Previously, we had identified gene expression patterns that predicted response to neoadjuvant docetaxel. Other studies have
validated that a high Recurrence Score (RS) by the 21-gene RT-PCR assay is predictive of worse prognosis but better response
to chemotherapy. We investigated whether tumor expression of these 21 genes and other candidate genes can predict response
to docetaxel. Core biopsies from 97 patients were obtained before treatment with neoadjuvant docetaxel (4 cycles, 100 mg/m
2 q3 weeks). Three 10-μm FFPE sections were submitted for quantitative RT-PCR assays of 192 genes that were selected from our
previous work and the literature. Of the 97 patients, 81 (84%) had sufficient invasive cancer, 80 (82%) had sufficient RNA
for QRTPCR assay, and 72 (74%) had clinical response data. Mean age was 48.5 years, and the median tumor size was 6 cm. Clinical
complete responses (CR) were observed in 12 (17%), partial responses in 41 (57%), stable disease in 17 (24%), and progressive
disease in 2 patients (3%). A significant relationship (
P < 0.05) between gene expression and CR was observed for 14 genes, including CYBA. CR was associated with lower expression
of the ER gene group and higher expression of the proliferation gene group from the 21 gene assay. Of note, CR was more likely
with a high RS (
P = 0.008). We have established molecular profiles of sensitivity to docetaxel. RT-PCR technology provides a potential platform
for a predictive test of docetaxel chemosensitivity using small amounts of routinely processed material.
Keywords Predictive markers - Docetaxel chemosensitivity - Paraffin-embedded material