Plain language summary: an analysis of the safety of futibatinib treatment in people with different types of cancer.

What is this summary about?: Researchers combined information from three separate phase 1 and 2 clinical trials, including over 400 people who had one of 33 different cancer types and who all received futibatinib in their clinical trial. This type of study is called a pooled analysis. Futibatinib is taken orally (by mouth) as a tablet and works by reducing the activity of a group of proteins called fibroblast growth factor receptors (FGFRs). FGFRs drive the growth of some cancers, especially cancer cells with changes in FGFR genes that make the proteins more active. Researchers wanted to look at how common some side effects were in people treated with futibatinib, how soon the side effects happened after taking futibatinib, and how they could be managed. Researchers also wanted to provide recommendations to other health care professionals on how to manage these side effects in people with cancer.

What were the results?: In this analysis, the researchers focused on side effects that they had seen in previously completed trials of futibatinib. Overall, futibatinib was safe and tolerable. Most people (82%) had a high phosphate level in their blood (hyperphosphatemia), 27% had nail disorders, 27% had liver side effects (changes in liver-related laboratory tests), 19% had a sore mouth (stomatitis), 13% had hand-foot syndrome (palmar-plantar erythrodysesthesia syndrome), 9% had a rash, 8% developed changes in the back of the eye (retinal disorders), and 4% of people developed cataracts. Most side effects were mild/moderate and reversible. The median time it took from starting treatment to experiencing a severe side effect ranged from 9 days (hyperphosphatemia) to 125 days (cataracts). Some side effects tended to occur early, while others developed later. Only 2% of people stopped taking futibatinib due to treatment-related side effects, and futibatinib caused no deaths.

What do the results mean?: The side effects from taking futibatinib were manageable and similar in people with different types of cancer. To fully understand the safety of futibatinib, researchers will need to look at what side effects are reported in people taking futibatinib over a longer time in the real-world setting (outside of clinical trials).