definiens: shall mean all indebtedness arising under ( a ) the Note PurchaseAgreement, dated March 12, 2015, by and among Seller and Deerfield Private Design Fund III, L.P., DeerfieldPartners, L.P., Deerfield International Master Fund, L.P., Deerfield Special Situations Fund, L.P., Deerfield PrivateDesign Fund II, L.P., Deerfield Private Design International II, L.P. and BioPharma Secured Investments III HoldingsCayman LP, Inteligo Bank Ltd. and Phemus Corporation and Deerfield Design Fund III, L.P., as amended by theConsent and First Amendment to Note Purchase Agreement, dated December 29, 2015, as amended by the Waiverand Second Amendment to Note Purchase Agreement, dated December 4, 2017, as amended by the Waiver, Consentand Third Amendment to Note Purchase Agreement and Partial Release of Security Interest, dated August 2, 2018,as amended by the Fourth Amendment to Note Purchase Agreement, dated January 8, 2019, and as amended by theFifth Amendment to Note 3 Purchase Agreement, dated August 9, 2019 and ( ii ) the Pledge and Security Agreement, dated April 2, 2015, betweenSeller and Deerfield Private Design Fund III, L.P