Epigenetic inactivation of the BRCA1 interactor SRBC and resistance to oxaliplatin in colorectal cancer.

BACKGROUND: A major problem in cancer chemotherapy is the existence of primary resistance and/or the acquisition of secondary resistance. Many cellular defects contribute to chemoresistance, but epigenetic changes can also be a cause. METHODS: A DNA methylation microarray was used to identify epigenetic differences in oxaliplatin-sensitive and -resistant colorectal cancer cells. The candidate gene SRBC was validated by single-locus DNA methylation and expression techniques. Transfection and short hairpin experiments were used to assess oxaliplatin sensitivity. Progression-free survival (PFS) and overall survival (OS) in metastasic colorectal cancer patients were explored with Kaplan-Meier and Cox regression analyses. All statistical tests were two-sided. RESULTS: We found that oxaliplatin resistance in colorectal cancer cells depends on the DNA methylation-associated inactivation of the BRCA1 interactor SRBC gene. SRBC overexpression or depletion gives rise to sensitivity or resistance to oxaliplatin, respectively. SRBC epigenetic inactivation occurred in primary tumors from a discovery cohort of colorectal cancer patients (29.8%; n = 39 of 131), where it predicted shorter PFS (hazard ratio [HR] = 1.83; 95% confidence interval [CI] = 1.15 to 2.92; log-rank P = .01), particularly in oxaliplatin-treated case subjects for which metastasis surgery was not indicated (HR = 1.96; 95% CI = 1.13 to 3.40; log-rank P = .01). In a validation cohort of unresectable colorectal tumors treated with oxaliplatin (n = 58), SRBC hypermethylation was also associated with shorter PFS (HR = 1.90; 95% CI = 1.01 to 3.60; log-rank P = .045). CONCLUSIONS: These results provide a basis for future clinical studies to validate SRBC hypermethylation as a predictive marker for oxaliplatin resistance in colorectal cancer.

Innovations therapy: mammalian target of rapamycin (mTOR) inhibitors for the treatment of neuroendocrine tumors.

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare neoplasms that require a multidisciplinary approach for an optimal management. The lack of effectiveness of traditional DNA-damaging agents has led to the exploration of new targeted drugs in order to exploit phenotypical features of GEP-NET therapy. However, due to the orphan setting of these tumors, deeper characterization of molecular features and pathways that characterize cell growth, apoptosis, angiogenesis, and invasion are lacking, particularly genetic mutations or epigenetic alterations that generate oncogenic dependency or even addiction. The PI3K-AKT-mTOR pathway has been implicated as having a crucial role in GEP-NETs not only due to the overexpression of several growth factors and their receptors that finally activate this axis but also hereditary syndromes with constitutive activation of the mTOR pathway with high incidence of GEP-NETs. In this article, we aim to review the recent development of the main molecules that target mTOR complex and have showed promising activity in the treatment of GEPNETs.

Increased levels of copper efflux transporter ATP7B are associated with poor outcome in colorectal cancer patients receiving oxaliplatin-based chemotherapy.

Recently, the copper efflux transporters ATP7B and ATP7A have been implicated in the transport of and resistance to platinum drugs in breast and ovarian cancers. Because of the extensive use of oxaliplatin in colorectal cancer (CRC), we examined the expression of both transporters in tumors from CRC patients treated with oxaliplatin/5FU and sought to determine whether their expression can predict clinical outcome in these patients. ATP7B and ATP7A levels were determined by quantitative real-time PCR in 50 primary tumors of previously untreated patients with advanced colorectal adenocarcinoma who were subsequently treated with oxaliplatin/5FU. Additionally, ATP7B protein expression was assessed by immunohistochemical staining using a tissue microarray. Patients with the lowest mRNA expression levels of ATP7B had a significantly longer time to progression (TTP) (p = 0.0009) than patients with the highest levels (12.14 months vs. 6.43 months) who also had an increased risk of progression (HR = 3.56; 95% CI, 1.6-7.9; p = 0.002). Furthermore, patients with low levels of both protein and mRNA of ATP7B derived the maximum benefit from oxaliplatin/5FU with the longest TTP as compared with patients with high levels of ATP7B protein and mRNA (14.64 months vs. 4.63 months, respectively, p = 0.01) and showed a nonsignificant trend toward a lower response rate (37.5% and 75%, respectively). In conclusion, ATP7B mRNA and protein expression in colorectal tumors is associated with clinical outcome to oxaliplatin/5FU. Prospective studies are required to evaluate the role of this marker in tailoring chemotherapy.

Colorectal cancer metastasis resectability after treatment with the combination of oxaliplatin, irinotecan and 5-fluorouracil. Final results of a phase II study.

PURPOSE: To investigate the response rate of the triple combination of oxaliplatin (L-OHP) in combination with irinotecan (CPT-11) and 5-fluorouracil (5-FU) and to assess its impact on secondary resectability of previously non-resectable liver metastasis (LM). PATIENTS AND METHODS: Patients > or = 18 with MCRC, ECOG grade 0-2, and no prior treatment received L-OHP (85 mg/m(2)), CPT-11 (150 mg/m(2)) and 5-FU (2 250 mg/m(2) in 48 h CI) on D1 every 15 days. RESULTS: Forty-seven patients with initially non-resectable metastatic disease were included. Median age 62 years (38-76); 28 males; 26 patients with 0 performance status (ECOG) 40 patients had prior surgery and four adjuvant chemotherapy. All patients were evaluable for toxicity and 42 for response. Main grade 3-4 toxicities were neutropenia (40%), febrile neutropenia (4%), diarrhea (21%), nausea/vomiting (11%/15%), fatigue (11%), anemia and alopecia (9% each); grade 3-4 neurotoxicity was observed in 28% patients. Secondary surgery was possible in 15 of 47 (31.9%) patients and 12/30 (40%) patients with only LM: in this cohort, median OS has not been reached at 22 months median follow-up, with 2/12 patients having died. Overall response rate was 69% (95% CI, 53-82%); 13 (31%) had stable disease. Median time to progression and overall survival (OS) were 10.9 (95% CI, 9.9-13.2) and 19.9 (95% CI, 11.7-TBD) months, respectively. CONCLUSION: This combination has shown promising activity with manageable toxicity as front-line treatment in MCRC, and has allowed the resectability of LM in a considerable number of patients, offering them the possibility of long-term survival.

Two consecutive phase II trials of biweekly oxaliplatin plus weekly 48-hour continuous infusion of nonmodulated high-dose 5-fluorouracil as first-line treatment for advanced colorectal cancer.

The combination of 5-fluorouracil (5-FU) plus leucovorin (LV) with oxaliplatin has become one of the standard treatments for advanced colorectal cancer (CRC). Two consecutive phase II trials assessed the efficacy and safety of combined therapy with oxaliplatin and high-dose 5-FU without LV for patients with advanced CRC. A total of 89 patients were enrolled in both trials. Fifty-nine patients in trial A underwent a scheduled regimen of biweekly oxaliplatin 85 mg/m(2) and weekly nonmodulated 5-FU 3.0 g/m(2). Increased incidence of toxicity led to a 25% reduction in the starting dose of 5-FU (2.25 g/m(2)) for trial B. Patients treated in trial B showed a higher cumulative dose and relative dose intensity for oxaliplatin and 5-FU than those treated in trial A. Response to treatment, time to progression (TTP), overall survival (OS), and duration of response were evaluated as efficacy variables. Overall response rate was preserved despite the reduction in 5-FU dose (55.9% and 63.0%, respectively). Median durations of responses were 10.6 and 10.4 months, median TTPs were 7.7 and 7.3 months, and OS times were 21.7 and 13.1 months, respectively. Reduction in the starting 5-FU dose from 3.0 to 2.25 g/m(2) resulted in a decrease in the main grade 3/4 hematologic toxicities (neutropenia, 22.0% to 10.0%) and nonhematologic toxicities (diarrhea, 52.5% to 23.3%; nausea/vomiting, 18.6% to 3.3%). Neurosensory toxicity was similar in both trials (16.9% and 16.7%). Biweekly oxaliplatin in combination with nonmodulated high-dose 5-FU is an active, well-tolerated treatment that offers a lower cost than a modulated schedule for patients with advanced, metastatic CRC.