ADDING and REPLACING Ra Pharmaceuticals Reports Third Quarter 2018 Financial Results and Provides Corporate Update

Add after last paragraph of release: two financial tables.

The updated release reads:

RA PHARMACEUTICALS REPORTS THIRD QUARTER 2018 FINANCIAL RESULTS AND PROVIDES CORPORATE UPDATE

Dosing completed in Phase 2 trial of zilucoplan in generalized myasthenia gravis

On track for topline data read-out around year-end 2018

Announces issuance of U.S. patent covering zilucoplan composition of matter and methods of use

Ra Pharmaceuticals, Inc. (Nasdaq:RARX) today announced financial results for the third quarter ended September 30, 2018 and highlighted recent progress in advancing its pipeline programs, including zilucoplan for the treatment of generalized myasthenia gravis (gMG), paroxysmal nocturnal hemoglobinuria (PNH), and complement-mediated renal disorders.

“We are pleased to report that dosing in our Phase 2 trial of zilucoplan for gMG is now complete and we look forward to reporting top-line data around year-end,” said Doug Treco, PhD, Chief Executive Officer of Ra Pharma. “The rapid over-enrollment of this study underscores both patient and physician enthusiasm for an accessible and convenient self-administered, subcutaneous, complement inhibitor. Notably, to date, over 12,000 doses of zilucoplan have been self-administered and were well-tolerated by patients across our clinical programs.”

Third Quarter 2018 Highlights and Recent Developments

• In August, Ra Pharma completed enrollment in the Phase 2 trial evaluating zilucoplan for the treatment of gMG. The multi-center, randomized, double-blind, placebo-controlled trial enrolled a total of 44 patients. At the outset of the 12-week treatment period, patients were randomized in a 1:1:1 ratio and received daily SC doses of 0.1 mg/kg of zilucoplan, 0.3 mg/kg of zilucoplan, or matching placebo. Dosing was completed at the end of October 2018 and the Company plans to report top-line data around year-end 2018. All 44 patients completed the 12-week study and, of these, 43 (98%) elected to enter a long-term extension to receive active study drug.
• In September, Ra Pharma announced the completion of End-of-Phase 2 interactions with the U.S. Food and Drug Administration (FDA) for its global Phase 3 program of zilucoplan for the treatment of PNH. Based on FDA feedback and advice provided by the Medicines and Healthcare products Regulatory Agency in the UK (MHRA) and Health Canada, and pending discussions with the European Medicines Agency (EMA) in the fourth quarter of 2018, Ra Pharma plans to initiate a global, pivotal, single-arm Phase 3 trial to evaluate the safety and efficacy of zilucoplan in approximately 40 treatment-naïve PNH patients in the first half of 2019. In addition, the Company expects to initiate a supportive trial in approximately 40 transfusion-independent patients switching from eculizumab to zilucoplan. In a separate CMC Type C meeting, Ra Pharma has also reached agreement with the FDA on the pharmaceutical development program required to support the Phase 3 clinical program.
• In September, Ra Pharma reported positive results from the Phase 1b, multi-center, open-label, pharmacokinetic (PK) study of zilucoplan in patients with renal disease. The trial enrolled 16 patients, eight with severe renal impairment matched with eight healthy control subjects. The PK profile of zilucoplan was consistent and similar across both groups. These results support the expansion of zilucoplan into complement-mediated renal disorders without the need for dose adjustment.
• In September, Ra Pharma elected Aoife M. Brennan, M.B., B.Ch., to its Board of Directors. Dr. Brennan serves as President, Chief Executive Officer, and Chief Medical Officer of Synlogic, Inc. (Nasdaq:SYBX).
• Ra Pharma announced today that the U.S. Patent and Trademark Office (USPTO) has issued U.S. Patent No. 10,106,579 which covers a family of molecules, including zilucoplan. The patent provides composition of matter protection of zilucoplan and methods of use in the treatment of complement-mediated disorders. This patent is the first in a series of composition of matter and treatment filings that is designed to protect zilucoplan through at least 2035.

Third Quarter 2018 Financial Results

For the third quarter of 2018, the Company reported a net loss of $16.5 million, or a net loss of $0.51 per share (basic and diluted), compared to a net loss of $15.3 million, or a net loss of $0.68 per share for the same period in 2017.

Research and development expenses for the third quarter of 2018 were $13.4 million, compared to $13.1 million for the same period in 2017. The increase in R&D expenses for the third quarter of 2018 was primarily due to clinical development costs associated with our lead program, zilucoplan.

General and administrative expenses for the third quarter of 2018 were $3.5 million, compared to $2.3 million for the same period in 2017. The increase in G&A expenses for the third quarter of 2018 was primarily due to employee-related costs due to the increase in headcount to support the growth of the Company and cost associated with pre-commercialization planning.

There was no revenue earned in the three months ended September 30, 2018 or the three months ended September 30, 2017.

As of September 30, 2018, Ra Pharma reported total cash and cash equivalents of $81.1 million. The Company expects that its cash and cash equivalents will be sufficient to fund our operating expenses and capital expenditure through the end of 2019.

About Zilucoplan (formerly RA101495 SC)

Ra Pharma is developing zilucoplan for generalized myasthenia gravis (gMG), paroxysmal nocturnal hemoglobinuria (PNH), and other complement-mediated disorders. The product candidate is designed for convenient, once-daily subcutaneous self-administration. Zilucoplan is a synthetic, macrocyclic peptide discovered using Ra Pharma's powerful proprietary drug discovery technology. The peptide binds complement component 5 (C5) with sub-nanomolar affinity and allosterically inhibits its cleavage into C5a and C5b upon activation of the classical, alternative, or lectin pathways. By binding to a region of C5 corresponding to C5b, zilucoplan is additionally designed to disrupt the interaction between C5b and C6 and prevent assembly of the membrane attack complex. This activity may define an additional, novel mechanism for the inhibition of C5 function.

About Ra Pharmaceuticals

Ra Pharmaceuticals is a clinical stage biopharmaceutical company focusing on the development of next-generation therapeutics for complement-mediated diseases. The Company discovers and develops peptides and small molecules to target key components of the complement cascade. For more information, please visit: www.rapharma.com.

Forward-Looking Statement

This press release contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, including, but not limited to, statements regarding the potential safety, efficacy and regulatory and clinical progress of our product candidates, including without limitation zilucoplan, beliefs regarding clinical trial data, statements regarding trial design, timeline and enrollment of our ongoing and planned clinical programs, including without limitation our Phase 3 trial of zilucoplan for the treatment of PNH, pending discussions with the EMA in the fourth quarter of 2018, and upcoming milestones, including without limitation the release of top-line data in gMG around year-end 2018. All such forward-looking statements are based on management's current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include the risks that Ra Pharma's product candidates, including zilucoplan, will not successfully be developed or commercialized, in the timeframe we expect or at all; the risk that topline results as of February 7, 2017 from the Company's global Phase 2 clinical program evaluating zilucoplan for the treatment of PNH may not be indicative of final study results; the risk that USAN does not approve the name zilucoplan; as well as the other factors discussed in the "Risk Factors" section in Ra Pharma's most recently filed Annual Report on Form 10-K, as well as other risks detailed in Ra Pharma's subsequent filings with the Securities and Exchange Commission. There can be no assurance that the actual results or developments anticipated by Ra Pharma will be realized or, even if substantially realized, that they will have the expected consequences to, or effects on, Ra Pharma. All information in this press release is as of the date of the release, and Ra Pharma undertakes no duty to update this information unless required by law.

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