Antigenic response to CT-P13 and infliximab originator in inflammatory bowel disease patients shows similar epitope recognition.

AIM: To test the cross-immunogenicity of anti-CT-P13 IBD patients' sera to CT-P13/infliximab originator and the comparative antigenicity evoked by CT-P13/infliximab originator sera. METHODS: Sera of patients with IBD with measurable anti-CT-P13 antibodies were tested for their cross-reactivity to 5 batches of infliximab originator and CT-P13. Anti-drug antibody positive sera from treated patients were used to compare antigenic epitopes. RESULTS: All 42 anti-CT-P13 and 37 anti-infliximab originator IBD sera were cross-reactive with infliximab originator and CT-P13 respectively. Concentration of anti-drug antibodies against infliximab originator or CT-P13 were strongly correlated both for IgG1 and IgG4 (P < 0.001). Anti-CT-P13 sera of patients with IBD (n = 32) exerted similar functional inhibition on CT-P13 or infliximab originator TNF binding capacity and showed reduced binding to CT-P13 in the presence of five different batches of CT-P13 and infliximab originator. Anti-CT-P13 and anti-infliximab originator IBD sera selectively enriched phage-peptides from the VH (CDR1 and CDR3) and VL domains (CDR2 and CDR3) of infliximab. Sera reactivity detected major infliximab epitopes in these regions of infliximab in 60%-79% of patients, and no significant differences were identified between CT-P13 and infliximab originator immunogenic sera. Minor epitopes were localised in framework regions of infliximab with reduced antibody reactivity shown, in 30%-50% of patients. Monoclonal antibodies derived from naïve individuals and ADA-positive IBD patients treated with CT-P13 provided comparable epitope specificity to five different batches of CT-P13 and infliximab originator. CONCLUSIONS: These results strongly support a similar antigenic profile for infliximab originator and CT-P13, and point toward a safe switching between the two drugs in anti-drug antibody negative patients.

Suppression of anti-drug antibodies to infliximab or adalimumab with the addition of an immunomodulator in patients with inflammatory bowel disease.

BACKGROUND: Loss of response to anti-tumour necrosis factor (TNF) therapy in patients with inflammatory bowel disease (IBD) is often caused by anti-drug antibody formation with neutralisation of drug effect. Addition of an immunomodulator has been suggested to reduce immunogenicity, leading to regained response. AIM: To investigate whether addition of an immunomodulator to anti-TNF monotherapy could lead to anti-drug antibody suppression and regained clinical response in IBD patients. METHODS: We retrospectively collected measurements of infliximab or adalimumab serum concentrations and anti-drug antibodies to identify anti-drug positive patients with loss response who were given an immunomodulator. RESULTS: Anti-drug antibodies against infliximab and adalimumab were detected in 98/376 (26%) and in 61/226 (27%) patients, respectively. Immunomodulators were given to 17/159 patients. Clinical response was recaptured in 6/10 patients receiving a thiopurine and in all (7/7) patients receiving methotrexate. In 7/8 patients on infliximab, serum concentrations increased (median 2.84 µg/mL; IQR: 1.19-4.98) and in 6/9 patients on adalimumab (median 3.10 µg/mL; IQR: 1.45-4.45). This was accompanied by a decrease in anti-drug antibodies to undetectable levels (median 11 months for both anti-TNF agents). In 23 patients, no immunomodulator was added but anti-TNF interval was shortened (17/23) or dosage was increased (6/23), which resulted in a clinical response in 10/17 and 2/6 patients, respectively. CONCLUSION: In 77% of IBD patients with loss of response due to immunogenicity, addition of immunomodulator resulted in undetectable anti-drug antibody levels, increased serum drug concentrations and regained clinical response. This strategy should be considered in this patient population before switching to other agents.

Optimization of anti-TNF therapy in patients with Inflammatory Bowel Disease.

After the introduction of anti-tumor necrosis factor (anti-TNF) agents, the clinical outcome of patients with Inflammatory Bowel Disease (IBD) has improved significantly. However, use of anti-TNF therapy is complicated by loss of response. In order to maintain remission, adequate serum levels are required. Hence, therapeutic drug monitoring (TDM) is important in order to optimize serum drug levels, especially in patients with loss of response to these agents. Optimization of anti-TNF therapy by applying TDM enables clinicians to regain response to TNF blockers in a significant proportion of patients. It is important to use anti-TNF agents in their most optimal way, since these therapeutic agents are expensive and the medical options after failing anti-TNF therapy are limited. Here, we will discuss how to optimize treatment with anti-TNF agents in IBD patients in order to improve treatment efficacy, prevent anti-drug antibody formation, reduce side effects, discontinue unnecessary treatment and manage costs.

Early and late effects of the immunosuppressants rapamycin and mycophenolate mofetil on UV carcinogenesis.

Increased skin cancer risk in organ transplant recipients has been experimentally emulated with enhanced UV carcinogenesis from administering conventional immunosuppressants. However, newer generation immunosuppressive drugs, rapamycin (Rapa) and mycophenolate mofetil (MMF), have been shown to impair angiogenesis and outgrowth of tumor implants. To ascertain the overall effect on UV carcinogenesis, Rapa and MMF were admixed into the food pellets of hairless SKH1 mice receiving daily sub-sunburn UV dosages. With immunosuppressive blood levels neither of the drugs affected onset of tumors (<2 mm), but in contrast to MMF, Rapa significantly increased latency of large tumors (>or=4 mm, medians of 190 vs 125 days) and reduced their multiplicity (1.6 vs 4.5 tumors per mouse at 200 days). Interestingly, tumors (>2 mm) from the Rapa-fed group showed a reduction in UV-signature p53 mutations (39% vs 90%) in favor of mutations from putative base oxidation. This shift in mutation spectrum was not essentially linked to the reduction in large tumors because it was absent in large tumors similarly reduced in number when feeding Rapa in combination with MMF, possibly owing to an antioxidant effect of MMF. Significantly fewer tumor cells were Vegf-positive in the Rapa-fed groups, but a correspondingly reduced expression of Hif1alpha target genes (Vegf, Ldha, Glut1, Pdk1) that would indicate altered glucose metabolism with increased oxidative stress was not found. Remarkably, we observed no effect of the immunosuppressants on UV-induced tumor onset, and with impaired tumor outgrowth Rapa could therefore strongly reduce skin carcinoma morbidity and mortality rates in organ transplant recipients.

Peptidylarginine deiminase (PAD) 6 is essential for oocyte cytoskeletal sheet formation and female fertility.

Peptidylarginine deiminase 6 (PAD6) is an enzyme that is uniquely expressed in male and female germ cells. To study the function of this enzyme in vivo we generated mice deficient for PAD6. Here we show that inactivation of the PAD6 gene in mice leads to female infertility whereas male fertility is not affected. The absence of the PAD6 protein and consequently absence of citrullination activity in oocytes results in dispersal of the cytoskeletal sheets in oocytes, indicating an essential role of these germ cell-specific structures in zygote/embryo development. PAD6 deficient mice do not show any other overt phenotype. Thus, we identify citrullination as a new regulator of fertility.

Effects of nicotinamide and carbogen on oxygenation in human tumor xenografts measured with luminescense based fiber-optic probes.

BACKGROUND AND PURPOSE: In head and neck cancer, addition of both carbogen breathing and nicotinamide to accelerated fractionated radiotherapy showed increased loco-regional control rates. An assay based on the measurement of changes in tumor pO(2) in response to oxygenation modification could be helpful for selecting patients for these new treatment approaches. MATERIALS AND METHODS: The fiber-optic oxygen-sensing device, OxyLite, was used to measure changes in pO(2), at a single position in tumors, after treatment with nicotinamide and carbogen in three human xenograft tumor lines with different vascular architecture and hypoxic patterns. Pimonidazole was used as a marker of hypoxia and was analyzed with a digital image processing system. RESULTS: At the position of pO(2) measurement, half of the tumors showed a local increase in pO(2) after nicotinamide administration. Steep increases in pO(2) were measured in most tumors during carbogen breathing although the increase was less pronounced in tumor areas with a low pre-treatment pO(2). A trend towards a faster local response to carbogen breathing for nicotinamide pre-treated tumors was found in all three lines. There were significant differences in hypoxic fractions, based on pimonidazole binding, between the three tumor lines. There was no correlation between hypoxic marker binding and the response to carbogen breathing. CONCLUSION: Temporal changes in local pO(2) can be measured with the OxyLite. This system was used to quantitate the effects of oxygen modifying treatments. Rapid increases in pO(2) during carbogen breathing were observed in most tumor areas. The locally measured response to nicotinamide was smaller and more variable. Bio-reductive hypoxic cell marker binding in combination with OxyLite pO(2) determination gives spatial information about the distribution patterns of tumor hypoxia at the microscopic level together with the possibility to continuously measure changes in pO(2) in specific tumor areas.

Optical sensor-based oxygen tension measurements correspond with hypoxia marker binding in three human tumor xenograft lines.

Hypoxia has a negative effect on the outcome of radiotherapy and surgery and is also related to an increased incidence of distant metastasis. In this study, tumor pO(2) measurements using a newly developed time-resolved luminescence-based optical sensor (OxyLitetrade mark) were compared with bioreductive hypoxia marker binding (pimonidazole). Single pO(2) measurements per tumor were compared to hypoxia marker binding in tissue sections using image analysis. Both assays were performed in the same tumors of three human tumor lines grown as xenografts. Both assays demonstrated statistically significant differences in the oxygenation status of the three tumor lines. There was also a good correlation between hypoxia marker binding and the pO(2) measurements with the OxyLitetrade mark device. A limitation of the OxyLitetrade mark system is that it is not yet suited for sampling multiple sites in one tumor. An important strength is that continuous measurements can be taken at the same position and dynamic information on the oxygenation status of tumors can be obtained. The high spatial resolution of the hypoxia marker binding method can complement the limitations of the OxyLitetrade mark system. In the future, a bioreductive hypoxic cell marker for global assessment of tumor hypoxia may be combined with analysis of temporal changes in pO(2) with the OxyLitetrade mark to study the effects of oxygenation-modifying treatment on an individual basis.