Cancer drugs for solid tumors approved by the EMA since 2014: an overview of pivotal clinical trials.

The rule of 2 well-controlled trials was complied with in just over 50% of the authorized drugs, and even when there was only 1 pivotal trial supporting the authorization, the trial itself may not have been necessarily well-controlled; the authorization was revoked for a drug because the trial did not confirm the benefits expected from confirmatory trials; while for 2 drugs, the evidence of efficacy yielded by the trials was not considered exhaustive. Considering that sometimes clinical authorization trials do not provide complete data on safety and efficacy, it would be perhaps appropriate to gather more pre-marketing evidence or leverage post-marketing data to complete the available information and have greater certainty.