Oncology drug-companion diagnostic combinations.

With the development of trastuzumab for metastatic breast cancer a new era began in cancer drug development. The drug-diagnostic codevelopment model with its clinical enrichment trial design has enabled development of target specific drugs for molecular defined subsets of patients. Since the simultaneous approval of trastuzumab and the HercepTest in 1998, the number of FDA-approved drug-companion diagnostic combinations within oncology and hematology have steadily increased. By June 2021, the number of drugs that have a companion diagnostic (CDx) linked to its use has reached 46. For these drugs, the CDx assays play an important role in defining the patient population likely to respond and without the assay they will often lose their value. This short article is based on an analysis of the FDA List of Cleared or Approved Companion Diagnostic Devices and relevant information in the Drugs@FDA, and will focus on the drug-CDx combinations, drug classes, clinical development, and the regulatory path and status.