ImaginAb says initial focus will be on PET imaging agent for ovarian cancer.

Oxford BioMedica and ImaginAb inked a research collaboration focused on developing an antibody-based in vivo diagnostic imaging agent targeting BioMedica’s 5T4 tumor antigen. Under terms of the deal, ImaginAb could negotiate an exclusive license to a resulting imaging diagnostic product, and BioMedica could receive up to $4 million in initiation and development milestone payments, plus future sales royalties.

ImaginAb’s goal for the project is to develop a diagnostic imaging agent for positron emission tomography, initially for use in ovarian cancer imaging. “The 5T4 tumor antigen is an extremely promising diagnostic and therapeutic target,” comments Christian Behrenbruch, Ph.D., CEO. “We are particularly enthusiastic about this target for imaging ovarian cancer, as the diagnosis and staging of this tragic disease is still inadequately managed with existing clinical imaging techniques.”

Just last month BioMedica expanded its existing 5T4 antibody therapeutics collaboration with Pfizer to include diagnostic use of 5T4 antibodies. The amended deal grants Pfizer nonexclusive rights for the diagnostic use of 5T4 antibodies and includes an option for commercialization of a 5T4-based diagnostic.

ImaginAb is an early-stage biotechnology company specializing in the development of engineered antibody fragments for diagnostic imaging and radioimmunotherapy. In parallel with announcing its deal with Oxford BioMedica, ImaginAb separately announced the launch of custom radiolabeling services for proteins, peptides and other macromolecules. The firm says the new service is part of the its ongoing initiative to broaden the range of product and service offerings.

“Over the past 18 months we have grown our core antibody engineering program to over a dozen companion diagnostic programs with pharmaceutical companies in addition to our own internal pipeline,” comments Jenny Keppler, president and COO of ImaginAb. “In response to very high demand for our radiochemistry and, in particular our antibody-labeling expertise, we have decided to make this capability a standard service offering as part of our recent LA facility expansion.”

ImaginAb’s core platform involves attaching binding regions from an intact antibody to small protein scaffolds to create minibodies and cys-diabodies that retain the binding affinity and specificity of the intact antibody, but exhibit pharmacokinetic properties suitable for in vivo imaging using Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT), and optical imaging.

The deal with BioMedica follows just two days after ImaginAb inked a research agreement with GE Healthcare focused on developing a new antibody fragment-based PET diagnostic imaging agent for a cardiovascular target. ImaginAb has in addition just joined the Belgium-based KeyMarker consortium, which aims to discover new diagnostic and therapeutic targets for diabetes. The firm will engineer antibody fragments against cell surface targets as sensitive and selective agents for imaging and monitoring beta cell populations.

BioMedica, meanwhile, is focused on developing a 5T4 therapeutic vaccine, TroVax®, based on an attenuated modified vaccinia virus Ankara (MVA) engineered to deliver the 5T4 antigen. The vaccine is currently undergoing Phase II studies in hormone refractory prostate cancer, and is expected to start in a Phase I/II study against mesothelioma during 2011. An earlier Phase III trial in advanced and metastatic renal cell carcinoma failed to meet its primary endpoint, but BioMedica says analysis of the study data has identified subsets of patients who may potentially benefit from the treatment.

The firm says results from nine completed Phase I/II and II trials in colorectal, renal, and prostate cancer in approximately 190 patients have shown that TroVax is safe, well tolerated, and can be administered in combination with various other treatments. Approximately 90% of patients treated with TroVax mounted an anticancer immune response to the 5T4 antigen. Across all nine trials, a doubling in the 5T4-specific antibody response between the first and third vaccinations was associated with a reduction in the relative risk of death of 16%.

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