Aileron Therapeutics, Inc., a clinical stage biopharmaceutical company that is developing first-in-class therapeutics based on its proprietary Stapled Peptide drug platform, announced today that it has secured $33 million in an extension to its Series E equity financing, bringing the total raised in this round to $48 million.

This financing was co-led by three new investors including AJU IB Investment Co., Ltd. and two undisclosed private investment groups. The round also includes full participation by all existing investors including Apple Tree Partners, Excel Venture Management, Lilly Ventures, Novartis Venture Funds, Roche Venture Fund and SR One.

The proceeds will be used to advance ALRN-6924 into clinical trials. ALRN-6924 is a potent and specific re-activator of p53, a tumor suppressor protein that represents one of the most sought after oncology drug targets given its role in most liquid and solid tumors. ALRN-6924 will be the first clinical drug candidate that targets both the MDM2 and the MDMX suppressor proteins of p53, in contrast to all other drugs in clinical development that involve small molecules targeting only MDM2.

'This financing enables Aileron to rapidly move forward the clinical development of ALRN-6924 as well as ongoing translational research. P53 is one of the most exciting and valuable oncology targets given its potential to impact a very broad range of cancers and patients,' said Joseph A. Yanchik III, President and Chief Executive Officer of Aileron Therapeutics. 'This investment from our new and returning investors recognizes the progress and value that the Aileron team has created and gives us a strong foundation to accelerate the growth of this very important oncology drug as well as our unique drug platform.'

'We are very pleased with Aileron's progress and look forward to advancing the first Stapled Peptide drug for oncology into the clinic,' said Scott Kapnick, Chairman of Aileron's Board of Directors. 'We are grateful to have the full and continued participation of our existing investors. The high quality of the new investment groups that participated in this financing reflects the importance of this research to cancer treatment.'

About p53 and ALRN-6924
P53, known as 'the guardian of the genome' because it enables repair of damaged DNA or triggers cell death, is one of the most important tumor suppressor proteins, as it is known to be inactivated in virtually all human cancers. As half of all cancers circumvent p53's protective mechanisms by the inhibitory proteins MDM2 and MDMX, Aileron's stapled peptide, ALRN-6924, is novel in that it can selectively bind to and inhibit both proteins equally, thereby restoring p53 function. ALRN-6924, is planned for entry into Phase 1 clinical testing in 2014 in both liquid and solid tumor patients.

About Stapled Peptides
Stapled Peptides are an emerging class of drugs with a unique set of properties that fully capitalize on 25 years of genetic research to attack the critical drivers of complex diseases, including cancer, endocrine/metabolic disorders and infectious diseases. Aileron's proprietary Stapled Peptide drug platform locks peptides into their biologically active shape and imparts unprecedented pharmacokinetic and pharmaceutical stability. Stapled Peptide drugs are derived from natural peptides and are designed to potently and specifically target protein-protein interactions both inside and outside the cell. This new class of drugs represents a fundamentally new therapeutic approach to modulate signaling pathways to treat human disease.

About Aileron Therapeutics
Aileron Therapeutics is a clinical stage biopharmaceutical company that is developing first-in-class therapeutics based on its proprietary Stapled Peptide drug platform. Aileron's lead drug development candidate is ALRN-6924, a p53 re-activator for the treatment of cancer. With its proprietary Stapled Peptide platform, Aileron aims to dramatically improve the treatment of a wide range of diseases including cancer, endocrine/metabolic disorders and infectious diseases. For more information, please visit www.aileronrx.com.