Bosutinib for Ph+ CML: Indications, Dosing Adjustments, and Hepatic/Renal Safety

　　1.Indications and Place in Therapy

　　Bosutinib is an oral tyrosine kinase inhibitor targeting BCR-ABL and Src-family kinases,used in Philadelphia chromosome-positive chronic myeloid leukemia(Ph+CML).

　　Newly diagnosed adult chronic phase(CP):first-line option in eligible patients.

　　Adult CP with prior resistance or intolerance to another TKI:sequential or switch therapy.

　　Adult accelerated phase(AP)or blast phase(BP)with inadequate response or intolerance to prior therapy:use after comprehensive assessment.

　　Pediatric CP Ph+CML:selected ages may receive weight-or BSA-based dosing;AP,BP,and very young children require specialist evaluation.

　　2.Standard Dosing and Administration

　　Newly diagnosed adult CP:commonly 400mg once daily with food,swallow whole;do not split,crush,or chew.

　　Prior resistance/intolerance in adult CP,or AP/BP:commonly 500mg once daily with food.

　　Continue until progression,unacceptable toxicity,or treatment change per physician judgment.

　　Missed dose:if nearly time for the next dose or more than about 12 hours have passed,skip the missed dose;do not double.Exact rules follow the prescribed schedule.

　　If response is insufficient and toxicity is acceptable,adults may uptitrate in small increments,often 100mg steps up to a defined maximum.Hold,reduce,or stop for hepatotoxicity,severe diarrhea,significant non-hematologic toxicity,or myelosuppression.

　　3.Hepatic and Renal Impairment

　　Liver:check ALT,AST,and total bilirubin before therapy and at least monthly for the first 3 months.Hold for marked transaminase rises;resume at a reduced dose once improved.Transaminase elevation with hyperbilirubinemia requires evaluation for drug-induced liver injury.Moderate-to-severe hepatic impairment requires individualized reduction or delay.

　　Kidney:estimate creatinine clearance,monitor serum creatinine,eGFR,and proteinuria.Mild-to-moderate impairment may require dose modification;severe impairment or dialysis needs case-by-case planning rather than fixed self-adjustment.Newly diagnosed CP and prior-therapy populations have different starting doses,so renal adjustments must be assessed separately.

　　Throughout treatment,monitor hemoglobin,platelets,and neutrophils;manage cytopenias by severity grade.

　　4.Common and Serious Adverse Events

　　Common:diarrhea,abdominal pain,nausea,vomiting,rash,fatigue,headache,fever,decreased appetite,upper respiratory infection;laboratories may show ALT/AST rise,creatinine rise,anemia,thrombocytopenia,leukopenia,or neutropenia.

　　Serious issues to monitor:

　　Hepatotoxicity:jaundice,dark urine,marked fatigue,substantial transaminase increases.

　　Myelosuppression:fever,infection,bleeding,pronounced anemia.

　　Fluid retention:peripheral edema,pleural effusion,rapid weight gain,dyspnea.

　　Severe GI toxicity:persistent diarrhea or vomiting causing dehydration.

　　Rare but severe:thrombotic microangiopathy,severe cutaneous reactions.Assessment should combine symptoms with CBC,liver/renal tests,and clinical signs.

　　5.Mechanism,Resistance,and Contraindications

　　Bosutinib inhibits BCR-ABL signaling and Src-family kinases including Src,Lyn,and Hck,reducing proliferation of Ph+CML cells.It retains activity against several imatinib-resistance mutations but is weaker against certain mutations such as T315I and V299L.Suspected resistance should prompt BCR-ABL mutation testing before changing therapy.

　　Contraindication:known severe hypersensitivity to bosutinib or excipients.Review interactions with strong/moderate CYP3A inhibitors or inducers,PPI effect on absorption,and grapefruit products;pharmacist review is recommended.

　　6.Pregnancy,Lactation,and Storage

　　People of reproductive potential:effective contraception during therapy and for at least 2 weeks after the last dose.

　　Pregnancy:potential fetal harm;avoid unless specialist benefit-risk discussion supports use.

　　Lactation:not recommended during therapy and for at least 2 weeks after the last dose.

　　Storage:generally room temperature,protected from excessive heat and moisture;follow the specific product label.Avoid direct hand contact with broken-tablet powder.