Approving molecularly targeted drugs: different approval processes for cytotoxic agents

Recently, the approval of some molecularly targeted drugs has been questioned, due to differing opinions on their risks and benefits. The approval process remains a challenge in regulatory science.

We analyzed the molecularly targeted drugs listed in the 2013 Medical Formulary. For the 21 identified drugs, 32 published Pharmaceuticals and Medical Devices Agency (PMDA) reports were open to the public. Data regarding clinical trials were extracted from these reports and assessed in order to clarify the characteristic examinations required for the approval of molecularly targeted drugs.

There was no correlation between the application year and the time between application and approval (p = 0.139). The median number of clinical trials in these reports was 5 (range 1-22). Phase III studies were not included in the assessment materials for 11 reports. A survival benefit was demonstrated for six of the 32 drugs. The PMDA issued approval terms, including all-case surveillance and additional clinical trials, for 24 of these 32 drugs.

Molecularly targeted drugs were approved by the PMDA using a flexible process based on drug safety and efficacy. Doctors and patients who are administering or receiving these drugs should be fully informed about the lack of Japanese data assessment during these approval processes.