According to new research, more than half of the clinical trials that led to the US’s FDA approving anticancer medicines over the past 10 years are still not available for independent scrutiny.

The multi-national study, led by Flinders University, found that of the 304 trials which supported the registration of 115 anticancer drugs over the last 10 years, only 136 (45%) had individual patient data available for sharing.

Concerningly, the results – published July 28th in JAMA Oncology – also showed that 90% of the trial data for three of the globally top-selling anticancer drugs (nivolumab, pembrolizumab, and pomalidomide) was unavailable.

These three medicines generated over US$30 billion in revenue in 2020 and in Australia, two of them (nivolumab and pembrolizumab) are the most expensive antineoplastic drugs for the Australian taxpayer, costing over $800 million through the PBS in 2020-21.

Lead author Dr Ash Hopkins, an NHMRC Investigator Fellow and leader of the Clinical Cancer Epidemiology Lab at Flinders University, said the most common reason provided for the lack of transparency was that the collection of long-term follow-up data was still ongoing.

“This is the same reason given by Pfizer and Moderna for the clinical trial data on their respective COVID-19 vaccines not currently being available,” Dr Hopkins said.

“However, this excuse disregards any commitment to data transparency. Ongoing follow-up is of course needed, but it should not hinder the release of the key data that is implicated in the global release of medicines to tens of thousands of people.

“With profit correlating to global drug use, the finding that Astellas Pharma, Bristol Myers Squibb, GlaxoSmithKline, Merck Sharp & Dohme, and Teva Pharmaceutical Industries had less than 10% of their sampled oncology trials available for IPD sharing represents a missed opportunity.”

Data from early clinical trials remain the centrepiece of safety and efficacy assessments and the pharmaceutical industry had committed to improve data transparency back in 2014.

Co-author Natansh Modi, an NHMRC PhD candidate in the Clinical Cancer Epidemiology Lab at Flinders, explained that while the need for ongoing verification of clinical trial claims is clear, it is only one of several important benefits of data sharing.

“Evidence indicates that independent data requests are most often occurring to unlock insights into the risks and benefits of medicines in unexplored patient groups,” Mr Modi said.

“This aspect of research upholds the social contract that the industry enters into with trial participants, whereby they are told their participation will allow for further research to maximise the benefit to society.

“If the data isn’t made available it can’t be put to good use – trial participants and their families deserve better.”

The team is calling on the pharmaceutical industry to explicitly state in their transparency policies that trial data underpinning drug approvals will be available for independent investigation as soon as they are registered.

“Emerging policies drafted by the pharmaceutical industry offer an unparalleled opportunity to advance evidence-based medicine, support decision-making, and protect the community,” Mr Modi said.

“It is time that global regulators, governments, and journals establish mandates for data transparency on all major trials investigating registered medicines.

“Their purpose must be to protect and maximise public health and ensure the contributions of trial participants and their families reach their full potential.”