Ms. Mary Beth Breslin

Branch Chief

Office of Healthcare and Insurance

Division of Corporation Finance

U.S. Securities and Exchange Commission

100 F Street N.E.

Washington, D.C. 20549

Dear Ms. Breslin:

We are in receipt of the Staff’s letter dated December 13, 2018 with respect to the above-referenced confidential draft Registration Statement (the “Draft Registration Statement”). We are responding to the Staff’s comments on behalf of Gossamer Bio, Inc. (“Gossamer” or the “Company”) as set forth below. Simultaneously with the submission of this letter, the Company is publicly filing via EDGAR its Registration Statement on Form S-1 (the “Registration Statement”) responding to the Staff’s comments and updating the Draft Registration Statement. Courtesy copies of this letter and the Registration Statement (marked to show changes to the Draft Registration Statement) are being submitted to the Staff by hand delivery.

The Company’s responses set forth in this letter are numbered to correspond to the numbered comments in the Staff’s letter. All terms used but not defined herein have the meanings assigned to such terms in the Registration Statement. For ease of reference, we have set forth the Staff’s comments and the Company’s response for each item below.

Prospectus Summary, page 1

December 21, 2018

Page 2

Gossamer’s Response: The Company has revised the graphic on pages 1 and 91 of the Registration Statement in response to the Staff’s comment.

Gossamer’s Response: The Company has revised the disclosure on pages 2 and 92 of the Registration Statement in response to the Staff’s comment.

Business, page 91

Gossamer’s Response: The Company has revised page 110 of the Registration Statement to add disclosure regarding the Company’s payment obligations under the merger agreement in response to the Staff’s comment.

License Agreements, page 112

Gossamer’s Response: The Company has revised the disclosure on page 112 of the Registration Statement to reflect the terms of the license agreement between Gilead Sciences, Inc. and Pulmokine, Inc. and the effects of the termination of such agreement that would be material to an investor in understanding the Company’s rights under its license agreement with Pulmokine (the “Pulmokine Agreement”). Additionally, the Company respectfully advises the Staff that the intellectual property covered by the license between Pulmokine and The Rensselaer Center for Translational Research, the second third-party, concerns methods for detecting disease and is unrelated to GB002 or any other current product, and therefore immaterial to the Company and to an investor’s understanding of the Pulmokine Agreement. The Company respectfully advises the Staff that the UC Regents license under the license agreement with Aerpio Pharmaceuticals, Inc. (the “Aerpio Agreement”), provides a non-exclusive license to certain intellectual property which the Company does not believe is material to the Company’s intellectual property estate for GB004. Therefore, any termination of the UC Regents license under the Aerpio Agreement would not be expected to have a material adverse effect on the Company.

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December 21, 2018

Page 3

Any comments or questions regarding the foregoing should be directed to the undersigned at 858-523-3962. Thank you in advance for your cooperation in connection with this matter.