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.
combined positive score (cps)medical
A combined positive score (CPS) is a single lab metric that measures how many tumor and nearby immune cells show a specific biomarker, expressed relative to the total number of tumor cells. Think of it as one gauge that blends two readings—tumor and immune cell signals—into a single percentage-like value. Investors care because CPS often determines which patients receive a drug, influences clinical-trial outcomes, regulatory labeling and market size, and therefore can affect a therapy’s commercial prospects.
non-small cell lung cancer (nsclc)medical
A common group of lung cancers that arise from the lungs’ cell lining and grow in ways different from the faster-spreading “small cell” form; think of it as several related varieties of the same illness rather than one single disease. It matters to investors because diagnosis rates, new drugs, diagnostic tests, and clinical trial results for these cancers can drive large, sustained revenue opportunities and regulatory decisions that materially affect healthcare and biotech company valuations.
triple-negative breast cancer (tnbc)medical
A form of breast cancer that lacks three common proteins (estrogen receptor, progesterone receptor and HER2) that doctors often use as targets for standard treatments, so it is not responsive to those targeted therapies. Investors pay attention because limited treatment options make drug approvals, clinical trial results or new therapies especially valuable — like finding a new key for a locked door — and those breakthroughs can drive company value and regulatory scrutiny.
epithelial ovarian, fallopian tube, or primary peritoneal carcinoma (eoc)medical
A group of cancers that start in the thin, surface cell layers lining the ovaries, the nearby fallopian tubes, or the inner lining of the abdominal cavity; doctors treat them together because they behave and respond to treatments in similar ways. For investors, these diagnoses matter because they define the pool of patients for drugs, tests and devices, shape the design and potential success of clinical trials, and influence long‑term revenue and risk for companies developing therapies or diagnostics.
fluoropyrimidine-based chemotherapymedical
A group of cancer drugs built from modified versions of a natural cell-building molecule; they work by disrupting the machinery fast-growing tumor cells use to make DNA and RNA. For investors, these drugs matter because their effectiveness, side effects and role in treatment plans influence clinical trial results, drug sales, and the need for companion tests—similar to how a common tool in a toolkit can determine whether a construction project succeeds or stalls.
Test enables identification of patients whose tumors express PD-L1 for potential treatment with KEYTRUDA® (pembrolizumab)1, 2
SANTA CLARA, Calif.--(BUSINESS WIRE)--
Agilent Technologies Inc. (NYSE: A)today announced that it has received U.S. Food and Drug Administration (FDA) approval for PD-L1 IHC 22C3 pharmDx, Code SK006, as a companion diagnostic to aid in identifying patients with esophageal or gastroesophageal junction (GEJ) carcinoma who may be eligible for treatment with KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy.
PD-L1 IHC 22C3 pharmDx, Code SK006, is the only FDA-approved companion diagnostic indicated to identify patients with esophageal or GEJ carcinoma whose tumors express PD-L1 (Combined Positive Score (CPS) ≥ 1) who may be eligible for treatment with KEYTRUDA. This approval marks the eighth FDA approved companion diagnostic indication currently available for PD-L1 IHC 22C3 pharmDx, Code SK006, for use with KEYTRUDA.
“With the expanded FDA approval of PD-L1 IHC 22C3 pharmDx in esophageal or GEJ carcinoma, Agilent is proud to support clinicians in identifying patients eligible for treatment with KEYTRUDA,” said Nina Green, vice-president and general manager of Agilent’s Clinical Diagnostics Division. “This milestone reinforces Agilent’s commitment to advancing precision medicine and underscores its leadership in delivering trusted companion diagnostics that help enable treatment with anti-PD-1 therapies.”
In addition to esophageal or GEJ carcinoma, PD-L1 IHC 22C3 pharmDx, Code SK006, is also indicated 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), gastric or GEJ adenocarcinoma, and epithelial ovarian, fallopian tube, or primary peritoneal carcinoma (EOC) who may benefit from treatment with KEYTRUDA.
KEYTRUDA is indicated for the treatment of patients with locally advanced or metastatic esophageal or gastroesophageal junction (GEJ) (tumors with epicenter 1 to 5 centimeters above the GEJ) carcinoma that is not amenable to surgical resection or definitive chemoradiation in combination with platinum- and fluoropyrimidine-based chemotherapy for patients with tumors that express PD-L1 (CPS ≥ 1).
In 2025, esophageal cancer caused approximately 16,250 deaths in the United States, with a 5-year relative survival rate of 21.9 percent.3
PD-L1 IHC 22C3 pharmDx, Code SK006, was developed by Agilent in partnership with Merck (known as MSD outside the United States and Canada) as a companion diagnostic for KEYTRUDA.
KEYTRUDA® (pembrolizumab) is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.
References:
PD-L1 IHC 22C3 pharmDx, Code SK006 [Instructions for Use]. Santa Clara, CA: Agilent Technologies, Inc.; 2026.
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.
