Researchers analyzed formalin-fixed, paraffin-embedded tumor samples from 226 colon cancer patients from three studies of ERBITUX. The samples were examined for K-Ras gene mutations, which are commonly observed in colon cancer, and for the expression of 102 previously identified candidate genes that may be associated with disease control and progression-free survival in patients treated with ERBITUX.
Of the 226 analyzed samples, 36 percent (82 patients) had K-Ras mutations and a significantly lower disease control rate (23 percent) compared to those who did not exhibit the gene mutation (60 percent). Among all 226 samples, quantitative expression of 40 genes was significantly associated with disease control. Together, the results suggest that quantitative expression of a number of the candidate genes used in conjunction with K-Ras mutation status increases the ability to predict which patients might benefit from treatment with ERBITUX over K-Ras status alone.
"Based on these results, we believe there is a potential to develop a multi-gene test comprising K-Ras mutation status in combination with the expression levels of a small number of genes to select patients for cetuximab," said Joffre Baker, Ph.D., chief scientific officer of Genomic Health and lead author of the study.
The research for the second study, "Predictive utility of progesterone
receptor and multigene expression in identifying benefit from adjuvant
doxorubicin plus cyclophosphamide or docetaxel in intergroup trial E2197,"
(abstract 557) was led by the Eastern Cooperative Oncology Group (ECOG).
Researchers evaluated the predictive utility of progesterone receptor (PR)
protein expression by IHC in a central lab and quantitative RNA expression
by RT-PCR for 371 genes, including the current Oncotype DX 21-gene panel,
for treatment either with doxorubicin plus cyclophosphamide (AC), or with
doxorubicin plus docetaxel (AT). The study used samples
|SOURCE Genomic Health, Inc.|
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