A plain language summary of two trials for larotrectinib in people with TRK fusion-positive lung cancer to learn how well the drug works and how safe it is

What is this summary about? This is a summary of a publication that reported data from participants in two clinical trials that studied a targeted cancer medicine called larotrectinib in a total of 20 participants with TRK fusion-positive lung cancer that had spread outside of the lungs. ‘TRK fusion-positive’ means that a patient’s lung cancer had a specific change in the gene called NTRK. The researchers wanted to know whether larotrectinib could shrink the participants’ tumors and what side effects it caused. What were the main results reported by the researchers? Researchers found that among the participants who took 100 milligrams (mg) of larotrectinib twice a day, 73% had their tumors respond to treatment, which means that their tumors shrank by over 30% or disappeared completely. 81% of the participants whose tumors responded to treatment continued to respond for 1 year. After 2 years, 65% continued to respond. The median time that participants’ tumors continued to respond to treatment was 33.9 months. The median is the middle number in a set of numbers when ordered from lowest to highest. In this case, the ‘median’ means that half of the participants continued to respond to treatment for more than 33.9 months. The median time that participants lived without their tumors growing was 35.4 months. This means that half of the participants lived without their tumors growing for more than 35.4 months. The median time that participants lived during the trials after starting treatment was 40.7 months. 80% of participants (16 out of 20) developed side effects. Most of these side effects were manageable. In this summary, side effects are the medical problems that happened during both trials that the researchers thought were possibly related to larotrectinib. The most common side effect was muscle aches. 10% of participants (2 out of 20) had severe side effects. The severe side effects were an overreaction by the immune system in response to treatment like an allergic reaction, an increase in body weight, and muscle aches. Severe side effects may cause medical problems that are significant enough to require medical attention or hospital care and may require a change in treatment dose.