April 24, 2020 Jeffrey Hatfield Chief Executive Officer Zafgen, Inc. 3 Center Plaza, Suite 610 Boston, MA 02108 Re: Zafgen, Inc. Amendment 1 to Preliminary Proxy Statement on Schedule 14A Filed April 10, 2020 File No. 001-36510 Dear Mr. Hatfield: We have reviewed your amended registration statement and have the following comments. In some of our comments, we may ask you to provide us with information so we may better understand your disclosure. Please respond to this letter by amending your registration statement and providing the requested information. If you do not believe our comments apply to your facts and circumstances or do not believe an amendment is appropriate, please tell us why in your response. After reviewing any amendment to your registration statement and the information you provide in response to these comments, we may have additional comments. Unless we note otherwise, our references to prior comments are to comments in our April 4, 2020 letter. Amendment 1 to Schedule 14A filed April 10, 2020 Summary, page 1 1. We note your response to our prior Comment 1. Please further revise your disclosure to note that you are dependent on the intellectual property for the development of certain of your early-stage product candidates and identify such early-stage product candidates. Chondrial's Business Overview, page 159 2. We note your response to our prior Comment 3. We also note that you state that you do not believe that the referenced studies are material to Chondrial's business. Please either (i) expand your disclosure to discuss the significance (or lack of significance) to Jeffrey Hatfield Zafgen, Inc. April 24, 2020 Page 2 Chondrial's business; or (ii) remove the disclosure. Chondrial's Strategy, page 160 3. We note your response to our prior Comment 4. We also note your revision to your disclosure on page 159 and note no changes to page 160. We reissue our prior Comment 4. Please further revise your disclosure to remove any implication that Chondrial will be successful in obtaining regulatory approval for CTI-1601 in an accelerated manner. You may contact Michael Fay at (202) 551-3812 or Vanessa Robertson at (202) 551- 3649 if you have questions regarding comments on the financial statements and related matters. Please contact Courtney Lindsay at (202) 551-7237 or Celeste Murphy at (202) 551- 3257 with any other questions. Sincerely, FirstName LastNameJeffrey Hatfield Division of Corporation Finance Comapany NameZafgen, Inc. Office of Life Sciences April 24, 2020 Page 2 cc: Andrew Goodman, Esq. FirstName LastName