PS Imaging
The Growing Market for Molecular Imaging Agents
As therapeutic options for diseases have increased and personalized cancer therapies have
become a reality in recent years, the need to quickly assess a drug’s effectiveness in an
individual has heightened the demand for more accurate imaging technologies. In fact, the
global imaging agent market is expected to exceed $15 billion by 2015, with the majority of the
market being in the United States 1 .
PS Targeted Antibodies as Molecular Imaging Agents
Our researchers have found that phosphatidylserine (PS) is a specific
marker of tumor blood vessels, and also becomes exposed on dying tumor
cells themselves. Additionally, we have observed that chemotherapies and
radiation therapy increase the amount of exposed PS on tumor blood
vessels. These discoveries led to several successful preclinical studies
investigating the ability of our PS-targeting antibodies attached to various
imaging agents to generate clear images of tumors in animal models of
cancer.
NIR-PGN650 localizes to tumor Docetaxel + NIR-PGN650
In April 2012, Peregrine launched its experimental phosphatidylserine (PS)-targeting molecular
imaging candidate, 124I-PGN650, into clinical development for the imaging of multiple solid
tumor types. The primary goal of the trial is to estimate radiation dosimetry in critical and
non-critical organs. Secondary objectives of the trial are tumor imaging and safety. Patients are
currently being enrolled in the trial. We believe that our unique technology can achieve several
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important milestones, including:
- Further validation of bavituximab’s therapeutic target
Images in humans delineating the specificity of exposed PS in tumors could further validate
and support PS as a promising new therapeutic target for antibody therapy across multiple
tumor types, and also support PS-targeting antibodies and fragments as potential candidates for
antibody-drug conjugates (ADC).
- Evaluating the effectiveness of cancer therapies
Since cells expose PS on their surface when they are dying, cancer treatments that are
killing tumor cells will cause an increase in PS exposure in the tumor. Therefore, PS-targeted
imaging agents may have the ability to image the anti-tumor effectiveness of potentially any
cancer therapy. This could facilitate optimization of therapies for individual patients, where a
patient may remain on a therapy that appears to be effective, or quickly switch to a different
therapy if a response is not observed.
- Companion diagnostic to bavituximab therapy
The amount of exposed PS on tumor blood vessels may be indicative of bavituximab’s
potential to initiate a robust immune response to cancer. PS-targeting imaging agents may
therefore hold potential as companion diagnostics to select optimal patients for bavituximab
treatment.
About
124 I-PGN650
124 I-PGN650
is a first-in-class phosphatidylserine (PS)-targeting F(ab’) 2 fully human monoclonal
antibody fragment joined to the PET imaging radio-isotope iodine-124 (
124
I) that represents a new approach to imaging cancer. PS is a molecule usually located inside
the membrane of healthy cells, but "flips" and becomes exposed on the outside of cells that line
tumor blood vessels, creating a specific target for the imaging of multiple solid tumor types. In
preclinical studies,
124
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I-PGN650 accumulates in tumor vasculature and provides exceedingly clear in vivo tumor
images.
Click here to review our PS imaging data
1. Global Industry Analysts, Inc: Imaging Agents: A Global Strategic Business Report
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