Cancer - CytomX

CytomX's probody preparing to bind to the antigen in diseased tissue--Courtesy of CytomX

Developing the next generation of antibodies is hot in the biotech field right now. One upstart, CytomX, a 2013 Fierce 15 company, is working to create better and faster-working antibodies to treat cancer. CytomX's innovation is mixing up "probodies," highly tissue-targeted antibodies.

FierceBiotechResearch sat down with CytomX CEO Sean McCarthy back in April to talk about the San Francisco-based company's approach to cancer treatment. McCarthy explained that a Probody is an antibody that's constructed so the antigen-binding site is masked and can't see the target. These masks are engineered so they can be removed from the antibody only by enzymes associated with the disease tissue. In other words, the probodies remain inert in healthy tissue but are activated in a cancerous environment.

The company's lead program is focused on the Notch pathway activated by one of the Notch ligands, Jagged, which is known to be associated with various types of tumors. This month, CytomX revealed preclinical data showing that CTX-033, CytomX's anti-Jagged Probody, was effective in pancreatic cancer models as both a single agent and in combination with gemcitabine, a currently available FDA-approved antimetabolite drug.

"The Notch pathway is centrally implicated in tumor biology and is involved in the progression of a number of cancers, including pancreatic cancer, triple negative breast cancer and multiple myeloma," said Henry Lowman, chief scientific officer of CytomX, in a statement. "Our anti-Jagged Probody represents a novel approach to targeting the Notch signaling pathway, and our data establish preclinical proof-of-concept that selective activation of CTX-033 in the tumor microenvironment results in robust efficacy with an acceptable therapeutic index."

The new data follows preclinical research rolled out at the American Association for Cancer Research annual meeting in Washington, D.C., earlier this year. The research showed that the company's epidermal growth factor receptor Probody drug conjugate destroyed tumor tissues in mice and monkeys without harmful side effects.

The company's novel approach to cancer antibodies is catching the eye of Big Pharma. In June, Pfizer ($PFE) turned to CytomX to search for next-gen antibody-drug conjugates for cancer targets. CytomX landed $25 million in near-term payments and research support with a promise of up to $610 million more in payments from back-ended sales and regulatory milestones plus a royalty stream on any approved therapies. McCarthy says he's interested in forming more such partnerships in the future.

For more:
Special Report:
FierceBiotech's 2013 Fierce 15 - CytomX
Pfizer turns to upstart CytomX for $635M deal on armed antibody tech
CytomX's antibody therapies target cancer, leave healthy tissue intact

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