definiens: means ( a ) with respect to EISAI, a Third Party to whom EISAI has granted a license under Know - Howor Patents Controlled by EISAI, or a sublicense pursuant to Section 5.1.2 under Know - How or Patents licensed to EISAIpursuant to Section 5.1.1 of this Agreement, to Develop or Commercialize Licensed Compounds or Licensed Products in theField, excluding any Third Party acting solely as a distributor and ( b ) with respect to EPIZYME, a Third Party to whomEPIZYME has granted a license under Know - How or Patents Controlled by EPIZYME, or a sublicense pursuant toSection 5.3.2 under Know - How or Patents licensed to EPIZYME pursuant to Section 5.3.1 of this Agreement, to performEPIZYME ’s obligations under and in accordance with the Research and Development Plan