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Harms of new cancer drugs often go unreported – new study

A study released today warns that “estimates of the harms of oncological treatments based on published data might not be accurate,” based on an analysis that found considerable discrepancies and gaps in the reporting of clinical trial results.

The authors looked at 42 cancer trials submitted by pharma companies to the European Medicines Agency (EMA) between 2015 and 2018 and then compared the available data on the harms of the 13 drugs involved across three sources: journal articles, clinical trial registries and Clinical Study Reports (CSRs).

Key findings:

  • The number of deaths due to adverse events differed between CSRs and clinical trial registers in 92% of trials, and between CSRs and journal articles in 40% of trials

  • The number of patients with at least one serious adverse event was reported in only half of journal articles

  • Detailed explanations of how it was decided whether a death was due to an adverse event or progressive disease were usually completely unavailable

The authors also looked at the availability of results and at the time it took for results to be made public in all three forms:

  • On average, it took more than two years after the end of a trial until its results were made public in any form. Amazingly, the average time to publication on the European trial registry was over five years – despite long-standing rules that require companies to publish results there within just one year.

  • Ten out of 42 trial results had never been made public in journals, and in the case of one trial, no results had been made public in any form.

CSRs are detailed documents, often thousands of pages long, that describe the design, conduct and outcomes of clinical trials. Worldwide, pharma companies are required to submit CSRs to regulators when they want to bring a new drug onto the market.

Currently, only the EMA and Health Canada have a policy of providing access to CSRs. The American FDA and other regulators outside Europe continue to keep CSRs locked away, citing concerns about commercial confidentiality.

The EMA froze its disclosure programme in late 2018 and refuses to state when it will restart it. Today’s study is likely to increase pressure on the EMA to resume the programme, called Policy 0070.

The study published today is freely available online.

The study’s findings are consistent with previous research showing that CSRs contain more data on drug harms than other sources of information. TranspariMED’s website contains an overview of what CSRs are and why they are so important with links to relevant research, and an annotated bibliography on access to CSRs.


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