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C. Heidecke



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    P3.02 - Poster Session 3 - Novel Cancer Genes and Pathways (ID 149)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P3.02-009 - <b>ROR1 as a novel therapeutic target for EGFR-mutant non-small-cell lung cancer (NSCLC) patients with the EGFR T790M mutation</b> (ID 1395)

      09:30 - 09:30  |  Author(s): C. Heidecke

      • Abstract

      Background
      Molecular cross-talk between EGFR and other signaling pathways creates alternative means of tumor cell proliferation and promotes resistance to single-agent erlotinib therapy in NSCLC driven by EGFR mutations. ROR1 knockdown inhibited the growth of NCI-H1975 cells (harboring EGFR L858R and T790M mutations). A pro-survival function for ROR1/MEK/ERK signaling in cooperation with AKT has been demonstrated. We have assessed ROR1 expression in 45 patients from the EURTAC trial (clinicaltrials.gov NCT00446225), 27 of whom harbored pretreatment concomitant EGFR T790M mutations, and correlated results with outcome.

      Methods
      ROR1 mRNA expression was examined by quantitative RT-PCR and categorized by terciles; patients were classified as having low/intermediate or high ROR1 expression. The T790M mutation was determined by Taqman with a PNA to inhibit amplification of the wild-type (wt) allele. Tumor samples were run in octuplicates; this method can detect 1 mutated allele among 10,000 wt alleles.

      Results
      Median age 65; 68.9% female; 57.8% never-smokers; 95.6% ECOG PS <2; 91.1% adenocarcinoma; 68.9% exon 19 deletion. No differences in baseline characteristics were observed according to ROR1 expression levels. 24 patients (53.3%) were treated with erlotinib and 21 (46.7%) with chemotherapy. 10 (41.7%) erlotinib-treated patients and 6 (28.6%) chemotherapy-treated patients had high ROR1 mRNA levels. Among erlotinib-treated patients, response rate (RR) was 40% for the 10 patients with high ROR1 levels vs 71.4% for the 14 with low/intermediate levels (P=0.058). Among chemotherapy-treated patients, RR for the 15 patients with low/intermediate ROR1 levels was 6.7%; the 6 patients with high ROR1 levels did not respond. Progression-free survival (PFS) was 11.8 months (m) for erlotinib-treated patients with low/intermediate ROR1 levels vs 5.8 m for those with high levels. PFS for chemotherapy-treated patients was 5.6 and 9 m, respectively (P=0.0165). 15 erlotinib-treated patients harbored concomitant T790M mutations; for these patients, PFS was10.8 m for those with low/intermediate ROR1 levels vs 2.7 m for those with high levels (P=0.0138).

      Conclusion
      ROR1 expression has a differential effect on outcome to erlotinib and chemotherapy in EGFR-mutant NSCLC patients. High ROR1 expression significantly limits PFS in erlotinib-treated patients with T790M mutations and ROR1-directed therapies can enhance the efficacy of treatment. In contrast, high ROR1 expression confers longer PFS to chemotherapy in the same group of patients. The role of chemotherapy and erlotinib in EGFR-mutant NSCLC patients with high ROR1 expression warrants further investigation.

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    P3.06 - Poster Session 3 - Prognostic and Predictive Biomarkers (ID 178)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P3.06-006 - Integrated genomic analysis of EGFR-mutant non-small cell lung cancer immediately following erlotinib initiation in patients (ID 1003)

      09:30 - 09:30  |  Author(s): C. Heidecke

      • Abstract

      Background
      Major obstacles limiting the clinical success of EGFR TKI therapy in EGFR mutant non-small cell lung cancer (NSCLC) patients are heterogeneity and variability in the initial anti-tumor response to treatment. The underlying molecular basis for this heterogeneity has not been explored in patients immediately after initiation of therapy.

      Methods
      We conducted CT-guided core needle biopsies immediately prior to erlotinib treatment initiation and at 6 days and 60 days post erlotinib initiation in a patient with histologically confirmed NSCLC harboring an established activating mutation in EGFR. DNA and RNA from each of the frozen biopsies were analyzed by whole exome sequencing and whole transcriptome sequencing, respectively. High-resolution CT images were also obtained at the time of each biopsy to assess the degree of molecular and radiographic responses observed.

      Results
      Two established activating somatic mutations were identified in EGFR (p.G719A and p. R776H). Gene expression analysis revealed that several proapoptotic genes including BID, CASP3 and several growth inhibitory genes including GADD45B, GADD45G were upregulated at 6 days post erlotinib treatment, while at 60 days their expression levels decreased to below pretreatment levels. Other proapoptotic genes such as BAD and BAX and were noted to be upregulated most significantly 60 days, as was growth inhibitory gene CDKN1A. In contrast, the growth-promoting genes CCNB1 and CCND3 exhibited a progressive decrease in expression across time points. Whole exome sequencing demonstrated the progressive evolution of global copy number abnormalities. High-resolution CT scans revealed no interval radiographic change in tumor size after 6 days of erlotinib treatment, and a decrease in tumor size 60 days into therapy. No clinical complications were encountered.

      Conclusion
      This study is the first reported longitudinal integrated genomic analysis of EGFR-mutant NSCLC in a patient treated with an EGFR TKI. We documented the feasibility, safety and utility of this strategy to establish initial drug efficacy at the molecular level prior to any radiographic evidence of response (6 days), as well as evidence that acquired resistance can emerge early in the course of TKI therapy. Serial integrated genomic analysis is ongoing in other TKI treated patients to enhance the management of NSCLC patients on targeted therapy.