Detection of a new embryonic antigen (ESA-10) in the blood of patients with cancer: preliminary results in the United States

ESA-10 is an embryonic antigen expressed by tumor cells. A method to detect the antigen in the blood based on alterations in the erythrocyte sedimentation rate that occur when antiserum to ESA-10 is bound to the antigen in blood was devised and used here to determine the sensitivity and predictive value of the test in patients with biopsy proven non-hematologic malignancies, and in normal control subjects. The test was positive in 22 of 24 cancer patients tested, and negative in 30 of 35 control subjects. Of the five positive control subjects, one female had recently given birth and was lactating. Another control subject was recently diagnosed with prostate cancer, just months after having participated in this study. Therefore, this tumor marker test (Turtest(®)) had a sensitivity of 91.7% and a positive predictive value of 81.5% in patients with biopsy proven cancer, and a specificity and negative predictive value in control subjects of 88.2 and 93.8%, respectively, if the control subject who subsequently developed prostate cancer is removed from the control group. Therefore, this simple test has potential as a clinically useful tumor marker with sensitivity and specificity equal to or greater than other commercially available tumor markers and should be explored further in larger studies.

Application of a time-varying covariate model to the analysis of CA 19-9 as serum biomarker in patients with advanced pancreatic cancer

PURPOSE

The clinical relevance of CA 19-9 as surrogate biomarker in advanced pancreatic cancer is a matter of debate.

EXPERIMENTAL DESIGN

This retrospective multicenter study included patients with histologically confirmed advanced pancreatic cancer treated with first-line therapy. Analysis of CA 19-9 was done using the Elecsys assay (Roche Diagnostics). For an analysis of CA 19-9 kinetics, at least three measurements during first-line chemotherapy had to be available. The effect of pretreatment CA 19-9 levels on time-to-progression (TTP) and overall survival (OS) was modeled by Cox proportional hazards regression. The effect of CA 19-9 kinetics was also modeled by Cox proportional hazards regression where CA 19-9 was treated as a time-varying covariate.

RESULTS

One hundred and fifteen patients from five German centers were included; 73% of them were treated within prospective clinical trials. Median TTP was 4.4 months and median OS was 9.4 months; univariate analysis indicated that pretreatment CA 19-9 [as continuous variable, log (CA 19-9)] was significantly associated with TTP [hazard ratio (HR), 1.24; P < 0.001] and OS (HR, 1.16; P = 0.002). These associations remained significant within multivariate analysis. For CA 19-9 kinetics during chemotherapy, data from 69 patients (TTP) and 84 patients (OS) were available, respectively; log (CA 19-9) kinetics after start of treatment were found to be a significant predictor for TTP in univariate (HR, 1.48; P < 0.001) and multivariate (HR, 1.45; P < 0.001) analyses, and also for OS (univariate: HR, 1.34; P < 0.001; multivariate: HR, 1.38; P < 0.001).

CONCLUSION

Pretreatment CA 19-9 and CA 19-9 kinetics may serve as a useful serum biomarker in advanced pancreatic cancer.

Pharmacogenomic and pharmacoproteomic studies of cetuximab in metastatic colorectal cancer: biomarker analysis of a phase I dose-escalation study

PURPOSE

This study assessed biomarkers for cetuximab efficacy in tissue samples collected during a phase I dose-escalation study exploring every second week administration of cetuximab as first-line therapy in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Sixty-two patients received cetuximab monotherapy for 6 weeks, followed by cetuximab plus infusional fluorouracil, leucovorin, and irinotecan until disease progression. Patients in the control arm received cetuximab as a 400 mg/m(2) initial dose then 250 mg/m(2) per week; patients in the dose-escalation arms received 400 to 700 mg/m(2) every second week. Tumor and skin biopsies were taken for immunohistochemical and microarray expression analyses (tumor only) at baseline and week 4. Plasma was collected for proteomic analysis at baseline and week 4. KRAS tumor mutation status was assessed.

RESULTS

In subsets of paired skin samples from 35 patients, cetuximab treatment was associated with substantial downregulation of phospho(p)-EGFR, p-MAPK and proliferation and substantial upregulation of p27(Kip1) and p-STAT3 levels. No marked difference in these effects was noted for different schedules of administration and dose levels. In the cetuximab monotherapy phase, responses were seen only in patients whose tumors were wild-type for KRAS (eight of 29 v zero of 19 for KRAS mutant tumors; P = .015). Progression-free survival was longer for patients with KRAS wild-type compared with KRAS mutant tumors (log-rank P = .048). Genomics/proteomics analyses (42 and 45 patients, respectively) identified candidate biomarkers associated with response.

CONCLUSION

Biomarker analysis supported the functional equivalence of weekly and every second week administration of cetuximab and provided further confirmation that patients with KRAS wild-type mCRC were those most likely to benefit from cetuximab treatment.

Tumor marker evolution: comparison with imaging for assessment of response to chemotherapy in patients with colorectal liver metastases

Background

As the real clinical significance of carcinoembryonic antigen (CEA) and carbohydrate antigen 19.9 (CA19.9) evolution during preoperative chemotherapy for colorectal liver metastases (CLM) is still unknown, we explored the correlation between biological and radiological response to chemotherapy, and their comparative impact on outcome after hepatectomy.

Methods

All patients resected for CLM at our hospital between 1990 and 2004 with the following eligibility criteria were included in the study: (1) preoperative chemotherapy, (2) complete resection of CLM, (3) no extrahepatic disease, and (4) elevated baseline tumor marker values. A 20% change of tumor marker levels while on chemotherapy was used to define biological response (decrease) or progression (increase). Correlation between biological and radiological response at computed tomography (CT) scan, and their impact on overall survival (OS) and progression-free survival (PFS) after hepatectomy were determined.

Results

Among 119 of 695 consecutive patients resected for CLM who fulfilled the inclusion criteria, serial CEA and CA19.9 were available in 113 and 68 patients, respectively. Of patients with radiological response or stabilization, 94% had similar biological evolution for CEA and 91% for CA19.9. In patients with radiological progression, similar biological evolution was observed in 95% of cases for CEA and in 64% for CA19.9. On multivariate analysis, radiological response (but not biological evolution) independently predicted OS. However, progression of CA19.9, but not radiological response, was an independent predictor of PFS.

Conclusions

In patients with CLM and elevated tumor markers, biological response is as accurate as CT imaging to assess “clinical” response to chemotherapy. With regards to PFS, CA19.9 evolution has even better prognostic value than does radiological response. Assessment of tumor markers could be sufficient to evaluate chemotherapy response in a nonsurgical setting, limiting the need of repeat imaging.

Treatment of fistulizing inflammatory bowel disease

Fistulas manifest frequently in Crohn disease and can result in significant morbidity and often lead to the need for surgical intervention. Historically, it has been more difficult to obtain complete fistula closure in patients with perianal Crohn disease. Anti-tumor necrosis factor-alpha agents and the use of more accurate imaging modalities such as magnetic resonance imaging and rectal endoscopic ultrasound have enhanced the ability to manage fistulizing Crohn disease. A combined medical and surgical approach usually presents the best option for most patients.

Treatment of fistulizing inflammatory bowel disease

Fistulas manifest frequently in Crohn disease and can result in significant morbidity and often lead to the need for surgical intervention. Historically, it has been more difficult to obtain complete fistula closure in patients with perianal Crohn disease. Anti-tumor necrosis factor-alpha agents and the use of more accurate imaging modalities such as magnetic resonance imaging and rectal endoscopic ultrasound have enhanced the ability to manage fistulizing Crohn disease. A combined medical and surgical approach usually presents the best option for most patients.

Implications of KRAS mutation status for the treatment of metastatic colorectal cancer

Targeted agents have become an integral part of the treatment of a number of malignant diseases and regimens containing agents that disrupt the epidermal growth factor receptor (EGFR) signaling pathway are now considered a standard therapeutic approach for a range of tumor types. Recently, the mutational status of the KRAS gene in tumors was shown to be predictive of outcome to treatment with EGFR-targeted therapies in metastatic colorectal cancer (mCRC). The immoglobulin (Ig) G1 EGFR-targeting monoclonal antibody (mAb), cetuximab, has been shown to provide significant clinical benefits when added to standard irinotecan- and oxaliplatin-containing chemotherapy regimens, first-line, in patients with KRAS wild-type mCRC. Its effects on tumor response and resectability of metastases make cetuximab a particularly useful treatment option for patients with bulky or initially unresectable disease. With an ever-increasing array of management options available, it is important that patients with mCRC receive the treatment that offers them the best chance of prolonged survival. In view of this, testing for tumor KRAS mutation status should be mandatory at diagnosis of mCRC, prior to treatment decision-making.

Targeted therapies: the rare cancer paradigm

This review analyzes the state of the art of targeted therapies for several tumors, starting from the paradigmatic example of Imatinib treatment in chronic myelogenous leukemia (CML). We discuss how rare tumors can be models for various mechanisms of receptor tyrosine kinase (RTK) activation, and provide the opportunity to develop new therapies also for more common cancer types. We discuss the activation of the downstream RTK effectors as further targets for therapies in colorectal cancer. Finally, we highlight how a novel multidimensional approach which adds an in silico dimension to the in vitro and in vivo approach, can predict clinical results.

Lymphocytic reaction to colorectal cancer is associated with longer survival, independent of lymph node count, microsatellite instability, and CpG island methylator phenotype

PURPOSE

Host immune response to tumor may be an important prognostic factor for colon cancer patients. However, little is known on prognostic significance of histopathologic lymphoid reaction to tumor, independent of the number of lymph nodes examined and tumoral molecular alterations, including microsatellite instability (MSI) and the CpG island methylator phenotype (CIMP), both of which are associated with lymphocytic reaction and clinical outcome.

EXPERIMENTAL DESIGN

Using 843 colorectal cancer patients in two independent prospective cohorts, we examined patient prognosis in relation to four components of lymphocytic reaction (i.e., Crohn's-like reaction, peritumoral reaction, intratumoral periglandular reaction, and tumor-infiltrating lymphocytes) and overall lymphocytic score (0-12). CIMP was determined using eight markers including CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1. Cox proportional hazard models computed hazard ratio for mortality, adjusted for covariates including tumor stage, body mass index, lymph node count, KRAS, BRAF, p53, cyclooxygenase-2 (PTGS2), MSI, CIMP, and LINE-1 methylation.

RESULTS

Increasing overall lymphocytic reaction score including tumor-infiltrating lymphocytes was associated with a significant improvement in colorectal cancer-specific and overall survival (log-rank P < 0.003). These findings remained significant (adjusted hazard ratio estimates, 0.49-0.71; P(trend) < 0.009) in multivariate models that adjusted for covariates, including body mass index, MSI, CIMP, LINE-1 hypomethylation, and cyclooxygenase-2. The beneficial effect of tumoral lymphocytic reaction was consistent across strata of clinical, pathologic, and molecular characteristics.

CONCLUSIONS

Lymphocytic reactions to tumor were associated with improved prognosis among colorectal cancer patients, independent of lymph node count and other clinical, pathologic, and molecular characteristics.

Biomarkers predicting clinical outcome of epidermal growth factor receptor-targeted therapy in metastatic colorectal cancer

The monoclonal antibodies panitumumab and cetuximab that target the epidermal growth factor receptor (EGFR) have expanded the range of treatment options for metastatic colorectal cancer. Initial evaluation of these agents as monotherapy in patients with EGFR-expressing chemotherapy-refractory tumors yielded response rates of approximately 10%. The realization that detection of positive EGFR expression by immunostaining does not reliably predict clinical outcome of EGFR-targeted treatment has led to an intense search for alternative predictive biomarkers. Oncogenic activation of signaling pathways downstream of the EGFR, such as mutation of KRAS, BRAF, or PIK3CA oncogenes, or inactivation of the PTEN tumor suppressor gene is central to the progression of colorectal cancer. Tumor KRAS mutations, which may be present in 35%-45% of patients with colorectal cancer, have emerged as an important predictive marker of resistance to panitumumab or cetuximab treatment. In addition, among colorectal tumors carrying wild-type KRAS, mutation of BRAF or PIK3CA or loss of PTEN expression may be associated with resistance to EGFR-targeted monoclonal antibody treatment, although these additional biomarkers require further validation before incorporation into clinical practice. Additional knowledge of the molecular basis for sensitivity or resistance to EGFR-targeted monoclonal antibodies will allow the development of new treatment algorithms to identify patients who are most likely to respond to treatment and could also provide rationale for combining therapies to overcome primary resistance. The use of KRAS mutations as a selection biomarker for anti-EGFR monoclonal antibody (eg, panitumumab or cetuximab) treatment is the first major step toward individualized treatment for patients with metastatic colorectal cancer.

Imaging of perianal fistulas

Perianal fistulas, cryptoglandular or Crohn's disease-related, have a tendency to recur. Recurrence usually is owing to missed infection during surgery for cryptoglandular fistulas or insufficient response to medical treatment in Crohn's disease. It is now recognized that preoperative imaging (endoanal ultrasound and magnetic resonance imaging) can help to identify extensions that otherwise would be missed during surgery and therefore prevent recurrence. For medical therapy, the extent of the disease and the presence of abscesses are identified with imaging and therapy response can be monitored. The purpose of this review is to give an up-to-date overview of the anal anatomy, classification of perianal fistulas, and the role of imaging modalities in the management of patients with perianal fistulas.

Novel anti-filamin-A antibody detects a secreted variant of filamin-A in plasma from patients with breast carcinoma and high-grade astrocytoma

Identification of tumor-derived proteins in the circulation may allow for early detection of cancer and evaluation of therapeutic responses. To identify circulating tumor-derived proteins, mice were immunized with concentrated culture medium conditioned by human breast cancer cells. Antibodies generated by hybridomas were screened against conditioned media from both normal epithelial cells and tumor cells. Antibody selectively reacting with tumor cell-conditioned media was further characterized. This led to the development of a monoclonal antibody (Alper-p280) that reacts with a newly identified 280-kDa secreted variant of human filamin-A. Circulating filamin-A was detected in patient plasma samples using Alper-p280 in an ELISA assay. Human plasma samples from 134 patients with brain, breast, or ovarian cancer, 15 patients with active arthritis, and 76 healthy controls were analyzed. Filamin-A protein levels in human cell lines and tissues were analyzed by western blotting, immunohistochemistry, and electron and confocal microscopy. Circulating filamin-A was detected in the plasma of 109 of 143 patients with breast cancer and primary brain tumors. Plasma levels of filamin-A showed 89.5% sensitivity (95% confidence interval [CI] = 0.67% to 0.99%) and 97.8% specificity (95% CI = 0.88% to 0.99%) for glioblastoma at a cut-off of 21.0 ng/mL. Plasma levels of filamin-A (>36.0 ng/mL) had 96.7% sensitivity (95% CI = 0.80% to 0.99%) and 67.8% specificity (95% CI = 0.54% to 0.79%) for metastatic breast cancer. Filamin-A levels were increased in malignant breast or brain tissues, but not in normal control tissues. Filamin-A localized to lysosomes in MDA.MB.231 breast cancer cells, but not in normal human mammary epithelial cells, suggesting that filamin-A may undergo cancer-specific processing. Plasma filamin-A appears to be a specific and sensitive marker for patients with high-grade astrocytoma or metastatic breast cancer. Additional novel cancer biomarkers have been identified and are being developed alongside Alper-p280 for use in diagnosis of breast carcinoma and high-grade astrocytoma, and for use in the evaluation of therapeutic responses.

Successful prophylaxis with valaciclovir for relapsing HSV-1 in a girl treated with infliximab for moderate Crohn's disease

Biological agents such as inhibitors of tumour necrosis factor alpha (TNF-alpha ) are associated with the development of opportunistic infections. Although there are no international recommendations for the management of opportunistic infections, their prevention is a key safety issue for patients with inflammatory bowel disease (IBD). We report that chemoprophylaxis with oral valaciclovir was effective in preventing Herpes simplex virus (HSV-1) reactivation in a girl treated with infliximab for Crohn's disease.

Prognostic value of modeled PSA clearance on biochemical relapse free survival after radical prostatectomy

PURPOSES

Using population kinetic approach, we modeled PSA decline equations in patients with prostate cancer after radical prostatectomy (RP). We looked for relationships between early PSA decrease profile, characterized by PSA clearance (CL(PSA)) or half-life (HL(PSA)), and the 2-year biochemical relapse free survival (bRFS).

PATIENTS AND METHODS

We performed a retrospective study on 55 patients treated with RP and with at least 2 PSA measurements in the post-operative month. A population kinetic model was investigated with NONMEM. The prognostic factors regarding bRFS were assessed using univariate and multivariate analyses.

RESULTS

The best model describing the PSA post-operative decrease was bi-compartmental and fit patient data well. Median CL(PSA) was 0.034 (terciles were 0.023 and 0.048). The significant prognostic factors associated with a better bRFS with univariate analysis were lower CL(PSA) terciles (2-year bRFS = 100% vs. 85.1% vs. 66.7% if CL(PSA) < 0.023, 0.023 <or= CL(PSA) < 0.048 or CL(PSA) >or= 0.0480, P = 0.006) as well as initial PSA < 7 ng/ml, pT2 stage (vs. pT3), pN0 (vs. pN1) and low main Gleason score (3/5 vs. 4/5). Among these factors, CL(PSA) was the only independent prognostic factor with multivariate analysis regarding bRFS (HR = 0.92, 95%CI = [0.86-0.98], P = 0.0088).

CONCLUSION

CL(PSA) determined with 4 PSA concentrations in the first month following the RP may predict the biochemical relapse risk of prostate cancer patients, thus enabling early identification of high-risk patients requiring adjuvant treatment. A prospective validation of these results is required.

Comorbidity as prognostic variable in MDS: comparative evaluation of the HCT-CI and CCI in a core dataset of 419 patients of the Austrian MDS Study Group

BACKGROUND

The evaluation of comorbidity is of increasing importance in patients with hematologic disorders.

PATIENTS AND METHODS

In the present study, the influence of comorbidity on survival and acute myeloid leukemia (AML) evolution was analyzed retrospectively in 419 patients with de novo myelodysplastic syndromes (MDS) (observation period: 1985-2007). The median age was 71 years (range 24-91 years). Two different scoring systems, the hematopoietic stem-cell transplantation-specific comorbidity index (HCT-CI) and the Charlson comorbidity index (CCI) were applied.

RESULTS

The HCT-CI was found to be a significant prognostic factor for overall survival (OS, P < 0.05) as well as event-free survival (EFS, P < 0.05) in our patients, whereas the CCI was of prognostic significance for OS (P < 0.05), but not for EFS. For AML-free survival, neither the HCT-CI nor the CCI were of predictive value. A multivariate analysis including age, lactate dehydrogenase, ferritin, karyotype, number of cytopenias, French-American-British groups, and comorbidity was applied. Comorbidity was found to be an independent prognostic factor in patients with low- or int-1-risk MDS (P < 0.05) regarding OS and EFS.

CONCLUSIONS

Together, our data show that comorbidity is an important risk factor for OS and EFS in patients with MDS.

Azathioprine withdrawal in patients with Crohn's disease maintained on prolonged remission: a high risk of relapse

BACKGROUND & AIMS

Azathioprine (AZA) withdrawal in Crohn's disease after long-term remission under treatment is controversial. In a Groupe d'Etude Thérapeutique des Affections Inflammatoires du tube Digestif randomized, double-blind, placebo-controlled trial, the hypothesis that AZA withdrawal was not inferior to AZA continuation in patients in prolonged clinical remission could not be shown.

METHODS

A cohort of 66 patients in prolonged remission while being treated with AZA who stopped AZA, during or at the end of the randomized controlled trial, underwent long-term follow-up evaluation. The primary end point was clinical relapse. Prognostic factors of relapse were looked for through a proportional hazards model.

RESULTS

Median durations of AZA therapy and of clinical remission were 68.4 months (interquartile range, 52.8-85.2 mo) and 63.6 months (interquartile range, 48.0-55.7 mo), respectively. The median follow-up time after AZA interruption was 54.5 months; 32 of 66 patients had a relapse. The cumulative probabilities +/- SE of relapse at 1, 3, and 5 years were 14.0% +/- 4.3%, 52.8% +/- 7.1%, and 62.7% +/- 7.2%, respectively. C-reactive protein concentration of 20 mg/L or greater (risk, 58.6; 95% confidence interval, 7.5-457; P = .002), hemoglobin level less than 12 g/dL (risk, 4.8; 95% confidence interval, 1.7-13.7; P = .04), and neutrophil count 4 x 10(9)/L or greater (risk, 3.2; 95% confidence interval, 1.6-6.3; P = .003) were associated independently with an increased risk of relapse. Among the 32 relapsing patients, 23 were retreated by AZA alone, all but 1 up to successful remission.

CONCLUSIONS

Our results confirm that AZA withdrawal is associated with a high risk of relapse, whatever the duration of remission under this treatment. These data suggest that if AZA is well tolerated, it should not be interrupted.

Outcome for esophageal cancer following treatment with chemotherapy and radiotherapy but not esophagectomy: Nonsurgical treatment of esophageal cancer

Background:

More than 50% of patients with esophageal cancer are not suitable for surgery. The aim of this study was to analyze the outcome of patients undergoing standard nonsurgical treatment.

Methods:

Data of all patients undergoing nonsurgical treatment for esophageal cancer were identified from a prospective database.

Results:

Seventy-five patients were treated for localized disease, and 52 for metastatic disease at diagnosis. Except for age, which was higher in patients without metastases, there were no significant differences between the patients with vs. without metastatic disease. Kaplan–Meier analysis showed a median survival of 10.8 months for all patients. There was a significant difference in survival (p < 0.001) between the groups with versus without metastases, with median survival in the patients without metastases 13.6 months versus 6.5 months in patients with metastases. Patients undergoing nonsurgical treatment for localized disease had a five-year survival of 12%. No significant difference between adenocarcinoma and squamous cell carcinoma was identified. Subanalysis of patients who received chemoradiotherapy revealed similar results to the overall group of patients.

Conclusion:

In patients with localized disease at diagnosis, long-term survival can be achieved in some patients, whereas five-year survival is rare in patients who present with metastatic disease.

Safety and outcome of definitive chemoradiotherapy in elderly patients with oesophageal cancer

Little is known about chemoradiotherapy (CRT) in elderly patients with a locally advanced oesophageal cancer (OC). The aim of our study was to evaluate the tolerance and the outcome of elderly patients older than 70 years treated with CRT for a non-metastatic OC. Chemoradiotherapy was based on radiotherapy combined with a cisplatin-based chemotherapy. Clinical complete response (CCR) to CRT was evaluated on upper digestive endoscopy and computed tomography scan 6-8 weeks after CRT completion. One hundred and nine consecutive patients were included. A CCR was observed in 63 patients (57.8%) and 2-year survival was 35.5%. Adverse events > or =grade 3 were observed in 26 (23.8%) patients. Chemotherapy dose reduction, chemotherapy delays more than 1 week, and treatment discontinuation were observed in 33 (30.3%), 45 (41.3%), and 17 patients (15.6%), respectively. Comorbidity index according to Charlson score was significantly associated with treatment tolerance. In multivariate analysis, a CCR to CRT (P<0.01), a dose of radiotherapy > or =80% (P=0.02), and a Charlson score < or =2 (P=0.046) were identified as independent prognostic factors of overall survival. These results suggest that CRT could be considered as an effective treatment without major toxicity in elderly patients with OC.

Humoral and cellular monitoring to predict the development of infection in Crohn's disease patients beginning treatment with infliximab

Although severe infectious complications are rare, it is important to properly screen patients for predisposing conditions before beginning treatment with infliximab. We assessed immunity markers that might provide prognostic value for the development of infection in Crohn's disease patients after treatment with infliximab. In a prospective study, 34 fistulizing Crohn's disease patients (mean age 37 years) were studied. Patients were scheduled to receive three infusions of infliximab (5 mg/kg) at weeks 0, 2, and 6. Immunologic studies: Serum immunoglobulin (IgG, IgA, IgM), IgG-subclasses, and complement (C3, C4, factor B) determined by nephelometry; CD3+, CD3+CD4+, CD3+CD8+, CD19+, and CD56+CD3- lymphocyte subsets performed by flow cytometry. During a mean follow-up of 56 months, 1 patient had disseminated tuberculosis and 2 patients had severe bacterial infections. The presence of infection was associated with significantly higher IgM (246 vs. 121 mg/dL; Mann-Whitney test, P = 0.01), lower C3 (64 vs. 118, P = 0.02), lower C4 concentrations (12 vs. 25, P = 0.02), and with decreased levels of CD19 B cells (47 vs. 290, P = 0.03) in the baseline study. Further prospective studies in a larger number of patients are suggested to examine whether early monitoring of immunocompetence might help to identify the risk of infection in patients treated with infliximab.