Indolent systemic mastocytosis (ISM)

Active Ingredient: Avapritinib

Indication for Avapritinib

Population group: only adults (18 years old or older)
Therapeutic intent: Curative procedure

Avapritinib is indicated for the treatment of adult patients with indolent systemic mastocytosis (ISM) with moderate to severe symptoms inadequately controlled on symptomatic treatment.

For this indication, competent medicine agencies globally authorize below treatments:

25 mg once daily

For:

Dosage regimens

Oral, 25 milligrams avapritinib, once daily.

Detailed description

For ISM, the recommended dose of avapritinib is 25 mg orally once daily, on an empty stomach. This once daily 25 mg dose is also the maximum recommended dose that must not be exceeded in patients with ISM. Treatment of ISM should be continued until disease progression or unacceptable toxicity occurs.

Concomitant use of avapritinib with strong or moderate CYP3A inhibitors must be avoided.

Missed doses

If a dose of avapritinib is missed, the patient should make up for the missed dose unless the next scheduled dose is within 8 hours. If the dose has not been taken at least 8 hours prior to the next dose, then that dose must be omitted and the patient should resume treatment with the next scheduled dose.

If vomiting occurs after taking a dose of avapritinib, the patient must not take an additional dose but continue with the next scheduled dose.

Dose modifications for adverse reactions

Irrespective of indication, interruption of treatment with or without dose reduction may be considered to manage adverse reactions based on severity and clinical presentation.

The dose should be adjusted as recommended, based on safety and tolerability.

Dose reductions and modifications for adverse reactions are provided below.

Recommended dose reductions for avapritinib for adverse reactions:

25 mg once every other day.

ISM patients requiring dose reduction below 25 mg once every other day must discontinue treatment.

Recommended dose modifications for avapritinib for adverse reactions:

Adverse reactionSeverity*Dose modification
Intracranial haemorrhageAll GradesPermanently discontinue
avapritinib.
Cognitive effects**Grade 1Continue at the same dose,
reduce dose or interrupt until
improvement to baseline or
resolution. Resume at the same
dose or at a reduced dose.
Grade 2 or Grade 3Interrupt therapy until
improved to baseline, Grade 1,
or resolution. Resume at the
same dose or at a reduced dose.
Grade 4Permanently discontinue
avapritinib.
Other adverse reactionsGrade 3 or Grade 4Interrupt therapy until less than
or equal to Grade 2. Resume at
the same dose or at a reduced
dose, if warranted.

* The severity of adverse reactions graded by the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 4.03 and 5.0
** Adverse reactions with impact on Activities of Daily Living (ADLs) for Grade 2 or higher adverse reactions

Dosage considerations

The avapritinib tablets must be taken on an empty stomach at least 1 hour before or at least 2 hours after a meal.

Active ingredient

Avapritinib

Avapritinib is a Type 1 kinase inhibitor that has demonstrated biochemical in vitro activity on the PDGFRA D842V and KIT D816V mutants associated with resistance to imatinib, sunitinib and regorafenib with half maximal inhibitory concentrations (IC50) of 0.24 nM and 0.27 nM, respectively, and greater potency against clinically relevant KIT exon 11, KIT exon 11/17 and KIT exon 17 mutants than against the KIT wild-type enzyme.

Read more about Avapritinib

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