IMATINIB

What it is

Imatinib is supplied as film-coated tablets containing 100 mg or 400 mg of imatinib (as mesilate). The 100 mg tablet is dark yellow to brownish orange and round, while the 400 mg tablet is dark yellow to brownish orange and oval.

Approved indications

— Treatment of patients with chronic myeloid leukaemia (CML). — Treatment of adult and paediatric patients with newly diagnosed Philadelphia chromosome positive acute lymphoblastic leukaemia (Ph+ ALL) integrated with chemotherapy. — Treatment of adult patients with relapsed or refractory Ph+ ALL as monotherapy. — Treatment of adult patients with myelodysplastic/myeloproliferative diseases (MDS/MPD) associated with platelet-derived growth factor receptor (PDGFR) gene re-arrangements, where conventional therapies have failed. — Treatment of adult patients with aggressive systemic mastocytosis (ASM), where conventional therapies have failed. — Treatment of adult patients with hypereosinophilic syndrome (HES) and/or chronic eosinophilic leukaemia (CEL). — Treatment of patients with KIT (CD117) positive unresectable and/or metastatic malignant gastrointestinal stromal tumours (GIST). — Adjuvant treatment of adult patients at high risk of recurrence following complete gross resection of KIT (CD117)-positive primary GIST. — Treatment of adult patients with unresectable, recurrent and/or metastatic dermatofibrosarcoma protuberans (DFSP).

Dosing overview

Imatinib should be administered orally, with a meal and a large glass of water to minimise the risk of gastrointestinal disturbances. Doses of 400 mg or 600 mg should be administered once daily, whereas a daily dose of 800 mg should be administered as 400 mg twice a day. Therapy should be initiated by a physician experienced in the treatment of patients with haematological malignancies and malignant sarcomas, as appropriate.

Key safety warnings

If a severe non-haematological adverse drug reaction develops, such as severe hepatotoxicity or severe fluid retention, imatinib should be withheld until the event has resolved, after which treatment can be resumed depending on the initial severity. If elevations in bilirubin greater than 3 times the institutional upper limit of normal or in liver transaminases greater than 5 times the institutional upper limit of normal occur, imatinib should be withheld until bilirubin levels have returned to less than 1.5 times the institutional upper limit of normal and transaminase levels to less than 2.5 times the institutional upper limit of normal, after which treatment may be continued at a reduced daily dose. Monitoring of response to imatinib therapy in CML patients should be performed routinely and when therapy is modified, to identify suboptimal response, loss of response to therapy, poor patient compliance, or possible drug-drug interaction.

PBS listing

Information regarding PBS listing strengths, item numbers, restriction types, and ex-manufacturer pricing is not available in the provided documents.

Regulatory history

Imatinib (sponsored by Sun Pharma) was first registered on the ARTG on 26 November 2015, with 12 variants registered across 100 mg and 400 mg strengths in blister and bottle pack formats. In August 2017, the PBAC recommended changes to the authority level of imatinib listings for CML and GIST, with authority-required restrictions applied for initial and continuing treatment.