SCHEDULE 13D/A 0001727357 XXXXXXXX LIVE 2 Common Stock, $0.001 par value 09/24/2025 false 0001645469 61023L207 Monopar Therapeutics

1000 SKOKIE BLVD SUITE 350 WILMETTE IL 60091

Tactic Pharma LLC (847) 388-0349 c/o 1000 Skokie Blvd, Ste 350 Wilmette IL 60091 0001727357 N Tactic Pharma LLC OO N DE 272026.00 0.00 272026.00 0.00 272026.00 N 4.1 OO 0001727393 N Mazar Andrew Paul OO N X1 1.00 272026.00 1.00 272026.00 272026.00 N 4.1 IN 0001727334 N Robinson Chandler OO N X1 234173.00 272026.00 234173.00 272026.00 506199.00 N 7.5 IN SOLE VOTING AND DISPOSITIVE POWER AND AGGREGATE AMOUNT INCLUDES 8,726 RESTRICTED STOCK UNITS SCHEDULED TO VEST WITHIN 60 DAYS AND 152,105 STOCK OPTIONS CURRENTLY EXERCISABLE OR SCHEDULED TO VEST AND BE EXERCISABLE WITHIN 60 DAYS 0001727481 N O'Halloran Thomas V. OO N X1 2801.00 272026.00 2801.00 272026.00 272026.00 N 4.1 IN 0001035909 N Brown Michael J OO N X1 66051.00 272026.00 66051.00 272026.00 338067.00 N 5.1 IN SOLE VOTING AND DISPOSITIVE POWER AND AGGREGATE AMOUNT INCLUDES 18,878 STOCK OPTIONS Common Stock, $0.001 par value Monopar Therapeutics 1000 SKOKIE BLVD SUITE 350 WILMETTE IL 60091 This Amendment No. 2 ("Amendment No. 2") amends and supplements the Schedule 13D filed with the Securities and Exchange Commission on December 23, 2019 (the "Initial Schedule 13D" and together with Amendment No. 1 filed on December 17, 2024 and this Amendment No. 2, the "Schedule 13D") by Tactic Pharma LLC ("Tactic Pharma"), Andrew Mazar, Chandler Robinson, Thomas O'Halloran and Michael Brown (the "Reporting Persons") with respect to the Common Stock, par value $0.001 per share, of Monopar Therapeutics Inc (the "Issuer"). Capitalized terms used herein and not otherwise defined in this Amendment No. 2 shall have the meanings set forth in the Initial Schedule 13D. This Amendment No. 2 amends Item 1, 5 and 6 to the extent set forth below. Refer to the cover pages. All percentages are calculated based on 6,611,661 shares of Common Stock outstanding as reported in the Issuer's final prospectus supplement dated September 23, 2025 and filed with the Securities Exchange Commission on September 24, 2025, after giving effect to the offering described therein (the "Offering"). Refer to the cover pages. All percentages are calculated based on 6,611,661 shares of Common Stock outstanding as reported in the Issuer's final prospectus supplement dated September 23, 2025 and filed with the Securities Exchange Commission on September 24, 2025, after giving effect to the Offering. On September 24, 2025, Tactic Pharma entered into a privately negotiated stock purchase agreement with the Issuer, pursuant to which Tactic Pharma agreed to sell 550,229 shares of Common Stock to the Issuer for $63.6098 per share. The per share purchase price is the same price at which shares were sold by the Issuer in the Offering, less underwriting discounts and commissions. The transaction is conditioned on closing of the Offering and is expected to close promptly thereafter. Not applicable. As a result of the transaction described in Item 5(c) above, as of September 24, 2025, each of the Reporting Persons (other than Chandler Robinson and Michael Brown) ceased to the beneficial owner of more than five percent of the Common Stock. Item 6 is hereby amended as follows: On December 9, 2024, TacticGem LLC ("TacticGem") made a pro rata distribution of all of the shares of Common Stock that were held by it to its members, Tactic Pharma and Gem Pharmecuticals, LLC ("Gem"). In connection with that distribution, the Reporting Persons and Gem agreed to lock-up provisions with each other prohibiting sales of the distributed Common Stock until December 31, 2025, without the mutual consent of representatives of both Tactic Pharma and Gem. Representatives of both Tactic Pharma and Gem agreed to a one-time waiver of these provisions in order to allow Tactic Pharma to engage in the transaction described in Item 5(c) above. Tactic Pharma LLC /s/ Chandler Robinson 09/24/2025 Mazar Andrew Paul /s/ Andrew Mazar 09/24/2025 Robinson Chandler /s/ Chandler Robinson 09/24/2025 O'Halloran Thomas V. /s/ Thomas O'Halloran 09/24/2025 Brown Michael J /s/ Michael Brown 09/24/2025