Gene copy number for epidermal growth factor receptor (EGFR) and clinical response to antiEGFR treatment in colorectal cancer: a cohort study

BACKGROUND: The antiepidermal growth factor receptor (antiEGFR) monoclonal antibodies cetuximab and panitumumab have good clinical activity in about 10% of patients with metastatic colorectal cancer that is resistant to chemotherapy. The molecular mechanisms underlying clinical response or resistance to these agents are unknown. METHODS: Tumours from 31 patients with metastatic colorectal cancer who had either an objective response (n=10) or stable disease or progressive disease (n=21) after treatment with cetuximab or panitumumab were screened for genetic changes in EGFR or its immediate intracellular effectors. Specifically, we assessed the EGFR copy number and the mutation profile of the EGFR catalytic domain and of selected exons in KRAS, BRAF, and PIK3CA. RESULTS: Eight of nine of patients with objective responses who were assessable by fluorescence in-situ hybridisation (FISH) had an increased EGFR copy number. By contrast, one of 21 non-responders assessable by FISH had an increased EGFR copy number (p<0.0001 for responders vs non-responders, Fisher's exact test). The mutation status of the EGFR catalytic domain and its immediate downstream effectors PIK3CA, KRAS, and BRAF did not correlate with disease response. In colorectal-cancer cell lines, the concentration of cetuximab that completely inhibited proliferation of cells with amplified EGFR copy number did not affect proliferation of cells with unamplified EGFR. INTERPRETATION: We propose that the response to antiEGFR treatment has a genetic basis and suggest that patients might be selected for treatment on the basis of EGFR copy number.     

Spigelian Hernia

We report on the evolution in concept and techniques that allowed us to improve the treatment of spigelian hernia, operable in day surgery in 90% of cases and through a preperitoneal and recently a preperitoneal and subfascial prosthetic repair (PHS). Background data. We propose an innovative use of the PHS mesh for spigelian hernia repair. With this new implementation, we confront the standard surgical technique and its postoperative period. Methods. From January 1992 to March 2004, we performed 2,500 hernia surgical operations, including 32 spigelian hernia repairs (1.3% of total case series). The first surgical approach used for 20 of these 32 patients (62.5% of total spigelian hernias), all electively operated on, was a classical preperitoneal repair (Wantz), performed when possible by size of defect and weight (Body Mass Index) of the patient, under local anesthesia and on a day-surgery basis. Our new modified technique takes place through the insertion of a PHS large-type mesh, whose bottom underlay portion lies flat in the preperitoneal space with the connector obliterating the hernial orifice and with the overlay portion lying on the internal oblique muscle, covered by the aponeurosis of the external oblique muscle. Results. Our modification to the classical technique consisted only in the application of a product, such as the PHS, in a hernia defect, which presented with an orifice of the size of the connector and, therefore, was easily repairable with the use of the PHS device. This approach is easier than the preperitoneal approach, its always suitable for local anaesthesia, and it gives a more comfortable postoperative period. The surgical approach may be performed completely in day surgery. Conclusions. We believe that spigelian hernia surgical repair should always be performed by means of a preperitoneal prosthesis under local anaesthesia when the patients clinical and physical conditions allow for it, always in day surgery, and using the PHS mesh when the hernia defect size fits with the connector diameter. This last possibility seems to be easier and more comfortable for the patient in the postoperative period.     

Prevalence and immunohistochemical findings of subclinical kidney allograft rejection and its association with graft outcome

Subclinical acute rejection (SAR) occurs in about 30% of stable renal transplant patients and may be a risk factor for a poor allograft outcome. In the present study, the prevalence and clinical features of subclinical rejection, and the expression of immune activation markers in surveillance graft biopsies were assessed and correlated with late graft outcomes. Protocol biopsies were obtained at 2 and 12 months post-transplant in 32 and 26 patients, respectively, with stable renal function. The Banff 1997 criteria were used for histological diagnosis. Graft function and survival and proteinuria were assessed during the 36 months of follow-up. Immunohistochemical evaluation of cell subpopulations and immunoactivation markers were performed on protocol biopsies. The prevalence of SAR at 2 months and of chronic allograft nephropathy (CAN) at 12 months in representative biopsies was 55 and 50%, respectively. Patients with SAR presented mononuclear cell infiltration with an increased expression of CD3, CD4, CD68, IL-2R and granzyme B. Kidney graft function was significantly worse in patients with SAR at 2 months who had chronic rejection on biopsy at 12 months, but SAR was not associated with a worse graft function, greater proteinuria or a lower graft survival in 3 yr of follow-up. In conclusion, we found an elevated prevalence of SAR at 2 months after transplantation with an increased expression of activation markers. Although an association of SAR with poor graft outcome was not observed, our results suggest that SAR is an immunologically active process and underscore the importance of protocol biopsies in the surveillance of transplanted kidneys.     

Effect of curriculum reform on graduating student performance

With the aim of evaluating the efficacy of a new curriculum implemented in the Faculty of Medicine of Ribeir?o Preto (University of S?o Paulo, Brazil), a yearly objective assessment of both cognitive and practical skills of undergraduate (sixth year) students was performed. All graduating student underwent a multiple-choice questions (MCQs) test and groups of 18-20 students were randomly assigned to OSCEs for either clinical (real and standardized patients) or procedure (manikins) skills. The average MCQs score for the students graduating in the new curriculum (63.1, SD = 8.9, n = 261) was significantly higher (p < 0.001) than for the previous curriculum (55.3, SD = 8.1, n = 222). Results for practical exams showed that the new curriculum was associated with significantly improved performance in five out of the six stations for procedure skills, but in only two of the 10 clinical skills stations. Final evaluation of graduating students revealed deficiencies in the local curriculum and may serve as a guide to take measures to correct them.     

Monoclonal antibodies in the treatment of colorectal cancer

Monoclonal antibodies have been developed to target specific proteins involved in the development and progression of cancer. These reagents have the advantage of exquiste specificity, and as currently engineered, low toxicity. The impact monoclonal antibody therapy has recently been demonstrated in colorectal cancer, in which two pathways critical to carcinogenesis have been targeted. The targets are the epidermal growth factor receptor signaling pathway and angiogenesis. Antibodies directed to proteins in both pathways have shown significant activity especially in combination with chemotherapy, and studies in the adjuvant setting are in progress. We review the use of monoclonal antibodies in the treatment of colorectal cancer with particular attention to edrecolomab (Mab 17-1A), bevacizumab (Avastin), cetuximab (IMC-C225), ABX-EGF and EMD 72000. Additional compounds are in earlier stages of development, and the future of this approach in solid tumours is promising.     

Immunogenicity and safety in infants of a DTwPHib full liquid vaccine

Aim: Combining paediatric vaccines is a rational solution to reduce the number of injections during a single clinical visit, to maintain parents' compliance and to extend vaccine coverage. Different diphtheria, tetanus and whole cell pertussis (DTwP)-containing combination vaccines are licensed and used world-wide. This study assessed the immunogenicity and safety in infants of a combined diphtheria-tetanus-whole cell pertussis-Haemophilus influenzae type b-CRM₁₉₇ conjugate full liquid vaccine. Methods: The safety and efficacy of a combined ready-to-use liquid vaccine containing diphtheria and tetanus toxoids, cell suspension of Bordetella pertussis and H. influenzae type b-CRM₁₉₇ conjugate vaccine (DTwPHib) were assessed in infants eligible for the local Expanded Programme on Immunization (EPI) in Valencia, Spain. The comparative group received separate injections of reference vaccines DTwP + Hib. Results: Local and systemic reactions and adverse events were generally mild and similar in the two groups. DTwPHib elicited anti-PRP antibody titres ≥0.15 μg ml^-1 in 97% and DTwP + Hib in 94% of infants. Furthermore, 89% of DTwPHib and 78% of DTwP + Hib recipients attained anti-PRP antibody titres ≥1.0 μg ml^-1, signifying long-term protection. The anti-PRP geometric mean titre was significantly higher in the combined DTwPHib vaccine group (6.65 vs 3.57 μg ml^-1). In both groups, 99% of infants achieved protective (≥0.01 IU ml^-1) anti-diphtheria antibody levels and all children achieved protective (≥0.1 IU ml^-1) anti-tetanus antibody levels. DTwPHib caused a ≥2-fold increase in anti-pertactin antibody titres in 91% and a ≥4-fold increase in 82% of recipients. The corresponding proportions in the DTwP + Hib group were 95% and 90%. DTwPHib induced a ≥2-fold increase in anti-Aggl2 and 3 antibody levels in 79% and a ≥4-fold increase in 73% of recipients. The corresponding proportions among DTwP + Hib infants were 85 and 82%. Conclusion: Overall, the combined liquid vaccine DTwPHib is a safe and effective immunogenic vaccine for EPI use in infants.     

Effect of mibefradil on CYP3A4 in vivo

Mibefradil, a calcium channel blocker, was removed from the market because of adverse drug interactions with coadministered CYP3A4 substrates. This study examined the effect of mibefradil on the activity of hepatic and intestinal CYP3A4 in vivo, employing the erythromycin breath test (EBT) and oral midazolam pharmacokinetics. This was a two-period, single-blind, placebo-controlled crossover study in which 8 male volunteers were randomized to the order of receiving placebo and a single 100-mg oral dose of mibefradil. Oral midazolam was coadministered with intravenous [14C N-methyl] erythromycin 1 hour after mibefradil/placebo administration. The EBT was performed 20 minutes following erythromycin administration. Blood and urine were collected during the 36 hours following probe drug administration for analysis of midazolam pharmacokinetics. Coadministration of mibefradil increased the Cmax of midazolam 3-fold, the AUC 8- to 9-fold, and the t1/2 4-fold. Mibefradil coadministration decreased the amount of exhaled 14CO2 in 6 of 8 subjects, with a mean decrease of 25%. It was concluded that a single oral dose of mibefradil significantly inhibits CYP3A4 in intestine and liver. These data support that adverse drug interactions involving mibefradil reflect inhibition of CYP3A4 in intestine and liver. Also, they suggest that the EBT, while a valid probe of in vivo hepatic CYP3A4 activity, is a single time point measurement and may be less sensitive than oral midazolam pharmacokinetics in detecting CYP3A4 inhibition.     

Exposure-dependent inhibition of intestinal and hepatic CYP3A4 in vivo by grapefruit juice

Consumption of typical quantities of grapefruit juice (GFJ) increases the oral bioavailability of several CYP3A4 substrates without affecting their elimination, consistent with selective inhibition of intestinal but not hepatic CYP3A4. However, increases in the AUCs of CYP3A4 substrates recently associated with the consumption of large amounts of GFJ were similar to those observed with potent inhibitors of hepatic CYP3A4. The current study compared the effects of consuming large quantities and more typical amounts of GFJ on the activity of hepatic and intestinal cytochrome P450 3A4 in vivo, employing the erythromycin breath test (EBT) and oral midazolam pharmacokinetics. This was a two-phase, randomized, placebo-controlled crossover study, with each phase conducted with a separate panel of subjects. In Phase I, 8 male volunteers were randomized to the order of receiving one glass (240 mL) of water (placebo) or double-strength (DS) GFJ tid for 2 days and then 90, 60, and 30 minutes prior to administration of probe drugs on the 3rd day. In Phase II, 16 male volunteers were randomized to the order of receiving one glass of (1) single-strength (SS) GFJ, (2) DS GFJ, and (3) water (placebo). All treatments were administered in a fasted state. There was at least a 7-day washout period between treatments. Probe drugs, administered 30 minutes or 1 hour following each treatment in Phase I or II, respectively, consisted of oral midazolam (2 mg) coadministered with IV [14G N-methyl] erythromycin (0.03 mg). The EBT was performed 20 minutes following erythromycin administration. Blood was collected during the 24 hours following probe drug administration for the analysis of midazolam pharmacokinetics. In Phase I, consumption of one glass of DS GFJ tid for 3 days increased the Cmax of midazolam 3-fold, the AUC 6-fold, and the t1/2 2-fold and decreased the amount of exhaled 14CO2 in all 8 subjects, with a mean decrease in EBT of 18%. In Phase II, consumption of one glass of DS GFJ significantly increased the AUC and Cmax of midazolam approximately 2-fold without a significant effect on the t1/2 of midazolam or the EBT. The effects of consuming one glass of SS GFJ on midazolam pharmacokinetics and the EBT were not significantly different from those of one glass of DS GFJ. It was concluded that consumption of one glass of DS GFJ tid for 3 days significantly increased the AUC, Cmax, and t1/2 of midazolam and reduced EBT values, reflecting inhibition of both hepatic and intestinal CYP3A4. In contrast, consumption of one glass of SS or DS GFJ increased midazolam AUC and Cmax, with little effect on the midazolam t1/2 and EBT values, reflecting preferential inhibition of intestinal CYP3A4. Alterations of midazolam AUC and Cmax induced by nine glasses of DS GFJ were significantly greater than those produced by one glass of SS or DS GFJ. These data suggest that GFJ inhibits intestinal and hepatic CYP3A4 in an exposure-dependent fashion and that patients taking medications that are CYP3A4 substrates are at risk for developing drug-related adverse events if they consume large amounts of grapefruit juice.     

PEGylation of the antimicrobial peptide nisin A: problems and perspectives

Nisin is a natural antimicrobial peptide produced by Lactococcus lactis and widely employed as food preservative. Its low solubility in neutral aqueous solutions, its instability at physiological pH and its rapid breakdown by proteolytic enzymes has limited its use for processed foods (processed cheese, milk and derivatives, canned vegetables). The conjugation to poly(ethylene glycol) (PEG) could improve its solubility and protect it towards enzymes present in non optimally processed food. We report the synthesis of a PEG-nisin conjugate, and the microbiology assays against some bacterial cell lines.