Proteostasis Files Investigational New Drug Application For PTI-808, Cystic Fibrosis Potentiator

CAMBRIDGE, Mass., June 23, 2017 (GLOBE NEWSWIRE) -- Proteostasis Therapeutics, Inc. (NASDAQ:PTI), a biopharmaceutical company developing small molecule therapeutics to treat diseases caused by dysfunctional protein processing such as cystic fibrosis (CF), today announced that the Company has filed an Investigational New Drug (IND) application with the U.S. Food and Drug Administration (FDA) for PTI-808, its cystic fibrosis transmembrane conductance regulator (CFTR) potentiator. Proteostasis plans to initiate a Phase 1 study of PTI-808 in healthy volunteers in July.

“While potentiators are an established part of CF therapy, there remains significant room for improvement in this critical component of therapy, and we believe PTI-808, with potential once a day dosing regimen, offers the potential to fill this gap,” said Meenu Chhabra, president and chief executive officer of Proteostasis Therapeutics. “Each component of our potential triple combination therapy is now clinical stage, with active and ongoing clinical development programs for both PTI-428, an amplifier, and PTI-801, a new generation corrector. With the filing of an IND for the potentiator PTI-808, the third and final piece of our triple combination, we have reached an important milestone in assembling PTI-NC-733. Pending positive results from ongoing clinical trials with PTI-428 and PTI-801, we expect to initiate a trial combining all three proprietary CFTR modulators before the end of 2017.”

By the end of June, Proteostasis expects to report preliminary data from multiple ascending dose (MAD) cohorts of two different CF patient populations: CF subjects receiving PTI-428 or placebo in addition to Orkambi® as their background therapy for seven days and CF subjects receiving PTI-428 as their sole CFTR modulator therapy or placebo for seven days. After a washout period, patients on Orkambi® background therapy who were enrolled in the 7-day dosing MAD cohort are eligible to enroll in a 28-day clinical study for PTI-428.

Proteostasis is currently conducting a 14-day MAD Phase 1 study of PTI-801 in healthy volunteers in the U.S., to be followed by dosing in CF patients. If positive results are achieved in the Company’s PTI-428 and PTI-801 programs, Proteostasis intends to initiate a dose range finding (DRF) study at the end of 2017 in an F508del homozygous population who are not taking Orkambi®. The study design is expected to include DRF of PTI-808 with fixed dose combination of PTI-428 and PTI-801 in a triple combination also known as PTI-NC-733.

About Proteostasis Therapeutics, Inc.

Proteostasis Therapeutics, Inc. is a biopharmaceutical company dedicated to the discovery of groundbreaking therapies to treat diseases caused by dysfunctional protein processing, such as cystic fibrosis (CF). Headquartered in Cambridge, MA, the Proteostasis Therapeutics team focuses on identifying therapies that restore protein function. In addition to its multiple programs in cystic fibrosis, Proteostasis Therapeutics has formed a collaboration with Astellas Pharma, Inc. to research and identify therapies targeting the Unfolded Protein Response (UPR) pathway. For more information, visit

Safe Harbor

To the extent that statements in this release are not historical facts, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Words such as “aim,” “may,” “will,” “expect,” “anticipate,” “estimate,” “intend,” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. Examples of forward-looking statements made in this release include, without limitation, statements regarding the expected timing of the initiation of, patient enrollment in, data from, and our completion of, our clinical studies and cohorts for PTI-428, PTI-801, PTI-808 and our triple combination therapy candidate, PTI-NC-733. Forward-looking statements made in this release involve substantial risks and uncertainties that could cause actual results to differ materially from those expressed or implied by the forward-looking statements, and we therefore cannot assure you that our plans, intentions, expectations or strategies will be attained or achieved. Such risks and uncertainties include, without limitation, uncertainties inherent in the execution and completion of clinical trials (including, without limitation, the possibility FDA requires us to run cohorts sequentially or conduct additional cohorts or pre-clinical or clinical studies), in the enrollment of CF patients in our clinical trials, in the timing of availability of trial data, in the results of the clinical trials, in possible adverse events from our trials, in the actions of regulatory agencies, in endorsement, if any, by therapeutic development arms of CF patient advocacy groups, and those set forth in our Annual Report on Form 10-K for the year ended December 31, 2016, and our other SEC filings. We assume no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.


David Pitts
Argot Partners

Eliza Schleifstein
Argot Partners

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