X0306 4 2021-06-16 0001659617 Moleculin Biotech, Inc. MBRX 0000938419 KLEMP WALTER V C/O MOLECULIN BIOTECH, INC. 5300 MEMORIAL DR., SUITE 950 HOUSTON TX 77007 1 1 CEO and President Stock option (right to buy) 3.73 2021-06-16 4 A 0 223635 A 2031-06-16 Common Stock 223635 628785 D Restricted Stock Units 2021-06-16 4 A 0 100000 A Common Stock 100000 728785 D The options set forth in this table vest in four equal annual installments, beginning on the first anniversary of the Transaction Date, subject to the grantee's continued service to the Company on each vesting date. Issued in connection with the reporting person's employment with the Company. Each restricted stock unit represents a contingent right to receive one share of Company common stock. The restricted stock units set forth in this table vest in four equal annual installments beginning on the first anniversary of the Transaction Date, subject to the grantee's continued service to the Company on each vesting date. /s/ Walter V. Klemp 2021-06-21