To the Editor Observing that the US Food and Drug Administration (FDA) has, since 2008, been approving more and more cancer drugs on the basis of surrogate outcomes, Drs Kim and Prasad documented the tenuous or unknown links of surrogates with overall survival in a recent article in JAMA Internal Medicine and called for enforcement of follow-up studies that are legislatively required after all such approvals.1 This concern accords with a previous analysis2 that found that postmarketing studies were performed in only two-thirds of cases and with a median delay of 4 years.
Braillon A, Menkes DB. Balancing Accelerated Approval for Drugs With Accelerated Withdrawal. JAMA Intern Med. 2016;176(4):566-567. doi:10.1001/jamainternmed.2016.0351