PD-L1 is a protein found on the surface of some cells that acts like a stop sign for the immune system, telling certain immune cells to back off. It matters to investors because many cancer drugs and diagnostic tests target or measure PD-L1 to unlock immune responses or predict which patients will benefit, affecting clinical success, regulatory approval, and potential sales in the oncology market.
ihcmedical
Immunohistochemistry (IHC) is a laboratory technique that uses labeled antibodies to detect and visually highlight specific proteins inside tissue samples, producing stained patterns pathologists can see under a microscope. For investors, IHC matters because it helps confirm whether a drug or diagnostic hits the intended target in real patient tissues and can support patient selection, clinical trial design and regulatory filings — essentially acting like a map that shows where a therapy is likely to work and reducing clinical and regulatory risk.
companion diagnosticmedical
A companion diagnostic is a medical test designed to identify which patients are likely to benefit from a specific drug or medical treatment, much like a key that shows whether a particular lock will open. For investors, these tests matter because they can increase a drug’s chances of approval and market uptake, create a separate revenue stream, and reduce commercial risk by matching treatments to the patients most likely to respond.
keytrudamedical
A prescription cancer immunotherapy drug (pembrolizumab) that works like a guide, helping a patient’s immune system spot and attack cancer cells by blocking a protein that hides tumors. For investors, it behaves like a company’s flagship product: approvals, trial results, patent status, label expansions, and competing treatments can strongly affect sales forecasts, earnings and the stock price of the drugmaker.
pembrolizumabmedical
A cancer immunotherapy drug that helps the body’s immune system recognize and attack tumor cells by blocking a molecular “brake” that tumors use to hide. Investors watch it because regulatory approvals, clinical trial results, dosing rules, and competition directly affect potential sales, profit forecasts, and the valuation of companies that sell or license the drug—think of trial outcomes as checkpoint signs that can open or close a revenue road.
anti-pd-1medical
Anti-PD-1 is a type of drug that blocks a protein called PD-1 on immune cells, effectively releasing the immune system’s “brakes” so it can better recognize and attack cancer cells. For investors, these drugs matter because they can produce durable responses in multiple cancers, drive large sales if approved, and influence valuations through trial results, regulatory decisions, partnerships and competition in the oncology market.
car t therapymedical
A type of cancer treatment that takes a patient’s own immune cells, reprograms them to recognize and attack tumor cells, then returns them to the body much like retraining soldiers to spot a hidden enemy. It matters to investors because these therapies can command high prices, offer long-lasting remissions for some hard-to-treat cancers, and carry manufacturing, regulatory and safety risks that can strongly affect a company’s revenue and valuation.
Approval expands first-line PD-L1 testing to support treatment decisions with KEYTRUDA® (pembrolizumab)1, 2
SANTA CLARA, Calif.--(BUSINESS WIRE)--
Agilent Technologies Inc. (NYSE: A) today announced that the U.S. Food and Drug Administration (FDA) has approved PD-L1 IHC 22C3 pharmDx, Code SK006, as the only FDA-approved companion diagnostic indicated to aid in identifying first-line patients with epithelial ovarian, fallopian tube, or primary peritoneal carcinoma (EOC), whose tumors express PD-L1 and who may be eligible for treatment with KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy.
PD-L1 IHC 22C3 pharmDx, Code SK006, enables pathologists to assess PD-L1 expression at the time of diagnosis, supporting informed treatment decisions in a disease where therapeutic options remain limited for many patients. This approval marks the seventh FDA approved companion diagnostic indication currently available for PD-L1 IHC 22C3 pharmDx, Code SK006, for use with KEYTRUDA.
Nina Green, vice president and general manager of Agilent’s Clinical Diagnostics Division, stated: “Delivering effective precision oncology requires close collaboration between diagnostics and therapeutics, and this FDA approval reflects Agilent’s long-standing industry partnership in companion diagnostics. We are proud to enable pathologists to identify patients with EOC who may benefit from immunotherapy in the first-line setting. As the first immuno-oncology approval for this disease, this milestone underscores our commitment to advancing precision medicine and expanding access to innovative cancer treatments worldwide.”
PD-L1 expression in EOC was evaluated using PD-L1 IHC 22C3 pharmDx, Code SK006, in the KEYNOTE-B96 clinical trial supporting its use in identifying patients who may benefit from KEYTRUDA in the first-line setting.
In the U.S., ovarian cancer caused approximately 12,730 deaths in 2025 and has a 5-year survival rate of 51.6% between 2015 to 20213.
In addition to EOC, PD-L1 IHC 22C3 pharmDx, Code SK006, is indicated in the U.S. to help physicians identify patients with non-small cell lung cancer (NSCLC), esophageal squamous cell carcinoma (ESCC), cervical cancer, head and neck squamous cell carcinoma (HNSCC), triple-negative breast cancer (TNBC), and gastric or gastroesophageal junction (GEJ) adenocarcinoma who may benefit from treatment with KEYTRUDA.
PD-L1 IHC 22C3 pharmDx, Code SK006, was developed by Agilent in partnership with Merck & Co. (known as MSD outside the United States and Canada) as a companion diagnostic for KEYTRUDA.
KEYTRUDA is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.
About Agilent Technologies
Agilent Technologies, Inc. (NYSE: A) is a global leader in analytical and clinical laboratory technologies, delivering insights and innovation that help our customers bring great science to life. Agilent’s full range of solutions includes instruments, software, services, and expertise that provide trusted answers to our customers' most challenging questions. The company generated revenue of $6.95 billion in fiscal year 2025 and employs approximately 18,000 people worldwide. Information about Agilent is available at www.agilent.com. To receive the latest Agilent news, subscribe to the Agilent Newsroom. Follow Agilent on LinkedIn and Facebook.
References:
PD-L1 IHC 22C3 pharmDx, Code SK006 [Instructions for Use]. Santa Clara, CA: Agilent Technologies, Inc.; 2026.
