For gefitinib treatment for non-small cell lung cancer (NSCLC), KRAS mutations reportedly behave as a resistance marker, and the epidermal growth factor receptor (EGFR) as a responsive marker. It is known that Asians and Caucasians have different responses to gefitinib. We investigated the KRAS and EGFR mutation status in a group of Chinese patients with advanced NSCLC who were treated with gefitinib after a failed chemotherapy.
Genomic DNA extracted from tumor specimens of 24 patients with advanced NSCLC, who failed at least 1 prior platinum-based chemotherapy regimen before gefitinib treatment, was subjected to nested polymerase chain reaction (PCR) to amplify codons 12, 13, 59, and 61 of the KRAS gene and exons 18-21 of the EGFR gene for direct sequencing.
For the 24 patients, no KRAS gene mutation was found. 15 patients (62.5%, 15/24) harbored EGFR mutations which included deletion mutations in exon 19 and missense mutations in exon 21.
KRAS mutation may occur at a very low frequency in Chinese NSCLC patients regardless of pathology, smoking status, or gender. Unlike EGFR, the low incidence of KRAS mutations may undermine its role in predicting the clinical response to EGFR tyrosine kinase inhibitors.
"). PFS and OS were longer in Asian patients, 4.05 (n = 429) and 12.68 (n = 407) months, respectively (Kim et al., 2008; Maruyama et al., 2008; Zhang et al., 2005; Chen et al., 2007; Wang et al., 2008). "
[Show abstract][Hide abstract] ABSTRACT: Platinum-based chemotherapy is the standard of care for ovarian cancer and non-small cell lung cancer (NSCLC). However, resistance to platinum agents invariably develops. Targeted therapies, such as tyrosine kinase inhibitors (TKIs), have great potential here as they exert their anti-tumour effect via alternative mechanisms to platinum-based drugs and as such may remain unaffected by emergent resistance to platinum.
A systematic review was conducted to investigate whether two EGFR-TKIs, erlotinib and gefitinib, have efficacy in the platinum-resistance setting. Preclinical studies of platinum-resistant cancer cell lines, which had been subsequently treated with EGFR-TKIs, were sought to establish proof-of-concept. Clinical trials reporting administration of EGFR-TKIs to ovarian cancer and NSCLC patients relapsed after therapy with platinum drugs were investigated to determine sensitivity of these cohorts to EGFR-TKI treatment. The role of EGFR mutation, copy number and protein expression on response to EGFR-TKIs after failure of platinum chemotherapy were also investigated.
Preclinical models of platinum-resistant cancer were found which display a spectrum of cross-resistance profiles to EGFR-TKIs. Sensitivity to EGFR-TKIs is dependent on the activation of the EGFR pathway or EGFR interacting proteins such as HER-2. EGFR-TKIs show favourable response rates in platinum-pretreated NSCLC, 11.14% and 15.25% for 150mg/day erlotinib and 250mg/day gefitinib, respectively. These response rates significantly improve in patients of Asian descent (28.3% and 29.17%, respectively) and patients with EGFR activation mutations (41.6% and 63.89%, respectively) or increased copy number (33.3% and 45.45%, respectively). Gefitinib significantly outperformed erlotinib and should therefore be the EGFR-TKI of choice in platinum-pretreated relapsed NSCLC. In contrast, response rates are very poor to both erlotinib and gefitinib in platinum pretreated ovarian cancer, 0-5.9% and they should not be used in this cohort of patients. Preclinical models demonstrate that, while cross resistance can occur between platinums and EGFR-TKIs, there is not a generalised cross-resistance phenotype. Erlotinib and gefitinib are suitable for the treatment of platinum-pretreated NSCLC, particularly in patients with EGFR mutations or increases in copy number. Unfortunately, the high rates of EGFR protein overexpression in ovarian cancer are not translating to a clinically useful therapeutic target for EGFR-TKIs; EGFR mutations are rare in ovarian cancer. Newer TKIs may improve response rates in these cohorts and future clinical trials need to collect tumour biopsies from all patients to ensure the success of personalised chemotherapy.
Drug resistance updates: reviews and commentaries in antimicrobial and anticancer chemotherapy 03/2011; 14(3):177-90. DOI:10.1016/j.drup.2011.02.004 · 9.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An antenna for the cellular phone terminal is designed to have the
best performance when it is used as a phone. In this case, the terminal
is attached to the ear. Recently a function as a viewer terminal was
very popular because Internet service for the cellular phone increased
remarkably. Therefore this paper investigated the effect of operator
body on the viewer terminal by using a ceramic phantom
[Show abstract][Hide abstract] ABSTRACT: Clinical experience with the EGFR-TKI gefitinib in Asian patients with NSCLC will be reviewed, both in patients who have previously failed chemotherapy and in the first-line setting (gefitinib is currently not licensed for first-line treatment). Tolerability and specific adverse events in patients of Asian origin will be discussed. Differing objective response rates between patients of Asian and non-Asian origin when treated with gefitinib (and standard cytotoxics) will also be discussed along with EGFR mutations and drug resistance. Reports of Phase II/III clinical experience with gefitinib 250 mg/day in Asia were identified by searching in Medline and ASCO databases for publications between 1993 and 2008. Defined search criteria included (gefitinib OR Iressa OR ZD1839) AND NSCLC AND (Asia OR Japan OR China OR Taiwan OR Korea) or 'Clinical trial' type, with additional searches, including AND 'interstitial lung disease (ILD)' or 'EGFR mutation'. Numerous Phase II/III trials including patients of Asian origin with previously treated advanced NSCLC report a consistent clinical benefit of gefitinib. Gefitinib is generally well tolerated by patients with NSCLC although the incidence of ILD in Japanese patients must be noted. Studies analyzing EGFR mutations indicate that these mutations occur at a much higher rate in patients of Asian origin than in non-Asian patients. Data from several studies indicate that EGFR mutation-positive patients of Asian origin have better efficacy outcomes with first-line gefitinib when compared with those who are EGFR mutation-negative. Research is ongoing to evaluate the role of tailoring patients' treatment according to their genetic phenotype.
Japanese Journal of Clinical Oncology 03/2009; 39(3):137-50. DOI:10.1093/jjco/hyn139 · 2.02 Impact Factor
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