Material Agreement, Financial Obligation, Private Placement (Form 8-K)

Item 1.01 Entry into a Definitive Material Agreement.

On January 15, 2026, Rein Therapeutics, Inc. (the "Company") entered into a securities purchase agreement (the "Purchase Agreement") with Funicular Funds, LP, a Delaware limited partnership managed by Cable Car Capital, LP ("Funicular"), pursuant to which the Company issued and sold to Funicular, in a private placement, an unsecured promissory note, dated January 15, 2026, in the original principal amount of $2,500,000 (the "Note"). Pursuant to the Purchase Agreement, the Company issued and sold to Funicular for a purchase price of $2,000,000, inclusive of an original issue discount of 20%.

The Note has a stated maturity date of the earlier of (i) the date of the closing of the next issuance and sale of securities of the Company, in a single transaction or series of related transactions, to investors resulting in gross proceeds to the Company of at least $10,000,000 (exclusive of the Note proceeds) or (ii) June 30, 2026. The Company's obligations under the Note are unsecured. There is no interest payable under the Note other than the 20% original issue discount. The Purchase Agreement contained representations, warranties, covenants and other terms customary for agreements of such nature.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-BalanceSheet Arrangement of a Registrant.

The information set forth under Item 1.01 of this Current Report on Form 8-Kis hereby incorporated by reference in its entirety.

Item 3.02 Unregistered Sales of Equity Securities.

The information set forth under Item 1.01 of this Current Report on Form 8-Kis incorporated herein by reference. The Note sold pursuant to the Purchase Agreement was offered and sold pursuant to exemptions from the registration requirements of the Securities Act of 1933, as amended, afforded by Section 4(a)(2) thereof and Rule 506 of Regulation D promulgated thereunder, for the sale of securities not involving a public offering.