Adjustment of azathioprine dose in NUDT15 intermediate metabolizers, COVID-19 in Georgia & COVID-19 Phase 1 Vaccine Study

LA Jackson et al. NEJM 2020; DOI: 10.1056/NEJMoa2022483. Link:  An mRNA Vaccine against SARS-CoV-2 — Preliminary Report  The mRNA-1273 vaccine induced anti–SARS-CoV-2 immune responses in all participants (n=45), and no trial-limiting safety concerns were identified.

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COVID-19 in Georgia (Data from 7/13/20):


B Kang et al. AP&T 2020; https://doi.org/10.1111/apt.15810. Thanks to Ben Gold for this reference. Full text: Adjustment of azathioprine dose should be based on a lower 6‐TGN target level to avoid leucopenia in NUDT15 intermediate metabolizers

Background: “In addition to TPMT polymorphisms, a recent genome‐wide association study reported that a missense variant of nudix hydrolase 15 (NUDT15 ), which encodes a novel thiopurine‐metabolizing enzyme, was strongly associated with thiopurine‐induced leucopenia especially in Asians”

Key findings:

  • Among the 167 pediatric patients included, leucopenia was observed in 16% (19/119), 44% (20/45) and 100% (3/3) of the NUDT15 normal, intermediate and poor metabolizers respectively ( < 0.001)
  • There was a positive association between 6‐TGN levels and leucopenia among the NUDT15 intermediate/TPMT normal metabolizers
  • In order to reduce the development of thiopurine‐induced leucopenia (<15%) in NUDT15 intermediate metabolizers, adjustment of azathioprine doses should be based on a lower 6‐TGN target level (<167.1 pmol/8 × 108 RBC)

Limitations: single-center, retrospective study and possible selection bias

My take: While 6-TGN levels between 235-400 are typically considered therapeutic, individuals with intermediate metabolism are at increased risk for leukopenia and may respond at lower levels.  This study indicates that careful dosing and close monitoring is needed for NUDT15 intermediate metabolizers

Related blog posts:

Disclaimer: This blog, gutsandgrowth, assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  Because of rapid advances in the medical sciences, the gutsandgrowth blog cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition

Video for Patients: Benefits and Risks of IBD Treatment & Risks of Untreated IBD

A recent study (NE Newman, KL Williams, BJ Zikmunde-Fisher, J Adler. JPGN 2020;70: e33-36) highlights work to communicate the benefits and risks of the treatment for inflammatory bowel disease (IBD) along with the risks of untreated IBD.  “We developed a simple video aid to illustrate competing risks associated with medications and underling disease in context of inflammatory bowel disease…Those who viewed the video aid had more realistic perceptions than those who did not view it.”

Here is a link to the ~13 minute online video: IBD: Risk of Disease and Treatments

Overall, the presentation is very helpful and thoughtful.  I think this would be an excellent overview for families.  For practitioners, a few points that could benefit from some nuance are noted below some screenshots.  It is worth stating that the authors had started this project a few years ago and some of the points below are related to more information that has emerged.

In the section of treatment benefits (above), the presentation suggests that thiopurines (azathioprine, 6-mercaptopurine) and methotrexate both are effective in about 50%; this is probably an overestimate; in addition, methotrexate as monotherapy is definitely less effective (if effective at all) for ulcerative colitis .  Also, it would be worthwhile to indicate that anti-TNF monotherapy with therapeutic drug monitoring may help achieve similar benefits as dual therapy.

In the section of colon cancer, the authors provide useful data that current treatments lower this risk substantially.  It is notable that more recent reports suggest that there have been improvements in the rates of colon cancer associated with IBD.

Overall, the section on lymphoma is very good.

In the section on other complications, the presentation suggests that there may be impaired wound-healing with anti-TNFs.  I think this risk is overstated in this slide. Also, I think the risk of severe infection with thiopurines is a little bit higher than stated; though, this can be mitigated with careful monitoring.

I think this summary slide could be improved by noting that the overall risk of serious cancers is likely lowered by treating IBD.  Since colon cancer is a fairly common cancer and IBD treatment reduces the risk, this likely outweighs the increased risk of other cancers (eg. lymphoma) which are much less common.

Another link to video: https://tinyurl.com/IBDTreatments

Related posts:

Disclaimer: This blog, gutsandgrowth, assumes no responsibility for any use or operation of any method, product, instruction, concept or idea contained in the material herein or for any injury or damage to persons or property (whether products liability, negligence or otherwise) resulting from such use or operation. These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  Because of rapid advances in the medical sciences, the gutsandgrowth blog cautions that independent verification should be made of diagnosis and drug dosages. The reader is solely responsible for the conduct of any suggested test or procedure.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

IBD Updates November 2019

M Lowenberg et al. Gastroenterol 2019; 157: 997-1006. This LOVE-CD study, a prospective study with 110 patients with active Crohn’s disease, found that treatment with vedolizumab resulted in 29% and 31% corticosteroid-free clinical remission at weeks 26 and 52 respectively (CDAI <150).  Endoscopic remission, based on intent-to-treat analysis, was 33% and 36% at weeks 26 and 52.  Serum vedolizumab levels above 10 mg/L at week 22 were associated with endoscopic remission at week 26.

S Danese et al. Gastroenterol 2019; 157: 1007-18.  This VERSIFY trial, a phase 3b, open-label, single-group study of 101 patients with Crohn’s disease, found that treatment with vedolizumab resulted in 11.9% and 17.9%  endoscopic remission at week 26 and 52 respectively. Remission by MRE was 21.9% and 38.1% at those respective time points. No notable safety issues were reported.

N Khan et al. Clin Gastroenterol 2019; 17: 2262-8. Using a retrospective cohort of 54,919 patients with IBD followed by the VA System (2000-2018), the authors identified 467 patients with incident squamous cell cancer (SCC); median age ~70 years.  11 patients with SCC died from related-complications.  In this group, 8 had been exposed to thiopurines.   Thus, exposure to thiopurines increased mortality related to SCC compared to those exposed to mesalamine therapy, though the absolute risk among the entire cohort was less than 1 in 5000.  My take: Long-term use of thiopurines should be paired with dermatology evaluation and good skin care.

Pics from Mechandise Mart Light Show, Chicago

A Role for Thiopurine Therapy

In high school, the usual advice on multiple choice questions was to avoid picking “always” and “never” on multiple choice questions.

A recent commentary (KH de Boer et al.”Thiopurine Therapy in Inflammatory Bowel Diseases: Making New Friends Should Not Mean Losing Old Ones”Gastroenterol 2019; 156: 11-4) makes the point that “never” is probably the wrong answer with regard to thiopurine usage.

Key points:

  • “Thiopurine therapy has proven its value in maintenance of remission, decreased need for surgery, lowered colorectal cancer risk, less phenotypic disease progression, and synergistic effects when used with infliximab therapy, including increased biologic drug levels and less antibody formation.”
  • “Notwithstanding the extensive experience by many physicians, the clinical use of conventional immunosuppressive therapies has been questioned in recent years.”
  • “In this issue of Gastroenterology, Hanauer et al share their expert opinion on the evolving use of thiopurines and methotrexate in daily practice. In their literature review, the importance of assessing the risks (infections and cancer risk) and benefits (maintenance of remission) of thiopurine therapy is highlighted”
  • Lymphoma risk: “The recent nationwide cohort study based on French National Health Insurance databases is illustrative. Including 189,289 patients, it was demonstrated that both thiopurine (adjusted hazard ratio of 2.6) and anti-TNF monotherapy (adjusted hazard ratio of 2.4) were associated with a similar small but statistically significant increased risk of lymphoma. Furthermore, combination therapy of thiopurine and anti-TNF was associated with a higher chance of developing a lymphoma (adjusted hazard ratio of 6.1).”
  • “The individual absolute risk remains low, especially in patients without additional risk factors such as a young age in male patients and negative Epstein-Barr virus serology.”

The author’s conclusion: “The thiopurines are not perfect regarding both efficacy and toxicity, but in recent years they may have been portrayed in a worse light than they deserved. No doubt, the thiopurines will be surpassed eventually by newer safe and economical (oral) therapies, but it is too early to discard these old friends.”

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Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Monticello

 

#NASPGHAN17 IBD Treat to Target and Tight Control

More information from this year’s annual NASPGHAN meeting.

This blog entry has abbreviated/summarized these presentations. Though not intentional, some important material is likely to have been omitted; in addition, transcription errors are possible as well.

IBD Treat to Target: Treat the Patient or Treat the Disease

Robert Baldassano  Children’s Hospital of Philadelphia

I missed the first few minutes of this presentation, even though I had highlighted this as one of my top priorities.  So, if anyone reading this post has some additional comments, they are certainly welcome.

Key points:

  • Do not rely on symptoms alone to assess patient improvement.
  • Best surrogate marker: calprotectin.  Frequent calprotectin levels can help determine objective improvement; it is much more helpful than CRP as ~25% of patients do not elevate their CRP levels
  • Therapeutic drug monitoring is important in improving outcomes. Dose optimization improves response rate and durability of infliximab response.
  • Evolving targets in ulcerative colitis.  Even histologic activity, in the absence of endoscopic activity, is associated with relapsing disease
  • Dr. Baldassano indicated that he no longer is starting patients on thiopurine therapy. There are “36 phase 3 trials underway.” Thus, many promising options for those who may burn through current treatments
  • This lecture reviewed data from the RISK study showing that early (1st 90 days w/in diagnosis) TNF therapy helps prevent penetrating disease (related post: CCFA Update 2017/RISK study)

Another presentation by Philip Minar et al (Cincinnati Children’s Hospital Medical Center) shows that CD64 suppression is an early biomarker of response to infliximab therapy.

#NASPGHAN17 Is it time to stop using thiopurine therapy?

This blog entry has abbreviated/summarized this presentation. Though not intentional, some important material is likely to have been omitted; in addition, transcription errors are possible as well.

Safety in Pediatric IBD Therapy: Is it time to stop using thiopurines?

Jeffrey Hyams  Connecticut Children’s Medical Center

Key points from this lecture:

  • Dr. Hyams:  “There are better options than thiopurines in 2017 due to infrequent but serious risks”
  • The DEVEVOP study showed that anti-TNF agents did NOT increase the risk of lymphoma or hemophagocytic lymphohistiocytosis (HLH).  In contrast, these risks do occur with thiopurines –this is infrequent but remains significant.
  • Therapeutic drug monitoring may obviate the need for combination/dual therapy which has been shown to improve response rates to anti-TNF agents; methotrexate may work for combination therapy and may be safer than thiopurines
  • If a thiopurine is used as part of combination therapy, short duration (~6 months) is likely to have low risks
  • In addition to Dr. Hyams, Dr. Baldassano, in his discussion of treat to target (discussed in subsequent post), echoed the sentiment that he no longer recommends thiopurine therapy

Dr. Hyams slides list some of the relative risks of thiopurine therapy.  To understand these risks, the absolute risk is probably more helpful.

My take: This lecture did not focus on the main benefit of thiopurines which is its use in combination therapy. Many experts consider combination therapy to be the standard of care for adults with Crohn’s disease.  The advantages of combination therapy are mainly due to improved durability of anti-TNF therapy and lower antidrug antibodies.  How this benefit stacks up against the risks discussed in this lecture and whether this benefit can be supplanted by the use of therapeutic drug monitoring is uncertain.

 

Related blog posts:

Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) should be confirmed by prescribing physician.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Infliximab Not Associated with Malignancy

JS Hyams et al. Gastroenterology http://dx.doi.org/10.1053/j.gastro.2017.02.004

Using the DEVELOP registry, a prospective study showed no increased risk of malignancy among 5766 pediatric participants with inflammatory bowel disease.

Link: Full Abstract

Immunosuppressive therapy for inflammatory bowel disease (IBD) in pediatric patients is thought to increase risk of malignancy and lymphoproliferative disorders, including hemophagocytic lymphohistiocytosis (HLH). We compared unadjusted incidence rates and of malignancy and HLH in pediatric patients with IBD exposed to infliximab compared with patients not exposed to biologics and calculated standardized incidence ratios (SIRs).

Methods

We collected and analyzed data from 5766 participants in a prospective study of long-term outcomes of pediatric patients with IBD (NCT00606346), from 2007 through 30 June 2016. Patients were 17 years old or younger and had Crohn’s disease, ulcerative colitis, or IBD unclassified with 24,543.0 patient-years of follow-up. We estimated incidence rates for malignancy and HLH as events/1000 patient-years of follow-up. We calculated age-, sex-, and race-adjusted SIRs, with 95% CIs, using the Surveillance, Epidemiology, and End Results Program (SEER) database.

Results

Thirteen of the 15 patients who developed a malignancy and all 5 of the patients who developed HLH had been exposed to thiopurine; 10 patients with malignancy patients had also been exposed to a biologic agent. Unadjusted incidence rates showed no increased risk of malignancy (0.46/1000 patient-years) or HLH (0.0/1000 patient-years) in patients exposed to infliximab as the only biologic vs those unexposed to biologics (malignancy: 1.12/1000 patient-years; HLH: 0.56/1000 patient-years). SIRs did not demonstrate an increased risk of malignancy among patients exposed to infliximab (SIR; 1.69; 95% CI, 0.46–4.32) vs patients not exposed to a biologic agent (SIR, 2.17; 95% CI, 0.59–5.56), even when patients were stratified by thiopurine exposure.

Conclusions

In determination of age-, sex- and race-adjusted SIRs using data from a large clinical trial and the SEER database, we found that infliximab exposure did not associate with increased risk of malignancy or HLH in pediatric patients with IBD. Thiopurine exposure is an important precedent event for the development of malignancy or HLH in pediatric patients with IBD.

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Support for Step-Up Therapy and Thiopurines

A retrospective study (H Bar-Yoseph et al. Clin Gastroenterol Hepatol 2017; 15: 69-75) indicated that thiopurine use before infliximab (IFX) was associated with the prevention of antidrug antibody formation in patients with Crohn’s disease.

The authors had 207 eligible patients which included 93 who received IFX monotherapy, 52 who received combination therapy after response to thiopurine, 34 who received IFX after lack of response to thiopurines (but continued with combination treatment), and 28 who received de novo combination therapy.  The total number of patients followed in these centers is much higher, but they excluded those with episodic infusions and for other reasons that could affect their conclusions.

Key findings:

  • Prior thiopurine therapy was associated with lower antidrug antibodies (ADA). At 1 year, past thiopurine responders had 19.3% ADA, past thiopurine failures had 16.1% ADA; both were much lower that the monotherapy rate of 46.6%  The de novo combination group had a rate of 21.9% which did not reach significance.
  • Interestingly, after the first 5 months, the de novo combination group did not develop further ADA but during the first 5 months the rate of ADA was quite similar to the monotherapy rate. This could be related to the notion that thiopurines may take 3-6 months to achieve full effect.
  • Combination therapy (compiled)  was associated with higher rates of clinical remission (58.8% vs 40.9%) and lower rates of active disease (8.8% vs. 21.5%).

Overall, this study showed high rates of ADA compared to many studies but the conclusions are similar to other published studies.  It could be that many of those with positive ADA were lower antibody levels and that many of these levels may not be clinically significant. The study has limitations mainly related to being a retrospective study.

My take: This study supports the following:

  1. Combination therapy is more effective than monotherapy
  2. Using an immunomodulator before starting infliximab may reduce ADA formation more effectively than starting combination therapy de novo.

Related blog posts:

Disclaimer: These blog posts are for educational purposes only. Specific dosing/usage of medications (along with potential adverse effects) should be confirmed by prescribing physician.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

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Cost Effectiveness & Underpowered Studies

A recent study (ALT Ma et al. J Pediatr 2016; 179: 216-8) reaches a conclusion that questions the cost-effectiveness of pretreatment TPMT activity in pediatric patients. In my opinion, this retrospective study is ridiculous. Here’s why:

The authors examined thiopurine transmethyltransferase (TPMT level) in 228 children before starting a thiopurine. They found the following:

  • Only 2 patients experienced mild neutropenia
  • 12% of their cohort had intermediate activity and 88% normal TPMT activity

I agree with their conclusion that routine blood tests are needed following institution of thiopurines, I think stating that “from an economic point of view –the cost for testing TPMT enzyme activity was high without major clinical benefit” cannot be made with such a small study.  Deficient TPMT activity occurs in about 1 in 300.  If a single patient develops bone marrow suppression due to a thiopurine medication, this can lead to a horrific and prolonged hospitalization.  The cost of such a hospitalization, both economically and emotionally, is enormous.

My take: If I were taking a thiopurine, I would want to know if I metabolized this medication at a slower rate and was at increased risk for bone marrow suppression.  My hunch is the authors would not forgo checking a TPMT level on themselves despite their study’s conclusion, particularly if they have ever witnessed a patient with thiopurine-induced bone marrow suppression.

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One Proposal to Reduce Thiopurine Combination Therapy

A recent review (X Roblin et al. Inflamm Bowel Dis 2016; 22: 1496-1501) provided a useful review of thiopurine/biologic combination therapy.  The part of this review that I found intriguing was their Figure 3: “Proposed algorithm that may guide drug discontinuation or de-escalation in patients with IBD who achieved sustained deep remission while on combination therapy.”

  • In those (in sustained deep remission) with an infliximab trough level >5 mcg/mL, this algorithm recommends discontinuation of thiopurine.
  • In those with an infliximab trough level 3-5 mcg/mL and with 6-TGN >250, this algorithm recommends reduction of thiopurine to obtain 6-TGN level >125.
  • In those with an infliximab trough level <2 mcg/mL and with 6-TGN >250, this algorithm recommends discuss stopping infliximab.

The authors acknowledge that this algorithm has not been studied and “needs to be investigated in prospective trials specifically addressing this issue.”

My take: Until more studies emerge, the best way to balance control of IBD and minimize drug toxicity remains uncertain.

Unrelated references:

  • “Crohn’s disease of the ileoanal pouch” AL Lightner et al. Inflamm Bowel Dis 2016; 22: 1502-8.
  • SZ Koh et al. Inflamm Bowel Dis 2016; 22: 1397-1402. This reference describes clinical factors associated with development of Crohn’s disease in patients with IBDU who have undergone ileal pouch (e.g. younger age).

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