Synta Pharmaceuticals Corp.'s Hsp90 inhibitor-drug conjugates may improve the therapeutic index of small molecule cancer agents by making them accumulate selectively in cancer cells. Synta thinks its products, dubbed HDCs, will reach higher concentrations in cancer cells than antibody-drug conjugates and thus can deliver effective doses of more types of cancer agents.

Synta last week disclosed it has synthesized more than 350 HDCs, including a portfolio of 18 it has made with marketed cancer agents.