FDA clinical trial holds saw a sharp increase in 2021, propelled in large part by holds on cell and gene therapy trials.

Last year’s spike was large enough to put the amount of clinical holds at double the historical average, according to an analysis of the past 12 years by investment banking firm Jefferies. One reason for the development, according to Jefferies equity analyst Michael Yee, is increased clinical trial activity in the cell and gene therapy space.

Cell and gene therapy trials accounted for approximately 40 percent of all clinical holds last year despite comprising far less than 40 percent of all trials, “suggest[ing] there are technical and safety questions that still need to be worked through” for such products, Yee wrote.

The analysis notes that 50 to 60 percent of clinical holds end up being lifted, with oncology and hematology seeing the highest rates of resumption and neurology and infectious disease seeing the lowest.

Overall, oncology has been responsible for half of all clinical holds since 2010. Yee noted that while cancer trials comprised a majority of holds between 2014 and 2019, last year’s surge (which extended partly into 2020) was fueled by other therapeutic areas that have seen development booms, including gene therapy, gene editing and neurology.

“This could be because of increased new drug development outside of oncology, but we also wonder whether developers are taking riskier approaches with nononcology drugs as well,” Yee said.