1p/19q codeletion
Loss of one copy each of chromosome arms 1p and 19q, together with an IDH mutation, defines oligodendroglioma in the WHO 2021 classification. It predicts a slower course and a good response to chemotherapy, and separates oligodendroglioma from astrocytoma.
Overview
The whole-arm codeletion is detected by FISH, array or sequencing-based copy-number analysis; partial deletions do not count. WHO CNS5 (2021) requires IDH mutation plus 1p/19q codeletion for the diagnosis of oligodendroglioma, IDH-mutant and 1p/19q-codeleted, grades 2 to 3. The long-term RTOG 9402 and EORTC 26951 results showed that adding PCV chemotherapy to radiotherapy roughly doubled survival in codeleted tumours. Vorasidenib's label covers grade 2 oligodendroglioma by IDH mutation, not by codeletion. As an arm-level change it has no single parent gene and sits under no target here.
If your glioma has an IDH mutation and 1p/19q codeletion it is an oligodendroglioma, which grows more slowly and responds well to chemotherapy with radiotherapy. Without the codeletion the same IDH-mutant tumour is an astrocytoma. Vorasidenib is on label for grade 2 tumours of either type after surgery.
Written only from the label or guideline text cited on this page. Not medical advice; your own report and the reading your team gives it come first.
Loss of the whole short arm of chromosome 1 and the whole long arm of chromosome 19 by FISH, chromosomal microarray or sequencing copy-number analysis, in a tumour with an IDH1 or IDH2 mutation.
“Oligodendroglioma, IDH-mutant, and 1p/19q-codeleted”
Louis et al., The 2021 WHO Classification of Tumors of the Central Nervous System, Neuro-Oncology 2021No approval uses this readout as a threshold. It is defined by WHO CNS5 classification (Louis et al., Neuro-Oncology 2021).
Matched on the name and aliases of the readout in the title, setting and summary of each trial; a match is a mention, not proof the readout was an entry criterion.
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