On April 3, 2019 Sierra Oncology, Inc. (Nasdaq: SRRA), a clinical stage drug development company focused on advancing targeted therapeutics for the treatment of patients with unmet needs in hematology and oncology, reported preclinical data for its novel oral Cdc7 inhibitor, SRA141, in a late-breaking poster being presented at the American Association of Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2019 in Atlanta, Georgia (Press release, Sierra Oncology, APR 3, 2019, View Source [SID1234534995]).

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"Prior studies demonstrated that SRA141 potently and selectively inhibits Cdc7, resulting in robust anti-tumor efficacy in colorectal xenograft models, however, the compound’s exact mechanism of action has not been characterized previously. Our findings reveal a potentially novel mechanism of cytotoxicity for Cdc7 inhibitors that is distinct from other agents, and thus SRA141 may herald a new class of cancer therapeutic agents with a differentiated anti-tumor profile," said Dr. Eric J. Brown, Associate Professor of Cancer Biology at the Perelman School of Medicine of the University of Pennsylvania, and member of Sierra’s DNA damage response (DDR) Advisory Committee.

"SRA141 does not induce G1 cell cycle arrest or replication stress, thereby distinguishing it from other agents such as palbociclib or SRA737. Rather, SRA141 alters DNA replication dynamics and delays cell cycle progression, ultimately resulting in caspase-dependent cell death associated with mitotic accumulation. Promisingly, we believe we have shown for the first time that this mechanism appears to synergize with anti-apoptotic drugs, such as venetoclax, and dysregulators of mitosis, such as barasertib. This differentiated mechanism of action supports a potentially unique spectrum of clinical opportunities for SRA141 as both monotherapy and in combination with pro-apoptotic and mitotic disrupting agents," said Dr. Christian Hassig, Chief Scientific Officer, Sierra Oncology.

SRA141 AACR (Free AACR Whitepaper) Late-Breaking Poster:
Date/Time: Wednesday, April 3rd from 8:00 am to 12:00 pm ET
Session: Late-Breaking Research: Molecular and Cellular Biology / Genetics 2
Title: CDC7 kinase inhibition by SRA141 induces a potentially novel caspase-dependent tumor cell apoptosis associated with altered DNA replication and cell cycle dynamics.
Authors: Veena Jagannathan, Snezana Milutinovic, Ryan J. Hansen, Bryan Strouse, Christian Hassig and Eric J. Brown.
Location: Georgia World Congress Center, Exhibit Hall B, Poster Section 41, Poster #5

The poster will be made available on the company’s website at www.sierraoncology.com.

About SRA141 targeting Cdc7
SRA141 is a novel, potent, orally bioavailable selective inhibitor of Cell division cycle 7 (Cdc7) kinase. Owing to its important role in DNA replication, and its overexpression in various neoplasms, Cdc7 is an attractive therapeutic target with emerging clinical validation in oncology.

Cdc7, together with its partner proteins Dbf4 or Drf1, is responsible for activating DNA replication origin firing during S-phase through phosphorylation and activation of the MCM2-7 helicase. Cdc7 also has functions within the DNA Damage Response (DDR) and mitosis. Over-expression of Cdc7 and its partner proteins is correlated with unfavorable clinical outcomes and poor survival in a broad range of solid tumors and hematological malignancies.

SRA141 has been shown to cause cancer cell death in a p53-independent manner and to induce tumor regression or stasis in a variety of in vivo cancer models, including complete and partial regressions in animal models of colorectal cancer.

An Investigational New Drug Application (IND) filing has been accepted by the U.S. Food and Drug Administration (FDA) for SRA141, and Sierra Oncology has prepared for a potential Phase 1/2 trial of the drug candidate in patients with advanced colorectal cancer. Sierra Oncology is currently evaluating the optimal timing to commence this trial within the context of its recently expanded portfolio.

Sierra Oncology retains the global commercialization rights to SRA141