Vorinostat
A recent study suggested that vorinostat also possesses some activity against recurrent glioblastoma multiforme, resulting in a median overall survival of 5.7 months (compared to 4–4.4 months in earlier studies). Further brain tumor trials are planned in which vorinostat will be combined with other drugs.
Glioblastoma
It is important to distinguish primary glioblastoma from secondary glioblastoma. These tumors occur spontaneously ("de novo") or have progressed from a lower-grade glioma, respectively. Primary glioblastomas have a worse prognosis, different tumor biology and may have a different response to therapy, which makes this a critical evaluation to determine patient prognosis and therapy. Over 80% of secondary glioblastoma carries a mutation in "IDH1", whereas this mutation is rare in primary glioblastoma (5–10%). Thus, "IDH1" mutations are a useful tool to distinguish primary and secondary glioblastomas since histopathologically they are very similar and the distinction without molecular biomarkers is unreliable.