EGFR FISH assay predicts for response to cetuximab in chemotherapy refractory colorectal cancer patients

BACKGROUND

Standardized conditions to distinguish subpopulations of colorectal cancer (CRC) patients more and less sensitive to cetuximab therapy remain undefined.

MATERIALS AND METHODS

We retrospectively analyzed epidermal growth factor receptor (EGFR) copy number by fluorescence in situ hybridization (FISH) in paraffin-embedded tumor blocks from 85 chemorefractory CRC patients treated with cetuximab. Results were analyzed according to different score systems previously reported in colorectal and lung cancers. The primary end point of the study was identification of the EGFR FISH score that best associates with response rate (RR).

RESULTS

Using receiver operating characteristic (ROC) analysis, the cut-off that best discriminated responders versus nonresponders to cetuximab was a mean of 2.92 EGFR gene copies per cell. This model showed sensitivity of 58.6% [95% confidence interval (CI) = 47.1-70.1) and specificity of 93.3% (95% CI = 80.6-100). EGFR FISH-positive patients (N = 43, 50.6%) had significantly higher RR (P = 0.0001) and significantly longer time to disease progression (P = 0.02) than EGFR FISH negative (N = 42, 49.4%). Other scoring systems resulted less accurate in discriminating patients with the highest likelihood of response to cetuximab therapy.

CONCLUSIONS

CRC patients with high EGFR gene copy number have an increased likelihood to respond to cetuximab therapy. Prospective clinical trials with a careful standardization of assay conditions and pattern interpretation are urgently needed.

EGFR, HER2 and Kras as predictive factors for cetuximab sensitivity in colorectal cancer

4021

Background: In colorectal cancer, biological mechanisms underlying response or resistance to cetuximab, a monoclonal antibody against the extracellular domain of the EGFR are not defined. Small retrospective studies suggested that EGFR increased gene copy number measured by fluorescence in situ hybridization (FISH) or presence of KRAS mutations were associated with cetuximab response or resistance, respectively. This study aimed to identify biological predictors for sensitivity/resistance to cetuximab treatment in colorectal cancer. We also compared biomarker results in primary tumors and corresponding metastases. Methods: We analyzed EGFR (IHC, FISH), HER2 (FISH), and KRAS (mutation) in paraffin embedded tumor blocks from 85 colorectal cancer patients treated with cetuximab. For FISH analyses, a positive result was defined according to criteria described in breast (Wolff et al. J Clin Oncol 2007), lung (Cappuzzo et al. JNCI 2005) and colorectal cancer (Moroni et al. Lancet Oncology 2005). EGFR, HER2 and PIK3CA mutation analyses are ongoing. Results: EGFR FISH positive patients (N=41), defined as ratio EGFR/nucleus =3, had a significantly higher RR (29.3% versus 6.8%, p=0.007) and TTP (6.6 versus 3.7 months, p=0.053) than EGFR FISH negative (N=44). No difference for clinical endpoints was observed using other scoring systems. EGFR expression assessed by IHC was not associated with any clinical end-point. Increased HER2 gene copy number was associated with shorter TTP (p=0.09) and survival (p=0.03). Compared to patients with wild type KRAS (N=49), KRAS mutation carriers (N=32) had a significantly lower RR (6.3% versus 26.5%, p= 0.02), shorter TTP (3.7 versus 6.3 months, p=0.07) and shorter survival (8.3 versus 10.8 months, p=0.2). In 22 patients with available primary and metastatic tumor tissue, there was no difference between these sites for EGFR FISH, HER2 FISH and KRAS results. Conclusions: This study, the largest biomarker analysis in colorectal cancer patients treated with cetuximab, shows a significant benefit in response and TTP for EGFR FISH positive patients. KRAS mutation analysis identifies a group of patients with the lowest chance to benefit from the therapy. Increased HER2 gene copy number predicts early escape from cetuximab therapy.

No significant financial relationships to disclose.

Role of EGFR but not HER2 or HER3 gene copy number in predicting sensitivity of head and neck squamous cell carcinoma (SCCHN) cell lines to EGFR tyrosine kinase inhibitors

6063

Background: EGFR gene copy number has previously been reported to predict for improved overall survival in NSCLC patients treated with gefitinib (IRESSA) or erlotinib compared with placebo [JCO 2006;24:5034–42 & N Engl J Med 2005;353:133–44]. The utility of EGFR gene copy number as a predictive biomarker in other tumour types such as squamous cell carcinoma of the head and neck (SCCHN) is currently under clinical investigation. The present study examined a panel of 20 SCCHN cell lines to identify potential biomarkers predicting in vitro sensitivity to EGFR tyrosine kinase inhibitors (TKIs). Methods: A panel of 20 SCCHN cell lines was screened for sensitivity to gefitinib, vandetanib or erlotinib using a viable cell number endpoint, with G150 values determined for each cell line (inhibitor concentration required to give 50% growth inhibition). Cell lines were blinded and assessed for EGFR, HER2 and HER3 protein expression by ELISA, mutation status by dye-terminator sequencing, and gene copy number by fluorescence in situ hybridisation (FISH). Results: A broad range in sensitivity was observed for all compounds across the panel of 20 SCCHN cell lines (G150 ranging from 0.001uM to =10uM). 12 cell lines were positive for EGFR genomic gain. Sensitivity (GI50 <1uM) to all EGFR TKIs was seen in 11 lines and resistance (GI50 >8uM) in 5 lines. Of the sensitive cell lines, 9 were positive for EGFR genomic gain compared with only 1 of the resistant lines. Furthermore, EGFR protein expression also had a direct association with EGFR TKI sensitivity. In contrast, only 4 cell lines were positive for HER2 or HER3 genomic gain and there was no correlation with sensitivity. The most sensitive cell line was positive for EGFR genomic gain and was the only line to have an EGFR TK mutation (S768I in exon 20). Conclusions: EGFR gene copy number and protein expression appeared to have predictive value in identifying SCCHN cell lines sensitive to EGFR TKIs.

No significant financial relationships to disclose.

Combined EGFR targeted therapy in a novel in vivo pancreas cancer model

14063

Background: EGFR inhibitors have a definite but limited activity in pancreatic cancer (PaCa). We have reported enhanced activity of dual EGFR therapy with a small molecule inhibitor (erlotinib) plus a monoclonal antibody (cetuximab) in head and neck cancer models. Human xenografted tumors recapitulate better the pathobiology of cancer than existing cell lines. Here we explored a dual EGFR targeting approach using a direct PaCa xenograft model, and sought after markers predicting efficacy. Methods: PaCa specimens obtained at the time surgery were implanted in nude mice and expanded to develop cohorts of tumor bearing mice suitable for drug evaluation. Ten cases were expanded, and within each case 4 groups of 6–8 mice each were treated with vehicle, erlotinib, cetuximab, and the combination of both for 28 days. Gene mutation analysis, gene amplification by fluorescence-in-situ hybridization, and immunohistochemistry (IHC) were done with untreated samples. Results: Two cases were sensitive to both single agents, but the combination did not induce higher efficacy in those. Two additional cases that were resistant to both single agents became sensitive with the combination. No egfr mutations were detected. Three and four cases carried low and high egfr polysomy (defined as [[Unsupported Character - ]] 4 copies in 10–40% and [[Unsupported Character - ]] 40% of the cells, respectively). No correlation was found between egfr copy number and efficacy. By IHC sensitive cases had a lower Ki67 proliferation index, and higher EGFR and nuclear pMAPK staining than resistant cases. The degree of Ki67 decrease after therapy correlated with efficacy. In cases resistant to the single agents but sensitive to the combination nuclear pMAPK only decreased with the dual targeting. Cases with high egfr polysomy were more labile to pharmacodynamic effects after treatment (such as EGFR or pMAPK decreases). Conclusions: EGFR inhibitors showed modest single agent antitumor effect that was enhanced with dual EGFR therapy in PaCa. No genomic markers predicted efficacy, although high egfr polysomy was associated with deeper pharmacodynamic inhibition, conceivably suggesting a phenomenon of pathway addiction. Higher pathway activation by IHC was linked with higher activity.

No significant financial relationships to disclose.

Analysis of potential predictive factors of clinical benefit in patients (pts) with metastatic colorectal cancer (MCRC) treated with single-agent cetuximab as first-line treatment

4120

Background: Our group has recently shown that single-agent cetuximab in first-line treatment of elderly MCRC pts has a favorable safety profile and similar activity to that observed in pretreated pts: 15% RR and 54% disease control (DC) (ESMO 2006: A324O). In this study, we aimed to identify predictive factors of clinical benefit from cetuximab without chemotherapy. Methods: This was a optional prospective ancillary study conducted in 36 of 41 pts included in the TTD 04–01 trial to explore potential predictive factors of response or resistance to single-agent cetuximab (400 mg/m2 as initial dose and 250 mg/m2 weekly thereafter). To this end we conducted a comprehensive analysis of potential predictive assays including polymorphisms of intron 1 of the EGFR gene, EGFR gene copy number by FISH (Varella-García Diagn Pathol 2006), IHC expression of signaling pathway proteins (EGFR, MAPK, AKT, PTEN), K-RAS, B-RAF, PI3KCA and PTEN mutations, as well as basal serum levels and dynamic changes of circulating EGFR after 4 weeks of treatment. Results: 9 of 41 pts (22%; 95%CI: 11–38) achieved DC at 12 weeks (2 CR, 4 PR, and 3 SD) with a median time to progression (TTP) of 8,3 months (range 4–11.3), similar to that observed with FOLFOX or FOLFIRI in first line treatment. Increased EGFR copy number (FISH+: scores 5–6) was observed in a total of 11 pts (11/36: 30,5%). Five of these 11 FISH+ pts had DC at 12w (45%) vs. 3 of 25 FISH- pts (12%) (p=0.04). No correlation was found between DC at 12w and polymorphisms of intron 1 of the EGFR gene, basal serum levels and dynamic changes of EGFR, IHC expression of pEGFR and pMAPK, or PI3KCA mutations. Analyses of PTEN and AKT by IHC, as well as K-RAS and PTEN mutations are ongoing. Conclusions: Although cetuximab provides higher efficacy in combination with chemotherapy, 22% of MCRC pts treated with monotherapy in first-line treatment present a remarkable median TTP of 8,3 months. This subgroup of pts can be selected in advance based on FISH+ combined or not with other possible predictive factors still under analysis. The full detailed analysis of data will be presented at the meeting.

[Table: see text]

Fluorescence in situ hybridization (FISH) subgroup analysis of TRIBUTE, a phase III trial of erlotinib plus carboplatin and paclitaxel in NSCLC

7570

Background: TRIBUTE was a phase III, placebo-controlled study of patients with previously untreated advanced NSCLC. Patients received erlotinib (E) (150 mg/d) or placebo, plus a course of 6 cycles of carboplatin and paclitaxel (CP), followed by maintenance E monotherapy (for those in the CP+E arm who were responding to treatment). 1,059 patients were randomized and treated (526 E; 533 placebo). There were no significant differences in OS, RR, or TTP between the two arms. In subgroup analyses of the pivotal 2nd line trial (BR21) of E in patients with relapsed NSCLC in which E significantly increased median survival (HR=0.71, p <0.0001), patients who scored positively for increased EGFR copy number by fluorescence in situ hybridization (FISH) exhibited prolonged OS (HR=0.44, p=0.008). Here we report on a similar subgroup analysis for TRIBUTE. Methods: FISH analysis was performed on all available tissue samples. FISH+ samples had a high level of polysomy (=four copies of the gene in =40% of cells), or gene amplification (presence of tight gene clusters, gene/chromosome per cell ratio =2, or =15 copies of the genes per cell in =10% of analyzed cells). Results: FISH analysis was successfully performed on 245 patients (121 E, 124 placebo). Outcome in the placebo patients from this subgroup was better than the overall population, suggesting that this subgroup may not be representative. Of the 100 patients (41%) that were FISH+, 33 had amplification and 67 had high polysomy. In FISH+ patients, OS was similar between those treated with CP+E and those treated with CP alone. However, FISH+ patients in the CP+E arm experienced a decrease in RR compared to those in the CP alone arm, and had a marginally significant longer TTP (HR=0.59, 0.35–0.99). The benefit in TTP appeared after approximately 6 months, during the maintenance portion of the trial. Conclusions: In this retrospective analysis, FISH+ did not predict survival benefit in TRIBUTE. A longer TTP, but a lower RR, was observed in the FISH+ patients. The lower RR in the CP+E arm in this group, taken together with the improved TTP during maintenance therapy, suggests that a non-concurrent combination approach (CP followed by E) warrants further investigation.

No significant financial relationships to disclose.

Epidermal growth factor receptor (EGFR) immunohistochemistry: Comparison of antibodies (Abs) and cut points to predict benefit from gefitinib in a phase III placebo-controlled study in advanced non-small cell lung cancer (NSCLC)

7576

Background: Tumor tissues obtained from the ISEL phase III trial assessing the efficacy of gefitinib vs placebo in chemotherapy-pretreated NSCLC were used to evaluate two Abs (DAKO and Zymed) and assess whether different cut points of EGFR protein expression improved prediction of response and survival benefit from gefitinib. Methods: EGFR protein expression in tumor samples was assessed by immunohistochemistry using DAKO EGFR pharmDx kit (scoring percent of tumor cells with positive staining, predefined cut point of =10%) and Zymed monoclonal Ab clone 31G7 (scoring proportion of positive cells times staining intensity [scale 0–400], predefined cut point of =200). Results: Clinical characteristics of the patients (pts) assessed with DAKO (n=379) and Zymed (n=357) Abs reflected the overall study population (N=1692) with the exception of fewer never-smokers and Asians. Of the pts evaluated with DAKO/Zymed Abs, females represented 32%/31%; never-smokers, 13%/14%; Asians, 6%/4%; adenocarcinomas, 44%/42%; and 88%/88% of pts were refractory to most recent chemotherapy. With the above criteria, 70% of tumor samples were scored as positive using DAKO Ab and 68% using the Zymed Ab (agreement between assessments 76%). The objective response rates in gefitinib treated EGFR-positive pts defined with various cut points with DAKO Ab (=1% to =90%) varied between 8% and 12%, and with Zymed Ab (score =50 to =350), between 10% and 13%. Lower cut points with the DAKO Ab provided the best discrimination between EGFR positive and EGFR negative patients in terms of survival hazard ratios (HRs) comparing gefitinib to placebo, with a significant treatment/cut point interaction for the 10% cut point (p=0.049). A similar trend was noted for Zymed Ab, although the discrimination between HRs was less apparent and not significant for any cut point analyzed. Conclusion: Assessment with DAKO PharmDx kit, according to percentage of positive staining, may provide more accurate prediction of survival benefit for gefitinib-treated pts than assessment with Zymed Ab and staining index. Use of higher cut points to define positivity does not improve discrimination of the test.

No significant financial relationships to disclose.

FISHing for lung cancer: Promising findings using multi-targeted interphase fluorescence in situ hybridization (FISH) for lung cancer detection in sputum

7567

Background: Lung CT imaging shows promise for early lung cancer detection, but may be insensitive for central lesions and will create a need for complementary biomarkers to guide clinical decisions. Methods: We have been conducting a prospective study to assess the performance of various biomarkers in sputum to detect lung cancer. Within a cohort of 3,269 people at high risk for lung cancer (over 30 pack-years of cigarette use and chronic obstructive lung disease) we have conducted a nested case-control study to assay stored samples from 85 incident lung cancer cases and 73 controls for cytologic morphology, DNA methylation, and multi-targeted FISH assays (LAVysion, Vysis/Abbott Molecular). The FISH assay targeted DNA sequences from centromere 6, 5p15.2, 7p12 (EGFR), and 8q24 (cMYC). Cytology was classified as abnormal if moderate or greater atypia was observed, methylation was abnormal if three or more of 8 selected genes were methylated, and FISH was abnormal if two or more scored cells were observed to contain chromosomal aneuploidy indicated by signal gain for at least two targets or signal gain for one and signal loss for two or more targets. Results: Among all subjects, regardless of the time between sputum collection and diagnosis, FISH was abnormal in 49/87 cases (56%) and 5/73 controls (7%) (odds ratio (OR) = 17.5, 95% CI = 6.4 to 47.8). Considering only the cases for which sputum had been collected within 18 months before the lung cancer diagnosis, FISH was abnormal in 37/49 cases (75%) and in 3/38 controls (8%) (OR = 36.0, 95% CI = 9.4 to 138). For this same time period, cytological atypia was abnormal in 37% of cases and 22% of controls (OR = 2.1, 95% CI = 0.8 to 5.3) and methylation was abnormal in 64% of cases and 36% of controls (OR = 4.5, 95% CI = 1.0 to 19.8). Conclusions: The LAVysion FISH assay is more sensitive than other currently available sputum tests for the prediction of invasive carcinoma in subjects and is highly specific with a low frequency of false positive and false negative results. The results suggest that chromosomal aneuploidy and by extrapolation, missegregation, are features of advanced premalignancy and should identify patients who are proximate to clinically overt lung cancer.

[Table: see text]

Epidermal growth factor receptor gene copy number and protein level are not associated with outcome of non-small-cell lung cancer patients treated with chemotherapy

BACKGROUND

Survival benefit of non-small-cell lung cancer (NSCLC) patients treated with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors is predicted by high EGFR gene copy number and by strong EGFR protein expression. Clinical relevance of these features in patients treated with chemotherapy has not been reported.

PATIENTS AND METHODS

This study included 82 NSCLC patients treated with chemotherapy. There were 45% of females, 6% of never smokers and 45% of patients diagnosed with adenocarcinoma. EGFR gene copy number was evaluated by fluorescence in situ hybridization and EGFR protein level by immunohistochemistry.

RESULTS

High EGFR gene copy number and protein level were found in 33% and 71% of patients, respectively. Both markers were significantly associated (P = 0.01). For objective response and disease control, there was no difference between patients defined as negative or positive for both EGFR gene copy number (P = 0.39 and P = 1.00, respectively) and for EGFR protein (P = 1.00 and P = 0.80, respectively). There were no differences in progression-free and overall survival according to EGFR gene copy number (P = 0.76 and P = 0.82, respectively) and protein level (P = 0.67 and P = 0.62, respectively).

CONCLUSION

In chemotherapy-treated NSCLC patients, EGFR gene copy number was positively associated with protein level but none of the features were predictive for either treatment response or survival.

Combination of EGFR gene copy number and protein expression predicts outcome for advanced non-small-cell lung cancer patients treated with gefitinib

BACKGROUND

Biological markers for optimal selection of patient to epidermal growth factor receptor (EGFR)-targeted therapies are not established in advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

EGFR/HER2 gene copy number by FISH, EGFR protein and pAKT expression by immunohistochemistry (IHC) and EGFR and KRAS mutations were tested in 204 gefitinib-treated NSCLC patients.

RESULTS

Increased EGFR and HER2 gene copy number (FISH+), EGFR protein overexpression (IHC+), EGFR mutations and pAKT overexpression were all associated with significantly higher response rates (33%, 29%, 22%, 39% and 20% respectively). EGFR FISH+ (32%) and IHC+ (61%) correlated with improved survival, while EGFR mutations (27%), KRAS mutations (26%) and pAKT expression (69%) did not. In multivariate survival analysis EGFR FISH and IHC were independent predictive markers. EGFR FISH+/IHC+ patients (23%) had a median survival of 21 months versus 6 months for double-negative patients (30%).

CONCLUSION

Combination of EGFR FISH and IHC is effective predictor for benefit from gefitinib. Patients with double-negative results are unlikely to benefit in western NSCLC populations.

Chromosomal aneusomy in sputum predicts for lung cancer in nested case-control study

7201

Background: Lung cancer usually is disseminated at diagnosis and prognosis is poor for most patients. Heavy smokers are known to be at high risk factor for lung cancer and are target population for lung cancer prevention. Sputum has long been considered a potential source of material for biomarker based early detection but no tests have been validated. Methods: Chromosome aneusomy was sought in sputum of 114 cases and 110 controls from the Colorado Sputum Screening Cohort Study, which includes heavy smokers with airflow obstruction matched on age, gender, and date of sample collection. Subject characteristics were as follows: mean age 67 (± 8 years), 75% males, 36% current smokers, mean pack-year 71.2 (± 33.5). The FISH probe LAVysion (Vysis/Abbott) was used, including the DNA targets EGFR, MYCC, 5p15 and CEP6. Results: The multi-target set showed the highest sensitivity (0.78) and specificity (0.95) rates in specimens collected within 12 months of lung cancer diagnosis. The individual probes EGFR, MYCC, 5p15 and CEP6 showed, respectively, decreasing sensitivity rates (0.78, 0.67, 0.62, and 0.29) and increasing specificity rates (0.84, 0.91. 0.86, and 0.95). Combinations of two specific probes (AND) or of any of two probes (OR) have not favorably impacted these coefficients. Proportion of abnormal sputum specimens was higher in squamous cell carcinoma than in adenocarcinoma or small cell carcinoma, both considering the set of specimens collected 12 months prior to disease diagnosis (92%, 75%, 60%) and all specimens (80%, 58%, 44%). Conclusions: Chromosomal aneusomy in sputum was demonstrated in a nested case-control cohort to be a promising marker for prediction of lung cancer risk in heavy smokers with airflow obstruction. Evaluation of four DNA targets was more effective than any single marker or combination of markers, and the test had high sensitivity in patients with squamous cell carcinoma.

[Table: see text]

Prognostic significance of EGFR FISH and IHC in non small-cell lung cancer patients treated with chemotherapy alone

7193

Background: High EGFR gene copy number by fluorescence in situ hybridization (FISH) predicts response and survival benefit in non small-cell lung cancer (NSCLC) patients (pts) treated with EGFR tyrosine-kinase inhibitors, but its prognostic value remains debated. We aimed to evaluate the association of EGFR FISH, EGFR immunohistochemistry (IHC) and prognosis in NSCLC pts treated with chemotherapy alone. Methods: 85 pts treated with platinum-containing chemotherapy (median follow up of 15 months [range: 2–29 months]) were included in the study. There were 47% females, 35% of pts with performance status (PS) 0, 53% PS = 1 and 12% PS = 2, 6% of never-smokers. Median age was 62 years (range: 41–80 years). Stage I-IIIA was diagnosed in 7%, stage IIIB - 44% and stage IV - 48% pts. Adenocarcinoma was the most common histology (51% pts). EGFR FISH was performed using LSI EGFR SpectrumOrange/CEP 7 SpectrumGreen probe and IHC using DAKO PharmDx kit. Results: FISH results were available in 79 pts (93%), and EGFR FISH-positive tumors (high polysomy or gene amplification) were found in 28 pts (35%). IHC results were available in 81 pts (95%) and 25 pts (31%) were scored as positive (staining index ≥200). Distribution of clinical characteristics did not differ according to either FISH or IHC result. FISH-positive pts had higher EGFR IHC staining indices as compared with FISH-negative pts (median 160 vs. 60, p = 0.005, Mann-Whitney U test). Median survival of FISH-positive pts was 12.6 months vs. 8.1 months in FISH-negative pts (log-rank p = 0.68; HR = 0.88 [95% CI: 0.49–1.59]) and the respective figures for progression-free survival (PFS) were 7.5 vs. 4.9 months, log-rank p = 0.72; HR = 0.91 [95% CI: 0.55–1.51]. Median survival in IHC-positive vs. IHC-negative pts was 6.6 months vs. 9.2 months (log-rank p = 0.44; HR = 1.27 [95% CI: 0.69–2.36]). There was no significant difference in PFS (median of 4.8 vs. 5.3 months, respectively; log-rank p = 0.71; HR = 1.11 [95% CI: 0.64–1.92]). FISH and IHC remained insignificant in a Cox regression survival analysis. Conclusion: In this cohort of NSCLC patients treated with chemotherapy alone, EGFR FISH was associated with EGFR IHC and both features had no statistically significant influence on prognosis.

[Table: see text]

High gene copy number of epidermal growth factor receptor by fluorescence in situ hybridization is frequent in head and neck squamous cell carcinomas and associates with worse recurrence-free survival

5502

Background: Epidermal growth factor receptor (EGFR) is expressed in 90–95% of head and neck squamous cell carcinoma (HNSCC). High EGFR gene copy number and activating mutations correlate with response and survival in lung cancer upon the treatment with EGFR tyrosine kinase inhibitors, but such findings have not been reported for HNSCC. A better understanding of the EGFR pathway may improve the use of EGFR inhibitors and provide a rationale for combination therapy. Methods: Tumor samples were obtained from 47 patients and analyzed for increased EGFR copy numbers by fluorescence in situ hybridization (FISH) (Vysis/Abbot) (N = 47), by immunohistochemistry (IHC) using antibodies against EGFR, phospho-EGFR (Tyr1173) and phospho-AKT (Ser473) (N = 31), for activating mutations in EGFR exons 18, 19 and 21 (N = 29), and for gene expression using Affymetrix Human 133U Plus 2.0 GeneChip (N = 18). Results from these assessments were tested for associations with patient characteristics and clinical endpoints. Univariate analysis was performed to test for differences in recurrence-free survival (RFS) and overall survival. Results: Twenty-six (63%) of 41 samples with FISH result demonstrated EGFR high polysomy and/or gene amplification (FISH+). The FISH(+) group did not differ from the FISH(−) group with regard to age, sex, race, tumor grade and site, disease stage, total EGFR, phospho-EGFR, or phospho-AKT, although the total EGFR protein score was close to significance (p = 0.10, Chi2-test for trend). The FISH(+) were associated with worse RFS, although this association did not reach significance (p = 0.057, Wilcoxon test). No activating EGFR point mutations were found. Using the FISH results as a supervising parameter, microarray data was interrogated and expression of genes involved in wnt signalling, cell motility, G-protein regulation and epithelial-mesenchymal transition pathways were found to be enhanced in the FISH(+) group (FDR <25%). Conclusions: High gene copy number of EGFR by FISH is frequent in HNSCC and may be a poor prognosticator. This data suggests that FISH(+) may be a marker of clinical benefit upon EGFR inhibition in HNSCC and further investigation is indicated.

[Table: see text]

Clinical and biological effects of gefitinib in EGFR FISH positive/phospho-akt positive or never smoker non-small cell lung cancer (NSCLC): Preliminary results of the ONCOBELL trial

7023

Background: Effectiveness of gefitinib, a tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR), in never smokers and/or EGFR FISH positive NSCLC patients has been evaluated only in retrospective studies and few data exist on the biological effects of gefitinib therapy in tumor samples. Methods: The ONCOBELL trial is a multicenter prospective phase II study designed to include 39 patients EGFR FISH positive/phospho-Akt (p-AKT) positive and/or never smokers with advanced or metastatic NSCLC. Gefitinib is given at the daily dose of 250 mg. When feasible, primary tumor biopsy was repeated immediately before therapy, during therapy and at progression. Specimens were evaluated for EGFR and HER2 gene copy number by FISH, EGFR gene mutation by DNA sequencing, and EGFR and p-AKT protein expression by immunohistochemistry. Results: Data from the first 28 enrolled patients are available: median age was 60 years (range, 43–80); male/female: 7/21; stage IIIB/IV: 2/26; ECOG PS 0/1/2: 18/6/4; 25 patients had a diagnosis of adenocarcinoma and/or bronchioloalveolar carcinoma; 13 patients had brain metastases, and in 10 cases gefitinib was offered as first-line therapy. Twenty-four patients were never smokers and 19 were EGFR FISH positive. Overall response rate was 54%, including 1 complete and 14 partial responses. Median time to progression was 6.45 months, and median survival was not reached. Response to therapy was not influenced by previous therapies or presence of brain metastases. Toxicity was mild, and consisted in grade 1–2 skin rash (68%) and diarrhea (57%). One patient developed grade 3 diarrhea and another patient was hospitalized for acute interstitial lung disease. In patients exposed to previous chemotherapy, no difference in EGFR or HER2 FISH results were observed in specimens collected at the time of original diagnosis compared to specimens collected immediately before gefitinib therapy. In 14 cases primary tumor biopsy was repeated during gefitinib therapy. Conclusions: These preliminary data indicate that gefitinib is highly effective in patients with trial characteristics. Clinical and biological data for the entire cohort will be available in June 2006.

No significant financial relationships to disclose.

EGFR genomic gain in Japanese non-small cell lung cancer patients treated with gefitinib

7164

Background: Increased EGFR gene copy numbers evaluated by fluorescence in situ hybridization (FISH) is excellent predictor of clinical benefit from EGFR tyrosine kinase inhibitors (TKIs) in Caucasian non small-cell lung cancer (NSCLC) patients. This study was performed to verify how this marker performs in Oriental patients. Methods: A cohort of 59 Japanese patients with recurrent NSCLC after surgery was treated with gefitinib 250 mg daily. The cohort included 46% of females, 47% of never-smokers, 68% of patients had prior chemotherapy and 59% had stage III-IV at the time of surgery. Adenocarcinoma was the most common histology (85%). FISH was performed using EGFR /CEP 7 and PathVysion probes (Vysis/Abbott). Specimens were classified as FISH+ when showing gene amplification or high polysomy (≥4 copies of the gene in ≥40% of tumor cells). Effectiveness of gefitinib was concluded when there was 30% tumor shrinkage in imaging studies and/or elevated CEA level decreased to <50% of baseline. Results: FISH results were available in 51 tumors: 35 (69%) were EGFR+ and 29 (57%) were HER2+. There was a significant association between EGFR+ and HER2+ (p = 0.012) and between EGFR FISH+ and of EGFR mutations (p = 0.003). All 9 tumors exhibiting clustered EGFR gene amplification harbored mutations. Response rate assessed in 43 patients was 59% in EGFR+ and 33% in EGFR- (p = 0.11). Gefitinib treatment produced response in 5 (83%) cases with gene amplification and 12 (52%) cases with high polysomy. Response rate was 77% in 22 cases positive for FISH and mutation and 100% in 5 cases with EGFR mutation/FISH- cases. No responses were observed in EGFR WT patients, neither in 9 FISH+ nor in 10 FISH- cases. Survival was not significantly impacted by EGFR (p = 0.42) or HER2 (p = 0.40) FISH status, while EGFR mutation was significantly associated with longer survival (p = 0.005). Conclusion: Patients in this Japanese cohort had more frequently FISH+ status than in the Caucasian populations, which may contribute to higher sensitivity to EGFR TKIs. However, the predictive power of EGFR FISH status for TKI sensitivity seems to be lower supporting significant differences in the mechanisms of EGFR pathway activation in Oriental and Caucasian populations.

[Table: see text]

Predicting clinical benefit from EGFR TKIs: Not all EGFR mutations are equal

7072

Background: EGFR mutations are associated with better response and in some studies (mainly Asian) also with prolonged survival after gefitinib therapy in patients with advanced NSCLC. Although a number of mutations have been reported, most frequent are exon 19 or exon 21 mutations of the EGFR tyrosine kinase domain.Whether clinical outcomes differ by subtype of EGFR mutation has not been previously reported. Methods: Mutation analysis (as previously described) was performed in 157 of 204 patients with advanced NSCLC treated with gefitinib (250 mg or 500 mg) in 2 study cohorts (Italian study of Iressa Expanded Access Program and SWOG 0126). Fifty nanograms of genomic DNA was isolated from pretreatment tumors, amplified for EGFR exons 19 and 21 by touchdown hemi-nested polymerase chain reaction and sequenced in both sense and antisense directions. Results: EGFR mutations were found in 43 pts (27%). Overall, patients with EGFR mutations had a response rate of 39% versus 7% for those without (p ≤ 0.001), disease control rate of 52% versus 37% (p = 0.14), time to progression of 3 months in both groups and median survival of 13 months versus 11 months (p = 0.14). Patients with exon 19 mutations exclusively (N = 11) had better outcome than those with exon 21 mutations exclusively (N = 31), with response rates of 67% versus 20% (p = 0.02), median time to progression of 15 months versus 2 months, and median survival of 26 months versus 10 months. There was a difference in time to progression (11 months versus 3 months) and overall survival (median 26 months versus 11 months) between patients with and without exon 19 mutations, while no difference was apparent in these outcome measures in patients with and without exon 21 mutations. Sample size provided insufficient power for significance tests of differences in survival outcomes. Conclusions: Not all EGFR mutations are created equal. Mutations in exon 19 are more predictive of response and survival after gefitinib than exon 21 mutations.

[Table: see text]

Correlation of epidermal growth factor receptor (EGFR) mutation, immunohistochemistry (IHC), and fluorescence in situ hybridization (FISH) in esophageal squamous cell carcinoma (ESCC)

4085

Background: ESCC remains a devastating cancer in Southern Thailand and novel therapeutic approach needs to be explored. EGFR tyrosine kinase (TK) inhibitor is a potential therapeutic agent against EGFR-expression tumors including ESCC. Forty-nine percent of ESCC patients in our institution overexpressed EGFR protein and 15% had EGFR gene amplification as published previously. Mutations within EGFR TK domain, particularly in exon 19 and 21, EGFR amplification or polysomy, and EGFR overexpression on IHC have all been associated with sensitivity and benefit to EGFR inhibitor treatment. To our best knowledge, no data on EGFR mutations in ESCC have been reported. This prompted us to perform analysis of EGFR mutations and correlate the status of each of these characteristics in ESCC. Methods: We studied 35 patients with ESCC whose data on EGFR IHC and FISH were available. DNA extraction was performed using a QIAamp DNA Kit. PCR for EGFR detection, using the oligonucleotide primers for amplification of exon 19 and 21, was sequenced and analyzed, using ABI Prism 377 sequencing analysis system and the Big Dye Terminator V3.0 Ready Reaction Cycle Sequencing Kit (ABI Prism). Results: Among 35 ESCC specimens evaluated, no EGFR somatic mutations in exon 19 or 21 were detected. Conclusions: EGFR mutations in exon 19 and 21 of ESCC were not identified in this study. EGFR overexpression and amplification do not correlate with EGFR mutation in Thai patients with ESCC. A clinical study of an EGFR inhibitor in esophageal carcinoma has been going on in our institution and the molecular markers as predictive factors need to be further evaluated and correlated with treatment outcome.

No significant financial relationships to disclose.

Insulin-like growth factor receptor 1 (IGFR-1) is significantly associated with longer survival in non-small-cell lung cancer patients treated with gefitinib

BACKGROUND

The aim of the study was to assess whether loss of PTEN and expression of insulin-like growth factor receptor 1 (IGFR-1) could be responsible for intrinsic resistance to the tyrosine kinase inhibitor (TKI) gefitinib.

PATIENTS AND METHODS

One hundred and twenty-four gefitinib-treated patients with advanced non-small-cell lung cancer (NSCLC) were analyzed for PTEN and IGFR-1 expression by immunohistochemistry.

RESULTS

IGFR-1 was evaluated in 77 patients and resulted positive in 30 (39.0%). IGFR-1 expression was not significantly associated with clinical or biological characteristics. No difference in response to gefitinib treatment (16.7% versus 12.8%, P = 0.74) and time to progression (2.6 versus 3.06 months, P = 0.83) was observed between IGFR-1+ and IGFR-1-. Median survival was significantly longer in IGFR-1+ patients (17.8 versus 7.3 months, P = 0.013). PTEN expression was successfully evaluated in 93 cases. Loss of PTEN was detected in 19 tumors (20.4%) and was not associated with any clinical or biological characteristic. No difference in terms of response, time to progression and survival was observed between PTEN+ and PTEN- patients. In multivariable analysis IGFR-1 negative status was significantly associated with higher risk of death (hazard ratio 2.21, P = 0.012).

CONCLUSIONS

IGFR-1 expression and loss of PTEN are not associated with intrinsic resistance to gefitinib. Clinical relevance of these two biomarkers as determinant for acquired resistance, and the prognostic role of IGFR-1 expression in patients not exposed to TKIs should be evaluated further.

HER3 genomic gain and sensitivity to gefitinib in advanced non-small-cell lung cancer patients

In non-small-cell lung cancer (NSCLC), sensitivity to tyrosine kinase inhibitors (TKIs) is associated with activating mutations and genomic gain of the epidermal growth factor receptor (EGFR). Preclinical data suggested that HER3 overexpression increases sensitivity to TKIs. A total of 82 NSCLC patients treated with gefitinib (250 mg), and previously evaluated for EGFR and HER2 status by fluorescence in situ hybridisation (FISH) and DNA sequencing, and for Phospho-Akt status by immunohistochemistry, were investigated for HER3 genomic gain by FISH. Patients with high polysomy and gene amplification were considered as HER3 FISH positive (+). HER3 FISH+ pattern was significantly associated with female gender (P=0.02) and never smoking history (P=0.02). Patients with HER3+ tumours (26.8%) had a significantly longer time to progression (3.7 vs 2.7, P=0.04) than patients with HER3− tumours, but not a significantly better response rate or survival. Patients with EGFR+/HER3+ tumours had higher objective response rate (36.4 vs 9.9%, P=0.03) and time to progression (7.7 vs 2.7 months, P=0.03) than patients with EGFR− and/or HER3− tumours, but no significantly longer survival. No difference in response was observed according to HER3 status in patients with EGFR+ tumours. Patients with HER2+/HER3+ tumours had similar outcome as patients with HER2− and/or HER3− tumours. Significantly different clinical end points were not observed between patients with HER3+/P-Akt+ and HER3− and/or P-Akt− tumours. Genomic gain for HER3 is not a marker for response or resistance to TKI therapy in advanced NSCLC patients.

Glioblastomas in the older old

CONTEXT

Recent studies have identified fundamental biological differences in the effects of epidermal growth factor receptor (EGFR) amplification on survival in older versus younger patients with glioblastoma multiforme (GBM). Cell cycle labeling indices have also been found to be inordinately high in older GBM patients and may contribute to the known adverse prognosis in this cohort. However, testing has not been conducted on significant numbers of patients of very advanced age, in whom these features might be expected to emerge as even more significant factors.

OBJECTIVE

To assess EGFR amplification status and MIB-1 indices in patients with GBM who are older than 75 years.

DESIGN

We identified 20 patients (female-male ratio, 11:9; 11 aged 75-79 years and 9 aged 80-87 years) and studied tumor tissue samples with immunohistochemistry for cell cycle labeling index and by fluorescence in situ hybridization for EGFR amplification. Survival data were obtained from the Colorado Tumor Registry.

RESULTS

Mean MIB-1 index was high (24.8%), but individual indices did not correlate with survival. EGFR amplification was detected in 25% of cases, with gain of chromosome 7 in all but one of the remaining patients. Ninety-five percent of patients manifested EGFR amplification and/or polysomy of chromosome 7. Heterogeneity was found within a given tumor, with 10% to 60% of cells showing gain of chromosome 7. Overall patient survival was poor (mean, 4.6 months), but was significantly longer in those with EGFR gene amplification (mean, 8.3 months; median, 10.5 months) versus those without (mean, 3.2 months; median, 2.0 months) (P = .04).

CONCLUSION

The presence of EGFR amplification is a significant predictor of survival time in older old patients.