targets

A protein on prostate cancer cells that lets doctors both see the cancer on a PET scan and hit it with a radioactive drug.

Somatostatin receptor 2 is a hormone receptor densely present on neuroendocrine tumours, and was the first theranostic target to reach routine care.

CD20 is a B-cell marker; rituximab against it was the first antibody approved for cancer, in 1997.

FAP (fibroblast activation protein) sits on the cancer-associated fibroblasts that scaffold more than 90% of epithelial cancers and is almost absent from normal adult tissue. FAPI PET tracers therefore light up tumours with high contrast, including pancreatic, gastric and low-grade cancers where FDG PET is weak, and FAP-targeted radioligands are in development.

A chemokine receptor that anchors blood cells in the marrow and helps cancer cells home to it; mutated in a third of Waldenström patients and targeted by plerixafor for stem-cell mobilisation.

A docking protein on the surface of cells that are building new blood vessels, including the blood vessels a growing tumour needs. Peptides that mimic the docking sequence (RGD) can be radiolabelled to see where this new blood-vessel growth, or the tumour cells themselves, are most active.

PARP is a DNA repair enzyme. Cancers that have already lost one repair system (BRCA) die when this second one is blocked; healthy cells survive.

A protein the placenta makes during pregnancy that many cancers switch back on while most healthy adult tissue does not. Antibody-drug conjugates against it have been tested in patients, and since 2024 the first radiolabelled versions have reached people in China.

The protein that clumps inside brain cells in Parkinson's disease and related conditions. Nobody can yet see those clumps in a living person, which is why these diseases are still diagnosed by watching the patient.

Sticky clumps of protein that build up in the brain in Alzheimer's disease. PET scans using tracers that bind these clumps can show a doctor how much amyloid is present, well before it would show up on a brain biopsy.

B7-H3 is an immune checkpoint-like surface protein found on 60 to 70% of small-cell lung cancers and 80 to 90% of castration-resistant prostate cancers, with little on normal tissue. It is used as an ADC address, chiefly by ifinatamab deruxtecan, now in phase 3 in small-cell lung cancer; whether blocking its immune-dampening role adds anything beyond payload delivery is unresolved.

The hard mineral that makes up bone. Certain radioactive drugs stick to this mineral wherever bone is being actively rebuilt, which is how bone scans find fractures, infection and cancer that has spread to bone, and how some treatments deliver radiation straight to bone metastases.

A receptor that healthy tissue barely makes but inflammation and many cancers switch on. Gallium-68 and fluorine-18 peptides built from B1R-blocking drugs give sharp PET images in mice, but no B1R tracer has been given to a patient.

A protein that clear cell kidney cancer makes almost all the time because of a gene fault. It helps the tumour survive in low-oxygen conditions, and antibodies that stick to it can be used to find or treat the cancer.

A docking site for the hormone gastrin, found at very high numbers on medullary thyroid cancer cells. Minigastrin-like radioactive drugs can bind it to find or treat that cancer, though they also light up the stomach because the same receptor lines it normally.

The classic 'CEA' tumour marker measured in blood, also present on the cell surface where ADCs can reach it.

A protein that seals the gaps between stomach lining cells. It stays on many stomach cancers as they spread, and two approved treatments are given only to patients whose biopsy shows it.

The main scaffold protein on the receiving side of brain synapses. Losing synapses tracks memory decline in Alzheimer's disease, but today's synapse PET scans only see the sending side (SV2A). No tracer for PSD-95 has been published, so the receiving side cannot yet be imaged.

A protein that appears on the surface of small-cell lung cancer cells, now hit by a drug that pulls T cells onto them.

A protein on the ends of brain cells that make dopamine, which recycles the dopamine after it has done its job. A scan using a tracer that sticks to this protein can show whether those brain cells are dying, which happens in Parkinson's disease.

Folate receptor alpha is a vitamin receptor that ovarian cancer cells carry in large numbers, used as the docking site for the ADC mirvetuximab.

The two-step system cells use to pull in and lock up glucose for energy. Many cancers rely on this system much more heavily than normal tissue, and a radioactive sugar look-alike called FDG exploits it to light up tumours on a PET scan.

Glypican-3 is a fetal liver protein that reappears in liver cancer, giving CAR-T and bispecifics a clean target.

GRPR is a hormone receptor abundant in early and hormone-sensitive prostate cancer, imaged and treated with bombesin-like radioligands.

A growth-signal receptor. Some cancers make far too much of it, and drugs that block it or use it as a docking site have transformed those cancers.

A receptor on the surface of most lung cancer cells that helps tumours resist treatment. Drugs aimed at it exist, but measuring how much of it a tumour carries has so far failed to predict who benefits.

A relative of PSA that stays attached to prostate cancer cells, used as a T-cell engager address by J&J.

A protein normally found only on the thin lining of the chest and abdomen, but made in large amounts by mesothelioma and by most pancreatic and many ovarian cancers. Because healthy organs barely make it, it is an attractive handle for antibody-based imaging and treatment.

Nectin-4 is an adhesion protein plentiful on bladder cancer cells, used as the docking site for the ADC enfortumab vedotin.

A protein in the thyroid that pulls iodine out of the blood to make thyroid hormone. It is the reason radioactive iodine can find and treat thyroid cancer almost anywhere in the body.

A protein on nerve cells and adrenal-type tumour cells that pulls noradrenaline back inside after it has been released. A radioactive drug called MIBG looks and acts enough like noradrenaline that this same protein carries it into neuroblastoma and phaeochromocytoma cells, so doctors can see or treat the tumour.

A receptor that pulls molecules into cells and is found at high levels in several cancers, including ovarian, endometrial and triple-negative breast cancer. A peptide-drug conjugate against it is in a phase 1 trial, and the first radioactive pair (one version for scans, one for treatment) was published in 2026.

STEAP1 is a protein on the surface of most prostate cancer cells, now the address for a T-cell engager in phase 3.

A protein that normally helps hold nerve cells together but, in Alzheimer's disease, twists into tangles inside the cells. A PET tracer called flortaucipir binds these tangles so doctors can see how far the disease has spread in the brain.

TROP2 is a surface glycoprotein present at high levels on most epithelial cancers (breast, lung, urothelial, gastric, pancreatic) and at low levels on normal tissue. It does not drive the cancer; it is a delivery address, used by the approved ADCs sacituzumab govitecan and datopotamab deruxtecan and by sacituzumab tirumotecan, with a TROP2 PET tracer in development to pick patients.

A protein that helps cancer cells break through surrounding tissue and spread. Higher amounts on a tumour are linked to more aggressive disease, and a PET tracer built on a small peptide can measure how much of it a tumour has.