Reviewer ’s report  
 
Title:  Drug persistence and need  for dose intensification to adalimumab therapy; the importance 
of therapeutic drug monitoring in inflammatory bowel diseases  
 
Version: 0 Date: 23 Jun 2017 
 
Reviewer:  Thomas  Van Stappen  
 
Reviewer’s report:  
 
The manuscript describes a relevant topic for gastroenterologists, i.e. the utility of me asuring 
adalimumab and anti -adalimumab antibody concentrations during adalimumab maintenance 
treatment. The conclusions, in favor of therapeutic drug monitoring, may be true, but I do have 
some important consideration regarding the manuscript's methodology  and result description, 
that strongly limit the power of this conclusion. In addition, the language in the manuscripts 
needs editing before being publishable, I listed some examples below.  
 
 
Major comments:  
 
-the high variability in the patient cohort and measured patient samples is a limitation to study 
time-dependent drug and anti -drug antibody occurrences, as anti -drug antibodies are typically 
observed in the early stages of therapy (first year). Were TDM data primarily available during 
the first months of adalimumab treatment or at later stages of the treatment?  
 
-Page 7, line 137 -140: The information regarding the ELISA kits is requires some 
reformulations. For example, what is a "conventional" ELISA? What is measured with the 
bridging assay, drug or ADA ? In addition, the cut -off value of 5 µg/mL is a literature -based 
cutoff and most likely not the assay cutoff, which will be much lower. Please adequately 
distinguish between these in the manuscript. It may help to add some subheadings in the 
"materials an d method" -section.  
 
-Page 7, line 147 -148: A large limitation of this study is that loss of response was defined as 
discontinuation of adalimumab therapy and not based on the CDAI and pMayo scores that were 
assessed simultaneously. Because the result of the rapeutic drug monitoring was available for the 
clinician, this may have biased the decision to continue or stop treatment and thus, the outcomes 
of the study. This is also confusingly described in the abstract, as patients were evaluated at 
suspected LOR. How do you 'only' suspect LOR as it is defined as treatment discontinuation? 
Please clarify. Please provide as well references for the clinical outcome scores.  
 
-Page 9, line 189 -193: The authors describe that 29.5% of patients required dose intensification  
throughout the study, however according to the Kaplan -Meier curve, up to 40% of patients 
required dose intensification. Could the authors clarify this seemingly discrepant results?  
 
-Page 9, line 196 -200: The ELISA used to measure anti -adalimumab antibodie s is I believe a 
drug-sensitive ELISA, as it is based on the bridging principle (to be verified with the 
manufacturers). Low anti -adalimumab antibodies do therefore have per definition low trough 
levels, as the assay cannot measure anti -drug antibodies in the presence of drug. The reported 
percentage (28.6%) of patients with low trough levels in patients with low ADA seems therefore 
an underestimation. In addition, where patients with low TL more likely to be transient? What is 
known in literature, however,  is that anti -infliximab antibodies are not cleared immediately upon 
a treatment stop. Where patients with anti -drug antibodies in the presence of detectable 
adalimumab concentrations prior infliximab failures? Then, it might be interesting to remeasure 
samples for anti -infliximab antibodies. Please discuss this as well adequately in the manuscript's 
discussion section.  
 
-The reported statistical methodology seems incomplete (for example, not only medians and 
interquartile ranges are reported in the manuscri pt (i.e. Table 1). It is unclear whether multiple 
TDM samples per patient or a single sample per patient was used in statistics? In addition, a 
multivariate analysis in addition to a univariate analysis to assess for predictors for dose 
intensification and  loss of response may be of benefit for the manuscript.  
 
 
Minor comments (not all), including some of the language issues that need editing:  
 
-The association between LOR and female gender, as well as the sensitivity analysis that was 
performed, is not very comprehensibly described in the methodology, results and discussion.  
 
-It is unclear from the manuscript how the patients were included in the study: At start of 
adalimumab induction treatment or during maintenance adalimumab treatment. Regarding table 
1: the different meaning of the "/" in the table is a bit confusing.  
 
-Page 5, line 97 -98: ADAs neutralize the Fab segment instead of the FC segment of adalimumab, 
as the Fab segment binds TNF -alpha via its paratope.  
 
-Page 5, line 98: please modify the word " to twit"  
 
-Page 5, line 104 -105: please correct sentence "TDM based dosing of infliximab therapy can 
result.. in … economic benefit  
 
-Page 5, line 105: Please update the reference, the TAXIT trial has already been published in 
2015 (Vande Casteele N, Gastro enterology, 2015).  
 
-"p value" should be rewritten as "p -value"  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the nec essary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
Are you able to assess  any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any  stocks or shares in an organisation that may in any way gain or lose 
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you currently applying for any patents relating to the content of the 
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare to have no personal conflicts of interest, however KU Leuven has licensed lab 
developed adalimuma b and anti -adalimumab ELISAs to apDia (Turnout, Belgium) and R -
Biopharm AG (Darmstadt, Germany).  
 
I agree to th e open peer review policy of the journal. I understand that my name will be included 
on my report to the authors and, if the manuscript is accepted for publication, my named report 
including any attachments I upload will be posted on the website along with  the authors' 
responses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understand that any comments 
which I do not wish to be included in my named report can be included as confidential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal  
Reviewer ’s report  
 
Title:  Drug persistence and need  for dose intensification to adalimumab therapy; the importance 
of therapeutic drug monitoring in inflammatory bowel diseases  
 
Version: 0 Date: 23 Jun 2017 
 
Reviewer:  Thomas  Van Stappen  
 
Reviewer’s report:  
 
The manuscript describes a relevant topic for gastroenterologists, i.e. the utility of me asuring 
adalimumab and anti -adalimumab antibody concentrations during adalimumab maintenance 
treatment. The conclusions, in favor of therapeutic drug monitoring, may be true, but I do have 
some important consideration regarding the manuscript's methodology  and result description, 
that strongly limit the power of this conclusion. In addition, the language in the manuscripts 
needs editing before being publishable, I listed some examples below.  
 
 
Major comments:  
 
-the high variability in the patient cohort and measured patient samples is a limitation to study 
time-dependent drug and anti -drug antibody occurrences, as anti -drug antibodies are typically 
observed in the early stages of therapy (first year). Were TDM data primarily available during 
the first months of adalimumab treatment or at later stages of the treatment?  
 
-Page 7, line 137 -140: The information regarding the ELISA kits is requires some 
reformulations. For example, what is a "conventional" ELISA? What is measured with the 
bridging assay, drug or ADA ? In addition, the cut -off value of 5 µg/mL is a literature -based 
cutoff and most likely not the assay cutoff, which will be much lower. Please adequately 
distinguish between these in the manuscript. It may help to add some subheadings in the 
"materials an d method" -section.  
 
-Page 7, line 147 -148: A large limitation of this study is that loss of response was defined as 
discontinuation of adalimumab therapy and not based on the CDAI and pMayo scores that were 
assessed simultaneously. Because the result of the rapeutic drug monitoring was available for the 
clinician, this may have biased the decision to continue or stop treatment and thus, the outcomes 
of the study. This is also confusingly described in the abstract, as patients were evaluated at 
suspected LOR. How do you 'only' suspect LOR as it is defined as treatment discontinuation? 
Please clarify. Please provide as well references for the clinical outcome scores.  
 
-Page 9, line 189 -193: The authors describe that 29.5% of patients required dose intensification  
throughout the study, however according to the Kaplan -Meier curve, up to 40% of patients 
required dose intensification. Could the authors clarify this seemingly discrepant results?  
 
-Page 9, line 196 -200: The ELISA used to measure anti -adalimumab antibodie s is I believe a 
drug-sensitive ELISA, as it is based on the bridging principle (to be verified with the 
manufacturers). Low anti -adalimumab antibodies do therefore have per definition low trough 
levels, as the assay cannot measure anti -drug antibodies in the presence of drug. The reported 
percentage (28.6%) of patients with low trough levels in patients with low ADA seems therefore 
an underestimation. In addition, where patients with low TL more likely to be transient? What is 
known in literature, however,  is that anti -infliximab antibodies are not cleared immediately upon 
a treatment stop. Where patients with anti -drug antibodies in the presence of detectable 
adalimumab concentrations prior infliximab failures? Then, it might be interesting to remeasure 
samples for anti -infliximab antibodies. Please discuss this as well adequately in the manuscript's 
discussion section.  
 
-The reported statistical methodology seems incomplete (for example, not only medians and 
interquartile ranges are reported in the manuscri pt (i.e. Table 1). It is unclear whether multiple 
TDM samples per patient or a single sample per patient was used in statistics? In addition, a 
multivariate analysis in addition to a univariate analysis to assess for predictors for dose 
intensification and  loss of response may be of benefit for the manuscript.  
 
 
Minor comments (not all), including some of the language issues that need editing:  
 
-The association between LOR and female gender, as well as the sensitivity analysis that was 
performed, is not very comprehensibly described in the methodology, results and discussion.  
 
-It is unclear from the manuscript how the patients were included in the study: At start of 
adalimumab induction treatment or during maintenance adalimumab treatment. Regarding table 
1: the different meaning of the "/" in the table is a bit confusing.  
 
-Page 5, line 97 -98: ADAs neutralize the Fab segment instead of the FC segment of adalimumab, 
as the Fab segment binds TNF -alpha via its paratope.  
 
-Page 5, line 98: please modify the word " to twit"  
 
-Page 5, line 104 -105: please correct sentence "TDM based dosing of infliximab therapy can 
result.. in … economic benefit  
 
-Page 5, line 105: Please update the reference, the TAXIT trial has already been published in 
2015 (Vande Casteele N, Gastro enterology, 2015).  
 
-"p value" should be rewritten as "p -value"  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the nec essary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
Are you able to assess  any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any  stocks or shares in an organisation that may in any way gain or lose 
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you currently applying for any patents relating to the content of the 
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare to have no personal conflicts of interest, however KU Leuven has licensed lab 
developed adalimuma b and anti -adalimumab ELISAs to apDia (Turnout, Belgium) and R -
Biopharm AG (Darmstadt, Germany).  
 
I agree to th e open peer review policy of the journal. I understand that my name will be included 
on my report to the authors and, if the manuscript is accepted for publication, my named report 
including any attachments I upload will be posted on the website along with  the authors' 
responses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understand that any comments 
which I do not wish to be included in my named report can be included as confidential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal  
Please review this paper.
user
Reviewer ’s report  
 
Title:  Drug persistence and need  for dose intensification to adalimumab therapy; the importance 
of therapeutic drug monitoring in inflammatory bowel diseases  
 
Version: 0 Date: 23 Jun 2017 
 
Reviewer:  Thomas  Van Stappen  
 
Reviewer’s report:  
 
The manuscript describes a relevant topic for gastroenterologists, i.e. the utility of me asuring 
adalimumab and anti -adalimumab antibody concentrations during adalimumab maintenance 
treatment. The conclusions, in favor of therapeutic drug monitoring, may be true, but I do have 
some important consideration regarding the manuscript's methodology  and result description, 
that strongly limit the power of this conclusion. In addition, the language in the manuscripts 
needs editing before being publishable, I listed some examples below.  
 
 
Major comments:  
 
-the high variability in the patient cohort and measured patient samples is a limitation to study 
time-dependent drug and anti -drug antibody occurrences, as anti -drug antibodies are typically 
observed in the early stages of therapy (first year). Were TDM data primarily available during 
the first months of adalimumab treatment or at later stages of the treatment?  
 
-Page 7, line 137 -140: The information regarding the ELISA kits is requires some 
reformulations. For example, what is a "conventional" ELISA? What is measured with the 
bridging assay, drug or ADA ? In addition, the cut -off value of 5 µg/mL is a literature -based 
cutoff and most likely not the assay cutoff, which will be much lower. Please adequately 
distinguish between these in the manuscript. It may help to add some subheadings in the 
"materials an d method" -section.  
 
-Page 7, line 147 -148: A large limitation of this study is that loss of response was defined as 
discontinuation of adalimumab therapy and not based on the CDAI and pMayo scores that were 
assessed simultaneously. Because the result of the rapeutic drug monitoring was available for the 
clinician, this may have biased the decision to continue or stop treatment and thus, the outcomes 
of the study. This is also confusingly described in the abstract, as patients were evaluated at 
suspected LOR. How do you 'only' suspect LOR as it is defined as treatment discontinuation? 
Please clarify. Please provide as well references for the clinical outcome scores.  
 
-Page 9, line 189 -193: The authors describe that 29.5% of patients required dose intensification  
throughout the study, however according to the Kaplan -Meier curve, up to 40% of patients 
required dose intensification. Could the authors clarify this seemingly discrepant results?  
 
-Page 9, line 196 -200: The ELISA used to measure anti -adalimumab antibodie s is I believe a 
drug-sensitive ELISA, as it is based on the bridging principle (to be verified with the 
manufacturers). Low anti -adalimumab antibodies do therefore have per definition low trough 
levels, as the assay cannot measure anti -drug antibodies in the presence of drug. The reported 
percentage (28.6%) of patients with low trough levels in patients with low ADA seems therefore 
an underestimation. In addition, where patients with low TL more likely to be transient? What is 
known in literature, however,  is that anti -infliximab antibodies are not cleared immediately upon 
a treatment stop. Where patients with anti -drug antibodies in the presence of detectable 
adalimumab concentrations prior infliximab failures? Then, it might be interesting to remeasure 
samples for anti -infliximab antibodies. Please discuss this as well adequately in the manuscript's 
discussion section.  
 
-The reported statistical methodology seems incomplete (for example, not only medians and 
interquartile ranges are reported in the manuscri pt (i.e. Table 1). It is unclear whether multiple 
TDM samples per patient or a single sample per patient was used in statistics? In addition, a 
multivariate analysis in addition to a univariate analysis to assess for predictors for dose 
intensification and  loss of response may be of benefit for the manuscript.  
 
 
Minor comments (not all), including some of the language issues that need editing:  
 
-The association between LOR and female gender, as well as the sensitivity analysis that was 
performed, is not very comprehensibly described in the methodology, results and discussion.  
 
-It is unclear from the manuscript how the patients were included in the study: At start of 
adalimumab induction treatment or during maintenance adalimumab treatment. Regarding table 
1: the different meaning of the "/" in the table is a bit confusing.  
 
-Page 5, line 97 -98: ADAs neutralize the Fab segment instead of the FC segment of adalimumab, 
as the Fab segment binds TNF -alpha via its paratope.  
 
-Page 5, line 98: please modify the word " to twit"  
 
-Page 5, line 104 -105: please correct sentence "TDM based dosing of infliximab therapy can 
result.. in … economic benefit  
 
-Page 5, line 105: Please update the reference, the TAXIT trial has already been published in 
2015 (Vande Casteele N, Gastro enterology, 2015).  
 
-"p value" should be rewritten as "p -value"  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the nec essary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
Are you able to assess  any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any  stocks or shares in an organisation that may in any way gain or lose 
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you currently applying for any patents relating to the content of the 
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare to have no personal conflicts of interest, however KU Leuven has licensed lab 
developed adalimuma b and anti -adalimumab ELISAs to apDia (Turnout, Belgium) and R -
Biopharm AG (Darmstadt, Germany).  
 
I agree to th e open peer review policy of the journal. I understand that my name will be included 
on my report to the authors and, if the manuscript is accepted for publication, my named report 
including any attachments I upload will be posted on the website along with  the authors' 
responses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understand that any comments 
which I do not wish to be included in my named report can be included as confidential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal  
assistant