Glancy Prongay & Murray LLP (“GPM”) continues its investigation on behalf of Proteostasis Therapeutics, Inc. (“Proteostasis” or the “Company”) (NASDAQ: PTI) investors concerning the Company and its officers’ possible violations of federal securities laws. To obtain information or aid in the investigation, please visit the Proteostasis investigation page on our website at www.glancylaw.com/case/proteostasis-therapeutics-inc.

On March 20, 2018, Kerrisdale Capital Management LLC published a report alleging that the Company’s claimed success of its Phase 2 proof-of-concept trial of PTI-428 “stems almost entirely from the anomalously bad performance of the 4-person placebo group, while, on average, patients taking PTI-428 barely improved.” The report also claimed that “Proteostasis has a habit of sweeping unpleasant or confusing findings under the rug.” On this news, shares of Proteostasis fell $1.83, or 26%, to close at $5.16 on March 20, 2018, thereby injuring investors.

Follow us for updates on Twitter: twitter.com/GPM_LLP.

If you purchased Proteostasis securities, have information or would like to learn more about these claims, or have any questions concerning this announcement or your rights or interests with respect to these matters, please contact Lesley Portnoy, Esquire, of GPM, 1925 Century Park East, Suite 2100, Los Angeles, California 90067 at 310-201-9150, Toll-Free at 888-773-9224, by email to shareholders@glancylaw.com, or visit our website at www.glancylaw.com. If you inquire by email please include your mailing address, telephone number and number of shares purchased.

This press release may be considered Attorney Advertising in some jurisdictions under the applicable law and ethical rules.