Advancements in PD-L1 Immunohistochemistry and Digital Pathology
In October 2017, the BluePrint Phase 2 (BP2) committee presented findings at the International Association for the Study of Lung Cancer (IASLC) 18th World Conference on Lung Cancer. This presentation compared five PD-L1 immunohistochemistry (IHC) assays, each utilizing a different PD-L1 antibody clone, to validate BP1 results using real-world clinical lung cancer samples. The IHC staining for this comparison was performed in CellCarta’s CAP-accredited laboratory in Belgium, with whole slide images (WSIs) prepared and uploaded to PathoTrainer™ for pathologist training in PD-L1 scoring.
The study confirmed the reliability of PD-L1 scoring of digital images, with Mark Kockx, MD, PhD, a pathologist and founder of CellCarta HistoGeneX, participating as a trainer and in slide scoring. Since the publication of BP2, the number of PD-1/L1 monoclonal antibody clinical trials has significantly increased, as evidenced by the Cancer Research Institute's dashboard of active interventional trials.
By the end of 2023, CellCarta was performing PD-L1 IHC in Phase III trials more than any other biomarker, utilizing all commercially available clones. PathoTrainer™ continues to be used for pathologist training, both in person and remotely, serving as an ideal tool for collaboration and proficiency testing. Scoring of PD-L1 is conducted by trained pathologists using established algorithms, with a turnaround time as short as 3 business days.
CellCarta's participation in companion diagnostic (CDx) studies has also grown, with involvement in more than 40 studies totaling over 70,000 slides as of 2022. The field of digital pathology has seen many advances since BP2, with the SARS-CoV-2 pandemic accelerating the need for remote digital pathology devices to reduce healthcare personnel exposure. The College of American Pathologists (CAP) updated its WSI guidelines in 2021, reflecting these changes.
The 2023 IASCL World Conference on Lung Cancer in Singapore featured Dr. Ming-Sound Tsao, a globally recognized leader in molecular testing in lung cancer and the lead author of the BP2 study, highlighting the ongoing advancements and importance of PD-L1 IHC and digital pathology in cancer research and treatment.