The idea behind a basket trial is to match a patient whose tumor shows a specific mutation- like BRAF or NRAS- to a drug that is know to work on that mutation. So a Melanoma patient with a BRAF mutation could be on that trial as well as a colon cancer patient with a BRAF mutation.
You can find an article on the topic here: http://goo.gl/JqfGs8
This type of trial will become increasingly important the more we learn about the genetic make-up of tumours and as the article says:
'Though randomized clinical trials are the preferred gold standard for FDA approval, the design is often not feasible in a timely manner for rare mutations and patients with rapidly advancing malignancies. - See more at: http://www.oncotherapynetwork.com/conference-report/basket-design-novel-approach-cancer-clinical-trials?GUID=5613AAF4-725E-4285-8C2F-CEDE506C383F&rememberme=1&ts=29062014#sthash.J1uzYQxP.dpuf'