Picking Apart the SERENE-CD Study & Constipation Vibrating Capsule FDA Approved

Several recent letters to the editor provide some insight into some of the shortcomings of the SERENE-CD study which reported that higher adalimumab induction dosing and proactive therapeutic drug monitoring (TDM) were not associated with improved outcomes.

“The rerandomization design of SERENE CD, which selectively enrolled patients with clinical response at week 12 to the TDM vs CA part of the study, may have resulted in the exclusion of those who would have benefited the most from early adjustment of their anti-tumor necrosis factor (TNF) dose. The rerandomization design and the late adaptation of the proactive strategy at week 12 were 2 significant aspects of the design that may have led to the negative results. On the other hand, PAILOT, which showed beneficial effects of proactive TDM, randomized patients as early as week 4 and assessed the outcome at week 72. This is distinct from the 1-year time frame used in most other studies, including SERENE CD.8 A properly designed, adequately powered clinical trial is needed before we can make a judgement on the use of proactive TDM in patients with inflammatory bowel disease. Until then, the jury remains out.”

“The study design only allowed patients in the TDM group with adalimumab concentrations of ≥5 and ≤10 μg/mL to be escalated to 40 mg every week if their CD activity index was ≥220 or their high-sensitivity C-reactive protein level was ≥10 mg/L.. The goal of proactive TDM is to attain a threshold concentration regardless of disease activity. This design probably led the 2 groups to have similar drug concentrations at week 56…

Second, a rather low targeted drug concentration of 5 μg/mL was used, although previous studies have suggested that higher concentrations are more appropriate.5678 A study from Ungar et al5 showed that adalimumab concentrations of 8–12 μg/mL are required to achieve mucosal healing in 80%–90% of patients with IBD, and the prospective PANTS (The Personalised Anti-TNF Therapy in Crohn’s Disease Study) study identified an adalimumab concentration of 12 μg/mL at week 14 associated with remission at both week 14 and week 54.8..

Third, dose escalation for the TDM group could only happen at weeks 14, 28, or 42 (and not earlier and more often). In the PAILOT RCT, proactive TDM based on adalimumab concentration evaluations started as early as week 4 followed by week 8 and every 8 weeks thereafter until the end of the follow-up at week 72.3 Fourth, there was a rather short follow-up of the patients (44 weeks).”

” Even with the assumption of a 30% benefit of proactive TDM and that 20% of patients would have low drug levels in the absence of symptoms, the sample size for 80% power would range from 1228 to 2170. Thus, although SERENE CD1 and other clinical trials3,4 have suggested a lack of benefit of proactive TDM in adults with inflammatory bowel disease, all were likely substantially underpowered to do so.”

My take: While the SERENE-CD results have suggested that a strategy of proactive TDM may not be helpful, there are a lot of reasons to disregard these findings. Achieving a therapeutic level is a fundamental principle and proactive TDM, particularly in pediatrics, is well-supported by other studies.

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