KRAS Mutant Type Research Articles

Abstract C22: The effect of irinotecan-induced in k-Ras wild and mutant type colon cancer cell lines.

Abstract Irinotecan (IRI) prevents DNA from unwinding by inhibition of topoisomerase [[Unable to Display Character: І]]. Its main use is in colon cancer, in particular, in combination with other chemotherapy agents. Recent studies, those with irinotecan treatment has a synergistic effect appears. However, there is no study on the effect of the irinotecan mono-treatment. In addition their roles and the underlying mechanism in anti-tumorigenic function of solid tumor, especially kras wild and mutant type colon cancer, are not yet known. Bax protein is a key mediator of apoptosis and might be related to chemosensitivity. In this work, we evaluated the anti-tumorigenic action of these irinotecan anti-cancer agents with especially k-ras wild and mutant type colon cancer cell lines, and investigated their apoptosis-inducing effects as the potential mechanism in this process. The results show that the growth inhibitory effects of 5-fuorouracil (5-FU), Oxaliplatin(OX) produced a dose- and time dependent fashion in k-ras wild (HT29, Colo205) and mutant type (HCT116, DLD-1) colon cancer cell lines. Otherwise, irinotecan produced a cell growth of k-ras wild type cell lines were resistant versus that shown in the sensitive k-ras mutant type cell lines. Cell cycle analysis by FACS indicated that IRI-treated cell lines showed an increase in the proportion of cells in sub-G1 phase, compared to untreated cells. Exposure of colon cancer cells to IRI also resulted in the increase in the percentage of annexin V- positive and PI-negative cells. The results by multiple in vitro experimental model, showed that IRI induces these k-ras mutant type colon cancer cells to undergo apoptosis with increased the Bax protein and a release of cytochrome C from mitochondria, the activation of caspase9, the cleavage of PARP. But Bax protein was inactivation in k-ras wild type colon cancer cell lines. Importantly, inhibition of ERK kinase activity demonstrated that IRI-induced apoptotic pathway was regulated by the ERK signaling cascade. These data indicate that anti-cancer agent, irinotecan, promotes Bax-mediate apoptosis of colon cancer cell lines by sequential activation of the ERK signaling pathway followed by the up-regulation of intrinsic pathway of caspase 9. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C22. Citation Format: Myoung Hee Kang, Bo Ram Kim, Sun il Lee, Jun Suk Kim, Sang Cheul Oh. The effect of irinotecan-induced in k-Ras wild and mutant type colon cancer cell lines. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C22.

Abstract 1040: The effect of Irinotecan in k-Ras wild and mutant type colon cancer cell lines.

Abstract Irinotecan(IRI) prevents DNA from unwinding by inhibition of topoisomerase1. Its main use is in colon cancer, in particular, in combination with other chemotherapy agents. Recent studies, those with Irinotecan treatment has a synergistic effect appears. However, there is no study on the effect of the Irinotecan mono-treatment. In addition their roles and the underlying mechanism in anti-tumorigenic function of solid tumor, especially kras wild and mutant type colon cancer, are not yet known. Bax protein is a key mediator of apoptosis and might be related to chemosensitivity. In this work, we evaluated the anti-tumorigenic action of these Irinotecan anti-cancer agent with especially k-ras wild and mutant type colon cancer cell lines, and investigated their apoptosis-inducing effects as the potential mechanism in this process. The results show that the growth inhibitory effects of 5-fuorouracil (5-FU), Oxaliplatin(OX) produced a dose- and time dependent fashion in k-ras wild(HT29, Colo205) and mutant type(HCT116, DLD-1) colon cancer cell lines. Otherwise, Irinotecan(IRI) produced a cell growth of k-ras wild type cell lines were resistant versus that shown in the sensitive k-ras mutant type cell lines. Cell cycle analysis by FACS indicated that IRI-treated cell lines showed an increase in the proportion of cells in sub-G1 phase, compared to untreated cells. Exposure of colon cancer cells to IRI also resulted in the increase in the percentage of annexin V- positive and PI-negative cells. The results by multiple in vitro experimental model, showed that IRI induce these k-ras mutant type colon cancer cells to undergo apoptosis with increased the Bax protein and a release of cytochrome C from mitochondria, the activation of caspase9, the cleavage of PARP. But Bax protein was inactivation in k-ras wild type colon cancer cell lines. Importantly, inhibition of ERK kinase activity demonstrated that IRI-induced apoptotic pathway was regulated by the ERK signaling cascade. These data indicate that Anti-cancer agent, Irinotecan, promotes Bax mediate apoptosis of colon cancer cell lines by sequential activation of the ERK signaling pathway followed by the up-regulation of intrinsic pathway of caspase 9. Citation Format: Joo Sung Park, Jung Guk Jeon, Myoung Hee Kang, You Jin Jang, Sun Il Lee, Jae Ho Byun, Jun Suk Kim, Sang Cheul Oh. The effect of Irinotecan in k-Ras wild and mutant type colon cancer cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1040. doi:10.1158/1538-7445.AM2013-1040

O-0021 Randomised Phase III Study of Bevacizumab + Chemotherapy Beyond Progression in Bevacizumab-Treated Patients with Metastatic Colorectal Cancer: TML Study Kras Subgroup Findings

ABSTRACT Introduction Bevacizumab in combination with fluoropyrimidine-based chemotherapy is a standard treatment for patients with metastatic colorectal cancer (mCRC) in the first-line and bevacizumab-naive second-line settings. This randomised study evaluated the benefit of continuing bevacizumab with standard chemotherapy as second-line treatment for patients with mCRC who progressed after receiving a standard bevacizumab-containing regimen in the first-line setting. The study included a broad biomarker collection as an exploratory objective. We present here analysis of outcomes according to tumour KRAS status. Methods Patients with unresectable, histologically confirmed mCRC who progressed within 3 months after discontinuation of first-line bevacizumab + chemotherapy were randomised to second-line fluoropyrimidine-based chemotherapy ± bevacizumab (2.5 mg/kg/wk equivalent). The choice of oxaliplatin- or irinotecan-based second-line chemotherapy was based on the regimen used in the first-line setting (crossover) and was included in the stratification variables. The primary endpoint was overall survival (OS); secondary endpoints included progression-free survival (PFS), response rate and safety. Subgroup analysis according to KRAS status was performed for both OS and PFS; no adjustment was made for multiplicity. Results Conclusive tumour KRAS mutation data were available for 616 of the 820 patients (75%). Baseline characteristics were similar in the biomarker and randomised populations. Overall, 300 (49%) patients had mutant-type (MT) KRAS tumours and 316 (51%) had wild-type (WT) KRAS tumours. Median OS in the KRAS WT group was 15.4 months for bevacizumab + chemotherapy vs 11.1 months for chemotherapy alone (p = 0.0052; HR = 0.69) and 10.4 months for bevacizumab + chemotherapy vs 10.0 months for chemotherapy alone in the KRAS MT group (p = 0.4969; HR = 0.91). Median PFS in the KRAS WT group was 6.4 months for bevacizumab + chemotherapy vs 4.5 months for chemotherapy alone (p Conclusion This is the first randomized study evaluating the benefit of continuing bevacizumab in combination with standard chemotherapy as second-line treatment for patients with mCRC who progressed after receiving a standard bevacizumab-containing regimen in the first-line setting. The biomarker findings from this study suggest that patients with both WT and MT KRAS tumours are likely to benefit from bevacizumab treatment.

Survival Outcome in Metastatic Colorectal Cancer Patients Treated with Bevacizumab Followed by Cetuximab

Background: Molecular targeted agents, such as bevacizumab and cetuximab, have been shown to improve the overall survival of metastatic colorectal cancer (mCRC) patients. However, we still do not know the best sequence in which to use the molecular targeted agents for mCRC, especially in K-ras wild-type cases. Methods: From July 2006 to November 2010, 63 chemotherapy-naive patients who were diagnosed with mCRC and received an oxaliplatin-based regimen as the first line, did not respond to a bevacizumab-containing regimen used as the first or second line, and received cetuximab or continued bevacizumab, were eligible for this analysis. Thirty-two patients received cetuximab as the third or fourth line chemotherapy due to the K-ras wild-type (Group A). Also, thirty-one patients continued a bevacizumab-containing regimen in spite of disease progression (Group B). Results: The difference in the rate of serious adverse events was not significant between the two groups, but the rate of overall adverse events tended to be higher in Group A than in Group B. The median overall survival (MST) was significantly higher in Group A than Group B (30.8 months and 23.13 months (95%CI: 15.80 - 30.47), respectively) (P = 0.031). Group A patients were all K-ras wild-type, and 21 of Group B were K-ras mutant type. Compared with Group B patients with the K-ras mutant type, MST of Group A patients was significantly longer (30.8 months and 25.73 months, respectively) (P = 0.025). Conclusion: Using cetuximab after progression with bevacizumab might be an effective sequence to improve the overall survival of K-ras wild-type mCRC patients. However, we need further prospective studies to identify the best sequence of chemotherapy for mCRC patients.