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.

Context: Chronic lymphocytic leukemia (CLL) cells depend on microenvironmental factors for proliferation and survival. In particular, the B-cell receptor (BCR) and nuclear factor- B (NF-B) pathways are activated in the lymph node (LN) microenvironment. Thus, model systems mimicking tumor-host interactions are important tools to study CLL biology and pathogenesis. We investigated whether the recently established NOD/scid/c(null) (NSG) mouse xenograft model can recapitulate the effects of the human microenvironment. We assessed, therefore, tumor characteristics previously defined in LN-resident CLL cells, including proliferation, and activation of the BCR and NF-B pathways. We found that the murine spleen (SP) microenvironment supported CLL cell proliferation and activation to a similar degree than the human LN, including induction of BCR and NF-B signaling in the xenografted cells. Next, we used this model to study ibrutinib, a Bruton's tyrosine kinase inhibitor in clinical development. Ibrutinib inhibited BCR and NF-B signaling induced by the microenvironment, decreased proliferation, induced apoptosis and reduced the tumor burden in vivo. Thus, our data demonstrate that the SP of xenografted NSG mice can, in part, recapitulate the role of the human LN for CLL cells. In addition, we show that ibrutinib effectively disrupts tumor-host interactions essential for CLL cell proliferation and survival in vivo. 
 Question: What is the name of Bruton's tyrosine kinase inhibitor that can be used for treatment of chronic lymphocytic leukemia?
ibrutinib

Context: Julien Malzieu (born 4 May 1983 in Le Puy-en-Velay, Auvergne) is a French rugby union and sevens player for Montpellier in the Top 14 competition. 
 Question: The sport Julien Malzieu is associated with is?
rugby union

Context: The Norgay Montes (/nre mntiz/; less officially, Norgay Mountains) are icy mountains, near the Hillary Montes, that reach 3.4 km (2.1 mi; 11,000 ft) above the surface of the dwarf planet Pluto, bordering the southwest region of Sputnik Planum in the south of Tombaugh Regio (or the part of Tombaugh Regio south of the equator). 
 Question: The astronomical body that Norgay Montes is on is what?

pluto