{"entity":{"id":"klk2","kind":"target","name":"KLK2 (kallikrein-2)","aka":[],"tldr":"A relative of PSA that stays attached to prostate cancer cells, used as a T-cell engager address by J&J.","summary":"Human kallikrein-2 (KLK2) is an androgen-regulated serine protease that activates PSA; unlike PSA it is retained on the prostate cell membrane, which makes it a usable address for cell-surface therapies. Expression is nearly universal in prostate cancer and prostate-restricted elsewhere, so a KLK2-directed drug can engage T cells against the tumour with little on-target damage to other tissues. The lead agent is Johnson & Johnson's pasritamig (JNJ-78278343, a KLK2 x CD3 bispecific), which showed low cytokine release and PSA responses in phase 1 and is in phase 3 (KLK2-P3-01) in metastatic castration-resistant prostate cancer. Open questions are whether KLK2 expression persists in neuroendocrine or AR-independent disease and how it compares with PSMA as an engager target. The plain version: KLK2 is a cousin of PSA that stays stuck to cancer cells, so drugs can grab it.","asOf":"2026-09-06","wikipedia":"https://en.wikipedia.org/wiki/KLK2","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/KLK2"}],"tags":["t-cell-engager-target"],"related":[],"cancers":["prostate"],"sections":[],"technologies":[],"targets":[],"drugs":["pasritamig"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":["Prevalence not recorded: no peer-reviewed KLK2 expression series with a stated denominator was found for prostate cancer; 'nearly universal' rests on KLK2 being an androgen-regulated, prostate-restricted gene rather than on a published positivity rate."],"symbol":"KLK2","role":[],"sources":[],"specificity":"tumour-associated","distribution":"one-type","specificityNote":"Tumour-associated overexpression: 1 cell-killing or cell-finding medicine (Pasritamig) aim at the antigen, which HPA finds stained high in 1 normal tissue; the medicine relies on the tumour carrying more of it than the normal tissue it shares it with. HPA KLK2: RNA tissue enriched (prostate 531 nTPM); high antibody staining in 1 normal tissue; highest cancer staining prostate cancer (8 of 10 high). Distribution: 1 cancer family in the corpus carries a prevalence row, label threshold or catalogue link for it (Prostate cancer); Open Targets associates it with 0 specific cancer types at or above 0.5. (Rule 5 of scripts/fetch-target-specificity.ts.)","specificitySources":[{"label":"Human Protein Atlas KLK2 tissue","url":"https://www.proteinatlas.org/ENSG00000167751-KLK2/tissue","note":"RNA tissue and blood lineage specificity, normal tissue antibody staining (version 25.1, CC BY-SA 3.0)"},{"label":"Human Protein Atlas KLK2 pathology","url":"https://www.proteinatlas.org/ENSG00000167751-KLK2/pathology","note":"patients per staining level per cancer type (version 25.1, CC BY-SA 3.0)"},{"label":"Open Targets ENSG00000167751 associations","url":"https://platform.opentargets.org/target/ENSG00000167751/associations","note":"cancer associations at or above 0.5 (CC0)"}],"hgnc":"HGNC:6363","ensembl":"ENSG00000167751","uniprot":"P20151","entrez":"3817","firstDescribed":1987,"firstDescribedBasis":"sequence","firstDescribedNote":"Earliest sequence paper UniProt cites for the protein: Schedlich L.J. et al, DNA, 1987, \"Primary structure of a human glandular kallikrein gene\".","firstDescribedSource":"https://pubmed.ncbi.nlm.nih.gov/2824146/","biology":"Serine protease activating PSA; androgen-regulated.","whereFound":["Prostate cancer (nearly universal)"],"targetClass":"surface-antigen","prevalence":[]},"route":"/targets/klk2/","neighbours":{"cancer":[{"id":"prostate","kind":"cancer","name":"Prostate cancer","route":"/cancers/prostate/"}],"drug":[{"id":"pasritamig","kind":"drug","name":"Pasritamig","route":"/drugs/pasritamig/"}]}}