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Many New Cancer Medications Don’t Receive Adequate Follow-Up
Research examining the FDA approval of cancer drugs from 2008 to 2012 has found that surrogate endpoints were used as the basis of approval in 36 out of the 54 cases. After an average of four years of follow-up, 31 of the medications still did not have data on overall survival (OS) or had failed to show improvements in survival.
Vinay Prasad, MD, MPH, of Oregon Health & Sciences University in Portland, and Chul Kim, MD, MPH, of the National Institutes of Health in Bethesda, Maryland, conducted the research, which states that a majority of the drugs that were included are frequently used in clinical settings.
According to MedPage Today, Prasad suggested that the FDA needs to enforce follow-up research, which is required in cases of accelerated drug approvals based on surrogate endpoints. "For any drug approved on the basis of surrogate — unless it's extremely well validated, which is very rarely true — patients deserve to have an answer to the question: Does the drug make them live longer or better?" Prasad said. "People say patients want more options, faster options, but my patients say they want better drugs. Are these better options? I don't think these are unreasonable questions to ask."
Prasad and Kim examined FDA market approvals for cancer drugs from 2008 through 2012, splitting them into accelerated versus traditional pathway categories and whether the surrogate endpoint (response rate, progression-free survival [PFS]) was used as the basis for approval. They found 54 cancer drugs that were approved in the study period, and 36 of those drugs (67%) were approved based on surrogate endpoints — 15 of those with accelerated approvals and 21 with traditional approvals.
The duo then looked for published literature about these drugs, including reports that used the drug in combination with other drugs or as second-line treatment, through August 2015. Reduction in tumor size and the rate of response for these cancer drugs were the primary measures of efficacy for 19 of the 36 (53%) of the drugs that were approved based on surrogate endpoints, and PFS or disease-free survival was used as the basis of approval for the other 17 (47%) of the drugs. After an average of 4.4 years of follow-up, later randomized studies showed improvements in OS for five of the 36 agents approved by surrogate endpoints — one accelerated and four traditional. However, 18 drugs (six accelerated, 12 traditional) failed to show improvements in OS as primary or secondary outcomes.
"Our results show that most cancer drug approvals have not been shown to, or do not, improve clinically relevant endpoints," the authors wrote. "Our results suggest that the FDA may be approving many costly, toxic drugs that do not improve overall survival. Enforcement of post-marketing studies is therefore of critical importance."
Sarah Peddicord, a spokesperson for the FDA, told MedPage Today in an email that "we have a longstanding commitment to regulatory flexibility regarding the evidence required to support approval of treatments for serious conditions for which there is unmet medical need."
Source: MedPage Today, October 19, 2015.