Circulating tumor cells (CTCs) are tumor cells that are separated from the primary site or metastatic lesion and disseminate in blood circulation. CTCs are considered to be part of the long process of cancer metastasis. As a 'liquid biopsy', CTC molecular examination and investigation of single cancer cells create an important opportunity for providing an understanding of cancer biology and the process of metastasis. In the last decade, we have seen dramatic development in defining the role of CTCs in lung cancer in terms of diagnosis, genomic alteration determination, treatment response and, finally, prognosis prediction. The aims of this review are to understand the basic biology and to review methods of detection of CTCs that apply to the various types of solid tumor. Furthermore, we explored clinical applications, including treatment monitoring to anticipate therapy resistance as well as biomarker analysis, in the context of lung cancer. We also explored the potential use of cell-free circulating tumor DNA (ctDNA) in the genomic alteration analysis of lung cancer.
There is growing concern, even among developed countries, about the increasing incidence of multidrug-resistant tuberculosis (MDR-TB). Results are reported from a study investigating ofloxacin used in the treatment of 57 patients with MDR-TB. Patients received ofloxacin 400 mg/day as well as three other sensitive anti-TB drugs based on susceptibility tests. Treatment duration was 9 months. Preliminary results of 35 evaluable patients show 55% of MDR-TB cases converted to smear and culture negative within 3 months of therapy. Ofloxacin in combination with other sensitive anti-TB medication shows promise in the treatment of MDR-TB and further studies are recommended.
Background
Lung cancer patients with mutations in epidermal growth factor receptor (EGFR) gene are treated with tyrosine kinase inhibitor (TKI).
Aims
We aimed to evaluate polymerase chain reaction (PCR)–high‐resolution melting (HRM), restriction fragment length polymorphism (RFLP), and direct sequencing (DS) to detect EGFR mutations in cell‐free DNA (cfDNA) before and after TKI treatment in real‐world settings of a developing country.
Methods
Paired cytology and plasma samples were collected from 116 treatment‐naïve lung cancer patients. DNA from both plasma and cytology specimens was isolated and analyzed using PCR‐HRM (to detect exon 19 insertion/deletion), RFLP (to genotypes L858R and L861Q), and DS (to detect uncommon mutations G719A, G719C, or G719S [G719Xaa] in exon 18 and T790M and insertion mutations in exon 20).
Results
EGFR genotypes were obtained in all 116 (100%) cfDNA and 110/116 (94.82%) of cytological specimens of treatment‐naïve patient (baseline samples). EGFR‐activating mutations were detected in 46/110 (40.6%) plasma samples, and 69/110 (63.2%) mutations were found in routine cytology samples. Using cytological EGFR genotypes as reference, we found that sensitivity and specificity of baseline plasma EGFR testing varied from 9.1% to 39.39% and 83.12% to 96.55%, respectively. In particular, the sensitivity and specificity of this assay in detecting baseline T790M mutations in exon 20 were 30% and 89.58%, respectively. Three months after TKI treatment, plasma T790M and insertion exon 20 mutations appeared in 5.4% and 2.7% patients, respectively.
Conclusions
Despite low sensitivity, combined DS, RFLP, and PCR‐HRM was able to detect EGFR mutations in plasma cfDNA with high specificity. Moreover, TKI resistance exon 20 insertions mutation was detected as early as 3 months post TKI treatment.
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