Table 2

EMA and FDA response to concerns regarding extrapolation of clinical data

ConcernEMAFDAPoints to consider
MOA may be distinct in each therapeutic indicationExtrapolation will be considered on a case-by-case basis. Where the MOA differs between indications or are not fully understood, separate clinical trials are likely to be necessaryFor instance, separate trials are likely to be necessary for rheumatology versus oncology
For a given MOA, several mechanisms may existAlmost superimposable biological data must be provided, covering all functional aspects of the agent, even if not considered clinically relevant. Where MOA are not fully understood, separate clinical trials are likely to be necessary
Risk of undertreating patients/varied safety profiles in different patient groupsData should be produced using a patient population and clinical endpoint most sensitive to detect clinically meaningful differences in efficacy and safetyDisease activity at baseline represents an important variable related to outcomes measures in RA–likely to have limited impact on a direct comparison between biosimilar and reference products when sensitive measures are used, but needs consideration when efficacy is compared with reference product trials
Individual patient characteristics may influence the responseHomogeneous population should be used–difference in response can then be attributed to the biosimilarCareful consideration must be given to comorbidities/concomitant medications and intersubject variabilityEMA approach–it will be difficult to identify a homogeneous population for a heterogeneous condition such as RA