On January 08, 2016 OncoMed Pharmaceuticals Inc. (NASDAQ:OMED), a clinical-stage company developing novel anti-cancer stem cell and immuno-oncology therapeutics reported the publication of a manuscript in Cancer Research describing OncoMed’s efforts to develop novel therapeutics against R-spondin (RSPO) targets and elucidating the link between expression of the RSPO cancer stem cell pathway and tumor growth (Press release, OncoMed, JAN 8, 2016, View Source [SID:1234508702]). OncoMed is currently conducting a Phase 1a/b clinical trial of its anti-RSPO3 (OMP-131R10) antibody.

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The article "Therapeutic Targeting of Tumor-Derived R-Spondin Attenuates beta-Catenin Signaling and Tumorigenesis in Multiple Cancer Types" (released online December 30, 2015) describes the generation of neutralizing monoclonal antibodies against RSPO-1, -2 or -3 and the successful use of these antibodies to treat diverse types of patient-derived xenografts, including colon, ovarian, pancreas and lung tumors. Of note, these anti-RSPO antibodies were effective in the tumor models regardless of whether the tumors overexpressed RSPO because of gene translocations or because of other tumor-intrinsic pathways. OncoMed is utilizing biomarker assays to prospectively screen patients for RSPO gene expression as part of its Phase 1a/b clinical program.

Mechanistically, the paper establishes a functional link between RSPO expression and tumor growth. Tumor-derived RSPO can activate beta-catenin, and antibody-mediated blocking of RSPO binding to its receptor potently inhibits tumor growth. This anti-tumor activity is associated with the modulation of beta-catenin and cancer stem cell pathways.

"R-spondins are emerging as an important cancer target. As key stimulators of beta-catenin activity in a variety of human tumor types, targeting the RSPO pathway may prove to be an effective approach to modulating this fundamental signaling axis," said John Lewicki, Ph.D., OncoMed’s Chief Scientific Officer. "Our first anti-RSPO candidate is being studied in Phase 1a/b clinical trials with a strong biomarker hypothesis and we expect to establish a single-agent dose and treat biomarker-positive patients this year."

About Anti-RSPO3
OncoMed’s anti-RSPO3 (OMP-131R10) is the first drug in its class to target the R-spondin-LGR pathway, an important cancer stem cell pathway identified by OncoMed researchers. The company’s ongoing Phase 1a/1b clinical trial is initially enrolling patients with advanced refractory solid tumors to assess the safety, pharmacokinetics, pharmacodynamics and initial evidence of efficacy of the anti-RSPO3 antibody. Once a single-agent dose has been identified, biomarker-selected patients will be enrolled in a Phase 1a expansion arm to evaluate possible anti-tumor activity. In the Phase 1b portion of the trial, anti-RSPO3 will also be tested in second-line colorectal cancer patients in combination with chemotherapy.

In preclinical studies OncoMed’s anti-RSPO3 antibody demonstrated robust in vivo anti-tumor efficacy as a single agent and in combination with standard of care across a range of solid tumors, including colon, lung, ovarian, and pancreatic cancers, among others. The anti-RSPO3 antibody delayed tumor recurrence following termination of chemotherapy, and decreased the frequency of cancer stem cells. Anti-RSPO3 antibody represents the third product candidate in the clinic that is part of OncoMed’s collaboration with Celgene.