A new diagnostic method based on RT-PCR and CLART technology for non-small cell lung cancer (NSCLC) to detect major EML4-ALK and ROS.1 translocations: CLART CMA ALK and ROS.1

e20045

Background: EML4-ALK and ROS1 translocations represent 3-6% and 1-2% of NSCLC patients, respectively. These patients would benefit for a tyrosine kinase inhibitor therapies. Currently, the gold standard for ALK and ROS.1 detection are break-apart fluorescence in situ hybridization (FISH) or inmunodetection (IHC) of the chimeric fusion proteins. FISH has both high sensitivity and specificity, although often present technical interpretation problems due to signal instability and scoring. IHC is a rapid and low cost technique; however it presents several challenges regarding sensitivity and reproducibility. CLART CMA ALK & ROS.1 kit is based RT-PCR and detection of the amplified product was carried out by a low-density microarray platform: CLART (Clinical Arrays Technology) of major fusion transcripts of EML4-ALK and ROS.1 translocations ( V1: E13;A20 , V6: E13; ins69;A20 , V2: E20;A20 , V3a: E6:A20 , V3b: E6;ins33 A20 ,V5a: E2;A20 and V5b: E2;ins117A20 for EML4-ALK and SDC4-ROS1 S2;R32/ S2;R34, CD74-ROS1 C6;R34 and SLC34A2-ROS1 S4;R32/S4;R34). Methods: The translocations analysis was performed with CLART CMA ALK & ROS.1 kit. Clinical testing was performed using the RNA extracted from 115 samples of NSCLC patients being 34 patients with translocations detected in ALK or ROS.1 genes and 81 patients without any translocations. The results were cross-checked by comparison to Next GenerationS methodology performed on the PGM platform with the Ion Ampliseq Panel Oncomide Solid Tumor Fusion and the concordance was 95.6%. Results: Analytical sensitivity was assessed using fusion transcripts cloned in recombinant plasmids. Results ranged from 10 to 100 copies/5µl of recombinant plasmids. The analysis of 115 clinical samples allowed establishing the diagnostic sensitivity and specificity in 90.9-100% and 99-100% respectively. Conclusions: CLART CMA ALK & ROS.1 emerges as a suitable alternative of FISH/IHQ for diagnosis of the most common translocations in EML4-ALK and ROS.1 genes in NSCLC samples and therefore selecting patients that would best benefit from a target therapy.

Noninvasive EGFR testing in plasma circulating free DNA (cfDNA) by a new diagnostic method to detect point mutations, deletions and insertions associated to non small cell lung cancer: CLART CMA EGFR LB

e20008

Background: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are current treatments for advanced non-small cell lung cancer (NSCLC) with activating EGFR gene mutations. Histological samples are the standard tumor materials for EGFR mutation analysis. However, the accessibility of tumor samples is not always possible in advanced NSCLC patients. Moreover, a high percentage of EGFR mutated NSCLC patients will develop resistance to EGFR-TKIs such as T790M mutation. CLART CMA EGFR LB is a novel diagnostic assay able to detect 39 high-prevalence mutations associated with sensitivity or resistance to tyrosine kinase inhibitor treatment. Methods: A highly sensitive and specific method was developed for detection of EGFR mutations (G719X, T790M, L858R, L861Q, insertions in exon 20, and deletions in exon 19) in plasma samples (cfDNA). CLART CMA EGFR LB is based on a preamplification step with a multiplex ARMS-PCR and microarray detection system. Clinical testing was performed using 51 clinical plasma samples: 27 contained L858R, T790M, and deletions in exon 19; 24 contained wild type alleles. 20 samples were cross checked by next generation sequencing performed on the PGM platform (Ion Ampliseq™ Custom, deep-coverage 15000x). Results: Analytical sensitivity was assessed using recombinant plasmids, results ranged between 10-1000 copies/5µl for all mutations. cfDNA from cell lines with the mutations L858R, T790M and deletions in exon 19 at different frequencies (cfDNA Reference Standard, Horizon) were assessed. The system was able to detect the mutations present in a frequency of 2%. The analysis of 51 samples allowed establishing the diagnostic sensitivity and specificity in 93.33% and 100% respectively. CLART CMA EGFR LB showed similar analytical and diagnostic sensitivity than NGS for detecting L858R, T790M and deletions in exon 19. Conclusions: Our data support the use of CLART CMA EGFR LB for clinical testing prior to the selection of the appropriate treatment in NSCLC, monitoring the patient evolution and the emergence of resistance mutations such as T790M in plasma samples.

Detection and quantification of multiple drug resistance mutations in HIV-1 reverse transcriptase by an oligonucleotide ligation assay

OBJECTIVES

To develop an assay for the early detection and quantification of minor human immunodeficiency virus-1 populations bearing multiple drug resistance (MDR) mutations.

STUDY DESIGN/METHODS

The oligonucleotide ligation assay (OLA) is based on ligation of probe and detector oligonucleotides annealed to a polymerase chain reaction amplicon strand with detection by an enzyme immunoassay. In OLA-MDR, oligonucleotides were designed to detect MDR mutations. The method was validated with wild-type and MDR mutant clones mixed at different proportions.

RESULTS

K103N mutants were detected as minor populations (5%-30%) by OLA in 6 of 18 samples from patients treated with nonnucleoside reverse transcription inhibitors and classified as wild type by sequencing. In one patient, the kinetics of the increase of MDR mutants could be followed in sequential samples, with K103N being detected earlier by OLA than by sequencing. Q151M mutants were detected as minor populations (13%-24%) by OLA but not by sequencing in 4 samples.

CONCLUSIONS

Oligonucleotide ligation assay MDR exhibits higher sensitivity than sequencing for detection of minor MDR mutant populations.