Precision medicine just witnessed two breakthroughs in oncology in 2017. 
Pembrolizumab (Keytruda), Merck's anti-programmed cell death-1 (PD-1) monoclonal 
antibody (mAb), received accelerated approval in May 2017 by the US Food and 
Drug Administration for the treatment of adult and pediatric patients with 
unresectable or metastatic solid tumors that have been identified as having 
microsatellite instability-high (MSI-H) or deficient DNA mismatch repair (dMMR). 
Shortly after, nivolumab (Opdivo), Bristol-Myers Squibb's anti-PD-1 mAb, gained 
an accelerated approval in August 2017 for adult and pediatric patients with 
MSI-H or dMMR metastatic colorectal cancer that has progressed after standard 
chemotherapy. These regulatory approvals marked an important milestone that a 
cancer treatment may be approved based on a common biomarker rather than the 
anatomic location in the body where the tumor originated, and therefore 
established a precedent for tumor type-agnostic therapy. In the 2017 American 
Society for Clinical Oncology annual meeting, larotrectinib (LOXO-101), 
Loxooncology's oral, potent, and selective inhibitor of tropomyosin receptor 
kinases (TRK), demonstrated unprecedented efficacy on unresectable or metastatic 
solid tumors with neurotrophic tropomyosin receptor kinase (NTRK)-fusion 
proteins in adult and pediatric patients. Both the anti-PD-1 mAbs and the 
TRK-targeting therapies share some basic features: (a) biomarker-based, 
well-defined rare patient population; (b) exceptionally high clinical efficacy, 
e.g., near 40% overall response rate (ORR) for pembrolizumab across 15 tumor 
types with MSI-H/dMMR and 75% ORR for larotrectinib across more than 12 tumor 
types with NTRK-fusion proteins; (c) durable responses lasting at least 6 months 
with complete responses observed; and (d) parallel development in adult and 
pediatric populations. With increasing accessibility to genetic analysis tools 
such as next-generation sequencing, tumor type-agnostic therapy has become a 
reality, both during clinical development and in clinical practice. Adjustments 
in our approaches to developing new anti-cancer drugs and to adopting these new 
cancer treatments in clinical practice need to occur in order to prepare 
ourselves for the new era of precision medicine.