Development of a highly sensitive and specific method for detection of circulating tumor cells harboring somatic mutations in non-small-cell lung cancer patients.

BACKGROUND: Oncogenic mutations are powerful predictive biomarkers for molecularly targeted cancer therapies. For mutation detection patients have to undergo invasive tumor biopsies. Alternatively, archival samples are used which may no longer reflect the actual tumor status. Circulating tumor cells (CTC) could serve as an alternative platform to detect somatic mutations in cancer patients. We sought to develop a sensitive and specific assay to detect mutations in the EGFR gene in CTC from lung cancer patients. METHODS: We developed a novel assay based on real-time polymerase chain reaction (PCR) and melting curve analysis to detect activating EGFR mutations in blood cell fractions enriched in CTC. Non-small-cell lung cancer (NSCLC) was chosen as disease model with reportedly very low CTC counts. The assay was prospectively validated in samples from patients with EGFR-mutant and EGFR-wild type NSCLC treated within a randomized clinical trial. Sequential analyses were conducted to monitor CTC signals during therapy and correlate mutation detection in CTC with treatment outcome. RESULTS: Assay sensitivity was optimized to enable detection of a single EGFR-mutant CTC/mL peripheral blood. CTC were detected in pretreatment blood samples from all 8 EGFR-mutant lung cancer patients studied. Loss of EGFR-mutant CTC signals correlated with treatment response, and its reoccurrence preceded relapse. CONCLUSIONS: Despite low abundance of CTC in NSCLC oncogenic mutations can be reproducibly detected by applying an unbiased CTC enrichment strategy and highly sensitive PCR and melting curve analysis. This strategy may enable non-invasive, specific biomarker diagnostics and monitoring in patients undergoing targeted cancer therapies.

Feasibility of preemptive biomarker profiling for personalised early clinical drug development at a Comprehensive Cancer Center.

PURPOSE: Multiple investigational drugs are currently explored in cancer patient populations defined by specific biomarkers. This demands a new process of patient selection for clinical trials. PATIENTS AND METHODS: Starting January 1, 2012, preemptive biomarker profiling was offered at the West German Cancer Center to all patients with advanced non-small-cell lung (NSCLC) or colorectal cancer (CRC), who met generic study inclusion criteria. Tumour specimens were subjected to prespecified profiling algorithms to detect 'actionable biomarkers' by amplicon sequencing, in situ hybridisation and immunohistochemistry. The clinical course was closely monitored to offer trial participation whenever applicable. RESULTS: Within 12 months, 267 patients (188 NSCLC, 79 CRC) were profiled. Estimated additional cost for biomarker profiling was 219615.51 EUR excluding histopathology workup and administration. The most prevalent biomarkers in pulmonary adenocarcinoma were KRAS mutations (29%), loss of PTEN expression (18%), EGFR mutations (9%), HER2 amplification (5%) and BRAF mutations (3%), while the prevalence of ALK translocations and PIK3CA mutations was extremely low. In pulmonary squamous cell carcinoma FGFR1 amplifications were found in 15%, PTEN expression was lost in 20% and DDR2 was mutated in a single case. KRAS mutations (41%) predominated in CRC, followed by loss of PTEN expression (16%), PIK3CA (5%) and BRAF (5%) mutations. So far 13 patients (5%) have entered biomarker-stratified clinical trials. Therapeutic decisions for approved drugs were guided in another 45 patients (17%). CONCLUSION: Preemptive biomarker profiling can be implemented into the diagnostic algorithm of a large Comprehensive Cancer Center. Substantial investments in diagnostics and administration are required.