One In Five Cancer Clinical Trials Fail To Meet Patient Accrual Targets

By Jill Drachenberg, Managing Editor

A recent study in the Journal of the National Cancer Institute found that one in five cancer clinical trials fail to enroll enough participants to reliably judge new treatments – leading to a “waste of scarce human and economic resources,” according to the researchers.

The researchers from Fred Hutchinson Cancer Research Center in Seattle looked at data from 787 National Clinical Trials Network-sponsored Phase II and Phase III oncology studies performed between 2000 and 2011, and also looked at 46 trials opened between 2012 and 2013 to use for prospective validation. Eighteen percent of the trials closed due to low patient accrual rates, or were accruing at less than 50% of the target three or more years after opening.

If a trial closes due to low accrual, enrolled patients still received the investigational drug – but there are not enough patients to study the effectiveness of the treatment.

The researchers also identified a number of risk factors that may predict low accrual rates for cancer trials. Trials with invasive eligibility screenings, such as a requiring a tissue sample or biopsy, saw lower enrollment. The same was also true for Phase III studies of investigational new drugs, where patient randomization comes into play and patients are not guaranteed the new drug. Low numbers were also linked to the number of study locations, and with a trial that had greater complexity.

Low-income patients are also less likely to enroll in cancer trials. An article in the December issue of IRB Advisor described a separate study lead by Joseph Unger, PhD, MS, also from the Fred Hutchinson Cancer Research Center, which found that patients with an annual household income below $50,000 were 32% less likely to participate in a clinical trial.

“If patient level income is related to cancer outcomes like survival, for example — and let’s say lower income patients have worse survival [rates] — if they are not adequately represented in trials of a new drug, that is going to end up influencing your results,” Unger told IRB Advisor. “The overall results are not going to be quite as representative of what’s going on in the population.”