Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Example Input: Context: Presently the Appalachian elktoe is considered critically endangered, and it is unknown if they are still in fact actively reproducing. 
 Question: What is the status of Appalachian elktoe?
Example Output: critically endangered

Example Input: Context: On November 13, 1982, 15-year-old Scott Safran of Cherry Hill, New Jersey, set a world record of 41,336,440 points on the arcade game Asteroids, beating the 40,101,910 point score set by Leo Daniels of Carolina Beach on February 6, 1982. In 1998, to congratulate Safran on his accomplishment, the Twin Galaxies Intergalactic Scoreboard searched for him for four years until 2002, when it was discovered that he had died in an accident in 1989. In a ceremony in Philadelphia on April 27, 2002, Walter Day of Twin Galaxies presented an award to the surviving members of Safrans family, commemorating the Asteroid Champions achievement. On April 5, 2010, John McAllister broke Safrans record with a high score of 41,838,740 in a 58-hour Internet livestream. 
 Question: Who had the highest score second playing Asteroids, Safran, Daniels or Mc Allister?
Example Output: safran

Example Input: Context: New treatment options are urgently needed for patients with relapsed chronic lymphocytic leukemia (CLL) who fail to respond to currently available therapies or cannot achieve a sustained response. Moreover, targeted agents with less myelotoxicity are necessary to treat patients with multiple comorbidities who would otherwise be unable to tolerate standard regimens. Ibrutinib, a Bruton's tyrosine kinase inhibitor, has shown highly encouraging results in phase I/II trials in patients with treatment-naive, relapsed and refractory CLL even in the presence of high risk disease or poor prognostic markers. In phase I/II trials, ibrutinib 420 mg or 840 mg - given continuously as single agent or at a dose of 420 mg daily in combination with a monoclonal antibody or chemoimmunotherapy - has been associated with high response rates and durable clinical remissions. Phase II and III trials are currently under way for treatment-naive patients, relapsed/refractory patients, and for those patients harboring a 17p deletion. 
 Question: What is the name of Bruton's tyrosine kinase inhibitor that can be used for treatment of chronic lymphocytic leukemia?
Example Output:
ibrutinib