CytomX advances CD71-targeting probody drug conjugate into GLP toxicology studies

Upon commencement of the GLP toxicology study, CytomX will receive a $15 million milestone payment from AbbVie as part of the 2016 strategic oncology collaboration between the companies.

“CD71 is highly attractive for delivery of cytotoxic payloads to cancer cells, but its presence on normal cells has precluded the development of antibody drug conjugates using this high-potential target. We have used our Probody platform to design and optimize CX-2029, a CD71-targeting Probody drug conjugate with the potential to safely and effectively treat a wide range of cancers,” said Sean McCarthy, D.Phil., president and chief executive officer of CytomX Therapeutics.

“Rapid progression of the CX-2029 program to this important milestone has been enabled by our close collaboration with AbbVie, and we look forward to advancing this first-in-class molecule into the clinic.”

CytomX and AbbVie are co-developing a PDC against CD71, with CytomX leading pre-clinical and early clinical development. CD71 is also known as the transferrin receptor 1 (TfR1), the biological function of which is to internalize iron-complexed transferrin into dividing cells.

CD71 is highly and homogeneously expressed on many solid and hematologic tumor types. These properties render CD71 an ideal target for antibody drug conjugate strategies except for the fact that the target is present on most normal cells. CX-2029 has been designed to target CD71 on tumor cells and spare normal cells by localizing the drug candidate’s activity primarily to cancer tissue.

AbbVie will lead later development and commercialization with global late-stage development costs shared between the two companies. CytomX received an upfront payment of $30 million and is eligible to receive up to $470 million in development, regulatory and commercial milestones, pending the achievement of pre-determined outcomes.

AbbVie will lead global commercial activities with CytomX eligible to receive a profit share in the U.S. and tiered double-digit royalties on net product sales outside of the U.S. CytomX retains an option to co-promote in the U.S.

AbbVie also receives exclusive worldwide rights to develop and commercialize Probody drug conjugates against up to two additional, undisclosed targets. Should AbbVie ultimately pursue these targets, CytomX is eligible to receive additional milestone and royalty payments per target on any resulting products.