase belumosudil to 200mg twice daily.

　　Proton pump inhibitors such as omeprazole or rabeprazole reduce belumosudil absorption through pH-dependent solubility;increase to 200mg twice daily.

　　Belumosudil inhibits/affects transporters and enzymes:avoid or monitor BCRP and OATP1B1 substrates and reduce substrate doses per labeling;avoid sensitive CYP1A2,CYP3A,P-gp,or UGT1A1 substrates when small exposure changes cause serious toxicity,otherwise reduce substrate doses.

　　Provide all prescription,over-the-counter,herbal,and supplement products to the transplant pharmacist before changes.

　　5.Hepatic Monitoring and Dose Rules

　　Mild hepatic impairment,Child-Pugh A,usually needs no dose change;moderate,Child-Pugh B,and severe,Child-Pugh C,without liver GVHD should generally be avoided,with specialist benefit-risk review if considered.

　　Liver tests:baseline and at least monthly total bilirubin,ALT,AST;distinguish drug hepatotoxicity from liver GVHD.

　　Hepatotoxicity rules:hold for ALT/AST grade 3,5–20×ULN,or bilirubin grade 2,1.5–3×ULN,resume recommended dose after recovery to grade 0–1;permanently stop for ALT/AST grade 4,>20×ULN,or bilirubin grade 3–4,>3×ULN.Other grade 3 adverse reactions:hold and resume after recovery;grade 4:permanently stop.

　　Renal impairment:mild-moderate often needs no change;severe impairment or dialysis has limited data,assess before starting.

　　6.Common Adverse Events and Alarm Signs

　　Common events including laboratory abnormalities are infections,asthenia,nausea,diarrhea,dyspnea,cough,edema,hemorrhage,abdominal pain,musculoskeletal pain,headache,hypophosphatemia,increased GGT,lymphopenia,and hypertension.Act on:

　　infection:fever,sore throat,pneumonia,worsening oral ulcers,suspected CMV or other opportunistic infection—CBC,cultures,imaging as needed;

　　respiratory:new or worsening shortness of breath,cough,hypoxemia—rule out infection,pulmonary GVHD,effusion;

　　GI:persistent diarrhea,abdominal pain,vomiting with dehydration—exclude infection and hepatobiliary causes;

　　blood pressure/edema:new hypertension,leg edema,rapid weight gain—assess cardiac,renal,and volume status;

　　bleeding:epistaxis,gingival,bruises,GI or urinary bleeding;

　　metabolic/hematology:low phosphate,low calcium,liver enzyme abnormalities,lymphocyte/neutrophil/platelet/hemoglobin drops;

　　persistent headache or severe fatigue affecting intake/activity—do not self-stop transplant drugs;reassess in the cGVHD clinic.