REGENERX BIOPHARMACEUTICALS INC SC 13D/A

AMENDMENT NO. 26 TO SCHEDULE 13D

JOINT FILING AGREEMENT

CONVERTIBLE NOTE AND WARRANT PURCHASE AGREEMENT, DATED AS OF JULY 3, 2023, BY AND BETWEEN THE ISSUER AND ESSETIFIN S.P.A

CONVERTIBLE PROMISSORY NOTE, DATED JULY 3, 2023

WARRANT, DATED JULY 3, 2023