Synopsis
Select molecularly targeted anticancer treatment only for a validated biomarker and tumour context, manage pathway-specific toxicity and interactions, and distinguish biological resistance from inadequate exposure.
- Targeted therapy inhibits a tumour dependency, receptor, kinase, repair defect or angiogenic pathway; the presence of a biological target does not guarantee clinical benefit.
- The biomarker, assay, specimen, disease stage and licensed or recommended indication must all match before treatment begins.
- Small-molecule inhibitors often have oral absorption, food, acid-suppression and enzyme-interaction issues, while monoclonal antibodies add infusion and immune-mediated risks.
Key red flags
New pneumonitis, cardiomyopathy, severe hypertension, hepatitis, perforation or ocular injury requires urgent interruption and specialist assessment.
Investigation priorities
Confirm eligibility for the specified targeted medicine.
Management branches
A tumour report identifies a potentially actionable alteration.
- Confirm histology, stage, line, assay and exact biomarker meet the national protocol or access criteria.
- Review organ reserve, interactions, pregnancy and prior toxicities and explain absolute benefit and uncertainty.
Cancer worsens after an initial response or stable interval.
Key medicines
Imatinib400 mg orally once daily with a meal and a large glass of water is a common licensed starting dose for chronic-phase BCR::ABL1-positive CML and for unresectable or metastatic KIT-positive GIST; other phases, indications and responses use different protocol doses.
Subcutaneous trastuzumab600 mg subcutaneously every 3 weeks, with no loading dose, for a licensed HER2-positive breast-cancer protocol; intravenous trastuzumab uses a different weight-based schedule and must not be substituted by assumption.