Good Safety Data on Infliximab vis a vis Malignancy and Hemophagocytic Lymphohistiocytosis

Using data from 5766 pediatric participants with inflammatory bowel disease in a prospective DEVELOP study (JS Hyams, MC Dubinsky et al. Gastroenterol 2017; 152: 1901-14) provide more reassurance regarding the safety of infliximab.  This study took place between 2007 to 2016 and accounted for 24,543 patient-years of followup.  While the study examined rates of malignancy, the SEER database does not include non-melanoma skin cancer; thus, the authors did not have a suitable comparator for this outcome; there were two cases of basal cell carcinoma in the study population.  This article’s abstract was published on this blog previously: Infliximab Not Associated with Malignancy

Key findings:

  • There was NO increased risk of malignancy or hemophagocytic lymphohistiocytosis (HLH) in patients exposed to infliximab as monotherapy.
  • Malignancy risk was 0.46 per 1000 patient-years in patients with infliximab exposure compared with 1.12/1000 patient-years in patients who had no exposure to biologics.
  • HLH risk was 0 in those with infliximab monotherapy compared with 0.56 per 1000 patient-years in those who had no exposure to biologics.
  • Patients exposed to thiopurines with or without biologics did have increased risks of malignancy compared with comparative populations. 13 of 15 patients who developed a malignancy and all 5 patients who developed HLH had thiopurine exposure.
  • Thiopurine exposed patients had 0.75 malignancy events per 1000 patient-years compared to 0.27 malignancy events per 1000 patient-years for patients who had no thiopurine exposure
  • Thiopurine exposed patients had 0.29 HLH events per 1000 patient-years compared to 0 HLH events per 1000 patient-years for patients who had no thiopurine exposure
  • In their discussion, the authors note that after discontinuation of thiopurine therapy for 1 or more years, the standardized incidence ratio (SIR) for malignancy approached the non-exposed group (1.48 compared to 1.30); whereas ongoing or recent thiopurine exposure had SIR of 4.45.

Limitations: Study duration (<10 years). Hard to detect changes in rare malignancies

My take: In this largest prospective pediatric cohort to date, there is NO increased risk of malignancy (excluding non-melanoma skin cancer) or HLH with infliximab therapy; however, there is a trend towards increased risk among those with thiopurine exposure. Nevertheless, as malignancy is a rare event, very low increased risk of malignancy with infliximab cannot be entirely excluded.

Related blog posts:

For HLH:

 

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