Drugmaker Shire Plc clinched its six-month pursuit of Baxalta International Inc on Monday with an agreed $32 billion cash and stock offer, catapulting it to a leading position in treating rare diseases. The London-listed group, which first approached the U.S. firm with an all-stock offer in July, won over the maker of treatments for rare blood conditions, cancers and immune system disorders after adding a cash sweetener.