Why measure infliximab (IFX) drug levels and

antibodies to infliximab (ATI)? Evidence from the Inflammatory Bowel Disease literature

1. To examine the reason for loss/lack of response to treatment and determine

subsequent management.

2. To optimize dose to give the best chance of remission whilst reducing the risk

of adverse effects.

Testing algorithm and suggested interpretation for the

scenario of loss/lack of response to treatment

ATI will only be performed if IFX is <2 mg/L

The presence of IFX in concentrations >2 mg/L interferes with the detection of ATI

therefore ATI will not be performed if the drug level is higher than this. The ATI will be

automatically performed if the IFX level is <2 mg/L.

Infliximab: drug levels and antibodies

April 2016

Department of Immunology

SSWPS Liverpool

Ordering the

tests

Paperwork Fill in the

preprinted request form. Testing

will proceed according to the algorithm shown at left.

Consent form –

required for any drug level or antibody testing to proceed (EXCEPT if on Inflectra. See explanation on following page)

Instructions to

patient Blood should

be collected as a trough level, just prior to the next dose of infliximab

The patient should have their blood collected at a public pathology collection centre or a centre that is happy to forward the sample to SSWPS Liverpool

>3 mg/L <2 mg/L 2 - 3 mg/L

Confirm symptoms are due to

active disease

ATI automatically performed

by the laboratory

Consider increasing IFX therapy

by increasing dose or decreasing

interval between infusions

Consider changing to

non-TNF based therapy

ATI not detected

or between

10-200 ng/mL

ATI >200 ng/mL

Recommend switching

to an alternative

Anti-TNF agent

Trough level IFX

(steady state)

Consent to charges for testing

Infliximab (IFX) level

If this is the only test which is performed, there

will be no charge over Medicare (no gap). This

test is performed at a loss to the laboratory.

However, testing will not begin without consent

in advance to the charge for ATI testing, if

required (see below).

Antibodies to infliximab (ATI)

ATI are NOT covered by the Medicare benefits

schedule (MBS).

There will be a charge (currently $140) for ATI if

this test is deemed to be required according to the

algorithm above.

… Except Inflectra

However, if the brand of infliximab called

Inflectra has been prescribed, no payment is

required. Testing is provided (IFX level and ATI if

required) as part of the distributor’s care program

for patients receiving Inflectra.

No consent form is required in this case.

Department of Immunology, Sydney South West Pathology Service (Liverpool Hospital)

Supervising Immunologist: Dr Catherine Toong

Phone: (02) 8738 5068 (laboratory)

Specimen reception: Cnr Campbell & Forbes St, Liverpool, NSW 2170. Ph: (02) 8738 5045. Fax: (02) 8738 9465

References and further reading

Baert, F. et al. Influence of immunogenicity on the long-term efficacy of infliximab in Crohn’s disease. New England Journal

of Medicine 2003; 348: 601-608.

Bortlik, M. et al. Infliximab trough levels may predict sustained response to infliximab in patients with Crohn’s disease.

Journal of Crohn’s and Colitis 2013; 7: 736-743.

Paul, S. et al. Therapeutic drug monitoring of infliximab and mucosal healing in inflammatory bowel disease: a prospective

study. Inflammatory Bowel Diseases 2013; 19: 2568-76

Steenholdt, C. et al. Use of infliximab and anti-infliximab antibody measurements to evaluate and optimize efficacy and

safety of infliximab maintenance therapy in Crohn’s disease. Danish Medical Journal 2013; 60: B4616.

Ternant, D. et al. Infliximab pharmacokinetics in inflammatory bowel disease patients. Therapeutic Drug Monitoring 2008;

30: 523-529.

Vande Casteele, N. et al. Antibody response to infliximab and its impact on pharmacokinetics can be transient. American

Journal of Gastroenterology 2013; 108: 962-971.

Vande Casteele, N. et al. Trough concentrations of infliximab guide dosing for patients with inflammatory bowel disease.

Gastroenterology 2015; 148: 1320-1329.

Specimen requirement

5 ml blood in a serum tube will be sufficient

for both tests. The serum sample should be

kept refrigerated.

Central Specimen Reception: RPAH Level 5 Building 77, RPAH Missenden Rd Camperdown NSW 2050 ph: 61 2 9515 8279 fax: 61 2 9515 7931 Liverpool – Cnr Campbell & Forbes St, Liverpool, NSW 2170

Ph: 61 2 8378 5045 Fax: 61 2 8738 9465 V3

Patient Consent for Non Rebateable (nonmbs) Test/s Please print all details clearly

I _______________________ (Patient name) understand that my medical practitioner has

requested a pathology test(s) that are not covered by Medicare Australia, Department of

Veteran Affairs or a private health fund.

I understand that I will receive an invoice from Sydney South West Pathology Service or

another pathology service depending on the test performed.

I agree to accept all responsibility for any out of pocket expenses for the test(s) as

requested.

Signature: _________________________ Date: ____________ Amount: $_____.___

Test Description Cost Required

N02085 ADH (Vasopressin) – MBS Unlisted Hormone Test $30.70

N02085 Adiponectin – MBS Unlisted Hormone Test $30.70

N05235 Allergy Array – Allergen Component Microarray $340.00

N05305 Antibodies to infliximab (Remicade) $140.00

N02051 Apolipoprotein A1 $19.90

N02050 Apolipoprotein E Genotype $40.00

N02010 Bile Acids – Miscellaneous Fluid $20.00

N02010 Bile Acids (If not pregnant or limit 3 reached) $20.00

N09012 Carbohydrate Deficient Transferrin $120.00

N02150 Cholinesterase Genotyping Screen – BCHE Butyrylcholinesterase $100.00

N02160 Cholinesterase Genotyping Sequence $100.00

N02085 Chromogranin A – MBS Unlisted Hormone Test $30.70

N05220 Eosinophilic Cationic Protein (>12 years old) $75.00

N05230 Interleukin 6 (IL6) $40.00

N02085 Leptin – MBS Unlisted Hormone Test $30.70

N02040 Lipoprotein (a) $30.20

N01330 Liquid Based Cytology – CYThinPrep Pap $35.00

N02170 Retinol Binding Protein $20.00

N96398 S/A Inhibin B level $80.00

N02096 Seminal Plasma Fructose $30.00

N06050 TB Interferon Gamma Release Assay $66.00

N02111 Transferrin Receptor (Soluble) $25.00

N02085 Vasopressin (ADH) - MBS Unlisted Hormone Test $30.70

N02060 VLDL Cholesterol (Ultracentrifuged) $30.20

N02060 VLDL Triglycerides (Ultracentrifuged) $30.20

Patient First Name Patient Surname Contact number

_____________________ ________________________ __________________

Affix addressograph or

lab sticker here.

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