The approach, known as Probody T-cell engaging bispecific antibodies, enables access to targets considered inaccessible to conventional antibodies due to their presence in healthy tissue and the resulting damage to cells.
The collaboration will focus on the development of bispecific antibodies against the epidermal growth factor receptor (EGFR), the first protein receptor proposed as a target for cancer therapy and present in multiple human cancer types.
Preclinical studies used bispecific antibodies against EGFR and CD3, a co-receptor present in T-cells. The results showed that the antibodies induced tumor shrinkage in mice and increased the therapeutic window for the high-potential cancer target.
The agreement between Amgen and CytomX includes co-development of a Probody T-cell antibody against EGFR and CD3. While CytomX will lead early development, Amgen will oversee later development and commercialization. Global late-stage costs will be shared between the two companies.
“Our collaboration with CytomX leverages Amgen’s development leadership in bispecifics and expands our immuno-oncology capabilities with an additional and complementary bispecific technology,” Sean E. Harper, MD, executive vice president of research and development at Amgen, said in a press release. “EGFR is a particularly compelling target on which to employ the CytomX Probody platform given its potential to localize activity within tumors while limiting potential toxicity.”
“Probody-based T-cell engaging bispecific antibodies offer significant potential in treating cancers by employing localized therapeutic activity within tumor tissue,” said Sean McCarthy, PhD, president and CEO at CytomX Therapeutics.
McCarthy added that the collaboration will take advantage of Amgen’s expertise to activate a patient’s immune system and “CytomX’s ability to design potent new therapies that exploit unique conditions in the tumor microenvironment. Development of Probody-based T-cell engaging bispecifics further validates the broad applicability of the Probody platform in addressing unmet needs in oncology.”
Under the agreement, Amgen will pay $40 million up front and purchase $20 million of CytomX stocks. Additional payments to CytomX will depend on completion of other milestones in the EGFR program.
Amgen also has exclusive worldwide rights to develop and commercialize up to three additional, undisclosed cancer targets. Should Amgen pursue development of products for all of these targets, CytomX is entitled to receive additional upfront and milestone payments. Conversely, CytomX will hold the rights to an undisclosed preclinical T-cell bispecific program, with Amgen potentially receiving payments on any resulting products.