Combined positive score (CPS)
A PD-L1 score that counts stained tumour cells and immune cells together.
(PD-L1+ tumour cells + lymphocytes + macrophages) / viable tumour cells × 100, using the 22C3 assay. CPS ≥10 defines pembrolizumab eligibility in TNBC; CPS ≥1 in head and neck, gastric, cervical. Distinct from TPS (tumour cells only, NSCLC) and SP142 IC score (atezolizumab).
Women with locally advanced cervical cancer that is node-positive or stage III-IVA should now be offered pembrolizumab alongside and after chemoradiotherapy, which improves the chance of cure. The result matters most in countries where cervical cancer is common but immunotherapy access is poorest, so its global impact depends on pricing and health-system capacity. It does not apply to early-stage disease treated with surgery or to lower-risk locally advanced disease without nodal involvement.
For stage II-III triple-negative breast cancer, chemotherapy plus pembrolizumab before surgery and pembrolizumab alone afterwards is now the standard approach worldwide, and the survival gain is real, not just a surrogate. It does not apply to stage I disease or to hormone-receptor-positive or HER2-positive cancers. The price is a year of immunotherapy with a meaningful chance of a permanent endocrine side effect such as hypothyroidism or adrenal insufficiency.
Patients with newly diagnosed advanced stomach or oesophageal adenocarcinoma whose tumour is HER2-negative and PD-L1 positive (CPS 5 or more, or at least 1 in some regions) should receive chemotherapy with nivolumab (or pembrolizumab, from KEYNOTE-859), which adds about three months of median survival and doubles the chance of being alive at three years. The benefit in PD-L1-negative tumours is doubtful, and these patients may be better served by chemotherapy alone or by trials.
Patients with head and neck squamous cell cancer that has recurred or spread should be treated first with pembrolizumab: alone if their tumour is strongly PD-L1 positive and they can wait for a slower response, or with chemotherapy if the tumour is bulky or PD-L1 low. Cetuximab-based chemotherapy is no longer the default. Long-term follow-up shows a small but real group of patients alive at four to five years, which was almost unheard of before.