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PD-1 is a brake on T cells. Blocking it releases the immune system against the tumour and has cured some previously incurable cancers.
PD-1 blockade (pembrolizumab, nivolumab, cemiplimab, dostarlimab and a growing list of biosimilar-adjacent agents) is standard across melanoma, NSCLC, RCC, urothelial, head and neck, MSI-high tumours, TNBC (with chemotherapy), Hodgkin lymphoma, and more. PD-1×VEGF bispecifics (ivonescimab) and PD-1×CTLA-4 combinations are the next wave.
In plain words · PD-1 is a brake on T cells. Blocking it releases the immune system against the tumour and has cured some previously incurable cancers.
Backbone ribbon from PDB 7CU5. RCSB PDB 7CU5. The ribbon widens where the chain is folded into a regular pattern and narrows where it is a loose loop.
PD-1 is a brake on T cells. Blocking it releases the immune system against the tumour and has cured some previously incurable cancers.
Inhibitory receptor on activated T cells; ligands PD-L1/PD-L2. Tumour PD-L1 expression, TMB, and MSI predict response imperfectly.
32 products aim at PD-1: antibodies, bispecific antibodies, cell therapies, small molecules and other agents. Checkpoint drugs are antibodies that cover one side of an immune ‘stand down’ handshake so T cells stay active.
Immune or microenvironment target: the record's class is immune checkpoint. HPA PDCD1: RNA tissue enhanced (heart muscle 6 nTPM, lymphoid tissue 15 nTPM); blood lineage lineage enriched (T-cells 12 nTPM); high antibody staining in 1 normal tissue. Distribution: 8 cancer families in the corpus carry a prevalence row, label threshold or catalogue link for it (Skin cancer (all types), Lung cancer (all types), Renal cell carcinoma, Bladder & urothelial cancer, Head and neck squamous cell carcinoma, Breast cancer (all types), Lymphoma and more); approvals of single-target medicines aimed at it also list Oesophageal cancer, Hepatocellular carcinoma, Nasopharyngeal carcinoma, Cervical cancer and more, not counted; Open Targets associates it with 16 specific cancer types at or above 0.5 (non-small cell lung carcinoma, melanoma, renal cell carcinoma, esophageal squamous cell carcinoma, nasopharyngeal carcinoma, head and neck squamous cell carcinoma and more). Tissue-agnostic: Dostarlimab US 2021: "dMMR recurrent/advanced endometrial cancer; dMMR solid tumours"; Pembrolizumab US 2017: "MSI-H/dMMR solid tumours (tumour-agnostic)"; Pucotenlimab CN 2022: "Previously treated MSI-high or dMMR advanced solid tumours; unresectable or metastatic melanoma after prior therapy". (Rule 1 of scripts/fetch-target-specificity.ts.)
Sources: Human Protein Atlas PDCD1 tissue; UniProt Q15116; Open Targets ENSG00000188389 associations
First described 1994. Earliest sequence paper UniProt cites for the protein: Shinohara et al, Genomics, 1994, "Structure and chromosomal localization of the human PD-1 gene (PDCD1)". Source.
Cell lines and mouse models for this target →
Inhibitory receptor on activated T cells; ligands PD-L1/PD-L2. Tumour PD-L1 expression, TMB, and MSI predict response imperfectly.
RNA: tissue enhanced (heart muscle 6 nTPM, lymphoid tissue 15 nTPM), detected in some normal tissues. Blood: lineage enriched (T-cells 12 nTPM).
Medium: Lymph node.
No cancer sample stained medium or high.
HPA PDCD1 tissue · HPA PDCD1 pathology · HPA protein class: CD markers, FDA approved drug targets
Human Protein Atlas version 25.1, antibody staining at reliability approved, enhanced or supported; used under CC BY-SA 3.0. Staining counts are patients per level in the atlas cohort, not population prevalence.
| Cancer | Prevalence | Measure | Note | Source |
|---|---|---|---|---|
| Melanoma | 30-40% | Objective response to PD-1 monotherapy (proxy) | Not an expression prevalence | Wikipedia |
| Non-small-cell lung cancer | 20-45% | Response by PD-L1 stratum (proxy) | Wikipedia |
Approximate, population-level figures; the measure column says what was counted. Ranges show the midpoint as a bar.
AI-081 is an experimental bispecific antibody from OncoC4 in phase 2 trials, aimed at PD-1 and VEGF / VEGFR.
AZD7789 is an experimental bispecific antibody from AstraZeneca in phase 2 trials for non-small-cell lung cancer and gastric & gastro-oesophageal junction cancer, aimed at PD-1 and TIM-3.
Balstilimab is a monoclonal antibody from Agenus Inc., in registered phase 2 trials for colorectal cancer.
BCD-217 is an experimental investigational agent whose form is not stated in the registry from Biocad in phase 3 trials for melanoma, aimed at PD-1 and CTLA-4.
A Chinese two-armed antibody that blocks PD-1 and CTLA-4 together, approved in China for cervical cancer and extending survival even in PD-L1-negative tumours.
Camrelizumab is Jiangsu Hengrui's humanised PD-1 antibody, approved in China for oesophageal, liver and lung cancer but not in the US, where its liver cancer combination with rivoceranib drew complete response letters in 2024 and 2025 over manufacturing and inspection issues. Its signature side effect is reactive cutaneous capillary endothelial proliferation, a skin reaction seen in most patients.
A Chinese immunotherapy-plus-anti-angiogenic pill combination that clearly beat sorafenib in liver cancer, yet remains unapproved in the US after three manufacturing-related rejections.
A PD-1 blocker that is the standard for advanced skin squamous cell carcinoma, and in 2025 became the first adjuvant immunotherapy for it.
Dostarlimab is a PD-1 blocker famous for making rectal cancer disappear without surgery in every patient with a mismatch-repair-deficient tumour.
GC101 TIL is an experimental tumour-infiltrating lymphocyte therapy from Shanghai Juncell Therapeutics in phase 2 trials for melanoma, aimed at PD-1 and BRAF.
IBI363 is an experimental fusion protein from Innovent Biologics (Suzhou) in phase 2 trials for melanoma, non-small-cell lung cancer and colorectal cancer, aimed at PD-1.
A Chinese bispecific that beat Keytruda head-to-head on progression-free survival in lung cancer, the first drug ever to do so.
LB1410 is an experimental bispecific antibody from L & L Bio, Ningbo, China in phase 2 trials, aimed at PD-1 and TIM-3.
Lorigerlimab is an experimental bispecific antibody from MacroGenics in phase 2 trials for ovarian cancer, vulvar cancer and cervical cancer, aimed at PD-1 and CTLA-4.
Nivolumab was the second PD-1 blocker and is often combined with ipilimumab. Long-term data show about half of advanced melanoma patients alive at 10 years on the combination.
Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.
Penpulimab is a Chinese PD-1 antibody approved in the US in 2025 for nasopharyngeal carcinoma, the second after toripalimab.
Pucotenlimab is Lepu Biopharma's PD-1 antibody, approved in China in 2022 for mismatch-repair-deficient solid tumours and for melanoma, and in a phase 3 trial in colorectal cancer.
Opdualag combines relatlimab, the first drug targeting the LAG-3 immune brake, with nivolumab for melanoma.
Retifanlimab is a PD-1 antibody approved for Merkel cell carcinoma and, with chemotherapy, as the first immunotherapy standard for advanced anal cancer.
Rilvegostomig is an experimental bispecific antibody from AstraZeneca in phase 2 trials for non-small-cell lung cancer, aimed at PD-1 and TIGIT.
Sasanlimab is an experimental monoclonal antibody from Pfizer in phase 3 trials for bladder & urothelial cancer, aimed at PD-1 and PD-L1.
Serplulimab is a Chinese PD-1 antibody with the largest survival gain of any first-line small-cell lung cancer immunotherapy trial, approved in China, Europe, and the UK but not yet the US.
Sintilimab is Innovent's PD-1 antibody, approved in China since 2018 for Hodgkin lymphoma and then, on the ORIENT trials, for first-line lung, liver, oesophageal and stomach cancer. In 2022 the FDA rejected its lung cancer application because a China-only trial against chemotherapy did not fit US practice, defining the agency's stance on single-country data.
SSGJ-705 is an experimental monoclonal antibody from Shenyang Sunshine Pharmaceutical in phase 2 trials, aimed at PD-1 and HER2.
SSGJ-706 is an experimental bispecific antibody from Shenyang Sunshine Pharmaceutical in phase 2 trials for non-small-cell lung cancer, aimed at PD-1 and PD-L1.
T3011 is an experimental small-molecule drug from ImmVira Pharma in phase 2 trials for melanoma, head and neck squamous cell carcinoma and sarcomas, aimed at PD-1 and PD-L1.
TAK-928 is an experimental bispecific antibody from Takeda in phase 3 trials for non-small-cell lung cancer, aimed at PD-1 and CD25 (IL-2 receptor alpha).
A Chinese-developed PD-1 blocker, engineered to avoid a side-channel that may blunt other PD-1 drugs, now approved in the US and EU for oesophageal and stomach cancer.
A Chinese-developed PD-1 blocker that became the first immunotherapy approved in the US for nasopharyngeal cancer.
TQB2450 is an experimental monoclonal antibody from Chia Tai Tianqing Pharmaceutical in phase 3 trials for renal cell carcinoma and non-small-cell lung cancer, aimed at PD-L1 and PD-1.
Zimberelimab is a PD-1 antibody approved in China in 2021 for relapsed classical Hodgkin lymphoma, and the checkpoint partner in Arcus and Gilead's Western trials of the TIGIT antibody domvanalimab.
The 48 most recent of 66 papers; see them all →
For patients with advanced melanoma, immunotherapy offers a realistic chance of long-term survival and probably cure, and the ten-year data show that patients who are alive and progression-free at three years rarely die of melanoma afterwards. Nivolumab plus ipilimumab gives the best long-term results but at a high price in serious side effects; nivolumab alone or nivolumab plus relatlimab are alternatives for patients at lower risk or with autoimmune concerns. The trial is also a caution about surrogate endpoints: the survival plateau took years to become visible.
For the first time a new drug has beaten pembrolizumab, the global first-line standard, in a randomised lung cancer trial, and it did so by combining checkpoint blockade with anti-angiogenesis in one molecule. For patients outside China nothing changes yet: the drug is not approved in the West, the trial was single-country, and survival benefit has not been shown. If confirmed in the global HARMONi-3 and HARMONi-7 trials, PD-1 x VEGF bispecifics could replace PD-1 antibodies as the immunotherapy backbone.
For mismatch repair-deficient rectal cancer, six months of a single antibody now replaces chemotherapy, radiotherapy and an operation, and the same appears to be true for early-stage mismatch repair-deficient cancers of other organs.
Evidence that the immune environment of gallbladder cancer differs by population even when the mutations do not; a reason to report gallbladder cancer and its regions separately in immunotherapy trials rather than as one biliary subgroup.
Patients with limited-stage small-cell lung cancer who complete chemoradiotherapy without progression should now be offered up to two years of durvalumab consolidation, which extends life by almost two years on average. This is the first survival improvement for limited-stage disease since twice-daily radiotherapy and prophylactic cranial irradiation, and small-cell lung cancer is no longer a disease where immunotherapy gives only marginal gains.
The first credible response signal in microsatellite stable colorectal cancer, and the reason the field's attention has moved to Fc engineering and to excluding patients with active liver metastases, in whom responses are rare.
Almost every patient newly diagnosed with advanced bladder or urothelial cancer should now be offered enfortumab vedotin plus pembrolizumab rather than chemotherapy, with median survival extended from about 16 months to over two and a half years. Neuropathy and skin toxicity need monitoring and dose adjustment, and patients with severe diabetes or pre-existing neuropathy need care. Platinum chemotherapy remains an option for those who cannot receive the combination.
For the first time a randomised trial suggests that a vaccine tailored to an individual's tumour can reduce relapse when combined with immunotherapy, which is a proof of concept for a field that had failed for decades. Nothing changes for patients yet: the trial was small, the confidence interval crossed one, and the phase 3 trial in melanoma (and parallel trials in lung and other cancers) must confirm it. If it does, personalised mRNA vaccines could become a routine adjunct to checkpoint inhibitors after surgery.
Query for this target: (TITLE:"PD-1" OR ABSTRACT:"PD-1" OR TITLE:"PDCD1" OR ABSTRACT:"PDCD1") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about PD-1, not a curated reading list.
Shares BCD-217, CheckMate 9DW, Autophagy promotes immune evasion of pancreatic cancer by degrading MHC-I, Paul Baas and the tag checkpoint.
Shares VISTA, RELATIVITY-047, Hussein A. Tawbi, Fianlimab + cemiplimab phase 3 (first-line melanoma) and the tag checkpoint.
Shares An Early Phase Trial of RPTR-1-201 in Advanced Solid Tumors, Imaging Advanced NSCLC Patients Undergoing PD-1/PD-L1 Directed Therapy Using [18F]-FARAG, Personalised Neoantigen-targeting Cancer Vaccine NECVAX-NEO1 in Anti-PD-1/PD-L1 Therapy in Patients With Solid Tumors, Insight Molecular Diagnostics (formerly Oncocyte) and the tag checkpoint.
Shares Compugen, TIM-3, Rilvegostomig, NK-cell recognition: missing self & stress ligands and the tag checkpoint.
Shares Tumour microenvironment (TME), Checkpoint (two meanings), Cold tumours and the immunosuppressive microenvironment and the tag checkpoint.
Shares CheckMate 9DW, Paul Baas, CheckMate 648, KEYNOTE-006.
Shares AI-081, Lenvatinib + pembrolizumab (pMMR endometrial cancer after platinum), Brian I. Rini, Nicoletta Colombo.
Shares Aurélien Marabelle, POD1UM-201 (retifanlimab in advanced Merkel cell carcinoma), CheckMate 026: first-line nivolumab in stage IV or recurrent non-small-cell lung cancer, Nivolumab plus Ipilimumab in Lung Cancer with a High Tumor Mutational Burden.