Cancer control after pausing treatment with larotrectinib in responding children with sarcoma and a TRK fusion: a plain language summary

Plain Language SummaryWhat is this summary about?This plain language summary describes a study that looked at children with a type of cancer called ‘sarcoma’ and it explains what happened when they stopped taking larotrectinib treatment.Larotrectinib is a targeted anti-cancer medication that treats cancers known as ‘TRK fusion cancers’, which are cancers that have a characteristic type of genetic change that is not normal. Anti-cancer treatments should control cancer, ideally by removing all traces of cancer from the body; if this is not possible, an effective treatment should shrink the tumor or at least prevent further growth.It is important to understand how long a child should stay on larotrectinib once the TRK fusion cancer has become well controlled on this treatment. This study looked at whether stopping larotrectinib treatment had any effect on control of the cancer, whether the cancer started to grow after larotrectinib was stopped, and if resuming larotrectinib treatment could control the cancer again.What are the key takeways?In a group of 47 children in whom the cancer was controlled with larotrectinib, the cancer remained well controlled after stopping treatment in 31 children (about 2 in every 3 of the overall group).The remaining 16 children had signs of their cancer getting worse, so they resumed larotrectinib. In 15 of these children, resuming larotrectinib controlled the cancer again. The remaining 1 child had surgery shortly after resuming larotrectinib, so it was not possible to clearly tell how much resuming treatment helped after surgery; however, the cancer remained controlled without taking any more larotrectinib after surgery.What were the main conclusions reported by the researchers?Children with TRK fusion sarcoma treated with larotrectinib may be able to stop this treatment once the cancer is controlled.For children who stop larotrectinib treatment, if the cancer starts to grow or comes back, larotrectinib can be resumed and this often brings back control of the cancer.Clinical trial number: NCT02637687Clinical trial number: NCT02576431