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According to a study published on Tuesday, cancer drugs that come to the market quickly based on encouraging preliminary studies do not show any obvious benefits when more in-depth follow-up testing is done.
Accelerated approval of these cancer drugs is being granted to give patients faster access to treatment and pharmaceutical companies to reap the benefits of their economic benefits more quickly. As a condition of this process, the Food and Drug Administration is asking pharmaceutical companies to conduct further research to confirm whether the drugs are effective and safe.
In 2018, the FDA reviewed 93 cancer drugs receiving accelerated approval and claimed that only five of them had been removed from the market in 25 years. A team of researchers from the Regulatory, Therapeutic and Law Program at Harvard Medical School dug deeper to see what was happening with others.
In follow-up studies, only 19 of the 93 drugs clearly extended the life of the patients taking them, according to the study published in the last report. JAMA internal medicine.
For example, Genentech's Avastin, or bevacizumab, was approved earlier to treat deadly glioblastoma from brain cancer, but the drug did not prolong patients' lives in a follow-up study.
Sometimes patients like drugs because they improve their quality of life. This drug did not do that either, but the FDA left it on the market as an approved treatment for glioblastoma.
"That was the most confusing thing," says Bishal Gyawali, an oncologist with the research team. "I find it very difficult to understand."
The researchers said that follow-up studies of these anti-cancer drugs often did not even use overall survival or improvement of quality of life as a reference.
Instead, many used the same measure that formed the basis of their preliminary approval – for example, removal of the tumor. These targets, called "surrogate parameters," often do not predict who will live longer or more comfortably.
"How can we use the same surrogate parameter and say that they have a clinical benefit in a confirmation test?" Gyawali asks, while this end point was clearly not enough for a full approval of the drug from the outset. (Gyawali is now at Queens University in Ontario).
"The reason for giving these approvals should be transparent," he says, but the FDA does not explain its reasoning.
A second study in the same issue examined approved anti-cancer drugs based on a specific surrogate criterion called "response rate". The response to a drug can range from dramatic and complete remission to weak and transient narrowing of the tumor. And these answers do not necessarily mean that people will live longer or be more comfortable.
The study examined 59 initially approved cancer drugs based on their response rate and found that only six of them ended up getting regular approval based on their survival benefits.
Studies based on the response rate do not include a comparison group, scientists at Oregon Health and Science University say it's hard to say whether these new drugs are better than other drugs already on the market.
Sometimes, there is no comparison group because it is rare cancers, or the drug targets a rare mutation of a common cancer. It is therefore difficult to conduct a randomized study of patients in different treatment groups, says Dr. Richard Schilsky, Executive Vice President. and Chief Medical Officer of the American Society of Clinical Oncology.
But in other circumstances, "if we invest in it, we will be able to do randomized controlled trials," says Emerson Chen, an oncology researcher at OHSU. These studies often add a year or more to a follow-up study, he says, but he defends them because they provide "more definitive information on the survival and outcomes reported by hospitalized patients".
"One of the reasons we do not do this kind of studies, is that people say that these drugs are so powerful that it would be wrong to do that kind of thing." 39 studies … ethical or practical, "says Vinay Prasad, oncologist, lead author of the paper. "But I think what we find is that these drugs are unfortunately not so powerful."
In a commentary, Dr. Ezekiel Emmanuel and colleagues at the University of Pennsylvania write that "there is no valid reason for the FDA to rely as much on an endorsement accelerated using response rates or other unreliable substitution criteria ".
"Medications whose effectiveness has not been proven are a false hope for desperate patients, who pay thousands of dollars out of pocket," he writes, "The approval of ineffective drugs also eliminates any innovation that can produce effective treatment. "
The FDA is under pressure from patients and pharmaceutical companies to accelerate the approval of new anti-cancer drugs and must constantly strike a balance between innovation and caution, Schilsky says of ASCO.
Randomized trials are the norm in cancer research, but it says that they can be difficult if a drug is already on the market.
"When the preliminary results of some of these new treatments seem very promising, it is particularly difficult to convince patients to accept randomization with a standard treatment that may be much lower – or at least seem much lower – than the new treatment." , Schilsky says.
He also opposes the "radical generalizations" of these two studies. "Regulatory decisions have to be made on a case-by-case basis and in a particular context," he said. But the FDA should be more transparent about its decisions so that scientists can better understand them.
The FDA has not provided NPR with details about its decision to leave Avastin on the brain cancer market. In a statement, a spokeswoman for the agency said the FDA was evaluating the risks and benefits, stating that it "has been widely acknowledged that the benefits can be demonstrated by a number of parameters, and not just by overall survival. "
You can contact NPR Scientific Correspondent Richard Harris at [email protected].
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