UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 19, 2019

Aileron Therapeutics, Inc.

(Exact Name of Company as Specified in Charter)

Registrant’s telephone number, including area code: (617) 995-0900

Not applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☒

On June 19, 2019, William T. McKee and Josef H. von Rickenbach were elected to the Board of Directors (the “Board”) of Aileron Therapeutics, Inc. (the “Company”), effective immediately. Mr. McKee will serve as a Class II director with a term expiring at the 2022 annual meeting of stockholders. Mr. von Rickenbach will serve as a Class III director with a term expiring at the 2020 annual meeting of stockholders. The Board also appointed Mr. McKee to serve as chairman of the Board’s Audit Committee. The Board did not appoint Mr. von Rickenbach to serve on any committee of the Board at this time.

Mr. McKee currently serves as the Chief Executive Officer of MBJC Associates, LLC, a business consulting firm serving the pharmaceutical and biotechnology industry, a position he has held since June 2010. Mr. McKee previously served as chief operating officer and chief financial officer for EKR Therapeutics, Inc. (“EKR”), from July 2010 until June 2012 when EKR was sold to Cornerstone Therapeutics Inc. From December 2008 until March 2010, Mr. McKee served as the executive vice president, chief financial officer and treasurer of Barr Pharmaceuticals, LLC, a subsidiary of Teva Pharmaceutical Industries Limited (“Teva”) and the successor entity to Barr Pharmaceuticals, Inc. (“Barr”), which was acquired by Teva in December 2008. Mr. McKee was also executive vice president and chief financial officer of Barr prior to its acquisition by Teva, after having served in positions of increasing responsibility at Barr from 1995 until its acquisition. Prior to joining Barr, Mr. McKee served as director of international operations and vice president-finance at Absolute Entertainment, Inc. from June 1993 until December 1994. From 1990 until June 1993, Mr. McKee worked at Gramkow & Carnevale, CPA’s, and from 1983 until 1990, he worked at Deloitte & Touche LLP. Mr. McKee serves as a member of the board of directors and chairman of the audit committee of Assertio Therapeutics, Inc., a specialty pharmaceutical company, and Agile Therapeutics, Inc., a biopharmaceutical company. Mr. McKee received a B.B.A. from the University of Notre Dame.

Mr. von Rickenbach is currently the managing director of Stet Vision LLC. He co-founded and served as President and Chief Executive Officer of HelioVision, Inc., a biotechnology company, from April 2017 until its acquisition by Aldeyra Therapeutics, Inc. in February 2019. Previously, Mr. von Rickenbach founded Parexel International Corporation (“Parexel”), in 1982 and served as a director, Chairman of the Board and Chief Executive Officer of Parexel from 1983 until Parexel’s acquisition by Pamplona Capital Management, LLP in September 2017. He also served as President of Parexel from 1983 to April 2001 and from July 2005 to July 2012. Mr. von Rickenbach received an M.B.A. from Harvard Business School and a B.A. in Business Economics from the Lucerne University of Applied Sciences and Arts in Switzerland.

Neither Mr. McKee nor Mr. von Rickenbach has any family relationships with any director, executive officer or any person nominated or chosen by the Company to become a director or executive officer. There are no arrangements or understandings between either Mr. McKee or Mr. von Rickenbach and any other person pursuant to which each was elected as a director of the Company.

In accordance with the Company’s director compensation program, Mr. McKee and Mr. von Rickenbach will each receive a pro-rated annual cash fee of $35,000 for service on the Board and Mr. McKee will receive an additional pro-rated cash fee of $22,500 for service as chairman of the Board’s Audit Committee, which fees are payable in arrears in four quarterly installments on the last day of each calendar quarter. In addition, under the Company’s director compensation program, upon their election as a director, Mr. McKee and Mr. von Rickenbach were each granted an option on June 19, 2019 to purchase 25,000 shares of the Company’s common stock at an exercise price of $0.86 per share. These options vest in three equal annual installments from June 19, 2019 and become exercisable in full upon the occurrence of a change of control of the Company.

In connection with their appointment to the Board, Mr. McKee and Mr. von Rickenbach will each also enter into the Company’s standard form of indemnification agreement, a copy of which was filed as Exhibit 10.12 to Amendment No. 1 to the Company’s Registration Statement on Form S-1 (File No. 333-218474) filed with the Securities and Exchange Commission on June 19, 2017. Pursuant to the terms of this agreement, the Company may be required, among other things, to indemnify Mr. McKee and Mr. von Rickenbach for some expenses, including attorney’s fees, judgments, fines and settlement amounts incurred by them in any action or proceeding arising out of their service as directors of the Company.

A copy of the Company’s press release announcing Mr. Mckee’s and Mr. von Rickenbach’s election is furnished, but not filed, as Exhibit 99.1 to this Current Report on Form 8-K.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Exhibit 99.1

Aileron Therapeutics Strengthens Board of Directors with Appointments of William T. McKee and Josef H. von Rickenbach

WATERTOWN, Mass., June 24, 2019 (GLOBE NEWSWIRE) — Aileron Therapeutics (NASDAQ: ALRN), the clinical-stage leader in the field of stabilized cell-permeating peptides to treat cancer and other diseases, today announced that William (“Bill”) T. McKee and Josef (“Joe”) H. von Rickenbach have been elected to the Board of Directors, effective immediately.

“We are very excited to have Bill and Joe, two industry executives with a tremendous breadth of experience and a strong track record of accomplishments, join our Board of Directors. We believe that Aileron will benefit greatly from their scope and depth of operational insight and experience,” said Dr. Manuel Aivado, CEO & President of Aileron.

Mr. McKee commented, “I am excited about the prospects for ALRN-6924, and the broad applicability of Aileron’s stabilized cell-permeating peptide platform. I look forward to working with the management team and the Board to advance this promising lead program and to help Aileron build and strengthen its operational capabilities.”

“I believe Aileron’s stabilized cell-permeating peptide platform technology is very promising. Aileron’s current clinical focus, combining ALRN-6924 with Pfizer’s palbociclib, also known as IBRANCE^®, in MDM2-amplified tumors, along with its plans to commence a myelopreservation trial with ALRN-6924 in September for cancer patients receiving chemotherapy, both represent exciting opportunities. Furthermore, I believe this platform is capable of producing additional novel drug candidates that address previously undruggable targets,” said Mr. von Rickenbach. “I look forward to helping Aileron leverage my experience to the benefit of patients and shareholders.”

Mr. von Rickenbach has built a long and successful career in the drug development industry. Last year, he retired after 35 years as the Chairman and Chief Executive Officer of PAREXEL, one of the world’s largest biopharmaceutical service providers with about 19,000 employees and operations in more than 50 countries. Mr. von Rickenbach co-founded PAREXEL in 1982, led the company through its IPO in late 1995 and more than 40 mergers and acquisitions. Pamplona Capital Management, a private

equity firm, took PAREXEL private for approximately $5 billion in September 2017. Mr. von Rickenbach started his career at Schering-Plough, Inc., and held positions at 3M (East), a division of 3M Company, and ERCO (later ENSECO), Inc. Currently the Managing Director of stet vision LLC, Mr. von Rickenbach recently was co-Founder, President & CEO of Helio Vision, Inc., a Boston-based ophthalmic biopharma company developing a therapy for proliferative vitreoretinopathy (PVR), that merged into Aldeyra, Inc. (NASDAQ: ALDX) in early 2019. Mr. von Rickenbach serves on the Board of Trustees of McLean Hospital and on the Board of Directors of NEHI (Network for Excellence in Health Innovation). Mr. von Rickenbach received an M.B.A. from Harvard Business School and a B.A. in Business Economics from Lucerne University in Switzerland.

Mr. McKee is a seasoned pharmaceutical industry executive and consultant. Currently, Mr. McKee serves as the Chief Executive Officer of MBJC Associates, LLC, a business consulting firm serving the pharmaceutical and biotech industry. Prior to joining MBJC Associates, Mr. McKee served as the Chief Operating Officer and Chief Financial Officer for EKR Therapeutics, Inc. from July 2010 until June 2012, when EKR was sold to Cornerstone Therapeutics Inc. From December 2008 until March 2010, Mr. McKee served as the executive vice president, chief financial officer and treasurer of Barr Pharmaceuticals, LLC, a subsidiary of Teva Pharmaceutical and the successor entity to Barr Pharmaceuticals, Inc., which was acquired by Teva in December 2008. Mr. McKee was also executive vice president and chief financial officer of Barr prior to its acquisition by Teva, after having served in positions of increasing responsibility at Barr from 1995 until its acquisition. McKee serves as a member of the board of directors and chairman of the audit committee of Assertio Therapeutics, Inc., a specialty pharmaceutical company, and Agile Therapeutics, Inc., a biopharmaceutical company. Mr. McKee received a B.B.A. from the University of Notre Dame.

About ALRN-6924

ALRN-6924 is a first-in-class, stabilized cell-permeating alpha-helical peptide that mimics the p53 tumor suppressor protein to disrupt its interactions with both its endogenous inhibitors, MDMX and MDM2. ALRN-6924 is currently being evaluated in multiple clinical trials for the treatment of a variety of cancers, including cancers with MDM2-amplified tumors. For information about Aileron’s clinical trials, please visit www.clinicaltrials.gov.

About Aileron

Aileron is a clinical-stage biopharmaceutical company advancing a

proprietary platform of cell-permeating alpha-helical peptides that address the most important intracellular targets in oncology and other therapeutic areas. The stabilized helical structure of our peptides allows the design of cell-permeating therapeutic agents with large molecular surfaces for optimal target binding properties, resulting in drug candidates like ALRN-6924. Our current focus is to improve the standard of care for patients with cancer by developing safe and effective therapies that leverage our proprietary peptide platform. For more information, visit www.aileronrx.com, and for more information about our clinical trials please visit www.clinicaltrials.gov.

Forward-Looking Statements

Statements in this press release about Aileron’s future expectations, plans and prospects, as well as any other statements regarding matters that are not historical facts, may constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, statements about the Company’s strategy and clinical development plans. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including whether Aileron’s cash resources will be sufficient to fund its continuing operations for the periods and/or trials anticipated; whether results obtained in preclinical studies and clinical trials will be indicative of results obtained in future clinical trials; whether Aileron’s product candidates will advance through the clinical trial process on a timely basis, or at all; whether the results of such trials will warrant submission for approval from the United States Food and Drug Administration or equivalent foreign regulatory agencies; whether Aileron’s product candidates will receive approval from regulatory agencies on a timely basis or at all; whether, if product candidates obtain approval, they will be successfully distributed and marketed; and other factors discussed in the “Risk Factors” section of Aileron’s quarterly report on Form 10-Q for the period ended March 31, 2019, filed on May 8, 2019, and risks described in other filings that Aileron may make with the Securities and Exchange Commission. Any forward-looking statements contained in this press release speak only as of the date hereof, and Aileron specifically disclaims any obligation to update any forward-looking statement, whether because of new information, future events or otherwise.

Investors:

Aileron Therapeutics

Don Dougherty, CFO

617-995-0900

ddougherty@aileronrx.com

Hans C. Vitzthum

LifeSci Advisors, LLC.

617-535-7743

hans@lifesciadvisors.com