X0206 3 2017-06-28 0 0001420565 AILERON THERAPEUTICS INC ALRN 0001709976 Gallagher Brian M. Jr. C/O S.R. ONE, LIMITED, 161 WASHINGTON STREET, SUITE 500 CONSHOHOCKEN PA 19428 1 0 0 0 Series D Preferred Stock Common Stock 682476 I See Footnote Series E-2 Preferred Stock Common Stock 148088 I See Footnote Series E-3 Preferred Stock Common Stock 128448 I See Footnote Series F Preferred Stock Common Stock 199173 I See Footnote The Series D Preferred Stock is convertible into Common Stock on a 9.937-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date. The Series E-2 Preferred Stock is convertible into Common Stock on a 9.937-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date. The Series E-3 Preferred Stock is convertible into Common Stock on a 9.937-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date. The Series F Preferred Stock is convertible into Common Stock on a 9.937-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date. S.R. One, Limited, an indirect, wholly-owned subsidiary of GlaxoSmithKline plc, is the record holder of 682,476 shares of Series D Preferred Stock, 148,088 shares of Series E-2 Preferred Stock, 128,448 shares of Series E-3 Preferred Stock and 199,173 shares of Series F Preferred Stock. Dr. Brian M. Gallagher, Jr. is a partner and Vice President at S.R. One, Limited and an employee of GlaxoSmithKline LLC, a wholly-owned subsidiary of GlaxoSmithKline plc. Dr. Gallagher disclaims beneficial ownership of all the shares held by S.R. One, Limited and this report shall not be deemed an admission of beneficial ownership of such shares for the purposes of Section 16 or for any other purpose except to the extent of his pecuniary interest therein. Exhibit Index: 24.1 Power of Attorney /s/ Kira A. Nelson, Kira A. Nelson, as attorney-in-fact for Brian M. Gallagher, Jr. 2017-06-28