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Half of European cancer drug trials ‘biased’, says BMJ

Report says studies exaggerate benefits

BMJ

A new study on clinical trials that supported European approvals for cancer drugs claims almost half could have been affected by bias that exaggerated their benefits.

The paper – published in the British Medical Journal – examined 41 published trials reported between 2014 and 2016 that were used as evidence to support the approval of 32 cancer drugs.

The researchers found that 19 of them (49%) were at high risk of bias for their primary outcome, mainly because of missing data or the parameters used to measure efficacy.

That means only nine of the 32 drugs had at least one randomised controlled trial that was judged “at low risk of bias and without major criticism from the EMA’s Committee for Medicinal Products for Human Use (CHMP),” said the authors in an accompanying blog post.

The study highlights some specific examples of products where the risk of bias was seen. That included Servier’s leukaemia treatment Oncaspar (pegaspargase), which had five studies deemed to be at risk, while others included Novartis’ Mekinist (trametinib; three studies) and Pfizer’s Ibrance (palbociclib; two studies).

Broadly, trials that used overall survival as a primary endpoint – 26% of the sample – were less likely to be at risk of bias than those that used surrogate endpoints such as progression-free survival, said the authors. They point to a “substantial shift” in recent years towards the use of surrogates in cancer drug studies.

They also note that in some cases the bias risk “might be unavoidable because of the complexity of cancer trials”.

One big obstacle for physicians trying to make treatment decisions based on trial data is that the methodological details are “scattered across different documents” and can be hard to track down, they noted.

They would like to see new, standardised approaches to collating and communicating information about the validity of trials, perhaps by including a risk of bias assessment in European Public Assessment Reports (EPARs) published by the EMA.

The European Clinical Trials Register (ECTR) could also demand the submission of a bias assessment alongside trial results, and similar requirements could also be implemented by peer-review journals, they suggest among other strategies.

An editorial accompanying the study said that the pressure to get new cancer drugs to patients as quickly as possible is starting to raise “serious concerns about low standards of evidence supporting new cancer drug approvals”.

It notes this isn’t the first study to draw attention to the issue, citing a US study which revealed that post-approval trials found a survival advantage for 20% of cancer drugs granted accelerated approvals in the US from 1992 to 2017.

“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,” said the editorial.

Article by
Phil Taylor

20th September 2019

From: Research

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