Phase IV Clinical Trials of Biosimilars for Cancer: Extrapolation of the ‘Basket Concept’ of Trials

Of late, the concept of ‘basket trials’, testing the effect of a single drug in multiple indications is receiving increased attention.[1] Can this concept be extrapolated to the clinical development of biosimilars? Majority of the regulatory agencies have the provision for the approval of biosimilars for one or more additional indications based on the concept of extrapolation without necessarily conducting trials in those indications. [2-4] However, such biosimilars that have been granted marketing approval based only on the extrapolation of data and not from the evidence of clinical trials in those indications may not provide the required confidence to the prescribers and patients alike. Furthermore, extrapolation of the immunogenicity findings to a different population may have its own limitations.