Federica Tosi

Tumor MGMT promoter hypermethylation changes over time limit temozolomide efficacy in a phase II trial for metastatic colorectal cancer

BACKGROUND Objective response to dacarbazine, the intravenous form of temozolomide (TMZ), in metastatic colorectal cancer (mCRC) is confined to tumors harboring O(6)-methylguanine-DNA-methyltransferase (MGMT) promoter hypermethylation. We conducted a phase II study of TMZ enriched by MGMT hypermethylation in archival tumor (AT), exploring dynamic of this biomarker in baseline tumor (BT) biopsy and plasma (liquid biopsy). PATIENTS AND METHODS We screened 150 mCRC patients for MGMT hypermethylation with methylation-specific PCR on AT from FFPE specimens. Eligible patients (n = 29) underwent BT biopsy and then received TMZ 200 mg/m(2) days 1-5 q28 until progression. A Fleming single-stage design was used to determine whether progression-free survival (PFS) rate at 12 weeks would be ≥35% [H0 ≤ 15%, type I error = 0.059 (one-sided), power = 0.849]. Exploratory analyses included comparison between MGMT hypermethylation in AT and BT, and MGMT methylation testing by MethylBEAMing in solid (AT, BT) and LB with regard to tumor response. RESULTS The PFS rate at 12 weeks was 10.3% [90% confidence interval (CI) 2.9-24.6]. Objective response rate was 3.4% (90% CI 0.2-15.3), disease control rate 48.3% (90% CI 32.0-64.8), median OS 6.2 months (95% CI 3.8-7.6), and median PFS 2.6 months (95% CI 1.4-2.7). We observed the absence of MGMT hypermethylation in BT in 62.7% of tumors. CONCLUSION Treatment of mCRC with TMZ driven by MGMT promoter hypermethylation in AT samples did not provide meaningful PFS rate at 12 weeks. This biomarker changed from AT to BT, indicating that testing BT biopsy or plasma is needed for refined target selection.

Effect of KRAS and BRAF Mutations on Survival of Metastatic Colorectal Cancer After Liver Resection: A Systematic Review and Meta-Analysis

Background: The purpose of the study was to evaluate whether the mutational status of Kirsten rat sarcoma viral oncogene homolog (KRAS) or b‐viral oncogene homolog B1 (BRAF) could be an independent prognostic factor in the subset of patients with colorectal cancer liver metastases (CRLM) who undergo complete liver resection. Materials and Methods: A systematic literature review was performed to identify articles reporting relapse‐free survival (RFS) and/or overall survival (OS) of patients who underwent complete liver resection for CRLM, stratified according to KRAS and BRAF mutational status. Hazard ratios (HRs) from multivariate analyses were pooled in the meta‐analysis. Results: Eleven studies, including 1833 patients, were eligible for the meta‐analysis. Nine of them reported OS stratified according to KRAS mutation. The pooled analysis revealed that KRAS mutation was negatively associated with OS (HR, 1.674; 95% confidence interval [CI], 1.341‐2.089; P < .001). Nine among 11 studies reported RFS stratified according to KRAS mutation and HRs in multivariate analysis were available in 7. In a pooled analysis, KRAS mutation was negatively associated with RFS (HR, 1.529; 95% CI, 1.287‐1.817; P < .001). In 3 studies HRs of the multivariate analysis regarding the OS according to BRAF mutational status were also available, showing a negative association with OS (HR, 3.055; 95% CI, 1.794‐5.204; P < .001). Conclusion: KRAS mutations are negatively associated with OS and RFS in patients who undergo complete liver resection for CRLM. A similar negative effect on OS was observed also for BRAF mutation, although fewer studies were included. These data support integration of KRAS and BRAF mutational status into a combined predictive score for prospective assessment of outcome after resection of CRLM in clinical studies. &NA; Treatment of metastatic colorectal cancer includes resection of liver metastases, however, no biomarkers drive selection of patients. We performed a meta‐analysis including 1833 patients treated with complete liver resection, showing that Kirsten rat sarcoma viral oncogene homolog and b‐viral oncogene homolog B1 mutations are negatively associated with survival. This supports integration of mutational status into a combined score to better identify candidates for resection of colorectal cancer liver metastases.

Tracking a CAD-ALK gene rearrangement in urine and blood of a colorectal cancer patient treated with an ALK inhibitor

Background Monitoring response and resistance to kinase inhibitors is essential to precision cancer medicine, and is usually investigated by molecular profiling of a tissue biopsy obtained at progression. However, tumor heterogeneity and tissue sampling bias limit the effectiveness of this strategy. In addition, tissue biopsies are not always feasible and are associated with risks due to the invasiveness of the procedure. To overcome these limitations, blood-based liquid biopsy analysis has proven effective to non-invasively follow tumor clonal evolution. Patients and methods We exploited urine cell-free, trans-renal DNA (tr-DNA) and matched plasma circulating tumor DNA (ctDNA) to monitor a metastatic colorectal cancer patient carrying a CAD-ALK translocation during treatment with an ALK inhibitor. Results Using a custom next generation sequencing panel we identified the genomic CAD-ALK rearrangement and a TP53 mutation in plasma ctDNA. Sensitive assays were developed to detect both alterations in urine tr-DNA. The dynamics of the CAD-ALK rearrangement in plasma and urine were concordant and paralleled the patients clinical course. Detection of the CAD-ALK gene fusion in urine tr-DNA anticipated radiological confirmation of disease progression. Analysis of plasma ctDNA identified ALK kinase mutations that emerged during treatment with the ALK inhibitor entrectinib. Conclusion We find that urine-based genetic testing allows tracing of tumor-specific oncogenic rearrangements. This strategy could be effectively applied to non-invasively monitor tumor evolution during therapy. The same approach could be exploited to monitor minimal residual disease after surgery with curative intent in patients whose tumors carry gene fusions. The latter could be implemented without the need of patient hospitalization since urine tr-DNA can be self-collected, is stable over time and can be shipped at specified time-points to central labs for testing.

TRKA expression and NTRK1 gene copy number across solid tumours

Aims Neurotrophic Tropomyosin Kinase Receptor 1 (NTRK1) gene encodes for the protein Tropomyosin-related kinase A (TRKA). Deregulated activity of TRKA has been shown to have oncogenic potential. We present here the results of an immunohistochemical (IHC) observational cohort study of TRKA expression together with gene copy number (GCN) assessment in various solid tumours. Methods Formalin-fixed, paraffin-embedded consecutive samples of different tumour types were tested for TRKA expression. Samples showing TRKA IHC staining in at least 10% of cells were analysed by fluorescence in situ hybridisation to assess NTRK1 gene rearrangements and/or individual GCN gain. All patients underwent this molecular assessment within the phase I ALKA-001 clinical trial. Results 1043 samples were tested and annotation for histology was available in 1023. Most of the samples were colorectal adenocarcinoma (CRC) (n=550, 52.7%) and lung adenocarcinoma (n=312, 29.9%). 24 samples (2.3%) were biliary tract carcinoma (BTC). Overall, 17 (1.6%) samples were characterised by TRKA IHC expression (four weak, eight moderate, five strong): 9/17 lung adenocarcinoma, 3/17 CRC, 3/17 BTC, 1/17 thyroid cancer and 1/17 cancer of unknown primary. Of these, 1/17 with strong TRKA IHC staining displayed NTRK1 gene rearrangement and 15/17 NTRK1 GCN gain by FISH. No correlation was found between intensity of TRKA IHC staining and number of copies of NTRK1. Conclusions TRKA expression can be found in 1.6% of solid tumours and can be paralleled by NTRK1 gene rearrangements or mostly GCN gain. The prognostic and translational therapeutic impact of the latter remains to be established.

54 MGMT methylation assessed by methyl-BEAMing technique is a prognostic and predictive biomarker in glioblastoma and metastatic colorectal cancer patients

L. Barault, A. Amatu, F.E. Bleeker, C. Moutinho, A. Cassingena, F. Tosi, T. Venesio, M. Esteller, A. Bardelli, S. Siena, A. Sartore-Bianchi, F. Di Nicolantonio. Candiolo Cancer Institute − FPO IRCCS, Experimental Clinical Molecular Oncology, Candiolo, Italy; Ospedale Niguarda Ca’ Granda, Department of Hematology and Oncology, Milan, Italy; Academic Medical Center University of Amsterdam, Department of Clinical Genetics, Amsterdam, Netherlands; Bellvitge Biomedical Research Institute (IDIBELL), Cancer Epigenetics and Biology Program (PEBC), Barcelona, Spain; Candiolo Cancer Institute − FPO IRCCS, Investigational Clinical Oncology, Candiolo, Italy; University of Torino, Department of Oncology, Candiolo, Italy