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Biased Agonism In GPCR Drug Discovery: Application To Somatostatin Agonists

Award Information
Agency: Department of Health and Human Services
Branch: National Institutes of Health
Contract: 2R44DK088501-02A1
Agency Tracking Number: R44DK088501
Amount: $2,162,550.00
Phase: Phase II
Program: SBIR
Solicitation Topic Code: NIDDK
Solicitation Number: PA12-088
Timeline
Solicitation Year: 2013
Award Year: 2013
Award Start Date (Proposal Award Date): N/A
Award End Date (Contract End Date): N/A
Small Business Information
6181 Cornerstone Ct, Ste106
SAN DIEGO, CA 92121-4727
United States
DUNS: 828902515
HUBZone Owned: No
Woman Owned: No
Socially and Economically Disadvantaged: No
Principal Investigator
 RICHARD STRUTHERS
 (858) 450-6464
 sstruthers@crinetics.com
Business Contact
 RICHARD STRUTHERS
Phone: (858) 450-6464
Email: sstruthers@crinetics.com
Research Institution
N/A
Abstract

DESCRIPTION (provided by applicant): Neuropeptide somatostatin analogs are important therapeutics for the treatment of hormone secreting tumors with annual sales of ~ 1.7B. However, the currently available peptide depots are effective in only half the patients with growth hormone secreting tumors, and patients with carcinoids can rapidly become resistant to these drugs. Somatostatin analogs act by stimulating sst2A, a G protein coupled receptor, but the currently available agents cause desensitization via internalization of the receptor, resulting in reduced or complete loss of efficacy. We hypothesized that biased agonists of the somatostatin receptor that maintain strong Gi activation, but do not cause desensitization, would normalize hormone levels in agreater percentage of patients and improve efficacy in patients not adequately controlled by currently available agents. In Phase I, we proposed to validate this hypothesis, using assays for both receptor activation and internalization to identify new nonpeptide, orally-active somatostatin biased agonists that do not cause desensitization, with the goal of providing improved therapeutic options for patients with these tumors. In Phase I, we identified several small molecule agonists that are indeed potent activators of Gi, but with far less propensity for, or no evidence of inducing receptor internalization and desensitization. These proof of concept studies showed that we can identify compounds with the desired profile using our assay cascade, and can support the medicinal chemistry lead optimization efforts required to identify a candidate suitable for clinical development. In Phase II, we will optimize our leads identified in Phase I to deliver a novel orally available drug candidate, which meets our defined criteria, to undergo the non-clinical toxicology studies necessary to support clinical development. In addition to improved clinical efficacy, orally delivered agents would also reduce the need for physician office visits, eliminate the pain and discomfort of depot injections, and lower the manufacturing costs compared to expensive peptide depot formulations. This project promises to deliver a new cost effective therapeutic agent with a novel pharmacological profile that leads to improved efficacy. Our approach towards the identification of such an agent is innovative in that we are incorporating receptor regulatory assays (to detect receptor desensitization), in addition to affinity (or activity-based) assays. This combination of assays wil be used to guide lead optimization efforts. Importantly, the G protein coupled receptor family is the largest gene family in the human genome and a rich source of proven targets for drug discovery, which share common regulatory and signaling mechanisms. Therefore, if successful, this work will not only provide improved agents for patients with hormone secreting tumors, but will also support a general novel strategy for optimizing agonist drugs that can be exploited to target many other GPCRs. PUBLIC HEALTH RELEVANCE PUBLIC HEALTH RELEVANCE: The goal of this project is to develop orally bioavailable, biased agonists of the somatostatin receptor sst2A, with improved and prolonged efficacy, for the treatment of hormone secreting tumors. If successful, this project promises to deliver a new cost effective therapeutic agent with a novel pharmacological profile leading to improved efficacy and reduced potential to cause desensitization. In addition, this work will provide the foundation for a general strategy for thedevelopment of optimized agonists for many additional GPCR drug targets.

* Information listed above is at the time of submission. *

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