X0306 4 2022-06-20 0001659617 Moleculin Biotech, Inc. MBRX 0001546797 Climaco John M C/O MOLECULIN BIOTECH, INC. 5300 MEMORIAL DR., SUITE 950 HOUSTON TX 77007 1 Stock option (right to buy) 1.49 2022-06-20 4 A 0 23333 A 2032-06-20 Common Stock 23333 47501 D Stock option (right to buy) 1.49 2022-06-20 4 A 0 15000 A 2032-06-20 Common Stock 15000 62501 D The options set forth in this table vest in three equal annual installments beginning on the first anniversary of the Transaction Date, subject to the grantee's continued service on the Company's Board of Directors on each vesting date. The options set forth in this table vest on the earlier of one year from the date of the Company's 2022 annual meeting of stockholders or on the date of the next annual meeting of stockholders, subject the grantee's continued service on the Company's Board of Directors on each vesting date. The options were issued in connection with the reporting person's Board of Director service to the Company. /s/ Jonathan Foster by Power of Attorney 2022-06-22