Multiplex digital PCR (dPCR) enables noninvasive and sensitive detection of circulating tumor DNA with performance unachievable by current molecular-detection approaches. Furthermore, picodroplet ...dPCR facilitates simultaneous screening for multiple mutations from the same sample.
We investigated the utility of multiplex dPCR to screen for the 7 most common mutations in codons 12 and 13 of the KRAS (Kirsten rat sarcoma viral oncogene homolog) oncogene from plasma samples of patients with metastatic colorectal cancer. Fifty plasma samples were tested from patients for whom the primary tumor biopsy tissue DNA had been characterized by quantitative PCR.
Tumor characterization revealed that 19 patient tumors had KRAS mutations. Multiplex dPCR analysis of the plasma DNA prepared from these samples identified 14 samples that matched the mutation identified in the tumor, 1 sample contained a different KRAS mutation, and 4 samples had no detectable mutation. Among the tumor samples that were wild type for KRAS, 2 KRAS mutations were identified in the corresponding plasma samples. Duplex dPCR (i.e., wild-type and single-mutation assay) was also used to analyze plasma samples from patients with KRAS-mutated tumors and 5 samples expected to contain the BRAF (v-raf murine sarcoma viral oncogene homolog B) V600E mutation. The results for the duplex analysis matched those for the multiplex analysis for KRAS-mutated samples and, owing to its higher sensitivity, enabled detection of 2 additional samples with low levels of KRAS-mutated DNA. All 5 samples with BRAF mutations were detected.
This work demonstrates the clinical utility of multiplex dPCR to screen for multiple mutations simultaneously with a sensitivity sufficient to detect mutations in circulating DNA obtained by noninvasive blood collection.
Cetuximab is efficient in advanced colorectal cancer (CRC). We previously showed that KRAS mutations were associated with resistance to cetuximab in 30 CRC patients. The aim of this study was to ...validate, in an independent larger series of 89 patients, the prognostic value of KRAS mutations on response to cetuximab and survival.
Eighty-nine metastatic CRC patients treated with cetuximab after treatment failure with irinotecan-based chemotherapy were analyzed for KRAS mutation by allelic discrimination on tumor DNA. The association between KRAS mutations and tumor response, skin toxicity, progression-free survival (PFS) and overall survival (OS) was analyzed.
A KRAS mutation was present in 27% of the patients and was associated with resistance to cetuximab (0% v 40% of responders among the 24 mutated and 65 nonmutated patients, respectively; P < .001) and a poorer survival (median PFS: 10.1 v 31.4 weeks in patients without mutation; P = .0001; median OS: 10.1 v 14.3 months in patients without mutation; P = .026). When we pooled these 89 patients with patients from our previous study, the multivariate analysis showed that KRAS status was an independent prognostic factor associated with OS and PFS, whereas skin toxicity was only associated with OS. In a combined analysis, median OS times of patients with two, one, or no favorable prognostic factors (severe skin toxicity and no KRAS mutation) was of 15.6, 10.7, and 5.6 months, respectively.
These results confirm the high prognostic value of KRAS mutations on response to cetuximab and survival in metastatic CRC patients treated with cetuximab.
The occurrence of KRAS mutation is predictive of nonresponse and shorter survival in patients treated by anti-epidermal growth factor receptor (anti-EGFR) antibody for metastatic colorectal cancer ...(mCRC), leading the European Medicine Agency to limit its use to patients with wild-type KRAS tumors. However, only half of these patients will benefit from treatment, suggesting the need to identify additional biomarkers for cetuximab-based treatment efficacy.
We retrospectively collected tumors from 173 patients with mCRC. All but one patient received a cetuximab-based regimen as second-line or greater therapy. KRAS and BRAF status were assessed by allelic discrimination. EGFR amplification was assessed by chromogenic in situ hybridization and fluorescent in situ hybridization, and the expression of PTEN was assessed by immunochemistry.
In patients with KRAS wild-type tumors (n = 116), BRAF mutations (n = 5) were weakly associated with lack of response (P = .063) but were strongly associated with shorter progression-free survival (P < .001) and shorter overall survival (OS; P < .001). A high EGFR polysomy or an EGFR amplification was found in 17.7% of the patients and was associated with response (P = .015). PTEN null expression was found in 19.9% of the patients and was associated with shorter OS (P = .013). In multivariate analysis, BRAF mutation and PTEN expression status were associated with OS.
BRAF status, EGFR amplification, and cytoplasmic expression of PTEN were associated with outcome measures in KRAS wild-type patients treated with a cetuximab-based regimen. Subsequent studies in clinical trial cohorts will be required to confirm the clinical utility of these markers.
The anti-epidermal growth factor receptor (anti-EGFR) cetuximab has been proven to be efficient in metastatic colorectal cancer. The molecular mechanisms underlying the clinical response to this drug ...remain unknown. Genetic alterations of the intracellular effectors involved in EGFR-related signaling pathways may have an effect on response to this targeted therapy. In this study, tumors from 30 metastatic colorectal cancer patients treated by cetuximab were screened for KRAS, BRAF, and PIK3CA mutation by direct sequencing and for EGFR copy number by chromogenic in situ hybridization. Eleven of the 30 patients (37%) responded to cetuximab. A KRAS mutation was found in 13 tumors (43%) and was significantly associated with the absence of response to cetuximab (KRAS mutation in 0% of the 11 responder patients versus 68.4% of the 19 nonresponder patients; P = 0.0003). The overall survival of patients without KRAS mutation in their tumor was significantly higher compared with those patients with a mutated tumor (P = 0.016; median, 16.3 versus 6.9 months). An increased EGFR copy number was found in 3 patients (10%) and was significantly associated with an objective tumor response to cetuximab (P = 0.04). In conclusion, in this study, KRAS mutations are a predictor of resistance to cetuximab therapy and are associated with a worse prognosis. The EGFR amplification, which is not as frequent as initially reported, is also associated with response to this treatment.
In metastatic colorectal cancer, phase III studies have demonstrated the superiority of fluorouracil (FU) with leucovorin (LV) in combination with irinotecan or oxaliplatin over FU + LV alone. This ...phase III study investigated two sequences: folinic acid, FU, and irinotecan (FOLFIRI) followed by folinic acid, FU, and oxaliplatin (FOLFOX6; arm A), and FOLFOX6 followed by FOLFIRI (arm B).
Previously untreated patients with assessable disease were randomly assigned to receive a 2-hour infusion of l-LV 200 mg/m(2) or dl-LV 400 mg/m(2) followed by a FU bolus 400 mg/m(2) and 46-hour infusion 2,400 to 3,000 mg/m(2) every 46 hours every 2 weeks, either with irinotecan 180 mg/m(2) or with oxaliplatin 100 mg/m(2) as a 2-hour infusion on day 1. At progression, irinotecan was replaced by oxaliplatin (arm A), or oxaliplatin by irinotecan (arm B).
Median survival was 21.5 months in 109 patients allocated to FOLFIRI then FOLFOX6 versus 20.6 months in 111 patients allocated to FOLFOX6 then FOLFIRI (P =.99). Median second progression-free survival (PFS) was 14.2 months in arm A versus 10.9 in arm B (P =.64). In first-line therapy, FOLFIRI achieved 56% response rate (RR) and 8.5 months median PFS, versus FOLFOX6 which achieved 54% RR and 8.0 months median PFS (P =.26). Second-line FOLFIRI achieved 4% RR and 2.5 months median PFS, versus FOLFOX6 which achieved 15% RR and 4.2 months PFS. In first-line therapy, National Cancer Institute Common Toxicity Criteria grade 3/4 mucositis, nausea/vomiting, and grade 2 alopecia were more frequent with FOLFIRI, and grade 3/4 neutropenia and neurosensory toxicity were more frequent with FOLFOX6.
Both sequences achieved a prolonged survival and similar efficacy. The toxicity profiles were different.
Purpose: Glutathione S -transferases (GST) are xenobiotic metabolizing enzymes involved in the detoxification of a variety of chemotherapeutic drugs,
including platinum derivatives. Genetic ...polymorphisms of GSTs have been associated with enzyme activity variations. Thus,
a study was done to investigate the relationship between GST polymorphisms and oxaliplatin-related cumulative neuropathy in
gastrointestinal cancer patients treated with oxaliplatin-based chemotherapy.
Experimental Design: Ninety patients were included. Clinical neurologic evaluation was done at baseline and before each cycle of treatment. We
determined genetic variants for GSTP1 exon 5 (Ile 105 Val), GSTP1 exon 6 (Ala 114 Val), GSTM1 (homozygous deletion), and GSTT1 (homozygous deletion). We conducted analyses in a subgroup of 64 patients receiving a minimal cumulative dose of 500 mg/m 2 of oxaliplatin to examine whether the GST polymorphisms are associated with oxaliplatin-related cumulative neuropathy.
Results: Among patients receiving a minimal cumulative dose of 500 mg/m 2 of oxaliplatin, 15 patients showed clinically evident oxaliplatin-related cumulative neuropathy scored grade 3 according
to an oxaliplatin-specific scale. The oxaliplatin-related cumulative neuropathy scored grade 3 was significantly more frequent
in patients homozygous for the GSTP1 105 Ile allele than in patients homozygous or heterozygous for the GSTP1 105 Val allele (odds ratio, 5.75; 95% confidence interval, 1.08-30.74; P = 0.02). No association was found with respect to any of the GSTM1, GSTT1 , or GSTP1 exon 6 genotypes.
Conclusions : The results of the current study suggest that the 105 Val allele variant of the GSTP1 gene at exon 5 confers a significantly decreased risk of developing severe oxaliplatin-related cumulative neuropathy.
Purpose: The target enzyme for 5-fluorouracil (5-FU) is thymidylate synthase (TS). The TYMS gene encoding this enzyme is polymorphic, having either double (2R) or tri-tandem (3R) repeats of a 28-bp ...sequence in the
promoter region and a 6-bp variation in the 3′-untranslated region (3′-UTR). TS expression predicts response to 5-FU-based
chemotherapy, and the expression seems to be determined by the TYMS gene promoter. The aim of this study was to investigate the utility of determining these two TYMS gene polymorphisms to predict the toxicity and efficacy of 5-FU treatment in patients with colorectal cancer.
Experimental Design: The determination of TYMS genotypes was performed in tumor and normal tissues by PCR amplification from 90 patients with colorectal cancer who were
treated with adjuvant or palliative 5-FU-based chemotherapy. Associations between polymorphisms in the TYMS promoter and in the 3′-UTR gene and clinical outcome of these 90 patients treated with 5-FU based chemotherapy were evaluated
individually. The linkage between TYMS promoter and TYMS 3′-UTR region polymorphisms was evaluated and a haplotype analysis was performed.
Results: Individuals who were homozygous for the double repeat in the TYMS promoter region had more severe side effects to 5-FU. Patients with a 2R/2R, a 2R/3R, or a 3R/3R genotype had a grade 3 or
4 toxicity rate of 43, 18, and 3% respectively ( P < 0.01). The TYMS promoter and TYMS 3′-UTR polymorphisms were in linkage disequilibrium, and the haplotype 2R/ins 6-bp was significantly associated with a high
risk of severe side effects to 5-FU. The TYMS promoter and TYMS 3′-UTR polymorphisms were not associated with a response to 5-FU and survival of patients who received palliative 5-FU-based
chemotherapy.
Conclusions: This study demonstrated that TYMS genotyping could be of help in predicting toxicity to 5-FU-based chemotherapy. TYMS genotyping might make it possible to individualize treatment for patients with colorectal cancer.
Abstract Objective To compare chemotherapy first (group 1) versus self-expanding metal stent first (group 2) for the management of malignant dysphagia in unresectable oesophageal or ...gastro-oesophageal junction cancer. Methods Patients from two university hospitals with severe malignant dysphagia (dysphagia score ≥ 2) uneligible for surgery or radiochemotherapy were evaluated retrospectively. Results Forty-two patients were included in group 1, and 29 in group 2. After 4 weeks, dysphagia scores improved by at least 1 point in 67% of patients in group 1 versus 93% in group 2 ( p = 0.01); 48% of patients in group 1 were able to eat solid food versus 68% in group 2 ( p = 0.054). In group 1, a self-expanding metal stent was secondarily placed in 18 patients (42.9%), whereas in group 2 dysphagia required a second self-expanding metal stent placement in 33.3% of patients. Conclusion Chemotherapy as the first treatment may be a valid option, avoiding self-expanding metal stent insertion in half of the patients.
Abstract Background This study aimed at evaluating the role of intraoperative enteroscopy (IOE) for the management of obscure gastrointestinal (GI) bleeding in patients who had been preoperatively ...explored by video-capsule endoscopy (VCE). Methods Eighteen patients who underwent IOE for obscure GI bleeding were prospectively recorded between November 2000 and January 2007. The bleeding site was preoperatively localized by VCE in the small bowel in 15 patients, but the origin of bleeding remained unknown in 3 patients. Results In the 3 patients with negative VCE, IOE was normal, but intraoperative conventional endoscopy identified gastric (n = 1) and colonic (n = 2) lesions. Among the 15 patients with VCE positive for small-bowel lesions, laparotomy and IOE yielded localization and treatment (surgical n = 11 and endoscopic n = 2) guidance for 13 of 15 (87%) lesions. At median 19-month follow-up, 3 bleeding recurrences (3 of 15 20%) were recorded, resulting in a 73% therapeutic efficacy of IOE. Conclusions IOE remains useful for the management of obscure GI bleeding when preoperative VCE is positive for small-bowel lesions that are not reachable by nonoperative enteroscopy. When VCE is negative, new conventional endoscopy should be proposed instead of IOE.
This paper reports the first case of a patient with hepatocellular carcinoma with lymph node metastasis treated by sorafenib combined with gemcitabine plus oxaliplatin,with a partial response and ...normalization of α fetoprotein,which allowed curative surgery.The potential synergy between these three drugs needs to be confirmed,and is currently being investigated in a randomized phase Ⅱ trial.
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