Sec Form 3 Filing - WINDSOR JAMES BRIAN @ AILERON THERAPEUTICS INC - 2023-10-31

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person WINDSOR JAMES BRIAN 2. Issuer Name and Ticker or Trading Symbol AILERON THERAPEUTICS INC [ ALRN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) See Remarks (Last) (First) (Middle) C/O AILERON THERAPEUTICS, INC., 738 MAIN STREET #398 3. Date of Earliest Transaction (MM/DD/YY) 10/31/2023 (Street) WALTHAM, MA02451 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 46 ( 1 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (right to buy) $ 0.29 ( 2 )( 8 ) 09/29/2025 Common Stock 8,532 D Stock Option (right to buy) $ 0.7 ( 3 )( 8 ) 10/09/2027 Common Stock 252,652 D Stock Option (right to buy) $ 0.7 ( 4 )( 8 ) 03/14/2028 Common Stock 34,736 D Stock Option (right to buy) $ 1.17 ( 5 )( 8 ) 02/25/2030 Common Stock 317,613 D Stock Option (right to buy) $ 1.17 ( 6 )( 8 ) 02/25/2030 Common Stock 139,900 D Stock Option (right to buy) $ 3.87 ( 7 )( 8 ) 10/19/2033 Common Stock 170,646 D Series X Non-Voting Convertible Preferred Stock ( 1 ) ( 9 ) ( 1 )( 9 ) ( 1 )( 9 ) Common Stock 2,709 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other WINDSOR JAMES BRIAN C/O AILERON THERAPEUTICS, INC. 738 MAIN STREET #398 WALTHAM, MA02451 See Remarks Signatures /s/ Manuel C. Alves-Aivado, M.D., Ph.D., as attorney-in-fact for James Brian Windsor 11/02/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On October 31, 2023, the Issuer completed its merger with Lung Therapeutics, Inc. (the "Merger") in accordance with the terms of the Agreement and Plan of Merger, dated October 31, 2023. In connection with the Merger, the Reporting Person received 46 shares of Issuer common stock and 2,709 shares of Issuer series X non-voting convertible preferred stock in exchange for an aggregate of 16,152 shares of Lung Therapeutics, Inc. preferred stock. ( 2 )In connection with the Merger, the Issuer assumed the Reporting Person's option to purchase 50,000 shares of Lung Therapeutics, Inc. common stock originally granted on September 30, 2015, which option was converted into an option to purchase 8,532 shares of Issuer common stock. The shares underlying the option are fully vested. ( 3 )In connection with the Merger, the Issuer assumed the Reporting Person's option to purchase 1,480,558 shares of Lung Therapeutics, Inc. common stock originally granted on October 10, 2017, which option was converted into an option to purchase 252,652 shares of Issuer common stock. 209,469 shares of Issuer common stock underlying the option have vested. The remaining 43,183 shares of Issuer common stock underlying the option vest upon the date of the first to occur of (i) a change of control in which Lung Therapeutics, Inc. is sold for a valuation per share of greater than $1.8573 per share of common stock or (ii) the completion of an offering of Lung Therapeutics, Inc.'s equity securities at a valuation of greater than $1.2382 per share of common stock, subject to the Reporting Person's continued service with the Issuer on the vesting date. ( 4 )In connection with the Merger, the Issuer assumed the Reporting Person's option to purchase 203,558 shares of Lung Therapeutics, Inc. common stock originally granted on March 15, 2018, which option was converted into an option to purchase 34,736 shares of Issuer common stock. The shares underlying the option are fully vested. ( 5 )In connection with the Merger, the Issuer assumed the Reporting Person's option to purchase 1,861,235 shares of Lung Therapeutics, Inc. common stock originally granted on February 26, 2020, which option was converted into an option to purchase 317,613 shares of Issuer common stock. 25% of the shares underlying the option vested on the first anniversary of the grant date, and, thereafter, the remaining 75% of such shares vest in thirty-six (36) equal monthly installments, subject to the Reporting Person's continued service with the Issuer on each applicable vesting date. ( 6 )In connection with the Merger, the Issuer assumed the Reporting Person's option to purchase 819,823 shares of Lung Therapeutics, Inc. common stock originally granted on February 26, 2020, which option was converted into an option to purchase 139,900 shares of Issuer common stock. 25% of the shares underlying the option vested on the first anniversary of the grant date, and, thereafter, the remaining 75% of such shares vest in thirty-six (36) equal monthly installments, subject to the Reporting Person's continued service with the Issuer on each applicable vesting date. ( 7 )In connection with the Merger, the Issuer assumed the Reporting Person's option to purchase 1,000,000 shares of Lung Therapeutics, Inc. common stock originally granted on October 20, 2023, which option was converted into an option to purchase 170,646 shares of Issuer common stock. The shares underlying the option are fully vested on the grant date. ( 8 )In connection with the Merger, the Reporting Person's options reported in this Form 3 were amended to provide that no shares underlying such options will vest as a result of the Merger and such options will not be exercisable until the Issuer's stockholders approve the conversion of the series X non-voting convertible preferred stock. ( 9 )Upon stockholder approval of the conversion of series X non-voting convertible preferred stock into shares of common stock, each share of series X non-voting convertible preferred stock will convert into 1,000 shares common stock, subject to certain limitations.

Remarks: Exhibit 24.1 Power of AttorneyPresident and Chief Operating Officer

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