Before
drugs can be prescribed on the NHS, they must be approved by the
European Medicines Agency (EMA).
The
EMA bases its decisions on clinical trial data submitted by
pharmaceutical manufacturers.
Cancer
drugs have comprised the single largest category of new drug
approvals in Europe. In 2017, more than a quarter (24/92) of EMA
approvals were for cancer drugs. Between
2014 and 2016, the EMA approved 32 new cancer drugs on the basis of
54 pivotal studies. Of these, 41 were randomised controlled trials
(RTCs) - considered the gold-standard for research because the new
drug is compared against a placebo, and participants do not know
whether they are on the medication or the placebo.
Researchers
warned thattreatment effects may have been exaggerated and called for
stricter rules on how new drugs were judged, including a renewed
focus on patients' overall survival instead of measures such as
progression-free survival or disease response which "do not
consistently translate to survival gains or quality of life
benefits". researchers
argue that uncertainty and exaggeration of the evidence that supports
approval of cancer drugs “causes direct harm if patients risk
severe or fatal adverse effects without likely benefit, or forgo more
effective and safer treatments.” Inaccurate evidence also leads to
intangible harms, which encourage false hope and create a distraction
from needed palliative care, they add.
The
researchers found that 19 of the 41 RCTs (49%) were at high risk of
bias "based on their design, conduct or analysis". Problems
included such things as participants not being properly randomised,
or a lack of "blinding" - a technique which means neither
the participants nor the researchers themselves know who is on the
drug or the placebo. Double-blind trials were less prone to bias, but
more expensive to organise.
Clinical
trials have increasingly looked to alternative ways of measuring a
drug's effectiveness in cancer patients, such as progression-free
survival - the length of time without relapse.
These
types of studies are cheaper and easier to organise because they can
use smaller sample sizes and results are generally reported earlier -
clinical trials are on average 11 months shorter than those using
overall survival as the outcome.
However,
the BMJ study found that bias was more common where these alternative
measures were used, and lowest in those which assessed drugs on
overall survival.
NHS
Scotland spent £1.7 billion on drugs in 2016/17, an increase of
nearly 20 per cent in five years.
Cancer
drugs are driving most of the increase in pharmaceutical spending
across the NHS, but the researchers noted that there is "no
association between magnitude of benefit and drug price".
In
the case of leukaemia drug, pegaspargase (Oncaspar), all five studies
examined were considered high risk, while breast cancer drug
palbociclib (Ibrance) was approved on the basis of two studies whose
results are considered potentially unreliable. The studies behind
skin cancer drug trametnib (Mekinst) and immunotherapy treatment
nivolumab (Opdivo) were also criticised by the researchers.
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