Cancer drugs that work like heat-seeking missiles to deliver chemicals directly to tumors are having a bit of a moment.

Pharmaceutical companies, in need of assets to counter flagging sales, are making these so-called antibody-drug conjugates the technology of choice in oncology dealmaking, as illustrated by the recent $10.1 billion acquisition of ImmunoGen by AbbVie.

If that trend sounds vaguely familiar, you have probably been following the pharma industry for too long. The field has gone through waves of hype and investment over the past several decades. This time, though, the hype is deserved.