Herceptin and HER2 Testing (1998)
September 1998What Happened
The FDA approved trastuzumab (Herceptin) for metastatic breast cancer alongside the HercepTest to identify patients whose tumors overexpress the HER2 protein. This was the first cancer drug approved with a required companion diagnostic, establishing the template for precision oncology that matches treatments to molecular targets rather than tumor location.
Outcome
Herceptin transformed outcomes for the approximately 20% of breast cancer patients with HER2-positive tumors, who previously faced the worst prognoses.
The drug-diagnostic co-development model became standard practice. By 2023, approximately 50% of new oncology drug approvals included companion diagnostic or biomarker requirements.
Why It's Relevant Today
The PBMF research extends this paradigm from single-gene testing to AI-discovered multi-factor biomarkers. Where HER2 testing identifies one known protein, PBMF discovers novel biomarker signatures from complex clinical and genomic data—potentially expanding precision medicine to cancers without obvious molecular targets.
