EU Clears PD-L1 IHC 22C3 pharmDx as Companion Diagnostic for Pembrolizumab in Ovarian Cancer

Agilent Technologies has received European Union certification for PD-L1 IHC 22C3 pharmDx, Code SK006, as a companion diagnostic to identify patients with epithelial ovarian, fallopian tube, or primary peritoneal carcinoma whose tumors express PD-L1 and who may be eligible to receive pembrolizumab (Keytruda), according to a news release from Agilent.¹

The approval represents the eighth CE-marked companion diagnostic indication for the assay in the EU, joining prior authorizations in non–small cell lung cancer (NSCLC), esophageal cancer, cervical cancer, head and neck squamous cell carcinoma (HNSCC), triple-negative breast cancer (TNBC), gastric or gastroesophageal junction (GEJ) adenocarcinoma, and urothelial carcinoma.

PD-L1 expression in epithelial ovarian, fallopian tube, or primary peritoneal carcinoma was assessed with the assay in the phase 3 KEYNOTE-B96/ENGOT-ov65 trial (NCT05116189), supporting its use in identifying patients eligible for pembrolizumab in the platinum-resistant setting.^1,2

In the double-blind, placebo-controlled KEYNOTE-B96/ENGOT-ov65 trial (n = 643), pembrolizumab plus weekly paclitaxel (n = 322), with or without bevacizumab (Avastin), improved progression-free survival (PFS) vs placebo plus paclitaxel (n = 321) in patients with a PD-L1 combined positive score (CPS) of 1 or higher.² The median PFS in the respective arms was 8.3 months and 7.2 months, respectively (HR, 0.72; 95% CI, 0.58-0.89; P = .0014). At the second interim analysis, overall survival (OS) in the CPS ≥1 population was 18.2 months with pembrolizumab vs 14.0 months with placebo (HR, 0.76; 95% CI, 0.61-0.94; P = .0053).

“Expanding access to precision oncology across regions is essential to improving patient outcomes,” Majken Nielsen, vice president and general manager of Agilent’s Clinical Diagnostics Division, stated in the news release.¹ Nielsen added that the approval builds on Agilent’s commitment to deliver companion diagnostics that support informed treatment decisions for patients with epithelial ovarian, fallopian tube, or primary peritoneal carcinoma.

How does PD-L1 IHC 22C3 pharmDx identify patients with epithelial ovarian, fallopian tube, or primary peritoneal carcinoma eligible for pembrolizumab?

PD-L1 IHC 22C3 pharmDx, Code SK006, is a qualitative immunohistochemical assay using the monoclonal antibody clone 22C3 to detect PD-L1 protein in formalin-fixed, paraffin-embedded tumor tissue.³

In epithelial ovarian, fallopian tube, or primary peritoneal carcinoma, as in several of the assay’s other approved indications, PD-L1 expression is scored using CPS — the number of PD-L1–staining tumor cells, lymphocytes, and macrophages divided by the total number of viable tumor cells, multiplied by 100. Staining is performed on the Autostainer Link 48 platform using the EnVision FLEX visualization system, and slides are interpreted by a pathologist using light microscopy against the cutoff specified in the approved pembrolizumab product labeling for the relevant country.

What additional trial data support pembrolizumab-based therapy in platinum-resistant ovarian cancer?

KEYNOTE-B96/ENGOT-ov65 randomly assigned 643 patients with platinum-resistant, histologically confirmed epithelial ovarian, fallopian tube, or primary peritoneal carcinoma who had received one to two prior systemic regimens, including at least one platinum-based regimen, to pembrolizumab plus weekly paclitaxel (with optional bevacizumab) or placebo plus paclitaxel (with optional bevacizumab) across 187 sites in 25 countries.² In the intention-to-treat population, the median PFS was 8.3 months with pembrolizumab vs 6.4 months with placebo (HR, 0.70; 95% CI, 0.58-0.84; P < .0001) At the time of the final analysis, OS in the overall population was 17.7 months with pembrolizumab vs 14.0 months with placebo (HR, 0.82; 95% CI, 0.69-0.97; P = .011).

What is the regulatory history of PD-L1 IHC 22C3 pharmDx as a companion diagnostic?

PD-L1 IHC 22C3 pharmDx was originally approved by the FDA in 2015 as a companion diagnostic to identify patients with NSCLC eligible for pembrolizumab, using a tumor proportion score cutoff of 50% or higher.⁴

In February 2026, the FDA cleared the assay as a companion diagnostic for pembrolizumab in ovarian cancer.⁵ In the EU, the assay is also indicated to aid in identifying patients with NSCLC, esophageal or GEJ carcinoma, cervical cancer, HNSCC, TNBC, gastric or GEJ adenocarcinoma, and urothelial carcinoma who may be eligible for pembrolizumab, in accordance with the approved product labeling.¹

References

1. Agilent receives EU approval for PD-L1 IHC 22C3 pharmDx in epithelial ovarian, fallopian tube, or primary peritoneal carcinoma. News release. Agilent Technologies. July 23, 2026. Accessed August 5, 2026. https://www.agilent.com/about/newsroom/presrel/2026/23jul-ca26027.html
2. Colombo N, Zsiros E, Parma G, et al. Pembrolizumab plus weekly paclitaxel in platinum-resistant recurrent ovarian cancer (ENGOT-ov65/KEYNOTE-B96): a multicentre, randomised, double-blind, phase 3 study. Lancet. 2026. doi:10.1016/S0140-6736(26)00602-1
3. PD-L1 IHC 22C3 pharmDx for Autostainer Link 48. Agilent Technologies. Accessed August 5, 2026. https://www.agilent.com/en/product/pharmdx/pd-l1-ihc-22c3-pharmdx/pd-l1-ihc-22c3-pharmdx-for-autostainer-link-48-9444
4. PD-L1 IHC 22C3 pharmDx [package insert]. Carpinteria, CA: Agilent Technologies (Dako North America); 2015. Accessed August 5, 2026. https://www.accessdata.fda.gov/cdrh_docs/pdf15/p150013c.pdf
5. Doherty K. PD-L1 IHC 22C3 pharmDx nets companion diagnostic approval for pembrolizumab in ovarian cancer. OncLive. Accessed August 5, 2026. https://www.onclive.com/view/pd-l1-ihc-22c3-pharmdx-nets-companion-diagnostic-approval-for-pembrolizumab-in-ovarian-cancer