Receptos Press Release About Clinical Trials for Multiple Sclerosis Drug Candidate

SAN DIEGO, CA, October 22, 2012 – Receptos, Inc., announced today that its selective sphingosine‐1‐ phosphate receptor 1 (S1P1) modulator, RPC1063, has been administered to the first patient in a Phase 2/3 study. RPC01‐201, a Phase 2/3 placebo‐controlled (Phase 2) and active comparator‐controlled (Phase 3) trial, is the first of two planned pivotal studies for RPC1063 in the indication of relapsing multiple sclerosis (RMS).

The Phase 2 portion of RPC01‐201 is a randomized, double‐blind comparison of two doses of RPC1063 to a placebo control in patients with RMS. The primary objective is to demonstrate the clinical efficacy of RPC1063 compared to placebo by showing a reduction in the cumulative number of total gadolinium enhancing (GdE) lesions by MRI from Week 12 to Week 24 of study treatment. The Phase 3 portion of RPC01‐201 is a randomized, double‐blind, double‐dummy comparison of RPC1063 to an active control in patients with RMS and is a pivotal registrational study. Patients will receive one of two doses of RPC1063 or interferon (IFN) β‐1a (Avonex®) 30 µg intramuscular weekly injection for at least two years. The primary objective will be to assess whether RPC1063 is superior to IFN β‐1a in reducing the rate of relapse at 24 months in patients with RMS. More than 1,100 patients are planned to be treated in total in the RPC01‐201 study.

Receptos completed a Phase 1 study with RPC1063 in the first quarter of 2012 which tested single ascending doses, multiple ascending doses and dose titration regimens in healthy volunteers. The Phase 1 results confirmed optimal pharmacokinetic, pharmacodynamic and safety features, which provide supportive data for the differentiation strategy for RPC1063 as a potential best‐in‐class second generation S1P1 receptor modulator. In particular, robust pharmacodynamic effects of peripheral lymphocyte count reduction were achieved in the Phase 1 study. Threshold lymphopenia levels are correlated to efficacy in the indication of MS and reaching these threshold levels enabled RPC1063 dose selection for the Phase 2/3 study.

"Our Phase 1 data indicate that RPC1063 has favorable intrinsic safety and pharmaceutical properties, creating a foundation for a highly differentiated clinical profile," said Faheem Hasnain, President and Chief Executive Officer of Receptos. "In addition, we are very excited to be moving into a Phase 2/3 study which also provides the opportunity to position RPC1063 as a potential next to market candidate in the S1P1 receptor modulator class of compounds."

About RPC1063 and S1P1 Modulators

RPC1063 is a novel, differentiated sphingosine 1‐phosphate 1 receptor (S1P1) selective modulator exhibiting picomolar potency that is effective in rodent models of both multiple sclerosis (MS) and inflammatory bowel disease (IBD), and possesses an excellent safety profile in non‐clinical toxicology studies. Receptos has completed a Phase 1 clinical safety study with RPC1063 under a US IND that supports the desired differentiation profile and establishes justification for initiation of MS and IBD clinical efficacy trials in 2012. S1P1 is a G protein‐coupled receptor (GPCR) that binds the lipid signaling molecule sphingosine 1‐phosphate (S1P). S1P is a circulating lipid that binds to five GPCRs termed S1P1‐5. S1P1 selectively regulates physiological functions in the immune and cardiovascular systems, including immune cell trafficking and the maintenance of endothelial integrity. In autoimmune disorders, S1P1 agonism works by selectively sequestering circulating lymphocytes, blunting the underlying cause of disease.

About Receptos

Receptos is a biopharmaceutical company developing therapeutic candidates for the treatment of autoimmune diseases through information ‐ driven drug discovery, including GPCR structure determination. The company’s lead program, RPC1063, is a potential best‐in‐class S1P1 small molecule modulator candidate for autoimmune indications. Patents supporting RPC1063 were exclusively licensed to Receptos from The Scripps Research Institute (TSRI). The discoveries originated in the NIH Molecular Libraries Probe Production Center at TSRI, which is part of the NIH Common Fund Molecular Libraries initiative ( Receptos’ expertise in S1P1 biology has been informed by the company’s high resolution protein crystal structure of the S1P1 receptor, published in Science earlier this year. Receptos has established partnerships for its GPCR structure determination technology platform with Eli Lilly, Ono Pharmaceutical and Janssen Pharmaceuticals, Inc. For more information visit