7185 Background: P-ADC is often a bronchioloalveolar carcinoma (BAC) variant in the 2004 WHO pathological classification. A French prospective multicentric phase II trial (IFCT0401) evaluated gefitinib as first line treatment in non-resectable P-ADC. Tissue samples were collected for central pathological review and molecular analysis in attempt to determine if an association existed between disease control (DC) by gefitinib and biological markers. Methods: Histologic types were classified according to the 2004 WHO classification as BAC variants and ADC, other types and as non-mucinous or mucinous/mixed. Immunohistochemistry were performed using antibodies against the following proteins: TTF1, Ki67, phosphorylated AKT, erbB2, and EGFR. Polysomy/amplification was examined for erbB2 and EGFR. EGFR 18–21 and K-ras 1 exons were amplified and sequenced. Results: A tissue specimen was collected from 67 of the 88 eligible participants, among which 35 were from surgical resection. This subgroup did not differ from the overall trial population in terms of sex ratio (0.51 vs 0.56), proportion of non-smokers (34 vs 55%) and DC rate (34 vs 29%). Results described herein were obtained in 22 of the 35 surgical specimens collected. Sixteen were BAC variants (73%) and 6 ADC other types. Of the 22, 14 were non-mucinous and 8 mucinous. TTF1, Ki67, P-AKT, erbB2 as well as EGFR expression did not differ between BAC variants and ADC other types. TTF1 and EGFR scores of expression were higher in non-mucinous than in mucinous P-ADC. DC on gefitinib was significantly associated with non-mucinous subtype (p = 0.006), higher TTF1 (p = 0.06) and EGFR (p = 0.07) scores of expression, but not with other markers. K-ras exon-1 codon 12 mutation was found in 6 tumors of which 5 progressed on gefitinib. Polysomy of EGFR was seen in 2 tumors, 1 of which also contained EGFR mutation (exon-19 deletion); both were controlled by gefitinib. Conclusions: Among patients with P-ADC who received gefitinib, non-mucinous subtype, high TTF1 or EGFR score of expression, and EGFR polysomy and/or mutation may have improved DC, while K-ras mutation seems associated with disease progression. [Table: see text]
Effect of Immunohistochemistry on Molecular Analysis of Tissue Samples