CytomX R&D day reveals Probody toxicity, chopped BMS deal

CytomX Therapeutics Inc. (NASDAQ:CTMX) lost $6.03 (32%) to $13.13 on Tuesday after reporting severe toxicity signals with its CD166 Probody-drug conjugate, and disclosing that partner Bristol-Myers Squibb Co. (NYSE:BMY) terminated three targets under their discovery collaboration. The stock move translates to a loss in market cap of more than $270 million.

CytomX’s Probody platform allows it to address targets expressed on tumors and healthy tissues by including a masking peptide over the antigen-binding region of the antibody that is cleaved by proteases exclusively found in the tumor microenvironment (see "ADCs' Inflection Point")...