Tag Archives: PML

Running out of options

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A series of articles on natalizumab were published which give practical advice for this drug which clinicians often turn to when ‘running out of options’ (Gastroenterol Hepatol 2012; 8: 4-17).

Slides from these articles should be available soon (not online on 1/2/13):

http://www.clinicaladvances.com/index.php/our_publications/gastro_hep-issue/gh_november_2012/

According to an algorithm on page 7, in patients with moderate-severe Crohn’s disease who have failed conventional therapies and anti-TNF drugs (or unable to tolerate), the next step is to obtain anti-JCV (John Cunningham Virus) antibody status.  Patients who test negative are ‘Okay to treat with natalizumab’ due to very low risk of progressive multifocal leukoencephalopathy (PML).  Repeated testing at least once a year is then recommended.

For patients who test positive for anti-JCV at any time point, natalizumab can be considered if no other treatment options are available, but the risk of PML is much greater. Previous blog entries (below) have discussed this in greater detail and have provided additional references:

Another article published the experience in 36 Mayo clinic patients between April 2008-September 2010 (Inflamm Bowel Dis 2012; 18: 2203-08).  Consecutive patients who received natalizumab were prospectively followed.  Of the 36 treated with natalizumab, 30 agreed to participate in the study.  23 patients had failed two anti-TNF agents and 7 had failed one anti-TNF agent.  Median age was 35 years.

Results:

  • 14 (46%) had a complete clinical response, 12 had a partial response, and four had no response.  Cumulative probability of a complete response within 1 year was 56%.
  • Time to response: 10% after 1st dose, 50% of patients had complete response after 4th dose
  • Adverse events were common –though this rarely caused drug cessation. Common events included headache and infections (listed in Table 4 of article).  Some infections prompted holding natalizumab for up to 8 weeks.
  • 11 stopped natalizumab due to lack of improvement.

Quantifying Risk of PML with Natalizumab

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Given the limited number of treatment options for inflammatory bowel disease, when Natalizumab became available, there was a great deal of enthusiasm.  This quickly diminished as reports of progressive multifocal leukoencephalopathy (PML) emerged.  So far, I have not prescribed this agent.

Due to its efficacy for multiple sclerosis and IBD, there has been continued interest in understanding the risk for PML (NEJM 2012; 366: 1870-80, editorial pg 1938-39).

Key findings:

  • 212 cases of PML among 99,571 patients treated with natalizumab (2.1 cases per 1000)
  • Three main risk factors: positive JC-virus antibody, previous use of immunosuppressants, and receiving natalizumab more than 2 years

Patients who were negative for anti-JC virus antibodies had an incidence of 0.09 cases or less per 1000 patients.  Among patients who test positive for anti-JC virus antibodies, the risk remained <1 per 1000 patients if no use of immunosuppressants and 2 per 1000 if prior use of immunosuppressants during the first two years of therapy.  The risks were five-fold higher after 2 years in both groups.

While the risks are becoming more clear, the benefits of natalizumab are fairly well-established for multiple sclerosis.  Natalizumab decreased the annualized rate of relapse among patients with relapsing–remitting multiple sclerosis by 68%.

Additional references:

  • -NEJM 2009; 361: 1067, 1075, 1081.  Asymptomatic detection of JC virus common in urine noted in patients Rx’d with natalizumab (19% baseline to 63% on Rx); actual leukoencephalopathy ~1/1000 patients.
  • -Gastroenterol 2007; 132: 1672.  ENCORE trial.
  • -JPGN 2007; 44: 185. n=31 children/adolescents.  55% response, 29% remission; dosed at 3mg/kg.
  • -IBD 2007; 13: 2.  n=79.  Trial of combination natalizumab & infliximab.
  • -NEJM 2006; 354: 899, 911, 924.  Natalizumab slows progression of MS.  Risk of PML due to JC virus 1:1000 in 18 months of Rx.
  • -NEJM 2005; 353: 1912/1965.  Natalizumab not significantly effective for Crohn’s in this study
  • -NEJM 2005; 353: 362, 369, 375, 414.  3 cases of PML associated with Natalizumab
  • -JPGN 2004; 39: S49 [abstract 0107].  Natalizumab in 38 adolescents was effective (Hyams et al).
  • -Gastroenterol 2004; 126: 1574-81. review.  Natalizumab benefitted subjects with elevated CRP. (dosing 300mg every 4 weeks.)
  • -NEJM 2003; 24-32 & 68.  Natalizumab improved response rates in pts c Crohn’s dz (similar to infliximab).  Drug blocks alpha4 integrins which are required for lymphocytes to enter the intestine.
  • -Gastroenterol 2001; 121: 268-74. Infusion of 3mg/kg decreases CDAI in Crohn’s dz.