(CHICAGO, IL) – The addition of procarbazine, lomustine and vincristine (PCV) chemotherapy to radiotherapy (RT) increases progression-free survival (PFS) and overall survival (OS) in patients with anaplastic oligodendroglial tumors and represents a new standard of care in those with 1p/19q co-deletions, long-term follow-up results of a phase 3 trial presented at the 2012 American Society of Clinical Oncology Annual Meeting has found.

In fact, patients with 1p/19q co-deletion appear to benefit most from the addition of PCV, with a trend for improved OS in those with MGMT methylation and IDH mutations, said Martin J. Van Den Bent, MD, of Erasmus University Medical Center, Daniel den Hoed Cancer Center, Rotterdam, Netherlands.

The EORTC Brain Tumor Group conducted a prospective study on adjuvant PCV in patients with newly diagnosed anaplastic oligodendroglioma, who were randomly assigned to focal RT 33 x 1.8 Gy and the same RT followed by 6 cycles of adjuvant PCV (PCV+RT).

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Between 1995 and 2002, 368 patients were enrolled in the study. The first report, in 2006, found adjuvant PCV increased PFS but not OS at a median follow-up of 60 months; however, median survival was not reached in the 1p/19q co-deleted tumors.

As of February 20, 2012, median follow-up was 140 months; 298 patients (81.0%) had disease progression and 86 (24.6%) were still alive. Median PFS after PCV+RT was significantly longer compared to RT alone, 24 months vs 13 months (HR = 0.66; P=0.003); OS was 42 vs 31 months, respectively (HR = 0.75; P=0.018).

In a preplanned analysis for 1p/19q co-deletion, 316 patients were tested and 80 (25%) were found to be co-deleted. Post hoc testing found of 178 patients tested for IDH mutations, 81 (46%) were mutated; of 183 tested for MGMT methylation, 136 (74%) were methylated.

More patients in the RT alone arm received chemotherapy at progression (75% vs 53%). 1p/19q co-deleted patients (n=80) treated with PCV+RT had improved OS compared to those in the RT arm (median OS not reached vs 112 months; HR = 0.56, P=0.059). In 236 patients without 1p/19q co-deletion, the difference in OS was nonsignificant, 25 months in the PCV+RT arm vs 21 months in the RT arm (HR = 0.83; P=0.19).

Dr. Van Den Bent said the intergroup CATNON trial in non-1p/19q co-deleted grade III tumors will further define which patients may benefit from chemotherapy.