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DFSP — SCE Medical Oncology MCQ

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HardSarcomaDFSPSCE Medical Oncology

A 55-year-old woman is diagnosed with dermatofibrosarcoma protuberans (DFSP) on her trunk. The tumour is 5 cm with characteristic COL1A1-PDGFB fusion confirmed on FISH. Wide excision is performed with positive margins. Re-excision is not feasible. What targeted therapy can be offered?

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Correct answer: D — Imatinib targeting fusion-driven PDGFB signalling

The COL1A1-PDGFB fusion drives PDGFR signalling in unresectable or margin-positive DFSP, providing a matched indication for imatinib. Pazopanib targeting fusion-driven PDGFB signalling: pazopanib inhibits several kinases but is not the specifically validated COL1A1-PDGFB therapy. Trabectedin targeting fusion-driven PDGFB signalling: trabectedin is active in selected sarcomas but does not directly inhibit PDGFR. Sunitinib targeting fusion-driven PDGFB signalling: sunitinib has PDGFR activity but lacks the established DFSP evidence base of imatinib. Larotrectinib targeting fusion-driven PDGFB signalling: larotrectinib targets TRK fusions rather than PDGFB signalling.

Reference: Imatinib 400 mg UK summary of product characteristics (Current UK SmPC, accessed July 2026): https://www.medicines.org.uk/emc/product/10133/smpc