Surrogate Markers on the Rise
Dr. Wallach’s group looked for published meta-analyses compiling randomized controlled trials reporting surrogate endpoints for more than 3 dozen chronic nononcologic conditions, including type 2 diabetes, Alzheimer’s, kidney disease, HIV, gout, and lupus. They found no meta-analyses at all for 59% of the surrogate markers, while for those that were studied, few reported high-strength evidence of an association with clinical outcomes.
The findings echo previous research. In a 2020 study in JAMA Network Open, researchers tallied primary endpoints for all FDA approvals of new drugs and therapies during three 3-year periods: 1995-1997, 2005-2007, and 2015-2017. The proportion of products whose approvals were based on the use of clinical endpoints decreased from 43.8% in 1995-1997 to 28.4% in 2005-2007 to 23.3% in 2015-2017. The share based on surrogate endpoints rose from 43.3% to roughly 60% over the same interval.
A 2017 study in the Journal of Health Economics found the use of “imperfect” surrogate endpoints helped support the approval of an average of 16 new drugs per year between 2010 and 2014 compared with six per year from 1998 to 2008.
Similar concerns about weak associations between surrogate markers and drugs used to treat cancer have been documented before, including in a 2020 study published in eClinicalMedicine. The researchers found the surrogate endpoints in the FDA table either were not tested or were tested but proven to be weak surrogates.
“And yet the FDA considered these as good enough not only for accelerated approval but also for regular approval,” said Bishal Gyawali, MD, PhD, associate professor in the department of oncology at Queen’s University, Kingston, Ontario, Canada, who led the group.
The use of surrogate endpoints is also increasing in Europe, said Huseyin Naci, MHS, PhD, associate professor of health policy at the London School of Economics and Political Science in England. He cited a cohort study of 298 randomized clinical trials (RCTs) in JAMA Oncology suggesting “contemporary oncology RCTs now largely measure putative surrogate endpoints.” Dr. Wallach called the FDA’s surrogate table “a great first step toward transparency. But a key column is missing from that table, telling us what is the basis for which the FDA allows drug companies to use the recognized surrogate markers. What is the evidence they are considering?”
If the agency allows companies the flexibility to validate surrogate endpoints, postmarketing studies designed to confirm the clinical utility of those endpoints should follow.
“We obviously want physicians to be guided by evidence when they’re selecting treatments, and they need to be able to interpret the clinical benefits of the drug that they’re prescribing,” he said. “This is really about having the research consumer, patients, and physicians, as well as industry, understand why certain markers are considered and not considered.”
Dr. Wallach reported receiving grants from the FDA (through the Yale University — Mayo Clinic Center of Excellence in Regulatory Science and Innovation), National Institute on Alcohol Abuse and Alcoholism (1K01AA028258), and Johnson & Johnson (through the Yale University Open Data Access Project); and consulting fees from Hagens Berman Sobol Shapiro LLP and Dugan Law Firm APLC outside the submitted work. Dr. Ramachandran reported receiving grants from the Stavros Niarchos Foundation and FDA; receiving consulting fees from ReAct Action on Antibiotic Resistance strategy policy program outside the submitted work; and serving in an unpaid capacity as chair of the FDA task force for the nonprofit organization Doctors for America and in an unpaid capacity as board president for Universities Allied for Essential Medicines North America.
A version of this article appeared on Medscape.com.