I finally got my test results back.
My doctor's note with the results was this: "Infliximab (Remicade) level low, antibodies present. Explains your loss of response. Will need to switch to a different drug in the same class and consider Imuran for 6-12 months to reduce the chance of further ab formation. Probably will start prior authorization process for Humira, unless you want to do something different. Can discuss further at our f/u appt next week."
Results: Infliximab Drug Level 3.3 ug/mL
In the presence of serum anti-infliximab antibodies, the
infliximab drug level reflects the antibody-unbound (free)
fraction of infliximab in serum.
Quantitation Limit: <0.4 ug/mL
Results of 0.4 or higher indicate detection of Infliximab.
- The optimal drug concentration depends upon patient-
specific factors including the disease and desired
- Target trough ranges of 3 to 7 ug/mL and 5 to 10 ug/mL
have been studied in inflammatory bowel disease (1,2).
- In severe CD, higher trough levels (>10 ug/mL) may be
necessary to achieve fistula healing (3).
- In rheumatoid arthritis, EULAR responders had higher
trough levels (median 3.6 ug/mL) than non-responders
(0.5 ug/mL) (4).
Anti-Infliximab Antibody 40 ng/mL
The above result is a LOW Antibody titer.
Quantitation Limit: <22 ng/mL.
of 22 or higher indicate detection of anti-
22 - 200 ng/mL: LOW antibody titer, little/no apparent
reduction in free drug level
201 - 1,000 ng/mL: INTERMEDIATE antibody titer,
variable reduction in free drug level
1,001 or greater ng/mL: HIGH antibody titer, notably
diminished or absent free drug level
- Anti-drug antibodies may develop at any time during the
course of biological therapy.
- Low titer anti-drug antibodies may have little/no effect
on drug level/efficacy. Antibodies in low
titers may be transient and disappear overtime (5,6) or
they may progress to higher titers (6).
- High titers are likely to be more consequential, leading
to loss of drug efficacy by preventing drug binding to TNF
and/or increasing drug clearance (6,7).
- Maintenance of drug levels greater than 3 ug/mL may reduce
the risk of developing anti-drug antibodies (8).
anti-infliximab antibody assay is not impeded by the
presence of infliximab in serum (up to 100 ug/mL), and all
positive antibody results are verified by a confirmatory
My notes and questions: I was only on 3 vials of Remi (I should have been on 4 for my weight but they never bothered to weigh me) at the time this bloodwork was taken. I got 4 vials at my last infusion, on Oct. 31. I was able to get off prednisone right before my 3rd infusion and felt like I was in remission for 2 months. These antibody levels seem pretty low, so should my doctor be trying anything else, like increasing my dose and frequency before moving on to Humira and imuran? What are my chances of Humira being effective if I failed Remicade?
I'm currently taking 50 mg of pred and still having symptoms (abdominal pain, sometimes blood, painful BMs, but formed and leaning more towards constipation past 2 days! I can't win... ). It's been 2 weeks. I've never had such a poor response to pred before in my life.
Please help me decipher my results and figure out the next best step before my appt. Nov. 18. Thanks!
Also, please share any experiences with Humira or imuran.
35 years old; diagnosed UC March 2007 (couldn't get scope all the way thru).
9-29-16: chronic and active proctosigmoiditis (infectious cause). Battled reoccuring campylobacter & c diff. Oct-Dec 2016. Remission since 12/25/16 until I started smoking again in 2018 after 9 yrs quit. Re-quit smoking. Maintenance: Delzicol, 6, 2xday; Rowasa nightly. Started Remicade 7/25/19. 50 mg pred 10/29/19.
Post Edited (Sara14) : 11/10/2019 7:59:18 AM (GMT-7)