[Show abstract][Hide abstract] ABSTRACT: VEGFR-2 has a role in gastric cancer pathogenesis and progression. We assessed whether ramucirumab, a monoclonal antibody VEGFR-2 antagonist, in combination with paclitaxel would increase overall survival in patients previously treated for advanced gastric cancer compared with placebo plus paclitaxel.
The Lancet Oncology 09/2014; · 25.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background In the international, phase III, randomized, double-blind CORRECT trial, regorafenib significantly prolonged overall survival (OS) versus placebo in patients with metastatic colorectal cancer (mCRC) that had progressed on all standard therapies. This post hoc analysis evaluated the efficacy and safety of regorafenib in Japanese and non-Japanese subpopulations in the CORRECT trial. Methods Patients were randomized 2 : 1 to regorafenib 160 mg once daily or placebo for weeks 1-3 of each 4-week cycle. The primary endpoint was OS. Outcomes were assessed using descriptive statistics. Results One hundred Japanese and 660 non-Japanese patients were randomized to regorafenib (n = 67 and n = 438) or placebo (n = 33 and n = 222). Regorafenib had a consistent OS benefit in the Japanese and non-Japanese subpopulations, with hazard ratios of 0.81 (95 % confidence interval [CI] 0.43-1.51) and 0.77 (95 % CI 0.62-0.94), respectively. Regorafenib-associated hand-foot skin reaction, hypertension, proteinuria, thrombocytopenia, and lipase elevations occurred more frequently in the Japanese subpopulation than in the non-Japanese subpopulation, but were generally manageable. Conclusion Regorafenib appears to have comparable efficacy in Japanese and non-Japanese subpopulations, with a manageable adverse-event profile, suggesting that this agent could potentially become a standard of care in patients with mCRC.
Investigational New Drugs 09/2014; · 3.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Interindividual variation in a drug response among patients is known to cause serious problems in medicine. Genomic information has been proposed as the basis for "personalized" health care. The genome-wide association study (GWAS) is a powerful technique for examining single nucleotide polymorphisms (SNPs) and their relationship with drug response variation; however, when using only GWAS, it often happens that no useful SNPs are identified due to multiple testing problems. Therefore, in a previous study, we proposed a combined method consisting of a knowledge-based algorithm, 2 stages of screening, and a permutation test for identifying SNPs. In the present study, we applied this method to a pharmacogenomics study where 109,365 SNPs were genotyped using Illumina Human-1 BeadChip in 168 cancer patients treated with irinotecan chemotherapy. We identified the SNP rs9351963 in potassium voltage-gated channel subfamily KQT member 5 (KCNQ5) as a candidate factor related to incidence of irinotecan-induced diarrhea. The p value for rs9351963 was 3.31×10-5 in Fisher's exact test and 0.0289 in the permutation test (when multiple testing problems were corrected). Additionally, rs9351963 was clearly superior to the clinical parameters and the model involving rs9351963 showed sensitivity of 77.8% and specificity of 57.6% in the evaluation by means of logistic regression. Recent studies showed that KCNQ4 and KCNQ5 genes encode members of the M channel expressed in gastrointestinal smooth muscle and suggested that these genes are associated with irritable bowel syndrome and similar peristalsis diseases. These results suggest that rs9351963 in KCNQ5 is a possible predictive factor of incidence of diarrhea in cancer patients treated with irinotecan chemotherapy and for selecting chemotherapy regimens, such as irinotecan alone or a combination of irinotecan with a KCNQ5 opener. Nonetheless, clinical importance of rs9351963 should be further elucidated.
PLoS ONE 08/2014; 9(8):e105160. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: AUY922 is a potent non-geldanamycin inhibitor of heat-shock protein 90. This study was carried out in Japanese patients to determine the maximum tolerated dose (MTD), and to characterize safety, tolerability and pharmacokinetics of single-agent AUY922.
Cancer Chemotherapy and Pharmacology 07/2014; · 2.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Trastuzumab for Gastric Cancer phase III trial demonstrated that combining trastuzumab with chemotherapy significantly improved overall survival compared with chemotherapy alone in HER2-positive advanced gastric or gastroesophageal junction cancer. We report health-related quality of life (HRQoL) and quality-adjusted time without symptoms of disease or toxicity (Q-TWiST) results from this trial.PATIENTS AND METHODS: Patients were randomized to receive six cycles of chemotherapy given every 3 weeks (capecitabine or fluorouracil, plus cisplatin) either alone or combined with administration of trastuzumab every 3 weeks until disease progression. At each clinical visit, HRQoL was assessed using two European Organization for Research and Treatment of Cancer quality of life questionnaires, QLQ-C30 and QLQ-STO22. Q-TWiST methodology was applied retrospectively using the clinical data and utility coefficients.RESULTS: Trastuzumab plus chemotherapy prolonged time to 10% definitive deterioration in all QLQ-C30 and QLQ-STO22 scores, including QLQ-C30 global health status versus chemotherapy alone, from 6.4 months to 10.2 months. In addition, trastuzumab plus chemotherapy extended Q-TWiST by 2.42 months compared with chemotherapy alone.CONCLUSION: Compared with chemotherapy alone, trastuzumab plus chemotherapy prolongs time to deterioration of HRQoL and increases quality-adjusted survival in patients with HER2-positive gastric or gastroesophageal junction cancer.
[Show abstract][Hide abstract] ABSTRACT: Human epidermal growth factor receptor 2 (HER2) protein overexpression and gene amplification are important biomarkers for trastuzumab treatment in breast and gastric cancer patients. Gastric cancer presents high rates of tumor heterogeneity, which may influence the results of HER2 testing. A novel gene-protein assay (GPA) can allow the simultaneous analysis of HER2 protein and gene status on a single slide.
[Show abstract][Hide abstract] ABSTRACT: In Asian countries, paclitaxel once per week is used as second-line treatment in advanced gastric cancer, including human epidermal growth factor receptor 2 (HER2) -positive tumors. The role of anti-HER2 agents, including lapatinib, in this setting and population is unclear.
Journal of Clinical Oncology 05/2014; 32(19):2039. · 18.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Olaratumab (IMC-3G3) is a fully human IgG1 monoclonal antibody that selectively binds the external domain of human platelet-derived growth factor receptor-alpha with high affinity and blocks ligand binding. This was a single-center, dose-escalation, phase I trial of olaratumab in Japanese patients with advanced/refractory solid malignancies. Three to 6 patients were enrolled into each of 3 cohorts: Patients received i.v. olaratumab: 10 mg/kg on Days 1 and 8 every 3 weeks (Cohort 1); 20 mg/kg every 2 weeks (Cohort 2); and 15 mg/kg on Days 1 and 8 every 3 weeks (Cohort 3). Doses were escalated from Cohort 1 through Cohort 3. The primary objective was to establish the safety and pharmacokinetic profile of olaratumab. Sixteen patients were treated across 3 cohorts. There were no dose-limiting toxicities, so the maximum tolerated dose was not reached. The most common olaratumab-related treatment-emergent adverse events (TEAEs) were proteinuria (25.0%) and elevated aspartate transaminase (12.5%). One patient (Cohort 2) had two olaratumab-related Grade 3 TEAEs (increased aspartate aminotransferase and tumor hemorrhage); otherwise, olaratumab-related TEAEs were Grade 1/2. Seven patients (43.8%) had a best response of stable disease. Based on the pharmacokinetic concentration profile of olaratumab, the trough concentrations following single and multiple doses at 15 mg/kg on Days 1 and 8 every 3 weeks (Cohort 3) and multiple doses at 20 mg/kg every 2 weeks (Cohort 2) were above the 155 μg/mL target. Thus, these two doses could represent an acceptable schedule for future trials in Japanese patients. Olaratumab had an acceptable safety profile and was well tolerated. Clinical Trials.gov identifier: NCT01199822 This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Background and study aims: Endoscopic submucosal dissection (ESD) is more difficult and has a higher rate of complications, such as perforation and bleeding, compared with conventional endoscopic resection. The aim of this study was to evaluate the feasibility of a new scissors-type electrosurgical knife for ESD, which was developed for improved durability and ease of use. Materials and methods: Initial ex vivo experiments and subsequent ESD procedures in live pigs were carried out. A human feasibility study was then performed in patients with early esophageal or gastric cancer. The primary end point was serious adverse events (SAE) related to ESD. Results: In the ex vivo and live animal models, no mechanical errors occurred and only minor damage to surrounding tissue was observed. Four patients were enrolled in the human feasibility study; all ESD procedures were completed with a mean procedure time of 31 minutes. All specimens were resected completely without any SAEs. The device worked smoothly, with no electrical problems noted. Conclusion: ESD using a novel scissors-type knife for early esophageal or gastric cancer is feasible.Clinical trial registration: UMIN000004941.
[Show abstract][Hide abstract] ABSTRACT: In advanced gastric cancer (AGC), no globally accepted prognostic scoring system has been developed. Therefore, we explored baseline prognostic factors in Japanese AGC patients using the data from a randomized controlled trial, Japan Clinical Oncology Group (JCOG) 9912, which investigated the efficacy of systemic chemotherapy as a first-line treatment.Patients and Methods.Prognostic factors and prognostic indices for overall survival were screened and evaluated in patients enrolled in JCOG9912 using the Cox proportional hazard model. The Royal Marsden Hospital prognostic model was also applied to the JCOG9912 trial.Results.A total of 650 (92.3%) of the 704 patients randomized in the JCOG9912 trial, for whom complete data were available for multivariate analyses, was included in the present study (5-fluorouracil arm, n = 215; irinotecan plus cisplatin arm, n = 216; S-1 arm, n = 219). The median survival time (MST) for all patients was 11.8 months. To construct a prognostic index, we selected four risk factors by multivariate analysis: performance status ≥ 1, number of metastatic sites ≥ 2, no prior gastrectomy, and elevated alkaline phosphatase. MSTs were 17.0 months for patients categorized into the low-risk group, who had zero or one risk factor (n = 225); 10.4 months for patients in the moderate-risk group, who had two or three risk factors (n = 368); and 5.0 months for patients in the high-risk group, who had all four risk factors (n = 57).Conclusion.In the present study, we propose a new prognostic index for patients with AGC. This can be used for more appropriate patient stratification in future clinical trials.
[Show abstract][Hide abstract] ABSTRACT: Some tyrosine kinase receptors (RTKs) play critical roles in gastric cancer progression. Not only trastuzumab, but also several other agents targeting RTKs are being investigated for gastric cancer therapy. However, the simultaneous expression of multiple RTKs, which may interfere with the effectiveness of therapeutic agents, has not been evaluated in a large cohort with gastric adenocarcinoma (GAC).
We performed a tissue microarray analysis in 950 patients with GAC who underwent a gastrectomy without preoperative chemotherapy. The protein expressions of HER2, EGFR, MET and FGFR2 were evaluated using immunohistochemistry, and the gene amplifications of HER2, EGFR and MET were examined using dual-color in situ hybridization.
The frequency of overexpression was 11.8 % for HER2, 23.5 % for EGFR, 24.9 % for MET and 31.1 % for FGFR2. Whereas strong staining for each of the RTKs was heterogeneous, tumors with homogeneously strong staining areas often exhibited gene amplification. Strong EGFR expression was significantly associated with a poor outcome, but no prognostic correlations were observed in other RTKs. The overexpression of single and multiple RTKs was observed in 40.4 and 22.7 % of the cases, respectively. HER2, EGFR, MET and FGFR2 predominance was observed in 10.1, 13.9, 16.1 and 22.9 % of the GACs, respectively.
Approximately two-thirds of patients with GAC exhibited the expression of at least one RTK and would be candidates for targeted therapies. Moreover, one-third of at least one RTK overexspressing cases showed multiple RTKs expression. Our results may be useful for selecting the most suitable patients for each targeted therapy.
[Show abstract][Hide abstract] ABSTRACT: Panitumumab was approved in Japan in April 2010 for the treatment of Kirsten rat sarcoma-2 virus oncogene wild-type unresectable and recurrent colorectal cancer. We conducted a post-marketing surveillance study to evaluate the safety and effectiveness of panitumumab.
After panitumumab was commercially available in Japan, all patients to be treated with panitumumab were enrolled. Data on baseline characteristics, treatment outcome, and incidence and severity of adverse drug reactions were collected.
In total, 3091 patients were registered. In the safety analysis set (n = 3085), panitumumab was administered as monotherapy (40.7%) or combination therapy (59.4%). The median treatment duration was 113 days (range: 1-559 days), and 451 (14.6%) patients received panitumumab for ≥10 months. The overall incidence rate of adverse drug reactions was 84.1%, and the most common adverse drug reaction was skin disorders (78.4%). The incidence rates (all grades) of interstitial lung disease, infusion reaction, electrolyte abnormalities and cardiac disorders were 1.3% (mortality rate: 0.6%), 1.5, 19.3 and 0.2%, respectively. The median survival time of patients treated with panitumumab monotherapy as the third-line, or later, therapy was 10.3 months.
This post-marketing survey in clinical practice confirmed the safety and effectiveness of panitumumab. The benefit/risk balance for panitumumab in Japanese patients with unresectable colorectal cancer remains favorable.
Japanese Journal of Clinical Oncology 02/2014; · 1.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Buparlisib (BKM120) is an oral pan-phosphatidylinositol 3-kinase inhibitor, targeting all four isoforms of class I PI3K (α, β, γ, and δ). This open-label, Phase I, dose-escalation study was conducted to determine the maximum tolerated dose of continuous daily buparlisib in Japanese patients with advanced solid tumors. Secondary objectives included safety and tolerability, pharmacokinetics, antitumor activity, and pharmacodynamic marker changes. Fifteen patients were treated at 25 mg/day (n=3), 50 mg/day (n=3), and 100 mg/day (n=9) dose levels. One dose-limiting toxicity of Grade 4 abnormal liver function occurred at 100 mg/day. Considering the safety profile and the maximum tolerated dose in the first-in-man study of buparlisib in non-Japanese patients, further dose escalation was stopped and 100 mg/day was declared the recommended dose. Most common treatment-related adverse events included rash, abnormal hepatic function (including increased transaminase levelss), increased blood insulin levels, and increased eosinophil count. Hyperglycemia was experienced by two patients, one each Grade 1 and 4, and mood alterations were experienced by three patients, two Grade 1 and one Grade 2. Pharmacokinetic results showed buparlisib was rapidly absorbed in a dose-proportional manner. Best overall response was stable disease for six patients, including one unconfirmed partial response. In these Japanese patients with advanced solid tumors, buparlisib had a manageable safety profile, with similar pharmacokinetics to non-Japanese patients. The recommended dose of 100 mg/day will be used in future studies of buparlisib in Japanese patients.(www.clinicaltrials.gov; NCT01283503) This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Previous reports of the influence of UGT1A1 gene polymorphisms on the pharmacokinetics of irinotecan metabolism have not assessed Asian patients treated with FOLFIRI plus bevacizumab for advanced and recurrent colorectal cancer. Twenty-one Japanese colorectal cancer patients received intravenous FOLFIRI (bolus irinotecan, folinic acid, and fluorouracil followed by 46-hour fluorouracil infusion) followed by bevacizumab (5 mg/kg) in Cycle 1. In Cycle 2, patients received bevacizumab followed by FOLFIRI. The regimen was in 2-week cycles. The area under-the-curves ratio (AUC0-last ) (Cycle 2/Cycle 1) was determined from plasma concentrations of irinotecan and metabolites (SN-38, SN-38G). Safety, efficacy, and drug-drug interactions were analyzed. Median observation period was 7.8 months; median number of cycles 15. Drug-drug interactions were evaluated in eight patients without irinotecan dose reduction. Mean AUC0-last ratios (with/without bevacizumab) of irinotecan, SN-38, and SN-38G were 0.959, 0.927, and 0.931 respectively. Response rate was 65%; median progression-free survival 16.4 months. Response occurred in four patients with, and nine without, UGT1A1 polymorphism. No significant differences occurred between efficacy, safety, or polymorphism status. This cohort showed no differences in safety or efficacy compared to previous reports. Bevacizumab did not affect the pharmacokinetics of irinotecan and its metabolites, irrespective of UGT1A1 polymorphism status.
The Journal of Clinical Pharmacology 01/2014; · 2.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background Efatutazone, a novel oral highly-selective peroxisome proliferator-activated receptor gamma (PPARγ) agonist, has demonstrated some inhibitory effects on disease stabilization in patients with metastatic colorectal cancer (mCRC) enrolled in previous phase I studies. Here, we evaluate the safety and pharmacokinetics of efatutazone combined with FOLFIRI (5-fluorouracil, levo-leucovorin, and irinotecan) as second-line chemotherapy in Japanese patients with mCRC. Methods Dose-limiting toxicities (DLTs) were evaluated at 2 efatutazone dose levels of 0.25 and 0.50 mg (the recommended dose [RD] of efatutazone monotherapy) twice daily in combination with FOLFIRI in a 3-9 patient cohort. Furthermore, tolerability at the RD level was assessed in additional patients, up to 12 in total. Blood samples for pharmacokinetics and biomarkers and tumor samples for archival tissues were collected from all patients. Results Fifteen patients (0.25 mg, 3; 0.5 mg, 12) were enrolled. No DLTs were observed. Most patients experienced weight increase (100 %) and edema (80.0 %), which were manageable with diuretics. Common grade 3/4 toxicities were neutropenia (93.3 %), leukopenia (46.7 %), and anemia (33.3 %). Stable disease was observed in 8 of the 14 patients evaluable for tumor response. The plasma adiponectin levels increased over time and increased dose. No clear relationship was detected between treatment efficacies and plasma levels of adiponectin as well as the expression levels of PPARγ and the retinoid X receptor in tumor tissues. Conclusions Efatutazone combined with FOLFIRI demonstrates an acceptable safety profile and evidence of disease stabilization in Japanese patients with mCRC. The RD for efatutazone monotherapy can be used in combination with FOLFIRI.
Investigational New Drugs 12/2013; · 3.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Two randomized phase III trials of first-line chemotherapy for advanced gastric cancer (JCOG9205 and JCOG9912) conducted by the Japan Clinical Oncology Group used 5-fluorouracil continuous infusion (5-FUci) as the control arm. New active agents (e.g., S-1, irinotecan, and taxanes) were introduced as second-line chemotherapy in the late 1990s after JCOG9205. This combined analysis evaluated whether patients in the 5-FUci arm of JCOG9912 exhibited better survival after adjusting for baseline factors and also investigated the cause of survival prolongation.
The subjects were patients assigned to the 5-FUci arms who met the eligibility criteria of both JCOG9205 and JCOG9912. Overall survival (OS), time to treatment failure (TTF), and survival after treatment failure in the first-line chemotherapy (OS-TTF) were compared after adjusting baseline characteristics using the Cox proportional hazard model. Second-line chemotherapy details were also reviewed.
The combined analysis included 89 and 230 patients in JCOG9205 and JCOG9912, respectively. After adjusting baseline characteristics, TTF was similar between groups (HR 0.95; 95 % CI, 0.73-1.26). However, both OS (HR, 0.74; 95 % CI, 0.56-0.99) and OS-TTF (HR, 0.76; 95 % CI, 0.57-1.01) were longer in JCOG9912. More patients in JCOG9912 received second-line chemotherapy (83 vs. 52 %) with new drugs (77 vs. 10 %) than in JCOG9205. OS-TTF was substantially prolonged in patients who received second-line chemotherapy (HR, 0.66; 95 % CI, 0.46-0.95).
OS and OS-TTF were longer in JCOG9912 than JCOG9205. Second-line chemotherapy with new drugs is a potential reason for the observed prolongation of survival.
[Show abstract][Hide abstract] ABSTRACT: The traditional endpoint for assessing efficacy of chemotherapies for advanced/recurrent gastric cancer is overall survival (OS), but OS requires prolonged follow-up. We investigated whether progression-free survival (PFS) is a valid surrogate for OS. Using individual patient data from the GASTRIC meta-analysis, surrogacy of PFS was assessed through the correlation between the endpoints and through the correlation between the treatment effects on the endpoints. External validation of the prediction based on PFS was also evaluated. Individual data from 4069 patients in 20 randomized trials were analyzed. The rank correlation coefficient between PFS and OS was 0.853 (95% confidence interval [CI] = 0.852 to 0.854). The R (2) between treatment effects on PFS and on OS was 0.61 (95% CI = 0.04 to 1.00). Treatment effects on PFS and on OS were only moderately correlated, and we could not confirm the validity of PFS as a surrogate endpoint for OS in advanced/recurrent gastric cancer.
[Show abstract][Hide abstract] ABSTRACT: The oral mammalian target of rapamycin inhibitor everolimus demonstrated promising efficacy in a phase II study of pretreated advanced gastric cancer. This international, double-blind, phase III study compared everolimus efficacy and safety with that of best supportive care (BSC) in previously treated advanced gastric cancer.
Patients with advanced gastric cancer that progressed after one or two lines of systemic chemotherapy were randomly assigned to everolimus 10 mg/d (assignment schedule: 2:1) or matching placebo, both given with BSC. Randomization was stratified by previous chemotherapy lines (one v two) and region (Asia v rest of the world [ROW]). Treatment continued until disease progression or intolerable toxicity. Primary end point was overall survival (OS). Secondary end points included progression-free survival (PFS), overall response rate, and safety.
Six hundred fifty-six patients (median age, 62.0 years; 73.6% male) were enrolled. Median OS was 5.4 months with everolimus and 4.3 months with placebo (hazard ratio, 0.90; 95% CI, 0.75 to 1.08; P = .124). Median PFS was 1.7 months and 1.4 months in the everolimus and placebo arms, respectively (hazard ratio, 0.66; 95% CI, 0.56 to 0.78). Common grade 3/4 adverse events included anemia, decreased appetite, and fatigue. The safety profile was similar in patients enrolled in Asia versus ROW.
Compared with BSC, everolimus did not significantly improve overall survival for advanced gastric cancer that progressed after one or two lines of previous systemic chemotherapy. The safety profile observed for everolimus was consistent with that observed for everolimus in other cancers.
Journal of Clinical Oncology 09/2013; · 18.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Owing to the risks of serious and sustained toxicity, anticancer drugs such as cisplatin and irinotecan cannot be readily administered to patients with gastric cancer and severe peritoneal metastasis. Therefore, a standard chemotherapy regimen has yet to be established for these types of patients. This randomized study investigated the utility of sequential methotrexate and 5-fluorouracil therapy vs. 5-fluorouracil continuous infusion for gastric cancer with peritoneal metastasis.
Eligible patients had radiologically confirmed peritoneal metastasis with intestinal stenosis, peritoneal tumor or ascites. Treatment with 5-fluorouracil continuous infusion (800 mg/m(2)/day, ci, d1-5, q4w) or methotrexate and 5-fluorouracil therapy (methotrexate, 100 mg/m(2), bolus infusion, followed 3 h later by 5-fluorouracil, 600 mg/m(2), bolus infusion, with leucovorin rescue, q1w) was continued until disease progression or unacceptable toxicity. The projected sample size was 236, providing 80% power to detect a 40% increase in median overall survival in methotrexate and 5-fluorouracil therapy with a one-sided α of 0.05.
All 237 randomized patients were included in the primary analysis. The methotrexate and 5-fluorouracil therapy arm was not superior to the 5-fluorouracil continuous infusion arm (median survival time, 9.4 months in the 5-fluorouracil continuous infusion arm, 10.6 months in the methotrexate and 5-fluorouracil therapy arm; hazard ratio, 0.94; 95% confidence interval, 0.72-1.22; one-sided P = 0.31). Frequencies of Grade 3 or higher neutropenia, Grade 3 or higher anorexia and treatment-related deaths were 0.9, 27.4 and 1.7%, respectively, in the 5-fluorouracil continuous infusion arm, and 31.9, 33.6 and 0.9%, respectively, in the methotrexate and 5-fluorouracil therapy arm.
Methotrexate and 5-fluorouracil therapy is not suitable for use as standard therapy for advanced gastric cancer with peritoneal metastasis.
Japanese Journal of Clinical Oncology 09/2013; · 1.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Retrospective analyses in the West suggest that mutations in KRAS codons 61 and 146, BRAF, NRAS, and PIK3CA are negative predictive factors for cetuximab treatment in colorectal cancer patients. We developed a novel multiplex kit detecting 36 mutations in KRAS codons 61 and 146, BRAF, NRAS, and PIK3CA using Luminex (xMAP) assay in a single reaction.
Tumor samples and clinical data from Asian colorectal cancer patients treated with cetuximab were collected. We investigated KRAS,BRAF, NRAS, and PIK3CA mutations using both the multiplex kit and direct sequencing methods, and evaluated the concordance between the 2 methods. Objective response, progression-free survival (PFS), and overall survival (OS) were also evaluated according to mutational status.
In total, 82 of 83 samples (78 surgically resected specimens and 5 biopsy specimens) were analyzed using both methods. All multiplex assays were performed using 50 ng of template DNA. The concordance rate between the methods was 100%. Overall, 49 (59.8%) patients had all wild-type tumors, 21 (25.6%) had tumors harboring KRAS codon 12 or 13 mutations, and 12 (14.6%) had tumors harboring KRAS codon 61, KRAS codon 146, BRAF, NRAS, or PIK3CA mutations. The response rates in these patient groups were 38.8%, 4.8%, and 0%, respectively. Median PFS in these groups was 6.1 months (95%confidence interval (CI): 3.1--9.2), 2.7 months (1.2--4.2), and 1.6 months (1.5--1.7); median OS was 13.8 months (9.2--18.4), 8.2 months (5.7--10.7), and 6.3 months (1.3--11.3), respectively. Statistically significant differences in both PFS and OS were found between patients with all wild-type tumors and those with KRAS codon 61, KRAS codon 146, BRAF, NRAS, or PIK3CA mutations (PFS: 95% CI, 0.11--0.44; P < 0.0001; OS: 95% CI, 0.15--0.61; P < 0.0001).
Our newly developed multiplex kit is practical and feasible for investigation of a range of sample types. Moreover, mutations in KRAS codon 61, KRAS codon 146, BRAF, NRAS, or PIK3CA detected in Asian patients were not predictive of clinical benefits from cetuximab treatment, similar to the result obtained in European studies.
BMC Cancer 09/2013; 13(1):405. · 3.33 Impact Factor