Tag Archives: azathioprine

More on IBD medicine risks

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As noted in a recent post (Assessing and discussing risk of lymphoma in IBD), diagrams can be useful to convey the absolute risks for IBD medicines; this risk is often poorly understood by patients and their families. Two articles add additional insight that may help with counseling. (Thanks to Ben Gold for forwarding these articles.)

  • Am J Gastroenterol 2012; 107: 964-70.
  • Am J Gastroenterol 2012; 107: 1051-63.

The first article reviews the risk of lymphoma with regard to inflammatory bowel disease treatment decisions.  Important points in this article include the following:

1. Relative risks may appear large while absolute risk may be quite low.  The estimate for absolute risk for lymphoma:

  • For azathioprine or 6-mercaptopurine: 1 additional case for every 4357 persons treated
  • For anti-TNF (infliximab, adalimumab, certolizumab): 1 additional case for every 2380 persons treated between ages 20-29.

2. Framing the discussion with regards to risk of continued active disease, continued exposure to steroids, and potential need for surgery can be helpful:

  • “It would take only three patients discontinuing their azathioprine to cause one additional relapse of IBD per year”
  • Seven patients stopping anti-TNF therapy would result in an additional hospitalization each year and 14 patients stopping anti-TNF therapy would result in an additional abdominal surgery each year
  • While the ‘relative risks of lymphoma associated with these medications may sound inappropriately large…A more appropriate comparison is the absolute risk of lymphoma versus the absolute risk of active/untreated disease or corticosteroid therapy.’  An example: if 2000 patients with IBD took one of these medications (eg. anti-TNF agent), probably one patient will develop a lymphoma; however, if none of those patients took an anti-TNF agent, it would result in more than 100 hospitalizations and nearly 60 surgeries.

3. “Patients can also be very sensitive to numerators and pay relatively insufficient attention to denominators.” This has been called “anchoring and adjustment” or “base-rate neglect.”  This issue has to do with “numeracy;” this is defined as the basic math skill needed for health-related activities. To help families, consider the following:

  • avoid labels such as “very low” when describing risk
  • use absolute risk data
  • use similar denominators when comparing risks
  • use visual aids

The second study cited is a pooled analysis of infections, malignancy, and mortality risks associated with infliximab and immunomodulator treatment in adult IBD patients.  This study collected safety data from 10 previous trials.  Five of these trials were randomized, controlled studies.  Table 3 and Table 4 detail extensive safety data for immunomodulators (eg. azathioprine) and for infliximab respectively.

With regard to immunomodulators, the combined studies enrolled 947 on immunomodulators in comparison to 1170 without immunomodulators.  With ulcerative colitis (UC) patients but not with Crohn’s disease (CD), immunomodulator use increased the risk of infections (120/100 patient years versus 92.5 among placebo-treated patients).  CD patients, but not UC patients, had an increased risk of malignancy with immunomodulator use (1.84/100 patient years compared with 0/100 patient years in the control group).  With the exception of the SONIC study, use of immunomodulator was not randomly assigned.  So, some of the increased risk in these patients could be due to having more severe IBD rather than due to the medication.

With regard to infliximab, and in contradiction to the previous article’s estimated risks, infliximab treatment did not appear to affect the incidence of infection, mortality, or malignancy.  This study and several others have not demonstrated an increased risk of malignancy with infliximab. This could be that even with this pooled data it is difficult to detect a rare adverse outcome.  More prospective studies and more long-term followup will be needed to truly determine the risk.

While it is known that these agents may increase the risk of some infections, the limited increase in infections which was detected only with immunomodulator use in UC is likely due to a lowered risk of infection when active inflammatory bowel disease is controlled.  A much bigger risk factor for infection is the use of corticosteroids.  When effective IBD medications are administered, this helps control inflammation and allows tapering of corticosteroids.

Related posts:

TNF-α antagonists and infections

Disease modifying treatment in IBD

Only one chance to make first impression

Natural laws not patentable: the case with Prometheus

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While most individuals might think of greek mythology or the recent movie when hearing the word “Prometheus,” pediatric gastroenterologists might think of the company that performs a number of useful diagnostic tests.  Recently, Prometheus has had a legal setback (NEJM 2012; 365: 2338-40). 

Since the 1990s, Prometheus has tested for azathioprine (& 6-mercaptopurine) metabolites.  A therapeutic level of 6-thioguanine (6-TG), a metabolite for these drugs, is recognized as generally between 230-400 pmol per 8×10(to the 8th) red cells.  Levels outside this range often require drug adjustments.

When the Mayo clinic started to offer a slightly different assay, priced 25% below Prometheus’s test, Prometheus sued for patent infringement.  The court held that “if a law of nature is not patentable, then neither is a process reciting a law of nature;”  hence, Prometheus’s patent was rejected.

There are implications of this lawsuit on the use of a large number of biomarkers.  For example, patents for BRCA DNA sequences that increase the risk for cancer will probably be overturned.  Industry groups argue that denying patents will halt progress as companies will not be able to recoup investments in biomarker development.  Congress could consider passing laws allowing exclusive marketing of these innovations.  Alternatively, adequate funding through the NIH (National Institutes of Health) could allow development of biomarkers without the need for patents; in fact, 100 projects are in progress at this time.

Assessing and discussing risk of lymphoma in IBD

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A recent article has shown that the absolute lymphoma risk from medications in children and young adults with IBD is quite low (Inflamm Bowel Dis 2012; 18: 838-43).

In this single center study from 1979-2008, 1374 pediatric IBD patients had charts reviewed to determine whether lymphoma developed.  In total, two male patients who had received thiopurines developed lymphoma (one Hodgkin, one anaplastic large cell) in 6624 patient-years of follow-up.  Both patients are alive after chemotherapy.  Mean follow-up was 4.8 years per patient.  The absolute lymphoma incidence rate was 3 per 10,000 patient-years; after thiopurine exposure, the rate was 4.5 per 10,000 patient-years compared to an expected 0.58 per 10,000 patient-years.

In this study, 22% of the patients had received TNF inhibitors.  None developed lymphoma.  The risk of biologics could not be fully assessed due to a limited study period: 713 person-years taking the medication.

The risk of thiopurine-associated lymphoma was similar to previous studies but did not reach statistical significance.  As related in other studies, the risk of biologic agents, like Remicade, Humira, and Cimzia, is heavily influenced by whether patients had also received immunomodulators.

One useful way to try to convey this risk has been with diagrams.  One useful diagram is a palette of one thousand people or of 10,000 people showing the absolute risk and one showing the risk for other complications like infection.  You can make your own by going to the following link:

Download Communication Tools

RiskComm

Additional references/blog entries:

Only one chance to make first impression

Biologics | Living Longer | Arthritis Today Magazine -From Arthritis magazine: biologics improve survival in Rheumatoid arthritis

Drug levels for inflammatory bowel disease

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In many conditions, drug levels are helpful to make sure the patient receives an adequate dose for the indication.  When we treat infections or seizures, drug levels predict the effectiveness of the medication and allow dosing adjustments to improve responses as well as to lower toxicity. Drug levels are helpful in inflammatory bowel disease (IBD) as well.  Drug levels may help with thiopurine dosing and with infliximab (IFX) dosing.

Infliximab (IFX) levels can guide therapy (Scand J Gastroeneterol 2011; 46: 310-18). This study examined 106 patients (85 with CD and 21 with UC) over a ten-year period. In this cohort, patients received concurrent hydrocortisone, acetaminophen, and cetirizine to prevent acute reactions and to try to limit anti-infliximab antibodies (ATI), also called anti-human antichimeric antibodies (HACA).  Infusion intervals ranged from 4-12 weeks.

69% of Crohn’s patients maintained response to IFX and 48% of UC patients.  Infliximab trough levels were significantly increased among patients who maintained their response.  A cutoff value of 0.5 μg/mL was defined as clinically relevant for IFX trough concentrations for Crohn’s patients and for UC the cutoff was 0.8 μg/mL .  Trough levels below this cutoff were 86% sensitive and 85% specific for identifying loss of response.  The overall accuracy for the test was 87% in identifying loss of response.

Also, ATIs were significantly higher in CD patients who had lost response to infliximab.  Patients who had been “re-treated,” were significantly more likely to have developed ATIs.  “Re-treated” was defined as having interruption of IFX treatment more than 6 months.

These specific cutoff values apply to the radioimmunoassay technique for measuring IFX and ATI.  These values may not extrapolate to ELISA assays.  At the same time, the findings suggest a practical approach in patients with symptoms while receiving IFX:

  • Check IFX level (at trough or at 4 weeks)
  • If low level and no ATI, likely to respond to dose escalation
  • If low level but positive for ATI, not likely to respond to dose escalation
  • Do not assume symptoms are due to drug failure; reassess with imaging &/or scope. Consider alternate etiologies (eg infections, stricture, celiac, IBS).
  • Cotherapy with an immunomodulator reduces ATIs and boosts levels of IFX.
More usage of IFX and ATI levels is likely; however, cost issues preclude frequent measurements.

Additional references:

  • Only one chance to make first impression.  Previous blog entry on use of infliximab.
  • -Clin Gastro & Hepatology 2011; 9: 395. Do not assume symptoms are due to drug failure -reassess with imaging &/or scope. Consider alternate etiologies (eg infections, stricture, celiac, IBS). Check IFX level –if >12 @ 4weeks or >1.4 mcg/mL at trough –>predicts good response.  If +HACA, ~90% response with alternative TNF.  In those with low level, 86% responded to dose escalation.
  • -DDW 2011, Abstract #772. If loss of response to IFX, **confirm active dz (labs, scope) & not due to CDT. **check HACA –if +, only 10-20% chance of responding to dose escalation; better chance of responding to similar agent **check IFX week 4 level, if low (& neg HACA) then 90% respond to dose escalation
  • -NEJM 2010; 362:1383-1395. SONIC study.  Patients with moderate-to-severe Crohn’s disease who were treated with infliximab plus azathioprine or infliximab monotherapy were more likely to have a corticosteroid-free clinical remission than those receiving azathioprine monotherapy.
  • -Gut 2010; 59: 49-54. Trough IFX levels in UC. n=115. Antibody status can only be measured at trough levels. Undetectable trough level (<1.4 mcg/mL) associated with lower remission (15% vs 69%) and lower endoscopic response (28% vs 76%) & higher colectomy rate (55% vs. 7%).
  • -Gastroenterology 2010; 139: 344 (review of above Gut article). Similar to Crohn’s disease: 82% remission with detectable trough vs 6% w/o detectable level.
  • –Lancet 354 (9194): 1932–9. doi:10.1016/S0140-6736(99)05246-0. PMID 10622295.”Infliximab (chimeric anti-tumour necrosis factor alpha monoclonal antibody) versus placebo in rheumatoid arthritis patients receiving concomitant methotrexate: a randomised phase III trial. ATTRACT Study Group”.
  • -Am J Gastroenterol 2010; 105: 1133-39. If lack/loss of response, may need dose escalation with humira or Cimzia (q2weeks):
  • -IBD 2011; 17: 141-51. Loss of response to biologics.
  • -Gastro & Hep 2008; 4: 12. “primary nonresponse can be determined after 2 doses” in table reiterating AGA consensus guidelines. 85% of responders show benefit by 2weeks & all responders benefit c/in 6 weeks (Am J Gastro 2001; 96: S303). Worsening Sx despite infliximab indicates need to look for stricture, infxn, etc.
  • -Clin Gastro & Hep 2006; 4: 1248. Clinical remission associated with measurable infliximab troughs; thus, if no measurable trough, increase dose or shorten interval. If level detected & no response, unlikely to respnd to TNF class. Also, concurrent immunomodulators were not helpful.
  • -Am J Gastro 2010; 105: 2617 (Oussalah et al). 2-3yrs 41% IFX failure in UC. withdrawal of AZA increase loss of response –7x more likely
  • -Am J Gastro ; 105: 1133-40. n=155. 23% ATI -92% respond to med change, 17% respond to dose change. Level <12 @ 4weeks, 86% respond to dose change
  • -Gut 2010; 59: 1363. n=121. Co-treatment helped reduce complications & flares relative to monotherapy (& azathioprine appeared to be more effective than methotrexate).

Only one chance to make first impression

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Infliximab (IFX) came into clinical practice in 1998 after impressive results, published in the New England Journal of Medicine, demonstrated remarkable success in refractory Crohn’s disease  and even allowed resolution of fistulas.  Due to its expense and perceived risks, IFX has been typically reserved for treatment failures & significant perianal disease.  Although there have been discussions about ‘top-down’ therapy for many years, more and more it has become apparent that the best opportunity to influence the natural history of Crohn’s disease is early in the course; and perhaps in some cases of ulcerative colitis early IFX treatment may be worthwhile.  Clinical experience and treatment trials have shown that IFX response is significantly greater in Crohn’s disease than ulcerative colitis.  
Data on the postoperative course of Crohn’s disease has been informative on this approach as have large studies demonstrating that IFX is likely at least as safe as any other medication treatments for moderate-to-severe disease (eg. thiopurines, corticosteroids, methotrexate, tacrolimus).  With regard to postoperative Crohn’s disease, it has been shown that microscopic disease may develop within one week of intestinal resection.  More than 70% of postoperative patients develop significant mucosal recurrence within 12months (i2 or greater); yet, symptoms may not develop for a much longer time.  When significant mucosal disease is present, it may already be too late to achieve optimal response to IFX and similar agents due to remodeling of the intestinal submucosa.  Early in the course of Crohn’s disease, the vast majority of patients have an inflammatory phenotype (Cosnes J, et al. Inflamm Bowel Dis. 2002; 8:244-25), whereas later in the course, stricturing and penetrating disease are increasingly common.  

Postoperative mucosal scoring system:

• i1 – 5 or fewer apthous lesions

• i2 – more than 5 apthous ulcers with normal mucosa between, or skip areas of larger lesions

• i3 – diffuse apthous ileitis with diffusely inflamed mucosa

• i4 – diffuse inflammation with large ulcers, nodules or narrowing

 Rutgeerts et al. Gastroenterology 1990;99:956-83

Top-down approach:

Benefits: higher efficacy, lower disease-related complications, decrease surgery, improvement in catchup growth/bone formation (both not shown in AZA trials)

Risks: higher costs (but probably cost-effective)

**IFX therapy early may save health care costs by reducing surgery/hospitalizations:  Jewell DP et al, Eur J Gastroenterol Hepatol 2005, Leombruno JP et al Pharmacoepidemiol Drug Saf 2011

Conventional approach with accelerated step-up:

Risks: lower efficacy, higher infection risk/mortality with repeated steroids

Benefits: possibly lower cost

Potential drawbacks with azathioprine or 6-mercaptopurine (thiopurine class):

  • IBD 2011; 17: 2138. AZA can achieve remission in only ~30%.
  • Canc Research 2009; 69: 7004.  AZA is carcinogen– incorporated into DNA & changes sun absorption.  Skin cancer risk never drops when stopping med.
  • Gastro 2011; 141: 1621: CESAME (n=19,486)  thiopurines associated with NHL risk.  HR 5.28.
**Much of the information on this posting was influenced by presentations at “Advances in IBD 2011.”  Specific speakers that influenced this posting include Robert Baldassano, Marla Dubinsky, and Miguel Regueiro.

Additional References:

  • IBD 2009; 15: 1583. Postoperative mgt: low risk (1st surg, short stricture) –>no Rx; moderate risk (<10yrs of dz, long stricture, inflammatory dz)–>6MP; high risk (penetrating dz, >2 surg) –>IFX.  Post-op scope @6-12mo
  • JPGN 2009; 48 suppl 2: S72
  • Clin Gastro & Hep 2009; 7:183. Long term results with surgery for small bowel Crohn’s. n=865 surgeries. Risk for repeat surgeries: younger age, upper small bowel location, stricturing
  • Gastroenterology 2009; 136: 441. IFX prevents recurrent Crohn’s post-op. n=24. 1/11 w recurrence vs 11/13 control patients.
  • Am J Gastro 2008; 103: S412 (abstract 1054) IFX reduces post-op recurrence. clinical recurrence 0% at week 54 vs 39% of controls. n=23. 90% in IFX group with endoscopic remission vs 15% of placebo group.
  • Lancet 2008; 371: 660-667.   top-down strategy more likely to achieve endoscopic remicssion after 2yrs: 73% vs 30%. n=129.
  • NEJM 2010; 362: 1383. Sonic study. Combination AZA/IFX with greater efficacy. 56.8% remission in combo Rx vs IFX monotherapy.
  • Gut 2010; 59: 1363.   n=121.  Co-treatment helpd reduce complications & flares relative to monotherapy (& azathioprine appeared to be more effective than methotrexate).
  • JPGN 2009; 49: 183.  REACH pediatric trial showed good perianal dz response to infliximab.