Mechanisms of resistance to anti-epidermal growth factor receptor inhibitors in metastatic colorectal cancer

The prognosis of patients with metastatic colorectal cancer(m CRC) remain poor despite the impressive improvement of treatments observed over the last 20 years that led to an increase in median overall survival from 6 mo, with the only best supportive care, to approximately 30 mo with the introduction of active chemotherapy drugs and targeted agents. The monoclonal antibodies(mo Abs) cetuximab and panitumumab, directed against the epidermal growth factor receptor(EGFR), undoubtedly represent a major step forward in the treatment of m CRC, given the relevant efficacy in terms of progression-free survival, overall survival, response rate, and quality of life observed in several phase Ⅲ clinical trials among different lines of treatment. However, the anti-EGFR mo Abs were shown only to be effective in a subset of patients. For instance, KRAS and NRAS mutations have been identified as biomarkers of resistance to these drugs, improving the selection of patients who might derive a benefit from these treatments. Nevertheless, several other alterations might affect the response to these drugs, and unfortunately, even the responders eventually become resistant by developing secondary(or acquired) resistance in approximately 13-18 mo. Several studies highlighted that the landscape of responsible alterations of both primary and acquired resistance to anti-EGFR drugs biochemically converge into MEK-ERK and PIK3CA-AKT pathways. In this review, we describe the currently known mechanisms of primary and acquired resistance to anti-EGFR mo Abs together with the various strategies evaluated to prevent, overcame or revert them.

Esophageal cell proliferation in gastroesophageal reflux disease: Clinical-morphological data before and after pantoprazole

AIM: To evaluate esophageal mucosal defense mechanisms at an epithelial level to establish if pantoprazole treatment can induce ultrastructural healing and improvement in the proliferation activity of the esophageal epithelium in gastroesophageal reflux disease (GERD). METHODS: This was a single-blinded study for pHmonitoring, and histological, ultrastructural and MIB1 immunostaining evaluation. Fifty eight patients with GERD were enrolled and underwent 24 h pH-monitoring and endoscopy. Patients were treated for 12 and 24 mo with pantoprazole. Esophageal specimens were taken for histological and ultrastructural evaluation, before and after the treatment. RESULTS: With transmission electron microscopy, all patients with GERD showed ultrastructural signs of damage with dilation of intercellular spaces (DIS). After 3 mo of therapy the mean DIS values showed asignificant reduction and the mean MIB1-LI values of GERD showed an increase in cell proliferation. A further 3 mo of therapy significantly increased cell proliferation only in the erosive esophagitis (ERD) group. CONCLUSION: Three months of pantoprazole therapy induced ultrastructural healing of mucosal damage in 89% and 93% of ERD and non-erosion patients, respectively. Moreover, long-term pantoprazole treatment may be helpful in increasing the capability for esophageal cell proliferation in GERD, particularly in ERD patients.

Cell proliferation of esophageal squamous epithelium in erosive and non-erosive reflux disease

AIM:To elucidate cell proliferation in erosive reflux disease (ERD) and non-erosive reflux disease (NERD), we evaluated markers in squamous epithelial cells. METHODS: Thirty-four consecutive patients with gas-troesophageal-reflux-disease-related symptoms (21 NERD and 13 ERD) were evaluated for the enrolment into the study. All patients underwent 24-h pH monitoring, standard endoscopy, and biopsy for histological evaluation. The expression of cyclins D and A was evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR) from isolated epithelial cells. In all samples, analysis of the isolated cell population revealed the presence of epithelial cells only. RESULTS:Real-time RT-PCR showed that, in patients with ERD, the relative expression of cyclin D1 mRNA in esophageal epithelium was strongly decreased in comparison with NERD patients. The mean value of relative expression of cyclin D1 mRNA in NERD patients was 3.44 ± 1.9, whereas in ERD patients, it was 1.32 ± 0.87 (P = 0.011). Real-time RT-PCR showed that, in patients with ERD, relative expression of cyclin A mRNA in esophageal epithelium was decreased in comparison with that in NERD patients (2.31 ± 2.87 vs 0.66 ± 1.11). The mean bromodeoxyuridine labeling index in the NERD patients was 5.42% ± 1.68%, whereas in ERD patients, it was 4.3% ± 1.59%. CONCLUSION:We confirmed reduced epithelial pro- liferation in ERD compared with NERD patients, and that individuals who develop ERD are characterized by weaker epithelial cell proliferation.

Role of conventional therapies in the era of biological treatment in Crohn’s disease

Outstanding progress regarding the pathophysiology of Crohn's disease (CD) has led to the development of innovative therapeutic concepts. Numerous controlled trials have been performed in CD. This review concentrates on the results of randomized,placebo-controlled trials,and meta-analyses when available,that provide the highest degree of evidence. Current guidelines on the management of CD recommend a step-up approach to treatment involving the addition of more powerful therapies as the severity of disease and refractoriness to therapy increase. The advent of biological drugs has opened new therapeutic horizons for treating CD,modifying the treatment goals. However,the large majority of patients with CD will be managed through conventional therapy,even if they are a prelude to biological therapy.